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GNU C Library master sources branch siddhesh/tunables created. glibc-2.24-382-gd4c1836
- From: siddhesh at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 16 Nov 2016 08:37:58 -0000
- Subject: GNU C Library master sources branch siddhesh/tunables created. glibc-2.24-382-gd4c1836
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=d4c18364755996514a2266750ba492b34f2bc845
commit d4c18364755996514a2266750ba492b34f2bc845
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Mon Oct 24 19:59:34 2016 +0530
User manual documentation for tunables
Create a new node for tunables documentation and add notes for the
malloc tunables.
* manual/tunables.texi: New chapter.
* manual/Makefile (chapters): Add it.
* manual/probes.texi (@node): Point to the Tunables chapter.
diff --git a/manual/Makefile b/manual/Makefile
index f2f694f..ecc2bf6 100644
--- a/manual/Makefile
+++ b/manual/Makefile
@@ -38,7 +38,8 @@ chapters = $(addsuffix .texi, \
message search pattern io stdio llio filesys \
pipe socket terminal syslog math arith time \
resource setjmp signal startup process ipc job \
- nss users sysinfo conf crypt debug threads probes)
+ nss users sysinfo conf crypt debug threads \
+ probes tunables)
add-chapters = $(wildcard $(foreach d, $(add-ons), ../$d/$d.texi))
appendices = lang.texi header.texi install.texi maint.texi platform.texi \
contrib.texi
diff --git a/manual/probes.texi b/manual/probes.texi
index 237a918..eb91c62 100644
--- a/manual/probes.texi
+++ b/manual/probes.texi
@@ -1,5 +1,5 @@
@node Internal Probes
-@c @node Internal Probes, , POSIX Threads, Top
+@c @node Internal Probes, Tunables, POSIX Threads, Top
@c %MENU% Probes to monitor libc internal behavior
@chapter Internal probes
diff --git a/manual/tunables.texi b/manual/tunables.texi
new file mode 100644
index 0000000..1f1f9fc
--- /dev/null
+++ b/manual/tunables.texi
@@ -0,0 +1,185 @@
+@node Tunables
+@c @node Tunables, , Internal Probes, Top
+@c %MENU% Tunable switches to alter libc internal behavior
+@chapter Tunables
+
+Tunables is a feature in @theglibc{} that allows application authors and
+distribution maintainers to alter the runtime library behaviour to match
+their workload. These are implemented as a set of switches that may be
+modified in different ways. The current default method to do this is via
+the @env{GLIBC_TUNABLES} environment variable by setting it to a string
+of colon-separated @var{name}=@var{value} pairs. For example, the following
+environment variable export enables malloc checking and sets the malloc
+trim threshold to 128 bytes.
+
+@code{export GLIBC_TUNABLES=glibc.malloc.trim_threshold=128:glibc.malloc.check=3}
+
+Tunables are not part of the @glibcadj{} stable ABI, and they are
+subject to change or removal across releases. Additionally, the method to
+modify tunable values may change between releases and across distributions.
+It is possible to implement multiple `frontends' for the tunables allowing
+distributions to choose their preferred method at build time.
+
+Finally, the set of tunables available may vary between distributions as
+the tunables feature allows distributions to add their own tunables under
+their own namespace.
+
+@menu
+* Tunable names:: The structure of a tunable name
+* Memory Allocation Tunables:: Tunables in the memory allocation subsystem
+@end menu
+
+@node Tunable names
+@section Tunable names
+
+A tunable name is split into three components, a top namespace, a tunable
+namespace and the tunable name. The top namespace for tunables
+implemented in @theglibc{} project is @code{glibc}. Distributions that
+choose to add custom tunables in their maintained versions of @theglibc{}
+may choose to do so under their own top namespace.
+
+The tunable namespace is a logical grouping of tunables in a single
+module. This currently holds no special significance, although that may
+change in future.
+
+The tunable name is the actual name of the tunable. It is possible that
+different tunable namespaces may have tunables within them that have the
+same name, likewise for top namespaces. Hence, we only support
+identification of tunables by their full name, i.e. with the top
+namespace, tunable namespace and tunable name, separated by periods.
+
+@node Memory Allocation Tunables
+@section Memory Allocation Tunables
+
+@deftp Namespace glibc.malloc
+Memory allocation behaviour can be modified by setting any of the
+following tunables in the @code{malloc} namespace.
+@end deftp
+
+@deftp Tunable glibc.malloc.check
+This tunable supersedes the @code{MALLOC_CHECK_} environment variable and is
+identical in features.
+
+Setting this tunable enables a special (less efficient) memory allocator for
+the malloc family of functions that is designed to be tolerant against simple
+errors such as double calls of free with the same argument, or overruns of a
+single byte (off-by-one bugs). Not all such errors can be protected against,
+however, and memory leaks can result. The following list describes the values
+that this tunable can take and the effect they have on malloc functionality.
+
+@itemize @bullet
+@item @code{0} Disable all error reporting. The alternate allocator is
+selected and heap corruption detection is in place, but any such errors
+detected are ignored. This is currently a supported use, but is not
+recommended.
+@item @code{1} Report errors. The alternate allocator is selected and heap
+corruption, if detected, is reported as diagnostic messages to @code{stderr}
+and the program continues execution.
+@item @code{2} Abort on errors. The alternate allocator is selected and if
+heap corruption is detected, the program is ended immediately by calling
+@code{abort}.
+@item @code{3} Fully enabled. The alternate allocator is selected and is fully
+functional. That is, if heap corruption is detected, a verbose diagnostic
+message is printed to @code{stderr} and the program is ended by calling
+@code{abort}.
+@end itemize
+
+Like @env{MALLOC_CHECK_}, @code{glibc.malloc.check} has a problem in that it
+diverges from normal program behavior by writing to @code{stderr}, which could
+by exploited in SUID and SGID binaries. Therefore, @code{glibc.malloc.check}
+is disabled by default for SUID and SGID binaries. This can be enabled again
+by the system administrator by adding a file @file{/etc/suid-debug}; the
+content of the file could be anything or even empty.
+@end deftp
+
+@deftp Tunable glibc.malloc.top_pad
+This tunable supersedes the @code{MALLOC_TOP_PAD_} environment variable and is
+identical in features.
+
+This tunable determines the amount of extra memory to obtain from the system
+when any of the arenas need to be extended. It also specifies the number of
+bytes to retain when shrinking any of the arenas. This provides the necessary
+hysteresis in heap size such that excessive amounts of system calls can be
+avoided.
+
+The default value of this tunable is @samp{0}.
+@end deftp
+
+@deftp Tunable glibc.malloc.perturb
+This tunable supersedes the @code{MALLOC_PERTURB_} environment variable and is
+identical in features.
+
+If set to a non-zero value, memory blocks are initialized with values depending
+on some low order bits of this tunable when they are allocated (except when
+allocated by calloc) and freed. This can be used to debug the use of
+uninitialized or freed heap memory. Note that this option does not guarantee
+that the freed block will have any specific values. It only guarantees that the
+content the block had before it was freed will be overwritten.
+
+The default value of this tunable is @samp{0}.
+@end deftp
+
+@deftp Tunable glibc.malloc.mmap_threshold
+This tunable supersedes the @code{MALLOC_MMAP_THRESHOLD_} environment variable
+and is identical in features.
+
+When this tunable is set, all chunks larger than this value are allocated
+outside the normal heap, using the @code{mmap} system call. This way it is
+guaranteed that the memory for these chunks can be returned to the system on
+@code{free}. Note that requests smaller than this threshold might still be
+allocated via @code{mmap}.
+
+If this tunable is not set, the default value is set as 128 KB and the
+threshold is adjusted dynamically to suit the allocation patterns of the
+program. If the tunable is set, the dynamic adjustment is disabled and the
+value is set as static.
+@end deftp
+
+@deftp Tunable glibc.malloc.trim_threshold
+This tunable supersedes the @code{MALLOC_TRIM_THRESHOLD_} environment variable
+and is identical in features.
+
+The value of this tunable is the minimum size (in bytes) of the top-most,
+releasable chunk in an arena that will trigger a system call in order to return
+memory to the system from that arena.
+
+If this tunable is not set, the default value is set as 128 KB and the
+threshold is adjusted dynamically to suit the allocation patterns of the
+program. If the tunable is set, the dynamic adjustment is disabled and the
+value is set as static.
+@end deftp
+
+@deftp Tunable glibc.malloc.mmap_max
+This tunable supersedes the @code{MALLOC_MMAP_MAX_} environment variable and is
+identical in features.
+
+The value of this tunable is maximum number of chunks to allocate with
+@code{mmap}. Setting this to zero disables all use of @code{mmap}.
+
+The default value of this tunable is @samp{65536}.
+@end deftp
+
+@deftp Tunable glibc.malloc.arena_test
+This tunable supersedes the @code{MALLOC_ARENA_TEST} environment variable and is
+identical in features.
+
+The @code{glibc.malloc.arena_test} tunable specifies the number of arenas that
+can be created before the test on the limit to the number of arenas is
+conducted. The value is ignored if @code{glibc.malloc.arena_max} is set.
+
+The default value of this tunable is 2 for 32-bit systems and 8 for 64-bit
+systems.
+@end deftp
+
+@deftp Tunable glibc.malloc.arena_max
+This tunable supersedes the @code{MALLOC_ARENA_MAX} environment variable and is
+identical in features.
+
+This tunable sets the number of arenas to use in a process regardless of the
+number of cores in the system.
+
+The default value of this tunable is @code{0}, meaning that the limit on the
+number of arenas is determined by the number of CPU cores online. For 32-bit
+systems the limit is twice the number of cores online and on 64-bit systems, it
+is 8 times the number of cores online.
+@end deftp
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=48862d6b16b49b88badc1a4dbfbdf0bfc2af1ae1
commit 48862d6b16b49b88badc1a4dbfbdf0bfc2af1ae1
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Oct 6 17:13:43 2016 +0530
Enhance --enable-tunables to select tunables frontend at build time
At the GNU Tools Cauldron 2016, the state of the current tunables
patchset was considered OK with the addition of a way to select the
frontend to be used for the tunables. That is, to avoid being locked
in to one type of frontend initially, it should be possible to build
tunables with a different frontend with something as simple as a
configure switch.
To that effect, this patch enhances the --enable-tunables option to
accept more values than just 'yes' or 'no'. The current frontend (and
default when enable-tunables is 'yes') is called 'valstring', to
select the frontend where a single environment variable is set to a
colon-separated value string. More such frontends can be added in
future.
* Makeconfig (have-tunables): Check for non-negative instead
of positive.
* configure.ac: Add 'valstring' as a valid value for
--enable-tunables.
* configure: Regenerate.
* elf/Makefile (have-tunables): Check for non-negative instead
of positive.
(CPPFLAGS-dl-tunables.c): Define TUNABLES_FRONTEND for
dl-tunables.c.
* elf/dl-tunables.c (GLIBC_TUNABLES): Define only when
TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring.
(tunables_strdup): Likewise.
(disable_tunables): Likewise.
(parse_tunables): Likewise.
(__tunables_init): Process GLIBC_TUNABLES envvar only when.
TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring.
* elf/dl-tunables.h (TUNABLES_FRONTEND_valstring): New macro.
(TUNABLES_FRONTEND_yes): New macro, define as
TUNABLES_FRONTEND_valstring by default.
* manual/install.texi: Document new acceptable values for
--enable-tunables.
* INSTALL: Regenerate.
diff --git a/INSTALL b/INSTALL
index ccacccc..55f6a23 100644
--- a/INSTALL
+++ b/INSTALL
@@ -161,7 +161,20 @@ will be used, and CFLAGS sets optimization options for the compiler.
'--enable-tunables'
Tunables support allows additional library parameters to be
customized at runtime. This is an experimental feature and affects
- startup time and is thus disabled by default.
+ startup time and is thus disabled by default. This option can take
+ the following values:
+
+ * NO This is the default if the option is not passed to
+ configure. This disables tunables.
+
+ * YES This is the default if the option is passed to configure.
+ This enables tunables and selects the default frontend
+ (currently VALSTRING).
+
+ * VALSTRING This enables tunables and selects the VALSTRING
+ frontend for tunables. This frontend allows users to specify
+ tunables as a colon-separated list in a single environment
+ variable GLIBC_TUNABLES.
'--build=BUILD-SYSTEM'
'--host=HOST-SYSTEM'
diff --git a/Makeconfig b/Makeconfig
index d0eb832..09ddb12 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -884,7 +884,7 @@ CPPFLAGS = $(config-extra-cppflags) $(CPPUNDEFS) $(CPPFLAGS-config) \
$(libof-$(<F)) $(libof-$(@F)),$(CPPFLAGS-$(lib))) \
$(CPPFLAGS-$(<F)) $(CPPFLAGS-$(@F)) $(CPPFLAGS-$(basename $(@F)))
-ifeq (yes,$(have-tunables))
+ifneq (no,$(have-tunables))
CPPFLAGS += -DTOP_NAMESPACE=glibc
endif
@@ -1064,7 +1064,7 @@ endif
# Build the tunables list header early since it could be used by any module in
# glibc.
-ifeq (yes,$(have-tunables))
+ifneq (no,$(have-tunables))
before-compile += $(common-objpfx)dl-tunable-list.h
$(common-objpfx)dl-tunable-list.h: $(..)scripts/gen-tunables.awk \
diff --git a/configure b/configure
index cbd5fb3..35a9ecf 100755
--- a/configure
+++ b/configure
@@ -1445,7 +1445,8 @@ Optional Features:
--disable-build-nscd disable building and installing the nscd daemon
--disable-nscd library functions will not contact the nscd daemon
--enable-pt_chown Enable building and installing pt_chown
- --enable-tunables Enable tunables support
+ --enable-tunables Enable tunables support. Known values are 'yes',
+ 'no' and 'valstring'
--enable-mathvec Enable building and installing mathvec [default
depends on architecture]
diff --git a/configure.ac b/configure.ac
index 3b7a0db..5e2c8ca 100644
--- a/configure.ac
+++ b/configure.ac
@@ -397,7 +397,7 @@ fi
AC_ARG_ENABLE([tunables],
[AS_HELP_STRING([--enable-tunables],
- [Enable tunables support])],
+ [Enable tunables support. Known values are 'yes', 'no' and 'valstring'])],
[have_tunables=$enableval],
[have_tunables=no])
AC_SUBST(have_tunables)
diff --git a/elf/Makefile b/elf/Makefile
index 477f8fc..34fc657 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -36,8 +36,10 @@ ifeq (yes,$(use-ldconfig))
dl-routines += dl-cache
endif
-ifeq (yes,$(have-tunables))
+ifneq (no,$(have-tunables))
dl-routines += dl-tunables
+tunables-type = $(addprefix TUNABLES_FRONTEND_,$(have-tunables))
+CPPFLAGS-dl-tunables.c = -DTUNABLES_FRONTEND=$(tunables-type)
endif
all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index 79ec8ef..128da29 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -30,7 +30,9 @@
#define TUNABLES_INTERNAL 1
#include "dl-tunables.h"
-#define GLIBC_TUNABLES "GLIBC_TUNABLES"
+#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
+# define GLIBC_TUNABLES "GLIBC_TUNABLES"
+#endif
/* Compare environment or tunable names, bounded by the name hardcoded in
glibc. */
@@ -48,6 +50,7 @@ is_name (const char *orig, const char *envname)
return false;
}
+#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
static char *
tunables_strdup (const char *in)
{
@@ -69,6 +72,7 @@ tunables_strdup (const char *in)
return out;
}
+#endif
static char **
get_next_env (char **envp, char **name, size_t *namelen, char **val)
@@ -234,6 +238,7 @@ tunable_initialize (tunable_t *cur, const char *strval)
}
}
+#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
static void
parse_tunables (char *tunestr)
{
@@ -299,6 +304,7 @@ parse_tunables (char *tunestr)
return;
}
}
+#endif
static size_t
min_strlen (const char *s)
@@ -319,6 +325,7 @@ disable_tunable (tunable_id_t id, char **envp)
if (env_alias)
tunables_unsetenv (envp, tunable_list[id].env_alias);
+#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
char *tunable = getenv (GLIBC_TUNABLES);
const char *cmp = tunable_list[id].name;
const size_t len = min_strlen (cmp);
@@ -335,6 +342,7 @@ disable_tunable (tunable_id_t id, char **envp)
}
tunable++;
}
+#endif
}
/* Disable the glibc.malloc.check tunable in SETUID/SETGID programs unless
@@ -365,6 +373,7 @@ __tunables_init (char **envp)
while ((envp = get_next_env (envp, &envname, &len, &envval)) != NULL)
{
+#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
if (is_name (GLIBC_TUNABLES, envname))
{
char *val = tunables_strdup (envval);
@@ -372,6 +381,7 @@ __tunables_init (char **envp)
parse_tunables (val);
continue;
}
+#endif
for (int i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++)
{
diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
index 10a644b..27b1b64 100644
--- a/elf/dl-tunables.h
+++ b/elf/dl-tunables.h
@@ -75,4 +75,8 @@ extern void __tunable_set_val (tunable_id_t, void *, tunable_callback_t);
/* Namespace sanity for callback functions. Use this macro to keep the
namespace of the modules clean. */
#define DL_TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name
+
+# define TUNABLES_FRONTEND_valstring 1
+/* The default value for TUNABLES_FRONTEND. */
+# define TUNABLES_FRONTEND_yes TUNABLES_FRONTEND_valstring
#endif
diff --git a/manual/install.texi b/manual/install.texi
index ffc166d..e34c7bf 100644
--- a/manual/install.texi
+++ b/manual/install.texi
@@ -192,7 +192,23 @@ Use this option to disable the vector math library.
@item --enable-tunables
Tunables support allows additional library parameters to be customized at
runtime. This is an experimental feature and affects startup time and is thus
-disabled by default.
+disabled by default. This option can take the following values:
+
+@itemize @bullet
+@item @var{no}
+This is the default if the option is not passed to configure. This disables
+tunables.
+
+@item @var{yes}
+This is the default if the option is passed to configure. This enables tunables
+and selects the default frontend (currently @var{valstring}).
+
+@item @var{valstring}
+This enables tunables and selects the @var{valstring} frontend for tunables.
+This frontend allows users to specify tunables as a colon-separated list in a
+single environment variable @var{GLIBC_TUNABLES}.
+
+@end itemize
@item --build=@var{build-system}
@itemx --host=@var{host-system}
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=ebe21d580a12e873203dada883e21ca87c28979c
commit ebe21d580a12e873203dada883e21ca87c28979c
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Mon Aug 15 21:49:13 2016 +0530
Initialize tunable list with the GLIBC_TUNABLES environment variable
Read tunables values from the users using the GLIBC_TUNABLES
environment variable. The value of this variable is a colon-separated
list of name=value pairs. So a typical string would look like this:
GLIBC_TUNABLES=glibc.malloc.mmap_threshold=2048:glibc.malloc.trim_threshold=1024
* elf/dl-tunables.c: Include mman.h and libc-internals.h.
(GLIBC_TUNABLES): New macro.
(tunables_strdup): New function.
(parse_tunables): New function.
(__tunables_init): Use the new functions and macro.
(disable_tunable): Disable tunable from GLIBC_TUNABLES.
* malloc/tst-malloc-usable-tunables.c: New test case.
* malloc/tst-malloc-usable-static-tunables.c: New test case.
* malloc/Makefile (tests, tests-static): Add tests.
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index 91340b6..79ec8ef 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -22,6 +22,7 @@
#include <stdbool.h>
#include <unistd.h>
#include <stdlib.h>
+#include <sys/mman.h>
#include <libc-internal.h>
#include <sysdep.h>
#include <fcntl.h>
@@ -29,7 +30,10 @@
#define TUNABLES_INTERNAL 1
#include "dl-tunables.h"
-/* Compare environment names, bounded by the name hardcoded in glibc. */
+#define GLIBC_TUNABLES "GLIBC_TUNABLES"
+
+/* Compare environment or tunable names, bounded by the name hardcoded in
+ glibc. */
static bool
is_name (const char *orig, const char *envname)
{
@@ -44,6 +48,28 @@ is_name (const char *orig, const char *envname)
return false;
}
+static char *
+tunables_strdup (const char *in)
+{
+ size_t i = 0;
+
+ while (in[i++]);
+
+ char *out = __mmap (NULL, ALIGN_UP (i, __getpagesize ()),
+ PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1,
+ 0);
+
+ if (out == MAP_FAILED)
+ return NULL;
+
+ i--;
+
+ while (i-- > 0)
+ out[i] = in[i];
+
+ return out;
+}
+
static char **
get_next_env (char **envp, char **name, size_t *namelen, char **val)
{
@@ -208,6 +234,82 @@ tunable_initialize (tunable_t *cur, const char *strval)
}
}
+static void
+parse_tunables (char *tunestr)
+{
+ if (tunestr == NULL || *tunestr == '\0')
+ return;
+
+ char *p = tunestr;
+
+ while (true)
+ {
+ char *name = p;
+ size_t len = 0;
+
+ /* First, find where the name ends. */
+ while (p[len] != '=' && p[len] != ':' && p[len] != '\0')
+ len++;
+
+ /* If we reach the end of the string before getting a valid name-value
+ pair, bail out. */
+ if (p[len] == '\0')
+ return;
+
+ /* We did not find a valid name-value pair before encountering the
+ colon. */
+ if (p[len]== ':')
+ {
+ p += len + 1;
+ continue;
+ }
+
+ p += len + 1;
+
+ char *value = p;
+ len = 0;
+
+ while (p[len] != ':' && p[len] != '\0')
+ len++;
+
+ char end = p[len];
+ p[len] = '\0';
+
+ /* Add the tunable if it exists. */
+ for (size_t i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++)
+ {
+ tunable_t *cur = &tunable_list[i];
+
+ /* If we are in a secure context (AT_SECURE) then ignore the tunable
+ unless it is explicitly marked as secure. Tunable values take
+ precendence over their envvar aliases. */
+ if (__libc_enable_secure && !cur->is_secure)
+ continue;
+
+ if (is_name (cur->name, name))
+ {
+ tunable_initialize (cur, value);
+ break;
+ }
+ }
+
+ if (end == ':')
+ p += len + 1;
+ else
+ return;
+ }
+}
+
+static size_t
+min_strlen (const char *s)
+{
+ size_t i = 0;
+ while (*s++ != '\0')
+ i++;
+
+ return i;
+}
+
/* Disable a tunable if it is set. */
static void
disable_tunable (tunable_id_t id, char **envp)
@@ -216,6 +318,23 @@ disable_tunable (tunable_id_t id, char **envp)
if (env_alias)
tunables_unsetenv (envp, tunable_list[id].env_alias);
+
+ char *tunable = getenv (GLIBC_TUNABLES);
+ const char *cmp = tunable_list[id].name;
+ const size_t len = min_strlen (cmp);
+
+ while (tunable && *tunable != '\0' && *tunable != ':')
+ {
+ if (is_name (tunable, cmp))
+ {
+ tunable += len;
+ /* Overwrite the = and the value with colons. */
+ while (*tunable != '\0' && *tunable != ':')
+ *tunable++ = ':';
+ break;
+ }
+ tunable++;
+ }
}
/* Disable the glibc.malloc.check tunable in SETUID/SETGID programs unless
@@ -246,6 +365,14 @@ __tunables_init (char **envp)
while ((envp = get_next_env (envp, &envname, &len, &envval)) != NULL)
{
+ if (is_name (GLIBC_TUNABLES, envname))
+ {
+ char *val = tunables_strdup (envval);
+ if (val != NULL)
+ parse_tunables (val);
+ continue;
+ }
+
for (int i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++)
{
tunable_t *cur = &tunable_list[i];
diff --git a/malloc/Makefile b/malloc/Makefile
index 4e4104e..a34e20c 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -33,11 +33,13 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
tst-mallocfork2 \
tst-interpose-nothread \
tst-interpose-thread \
+ tst-malloc-usable-tunables
tests-static := \
tst-interpose-static-nothread \
tst-interpose-static-thread \
- tst-malloc-usable-static
+ tst-malloc-usable-static \
+ tst-malloc-usable-static-tunables
tests += $(tests-static)
test-srcs = tst-mtrace
@@ -160,6 +162,8 @@ endif
tst-mcheck-ENV = MALLOC_CHECK_=3
tst-malloc-usable-ENV = MALLOC_CHECK_=3
tst-malloc-usable-static-ENV = $(tst-malloc-usable-ENV)
+tst-malloc-usable-tunables-ENV = GLIBC_TUNABLES=glibc.malloc.check=3
+tst-malloc-usable-static-tunables-ENV = $(tst-malloc-usable-tunables-ENV)
# Uncomment this for test releases. For public releases it is too expensive.
#CPPFLAGS-malloc.o += -DMALLOC_DEBUG=1
diff --git a/malloc/tst-malloc-usable-static-tunables.c b/malloc/tst-malloc-usable-static-tunables.c
new file mode 100644
index 0000000..8907db0
--- /dev/null
+++ b/malloc/tst-malloc-usable-static-tunables.c
@@ -0,0 +1 @@
+#include <malloc/tst-malloc-usable.c>
diff --git a/malloc/tst-malloc-usable-tunables.c b/malloc/tst-malloc-usable-tunables.c
new file mode 100644
index 0000000..8907db0
--- /dev/null
+++ b/malloc/tst-malloc-usable-tunables.c
@@ -0,0 +1 @@
+#include <malloc/tst-malloc-usable.c>
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=388332b4e2120c9c1ee6d5465fb9eaaa12702173
commit 388332b4e2120c9c1ee6d5465fb9eaaa12702173
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Fri Jul 1 23:42:34 2016 +0530
Add framework for tunables
The tunables framework allows us to uniformly manage and expose global
variables inside glibc as switches to users. tunables/README has
instructions for glibc developers to add new tunables.
Tunables support can be enabled by passing the --enable-tunables
configure flag to the configure script. This patch only adds a
framework and does not pose any limitations on how tunable values are
read from the user. It also adds environment variables used in malloc
behaviour tweaking to the tunables framework as a PoC of the
compatibility interface.
* manual/install.texi: Add --enable-tunables option.
* INSTALL: Regenerate.
* README.tunables: New file.
* Makeconfig (CPPFLAGS): Define TOP_NAMESPACE.
(before-compile): Generate dl-tunable-list.h early.
* config.h.in: Add HAVE_TUNABLES.
* config.make.in: Add have-tunables.
* configure.ac: Add --enable-tunables option.
* configure: Regenerate.
* csu/init-first.c (__libc_init_first): Move
__libc_init_secure earlier...
* csu/init-first.c (LIBC_START_MAIN):... to here.
[HAVE_TUNABLES]: Include dl-tunables.h.
(LIBC_START_MAIN) [!SHARED]: Initialize tunables for static
binaries.
* elf/Makefile (dl-routines): Add dl-tunables.
* elf/Versions (ld): Add __tunable_set_val to GLIBC_PRIVATE
namespace.
* elf/dl-support (_dl_nondynamic_init): Unset MALLOC_CHECK_
only when !HAVE_TUNABLES.
* elf/rtld.c (process_envvars): Likewise.
* elf/dl-sysdep.c [HAVE_TUNABLES]: Include dl-tunables.h
(_dl_sysdep_start): Call __tunables_init.
* elf/dl-tunable-types.h: New file.
* elf/dl-tunables.c: New file.
* elf/dl-tunables.h: New file.
* elf/dl-tunables.list: New file.
* malloc/tst-malloc-usable-static.c: New test case.
* malloc/Makefile (tests-static): Add it.
* malloc/arena.c [HAVE_TUNABLES]: Include dl-tunables.h.
Define TUNABLE_NAMESPACE.
(DL_TUNABLE_CALLBACK (set_mallopt_check)): New function.
(DL_TUNABLE_CALLBACK_FNDECL): New macro. Use it to define
callback functions.
(ptmalloc_init): Set tunable values.
* scripts/gen-tunables.awk: New file.
* sysdeps/mach/hurd/dl-sysdep.c [HAVE_TUNABLES]: Include
dl-tunables.h.
(_dl_sysdep_start): Call __tunables_init.
diff --git a/INSTALL b/INSTALL
index b5acedc..ccacccc 100644
--- a/INSTALL
+++ b/INSTALL
@@ -158,6 +158,11 @@ will be used, and CFLAGS sets optimization options for the compiler.
By default for x86_64, the GNU C Library is built with the vector
math library. Use this option to disable the vector math library.
+'--enable-tunables'
+ Tunables support allows additional library parameters to be
+ customized at runtime. This is an experimental feature and affects
+ startup time and is thus disabled by default.
+
'--build=BUILD-SYSTEM'
'--host=HOST-SYSTEM'
These options are for cross-compiling. If you specify both options
diff --git a/Makeconfig b/Makeconfig
index a785860..d0eb832 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -883,6 +883,11 @@ CPPFLAGS = $(config-extra-cppflags) $(CPPUNDEFS) $(CPPFLAGS-config) \
$(foreach lib,$(libof-$(basename $(@F))) \
$(libof-$(<F)) $(libof-$(@F)),$(CPPFLAGS-$(lib))) \
$(CPPFLAGS-$(<F)) $(CPPFLAGS-$(@F)) $(CPPFLAGS-$(basename $(@F)))
+
+ifeq (yes,$(have-tunables))
+CPPFLAGS += -DTOP_NAMESPACE=glibc
+endif
+
override CFLAGS = -std=gnu11 -fgnu89-inline $(config-extra-cflags) \
$(filter-out %frame-pointer,$(+cflags)) $(+gccwarn-c) \
$(sysdep-CFLAGS) $(CFLAGS-$(suffix $@)) $(CFLAGS-$(<F)) \
@@ -1057,6 +1062,17 @@ $(common-objpfx)libc-modules.stmp: $(..)scripts/gen-libc-modules.awk \
endif
+# Build the tunables list header early since it could be used by any module in
+# glibc.
+ifeq (yes,$(have-tunables))
+before-compile += $(common-objpfx)dl-tunable-list.h
+
+$(common-objpfx)dl-tunable-list.h: $(..)scripts/gen-tunables.awk \
+ $(..)elf/dl-tunables.list
+ $(AWK) -f $^ > $@.tmp
+ mv $@.tmp $@
+endif
+
common-generated += libc-modules.h libc-modules.stmp
# The name under which the run-time dynamic linker is installed.
diff --git a/README.tunables b/README.tunables
new file mode 100644
index 0000000..3d9c86a
--- /dev/null
+++ b/README.tunables
@@ -0,0 +1,84 @@
+ TUNABLE FRAMEWORK
+ =================
+
+Tunables is a feature in the GNU C Library that allows application authors and
+distribution maintainers to alter the runtime library behaviour to match their
+workload.
+
+The tunable framework allows modules within glibc to register variables that
+may be tweaked through an environment variable or an API call. It aims to
+enforce a strict namespace rule to bring consistency to naming of these tunable
+environment variables across the project. This document is a guide for glibc
+developers to add tunables to the framework.
+
+ADDING A NEW TUNABLE
+--------------------
+
+The TOP_NAMESPACE is defined by default as 'glibc' and it may be overridden in
+distributions for specific tunables if they want to add their own tunables.
+Downstream implementations are discouraged from using the 'glibc' namespace for
+tunables they don't already have consensus to push upstream.
+
+There are two steps to adding a tunable:
+
+1. Add a tunable ID:
+
+Modules that wish to use the tunables interface must define the
+TUNABLE_NAMESPACE macro. Following this, for each tunable you want to
+add, make an entry in elf/dl-tunables.list. The format of the file is as
+follows:
+
+TOP_NAMESPACE {
+ NAMESPACE1 {
+ TUNABLE1 {
+ # tunable attributes, one per line
+ }
+ # A tunable with default attributes, i.e. string variable.
+ TUNABLE2
+ TUNABLE3 {
+ # its attributes
+ }
+ }
+ NAMESPACE2 {
+ ...
+ }
+}
+
+The list of allowed attributes are:
+
+- type: Data type. Defaults to STRING. Allowed types are:
+ INT_32, SIZE_T and STRING.
+
+- minval: Optional minimum acceptable value. For a string type
+ this is the minimum length of the value.
+
+- maxval: Optional maximum acceptable value. For a string type
+ this is the maximum length of the value.
+
+- env_alias: An alias environment variable
+
+- is_secure: Specify whether the tunable should be read for setuid
+ binaries. True allows the tunable to be read for
+ setuid binaries while false disables it. Note that
+ even if this is set as true and the value is read, it
+ may not be used if it does not validate against the
+ acceptable values or is not considered safe by the
+ module.
+
+2. Call either the TUNABLE_SET_VALUE and pass into it the tunable name and a
+ pointer to the variable that should be set with the tunable value.
+ If additional work needs to be done after setting the value, use the
+ TUNABLE_SET_VALUE_WITH_CALLBACK instead and additionally pass a pointer to
+ the function that should be called if the tunable value has been set.
+
+FUTURE WORK
+-----------
+
+The framework currently only allows a one-time initialization of variables
+through environment variables and in some cases, modification of variables via
+an API call. A future goals for this project include:
+
+- Setting system-wide and user-wide defaults for tunables through some
+ mechanism like a configuration file.
+
+- Allow tweaking of some tunables at runtime
diff --git a/config.h.in b/config.h.in
index 33757bd..fd93bb3 100644
--- a/config.h.in
+++ b/config.h.in
@@ -246,4 +246,7 @@
/* PowerPC32 uses fctidz for floating point to long long conversions. */
#define HAVE_PPC_FCTIDZ 0
+/* Build glibc with tunables support. */
+#define HAVE_TUNABLES 0
+
#endif
diff --git a/config.make.in b/config.make.in
index 04a8b3e..6d0b607 100644
--- a/config.make.in
+++ b/config.make.in
@@ -93,6 +93,7 @@ use-nscd = @use_nscd@
build-hardcoded-path-in-tests= @hardcoded_path_in_tests@
build-pt-chown = @build_pt_chown@
enable-lock-elision = @enable_lock_elision@
+have-tunables = @have_tunables@
# Build tools.
CC = @CC@
diff --git a/configure b/configure
index d9f8c06..cbd5fb3 100755
--- a/configure
+++ b/configure
@@ -662,6 +662,7 @@ multi_arch
base_machine
add_on_subdirs
add_ons
+have_tunables
build_pt_chown
build_nscd
link_obsolete_rpc
@@ -776,6 +777,7 @@ enable_systemtap
enable_build_nscd
enable_nscd
enable_pt_chown
+enable_tunables
enable_mathvec
with_cpu
'
@@ -1443,6 +1445,7 @@ Optional Features:
--disable-build-nscd disable building and installing the nscd daemon
--disable-nscd library functions will not contact the nscd daemon
--enable-pt_chown Enable building and installing pt_chown
+ --enable-tunables Enable tunables support
--enable-mathvec Enable building and installing mathvec [default
depends on architecture]
@@ -3649,6 +3652,19 @@ if test "$build_pt_chown" = yes; then
fi
+# Check whether --enable-tunables was given.
+if test "${enable_tunables+set}" = set; then :
+ enableval=$enable_tunables; have_tunables=$enableval
+else
+ have_tunables=no
+fi
+
+
+if test "$have_tunables" = yes; then
+ $as_echo "#define HAVE_TUNABLES 1" >>confdefs.h
+
+fi
+
# The abi-tags file uses a fairly simplistic model for name recognition that
# can't distinguish i486-pc-linux-gnu fully from i486-pc-gnu. So we mutate a
# $host_os of `gnu*' here to be `gnu-gnu*' just so that it can tell.
diff --git a/configure.ac b/configure.ac
index de0a40f..3b7a0db 100644
--- a/configure.ac
+++ b/configure.ac
@@ -395,6 +395,16 @@ if test "$build_pt_chown" = yes; then
AC_DEFINE(HAVE_PT_CHOWN)
fi
+AC_ARG_ENABLE([tunables],
+ [AS_HELP_STRING([--enable-tunables],
+ [Enable tunables support])],
+ [have_tunables=$enableval],
+ [have_tunables=no])
+AC_SUBST(have_tunables)
+if test "$have_tunables" = yes; then
+ AC_DEFINE(HAVE_TUNABLES)
+fi
+
# The abi-tags file uses a fairly simplistic model for name recognition that
# can't distinguish i486-pc-linux-gnu fully from i486-pc-gnu. So we mutate a
# $host_os of `gnu*' here to be `gnu-gnu*' just so that it can tell.
diff --git a/csu/init-first.c b/csu/init-first.c
index 77c6e1c..465f25b 100644
--- a/csu/init-first.c
+++ b/csu/init-first.c
@@ -72,8 +72,6 @@ _init (int argc, char **argv, char **envp)
__environ = envp;
#ifndef SHARED
- __libc_init_secure ();
-
/* First the initialization which normally would be done by the
dynamic linker. */
_dl_non_dynamic_init ();
diff --git a/csu/libc-start.c b/csu/libc-start.c
index 99c040a..4e5cafa 100644
--- a/csu/libc-start.c
+++ b/csu/libc-start.c
@@ -21,6 +21,11 @@
#include <unistd.h>
#include <ldsodefs.h>
#include <exit-thread.h>
+#include <libc-internal.h>
+
+#if HAVE_TUNABLES
+# include <elf/dl-tunables.h>
+#endif
extern void __libc_init_first (int argc, char **argv, char **envp);
@@ -184,6 +189,13 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
}
# endif
+ /* Initialize very early so that tunables can use it. */
+ __libc_init_secure ();
+
+#if HAVE_TUNABLES
+ __tunables_init (__environ);
+#endif
+
/* Perform IREL{,A} relocations. */
apply_irel ();
diff --git a/elf/Makefile b/elf/Makefile
index 82c7e05..477f8fc 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -35,6 +35,11 @@ dl-routines = $(addprefix dl-,load lookup object reloc deps hwcaps \
ifeq (yes,$(use-ldconfig))
dl-routines += dl-cache
endif
+
+ifeq (yes,$(have-tunables))
+dl-routines += dl-tunables
+endif
+
all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
# But they are absent from the shared libc, because that code is in ld.so.
elide-routines.os = $(all-dl-routines) dl-support enbl-secure dl-origin \
diff --git a/elf/Versions b/elf/Versions
index 23deda9..1734697 100644
--- a/elf/Versions
+++ b/elf/Versions
@@ -64,5 +64,8 @@ ld {
# Pointer protection.
__pointer_chk_guard;
+
+ # Set value of a tunable.
+ __tunable_set_val;
}
}
diff --git a/elf/dl-support.c b/elf/dl-support.c
index c30194c..d350d6d 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -354,8 +354,10 @@ _dl_non_dynamic_init (void)
cp = (const char *) __rawmemchr (cp, '\0') + 1;
}
+#if !HAVE_TUNABLES
if (__access ("/etc/suid-debug", F_OK) != 0)
__unsetenv ("MALLOC_CHECK_");
+#endif
}
#ifdef DL_PLATFORM_INIT
diff --git a/elf/dl-sysdep.c b/elf/dl-sysdep.c
index eaa7155..68f30f2 100644
--- a/elf/dl-sysdep.c
+++ b/elf/dl-sysdep.c
@@ -44,6 +44,10 @@
#include <hp-timing.h>
#include <tls.h>
+#if HAVE_TUNABLES
+# include <dl-tunables.h>
+#endif
+
extern char **_environ attribute_hidden;
extern char _end[] attribute_hidden;
@@ -219,6 +223,10 @@ _dl_sysdep_start (void **start_argptr,
}
#endif
+#if HAVE_TUNABLES
+ __tunables_init (_environ);
+#endif
+
#ifdef DL_SYSDEP_INIT
DL_SYSDEP_INIT;
#endif
diff --git a/elf/dl-tunable-types.h b/elf/dl-tunable-types.h
new file mode 100644
index 0000000..d1591b6
--- /dev/null
+++ b/elf/dl-tunable-types.h
@@ -0,0 +1,46 @@
+/* Tunable type information.
+
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _TUNABLE_TYPES_H_
+# define _TUNABLE_TYPES_H_
+#include <stddef.h>
+
+typedef void (*tunable_callback_t) (void *);
+
+typedef enum
+{
+ TUNABLE_TYPE_INT_32,
+ TUNABLE_TYPE_SIZE_T,
+ TUNABLE_TYPE_STRING
+} tunable_type_code_t;
+
+typedef struct
+{
+ tunable_type_code_t type_code;
+ int64_t min;
+ int64_t max;
+} tunable_type_t;
+
+typedef union
+{
+ int64_t numval;
+ const char *strval;
+} tunable_val_t;
+
+#endif
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
new file mode 100644
index 0000000..91340b6
--- /dev/null
+++ b/elf/dl-tunables.c
@@ -0,0 +1,310 @@
+/* The tunable framework. See the README to know how to use the tunable in
+ a glibc module.
+
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <libc-internal.h>
+#include <sysdep.h>
+#include <fcntl.h>
+
+#define TUNABLES_INTERNAL 1
+#include "dl-tunables.h"
+
+/* Compare environment names, bounded by the name hardcoded in glibc. */
+static bool
+is_name (const char *orig, const char *envname)
+{
+ for (;*orig != '\0' && *envname != '\0'; envname++, orig++)
+ if (*orig != *envname)
+ break;
+
+ /* The ENVNAME is immediately followed by a value. */
+ if (*orig == '\0' && *envname == '=')
+ return true;
+ else
+ return false;
+}
+
+static char **
+get_next_env (char **envp, char **name, size_t *namelen, char **val)
+{
+ while (envp != NULL && *envp != NULL)
+ {
+ char *envline = *envp;
+ int len = 0;
+
+ while (envline[len] != '\0' && envline[len] != '=')
+ len++;
+
+ /* Just the name and no value, go to the next one. */
+ if (envline[len] == '\0')
+ continue;
+
+ *name = envline;
+ *namelen = len;
+ *val = &envline[len + 1];
+
+ return ++envp;
+ }
+
+ return NULL;
+}
+
+static int
+tunables_unsetenv (char **ep, const char *name)
+{
+ while (*ep != NULL)
+ {
+ size_t cnt = 0;
+
+ while ((*ep)[cnt] == name[cnt] && name[cnt] != '\0')
+ ++cnt;
+
+ if (name[cnt] == '\0' && (*ep)[cnt] == '=')
+ {
+ /* Found it. Remove this pointer by moving later ones to
+ the front. */
+ char **dp = ep;
+
+ do
+ dp[0] = dp[1];
+ while (*dp++);
+ /* Continue the loop in case NAME appears again. */
+ }
+ else
+ ++ep;
+ }
+
+ return 0;
+}
+
+/* A stripped down strtoul-like implementation for very early use. It does not
+ set errno if the result is outside bounds because it gets called before
+ errno may have been set up. */
+static unsigned long int
+tunables_strtoul (const char *nptr)
+{
+ unsigned long int result = 0;
+ long int sign = 1;
+ unsigned max_digit;
+
+ while (*nptr == ' ' || *nptr == '\t')
+ ++nptr;
+
+ if (*nptr == '-')
+ {
+ sign = -1;
+ ++nptr;
+ }
+ else if (*nptr == '+')
+ ++nptr;
+
+ if (*nptr < '0' || *nptr > '9')
+ return 0UL;
+
+ int base = 10;
+ max_digit = 9;
+ if (*nptr == '0')
+ {
+ if (nptr[1] == 'x' || nptr[1] == 'X')
+ {
+ base = 16;
+ nptr += 2;
+ }
+ else
+ {
+ base = 8;
+ max_digit = 7;
+ }
+ }
+
+ while (1)
+ {
+ unsigned long int digval;
+ if (*nptr >= '0' && *nptr <= '0' + max_digit)
+ digval = *nptr - '0';
+ else if (base == 16)
+ {
+ if (*nptr >= 'a' && *nptr <= 'f')
+ digval = *nptr - 'a' + 10;
+ else if (*nptr >= 'A' && *nptr <= 'F')
+ digval = *nptr - 'A' + 10;
+ else
+ break;
+ }
+ else
+ break;
+
+ if (result > ULONG_MAX / base
+ || (result == ULONG_MAX / base && digval > ULONG_MAX % base))
+ return ULONG_MAX;
+ result *= base;
+ result += digval;
+ ++nptr;
+ }
+
+ return result * sign;
+}
+
+/* If the value does not validate, don't bother initializing the internal type
+ and also take care to clear the recorded string value in STRVAL. */
+#define RETURN_IF_INVALID_RANGE(__cur, __val) \
+({ \
+ __typeof ((__cur)->type.min) min = (__cur)->type.min; \
+ __typeof ((__cur)->type.max) max = (__cur)->type.max; \
+ if (min != max && ((__val) < min || (__val) > max)) \
+ return; \
+})
+
+/* Validate range of the input value and initialize the tunable CUR if it looks
+ good. */
+static void
+tunable_initialize (tunable_t *cur, const char *strval)
+{
+ switch (cur->type.type_code)
+ {
+ case TUNABLE_TYPE_INT_32:
+ {
+ int32_t val = (int32_t) tunables_strtoul (strval);
+ RETURN_IF_INVALID_RANGE (cur, val);
+ cur->val.numval = (int64_t) val;
+ cur->strval = strval;
+ break;
+ }
+ case TUNABLE_TYPE_SIZE_T:
+ {
+ size_t val = (size_t) tunables_strtoul (strval);
+ RETURN_IF_INVALID_RANGE (cur, val);
+ cur->val.numval = (int64_t) val;
+ cur->strval = strval;
+ break;
+ }
+ case TUNABLE_TYPE_STRING:
+ {
+ cur->val.strval = cur->strval = strval;
+ break;
+ }
+ default:
+ __builtin_unreachable ();
+ }
+}
+
+/* Disable a tunable if it is set. */
+static void
+disable_tunable (tunable_id_t id, char **envp)
+{
+ const char *env_alias = tunable_list[id].env_alias;
+
+ if (env_alias)
+ tunables_unsetenv (envp, tunable_list[id].env_alias);
+}
+
+/* Disable the glibc.malloc.check tunable in SETUID/SETGID programs unless
+ the system administrator overrides it by creating the /etc/suid-debug
+ file. This is a special case where we want to conditionally enable/disable
+ a tunable even for setuid binaries. We use the special version of access()
+ to avoid setting ERRNO, which is a TLS variable since TLS has not yet been
+ set up. */
+static inline void
+__always_inline
+maybe_disable_malloc_check (void)
+{
+ if (__libc_enable_secure && __access_noerrno ("/etc/suid-debug", F_OK) != 0)
+ disable_tunable (TUNABLE_ENUM_NAME(glibc, malloc, check), __environ);
+}
+
+/* Initialize the tunables list from the environment. For now we only use the
+ ENV_ALIAS to find values. Later we will also use the tunable names to find
+ values. */
+void
+__tunables_init (char **envp)
+{
+ char *envname = NULL;
+ char *envval = NULL;
+ size_t len = 0;
+
+ maybe_disable_malloc_check ();
+
+ while ((envp = get_next_env (envp, &envname, &len, &envval)) != NULL)
+ {
+ for (int i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++)
+ {
+ tunable_t *cur = &tunable_list[i];
+
+ /* Skip over tunables that have either been set already or should be
+ skipped. */
+ if (cur->strval != NULL || cur->env_alias == NULL
+ || (__libc_enable_secure && !cur->is_secure))
+ continue;
+
+ const char *name = cur->env_alias;
+
+ /* We have a match. Initialize and move on to the next line. */
+ if (is_name (name, envname))
+ {
+ tunable_initialize (cur, envval);
+ break;
+ }
+ }
+ }
+}
+
+/* Set the tunable value. This is called by the module that the tunable exists
+ in. */
+void
+__tunable_set_val (tunable_id_t id, void *valp, tunable_callback_t callback)
+{
+ tunable_t *cur = &tunable_list[id];
+
+ /* Don't do anything if our tunable was not set during initialization or if
+ it failed validation. */
+ if (cur->strval == NULL)
+ return;
+
+ if (valp == NULL)
+ goto cb;
+
+ switch (cur->type.type_code)
+ {
+ case TUNABLE_TYPE_INT_32:
+ {
+ *((int32_t *) valp) = (int32_t) cur->val.numval;
+ break;
+ }
+ case TUNABLE_TYPE_SIZE_T:
+ {
+ *((size_t *) valp) = (size_t) cur->val.numval;
+ break;
+ }
+ case TUNABLE_TYPE_STRING:
+ {
+ *((const char **)valp) = cur->val.strval;
+ break;
+ }
+ default:
+ __builtin_unreachable ();
+ }
+
+cb:
+ if (callback)
+ callback (&cur->val);
+}
diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
new file mode 100644
index 0000000..10a644b
--- /dev/null
+++ b/elf/dl-tunables.h
@@ -0,0 +1,78 @@
+/* The tunable framework. See the README to know how to use the tunable in
+ a glibc module.
+
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _TUNABLES_H_
+# define _TUNABLES_H_
+# include <stddef.h>
+# include "dl-tunable-types.h"
+
+/* A tunable. */
+struct _tunable
+{
+ const char *name; /* Internal name of the tunable. */
+ tunable_type_t type; /* Data type of the tunable. */
+ tunable_val_t val; /* The value. */
+ const char *strval; /* The string containing the value,
+ points into envp. */
+ bool is_secure; /* Whether the tunable must be read
+ even for setuid binaries. Note that
+ even if the tunable is read, it may
+ not get used by the target module if
+ the value is considered unsafe. */
+ /* Compatibility elements. */
+ const char *env_alias; /* The compatibility environment
+ variable name. */
+};
+
+typedef struct _tunable tunable_t;
+
+/* Full name for a tunable is top_ns.tunable_ns.id. */
+#define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id
+
+# define TUNABLE_ENUM_NAME(top,ns,id) TUNABLE_ENUM_NAME1 (top,ns,id)
+# define TUNABLE_ENUM_NAME1(top,ns,id) top ## _ ## ns ## _ ## id
+
+#include "dl-tunable-list.h"
+
+extern void __tunables_init (char **);
+extern void __tunable_set_val (tunable_id_t, void *, tunable_callback_t);
+
+/* Check if the tunable has been set to a non-default value and if it is, copy
+ it over into __VAL. */
+# define TUNABLE_SET_VAL(__id,__val) \
+({ \
+ __tunable_set_val \
+ (TUNABLE_ENUM_NAME (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id), (__val), \
+ NULL); \
+})
+
+/* Same as TUNABLE_SET_VAL, but also set the callback function to __CB and call
+ it. */
+# define TUNABLE_SET_VAL_WITH_CALLBACK(__id,__val,__cb) \
+({ \
+ __tunable_set_val \
+ (TUNABLE_ENUM_NAME (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id), (__val), \
+ DL_TUNABLE_CALLBACK (__cb)); \
+})
+
+/* Namespace sanity for callback functions. Use this macro to keep the
+ namespace of the modules clean. */
+#define DL_TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name
+#endif
diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
new file mode 100644
index 0000000..11504c4
--- /dev/null
+++ b/elf/dl-tunables.list
@@ -0,0 +1,69 @@
+# Copyright (C) 2016 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <http://www.gnu.org/licenses/>.
+
+# Allowed attributes for tunables:
+#
+# type: Defaults to STRING
+# minval: Optional minimum acceptable value
+# maxval: Optional maximum acceptable value
+# env_alias: An alias environment variable
+# is_secure: Specify whether the environment variable should be read for
+# setuid binaries.
+
+glibc {
+ malloc {
+ check {
+ type: INT_32
+ minval: 0
+ maxval: 3
+ env_alias: MALLOC_CHECK_
+ is_secure: true
+ }
+ top_pad {
+ type: SIZE_T
+ env_alias: MALLOC_TOP_PAD_
+ }
+ perturb {
+ type: INT_32
+ minval: 0
+ maxval: 0xff
+ env_alias: MALLOC_PERTURB_
+ }
+ mmap_threshold {
+ type: SIZE_T
+ env_alias: MALLOC_MMAP_THRESHOLD_
+ }
+ trim_threshold {
+ type: SIZE_T
+ env_alias: MALLOC_TRIM_THRESHOLD_
+ }
+ mmap_max {
+ type: INT_32
+ env_alias: MALLOC_MMAP_MAX_
+ }
+ arena_max {
+ type: SIZE_T
+ env_alias: MALLOC_ARENA_MAX
+ minval: 1
+ }
+ arena_test {
+ type: SIZE_T
+ env_alias: MALLOC_ARENA_TEST
+ minval: 1
+ }
+ }
+}
diff --git a/elf/rtld.c b/elf/rtld.c
index 647661c..eb211a2 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -2527,11 +2527,13 @@ process_envvars (enum mode *modep)
}
while (*nextp != '\0');
+#if !HAVE_TUNABLES
if (__access ("/etc/suid-debug", F_OK) != 0)
{
unsetenv ("MALLOC_CHECK_");
GLRO(dl_debug_mask) = 0;
}
+#endif
if (mode != normal)
_exit (5);
diff --git a/malloc/Makefile b/malloc/Makefile
index b8efcd6..4e4104e 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -37,6 +37,7 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
tests-static := \
tst-interpose-static-nothread \
tst-interpose-static-thread \
+ tst-malloc-usable-static
tests += $(tests-static)
test-srcs = tst-mtrace
@@ -158,6 +159,7 @@ endif
tst-mcheck-ENV = MALLOC_CHECK_=3
tst-malloc-usable-ENV = MALLOC_CHECK_=3
+tst-malloc-usable-static-ENV = $(tst-malloc-usable-ENV)
# Uncomment this for test releases. For public releases it is too expensive.
#CPPFLAGS-malloc.o += -DMALLOC_DEBUG=1
diff --git a/malloc/arena.c b/malloc/arena.c
index eed4247..c2791b2 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -19,6 +19,11 @@
#include <stdbool.h>
+#if HAVE_TUNABLES
+# define TUNABLE_NAMESPACE malloc
+# include <elf/dl-tunables.h>
+#endif
+
/* Compile-time constants. */
#define HEAP_MIN_SIZE (32 * 1024)
@@ -204,6 +209,34 @@ __malloc_fork_unlock_child (void)
__libc_lock_init (list_lock);
}
+#if HAVE_TUNABLES
+static inline int do_set_mallopt_check (int32_t value);
+void
+DL_TUNABLE_CALLBACK (set_mallopt_check) (void *valp)
+{
+ int32_t value = *(int32_t *) valp;
+ do_set_mallopt_check (value);
+ if (check_action != 0)
+ __malloc_check_init ();
+}
+
+# define DL_TUNABLE_CALLBACK_FNDECL(__name, __type) \
+static inline int do_ ## __name (__type value); \
+void \
+DL_TUNABLE_CALLBACK (__name) (void *valp) \
+{ \
+ __type value = *(__type *) valp; \
+ do_ ## __name (value); \
+}
+
+DL_TUNABLE_CALLBACK_FNDECL (set_mmap_threshold, size_t)
+DL_TUNABLE_CALLBACK_FNDECL (set_mmaps_max, int32_t)
+DL_TUNABLE_CALLBACK_FNDECL (set_top_pad, size_t)
+DL_TUNABLE_CALLBACK_FNDECL (set_perturb_byte, int32_t)
+DL_TUNABLE_CALLBACK_FNDECL (set_trim_threshold, size_t)
+DL_TUNABLE_CALLBACK_FNDECL (set_arena_max, size_t)
+DL_TUNABLE_CALLBACK_FNDECL (set_arena_test, size_t)
+#else
/* Initialization routine. */
#include <string.h>
extern char **_environ;
@@ -238,6 +271,7 @@ next_env_entry (char ***position)
return result;
}
+#endif
#ifdef SHARED
@@ -272,6 +306,24 @@ ptmalloc_init (void)
#endif
thread_arena = &main_arena;
+
+#if HAVE_TUNABLES
+ /* Ensure initialization/consolidation and do it under a lock so that a
+ thread attempting to use the arena in parallel waits on us till we
+ finish. */
+ __libc_lock_lock (main_arena.mutex);
+ malloc_consolidate (&main_arena);
+
+ TUNABLE_SET_VAL_WITH_CALLBACK (check, NULL, set_mallopt_check);
+ TUNABLE_SET_VAL_WITH_CALLBACK (top_pad, NULL, set_top_pad);
+ TUNABLE_SET_VAL_WITH_CALLBACK (perturb, NULL, set_perturb_byte);
+ TUNABLE_SET_VAL_WITH_CALLBACK (mmap_threshold, NULL, set_mmap_threshold);
+ TUNABLE_SET_VAL_WITH_CALLBACK (trim_threshold, NULL, set_trim_threshold);
+ TUNABLE_SET_VAL_WITH_CALLBACK (mmap_max, NULL, set_mmaps_max);
+ TUNABLE_SET_VAL_WITH_CALLBACK (arena_max, NULL, set_arena_max);
+ TUNABLE_SET_VAL_WITH_CALLBACK (arena_test, NULL, set_arena_test);
+ __libc_lock_unlock (main_arena.mutex);
+#else
const char *s = NULL;
if (__glibc_likely (_environ != NULL))
{
@@ -340,6 +392,8 @@ ptmalloc_init (void)
if (check_action != 0)
__malloc_check_init ();
}
+#endif
+
#if HAVE_MALLOC_INIT_HOOK
void (*hook) (void) = atomic_forced_read (__malloc_initialize_hook);
if (hook != NULL)
diff --git a/malloc/tst-malloc-usable-static.c b/malloc/tst-malloc-usable-static.c
new file mode 100644
index 0000000..8907db0
--- /dev/null
+++ b/malloc/tst-malloc-usable-static.c
@@ -0,0 +1 @@
+#include <malloc/tst-malloc-usable.c>
diff --git a/manual/install.texi b/manual/install.texi
index de1c203..ffc166d 100644
--- a/manual/install.texi
+++ b/manual/install.texi
@@ -189,6 +189,11 @@ configure with @option{--disable-werror}.
By default for x86_64, @theglibc{} is built with the vector math library.
Use this option to disable the vector math library.
+@item --enable-tunables
+Tunables support allows additional library parameters to be customized at
+runtime. This is an experimental feature and affects startup time and is thus
+disabled by default.
+
@item --build=@var{build-system}
@itemx --host=@var{host-system}
These options are for cross-compiling. If you specify both options and
diff --git a/scripts/gen-tunables.awk b/scripts/gen-tunables.awk
new file mode 100644
index 0000000..b65b5a4
--- /dev/null
+++ b/scripts/gen-tunables.awk
@@ -0,0 +1,157 @@
+# Generate dl-tunable-list.h from dl-tunables.list
+
+BEGIN {
+ tunable=""
+ ns=""
+ top_ns=""
+}
+
+# Skip over blank lines and comments.
+/^#/ {
+ next
+}
+
+/^[ \t]*$/ {
+ next
+}
+
+# Beginning of either a top namespace, tunable namespace or a tunable, decided
+# on the current value of TUNABLE, NS or TOP_NS.
+$2 == "{" {
+ if (top_ns == "") {
+ top_ns = $1
+ }
+ else if (ns == "") {
+ ns = $1
+ }
+ else if (tunable == "") {
+ tunable = $1
+ }
+ else {
+ printf ("Unexpected occurrence of '{': %s:%d\n", FILENAME, FNR)
+ exit 1
+ }
+
+ next
+}
+
+# End of either a top namespace, tunable namespace or a tunable.
+$1 == "}" {
+ if (tunable != "") {
+ # Tunables definition ended, now fill in default attributes.
+ if (!types[top_ns][ns][tunable]) {
+ types[top_ns][ns][tunable] = "STRING"
+ }
+ if (!minvals[top_ns][ns][tunable]) {
+ minvals[top_ns][ns][tunable] = "0"
+ }
+ if (!maxvals[top_ns][ns][tunable]) {
+ maxvals[top_ns][ns][tunable] = "0"
+ }
+ if (!env_alias[top_ns][ns][tunable]) {
+ env_alias[top_ns][ns][tunable] = "NULL"
+ }
+ if (!is_secure[top_ns][ns][tunable]) {
+ is_secure[top_ns][ns][tunable] = "false"
+ }
+
+ tunable = ""
+ }
+ else if (ns != "") {
+ ns = ""
+ }
+ else if (top_ns != "") {
+ top_ns = ""
+ }
+ else {
+ printf ("syntax error: extra }: %s:%d\n", FILENAME, FNR)
+ exit 1
+ }
+ next
+}
+
+# Everything else, which could either be a tunable without any attributes or a
+# tunable attribute.
+{
+ if (ns == "") {
+ printf("Line %d: Invalid tunable outside a namespace: %s\n", NR, $0)
+ exit 1
+ }
+
+ if (tunable == "") {
+ # We encountered a tunable without any attributes, so note it with a
+ # default.
+ types[top_ns][ns][$1] = "STRING"
+ next
+ }
+
+ # Otherwise, we have encountered a tunable attribute.
+ split($0, arr, ":")
+ attr = gensub(/^[ \t]+|[ \t]+$/, "", "g", arr[1])
+ val = gensub(/^[ \t]+|[ \t]+$/, "", "g", arr[2])
+
+ if (attr == "type") {
+ types[top_ns][ns][tunable] = val
+ }
+ else if (attr == "minval") {
+ minvals[top_ns][ns][tunable] = val
+ }
+ else if (attr == "maxval") {
+ maxvals[top_ns][ns][tunable] = val
+ }
+ else if (attr == "env_alias") {
+ env_alias[top_ns][ns][tunable] = sprintf("\"%s\"", val)
+ }
+ else if (attr == "is_secure") {
+ if (val == "true" || val == "false") {
+ is_secure[top_ns][ns][tunable] = val
+ }
+ else {
+ printf("Line %d: Invalid value (%s) for is_secure: %s, ", NR, val,
+ $0)
+ print("Allowed values are 'true' or 'false'")
+ exit 1
+ }
+ }
+}
+
+END {
+ if (ns != "") {
+ print "Unterminated namespace. Is a closing brace missing?"
+ exit 1
+ }
+
+ print "/* AUTOGENERATED by gen-tunables.awk. */"
+ print "#ifndef _TUNABLES_H_"
+ print "# error \"Do not include this file directly.\""
+ print "# error \"Include tunables.h instead.\""
+ print "#endif"
+
+ # Now, the enum names
+ print "\ntypedef enum"
+ print "{"
+ for (t in types) {
+ for (n in types[t]) {
+ for (m in types[t][n]) {
+ printf (" TUNABLE_ENUM_NAME(%s, %s, %s),\n", t, n, m);
+ }
+ }
+ }
+ print "} tunable_id_t;\n"
+
+ # Finally, the tunable list.
+ print "\n#ifdef TUNABLES_INTERNAL"
+ print "static tunable_t tunable_list[] = {"
+ for (t in types) {
+ for (n in types[t]) {
+ for (m in types[t][n]) {
+ printf (" {TUNABLE_NAME_S(%s, %s, %s)", t, n, m)
+ printf (", {TUNABLE_TYPE_%s, %s, %s}, {.numval = 0}, NULL, %s, %s},\n",
+ types[t][n][m], minvals[t][n][m], maxvals[t][n][m],
+ is_secure[t][n][m], env_alias[t][n][m]);
+ }
+ }
+ }
+ print "};"
+ print "#endif"
+}
diff --git a/sysdeps/mach/hurd/dl-sysdep.c b/sysdeps/mach/hurd/dl-sysdep.c
index d730f82..40b5be5 100644
--- a/sysdeps/mach/hurd/dl-sysdep.c
+++ b/sysdeps/mach/hurd/dl-sysdep.c
@@ -44,6 +44,10 @@
#include <dl-machine.h>
#include <dl-procinfo.h>
+#if HAVE_TUNABLES
+# include <dl-tunables.h>
+#endif
+
extern void __mach_init (void);
extern int _dl_argc;
@@ -143,6 +147,10 @@ _dl_sysdep_start (void **start_argptr,
__libc_enable_secure = _dl_hurd_data->flags & EXEC_SECURE;
+#if HAVE_TUNABLES
+ __tunables_init (_environ);
+#endif
+
if (_dl_hurd_data->flags & EXEC_STACK_ARGS &&
_dl_hurd_data->user_entry == 0)
_dl_hurd_data->user_entry = (vm_address_t) ENTRY_POINT;
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=c11cd8dc939797a184db496e68e9f51f21c6ac03
commit c11cd8dc939797a184db496e68e9f51f21c6ac03
Author: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Date: Thu Nov 10 15:04:06 2016 -0200
New internal function __access_noerrno
This ia follow up patch for tunables requirement [1]. It Implement
an internal version of __access called __access_noerrno that
avoids setting errno. This is useful to check accessibility of files
very early on in process startup i.e. before TLS setup. This allows
tunables to replace MALLOC_CHECK_ safely (i.e. check existence of
/etc/suid-debug to enable/disable MALLOC_CHECK) and at the same time
initialize very early so that it can override IFUNCs.
Checked on x86_64.
Siddhesh Poyarekar <siddhesh@sourceware.org>
Adhemerval Zanella <adhemerval.zanella@linaro.org>
* hurd/hurd.h (__hurd_fail_noerrno): New function.
* include/unistd.h [IS_IN (rtld) || !defined SHARED]: Declare
__access_noerrno.
* io/access.c (__access_noerrno): New function.
* sysdeps/mach/hurd/access.c (hurd_fail_seterrno): New function.
(hurd_fail_seterrno): Likewise.
(access_common): Likewise.
(__access_noerrno): Likewise.
* sysdeps/nacl/access.c (__access_noerrno): Likewise.
* sysdeps/unix/sysv/linux/access.c (__access_noerrno): Likewise.
* sysdeps/nacl/nacl-interfaces.h (NACL_CALL_NOERRNO): New
macro.
[1] https://sourceware.org/ml/libc-alpha/2016-11/msg00399.html
diff --git a/hurd/hurd.h b/hurd/hurd.h
index ec07827..8bcb1ec 100644
--- a/hurd/hurd.h
+++ b/hurd/hurd.h
@@ -75,6 +75,36 @@ __hurd_fail (error_t err)
errno = err;
return -1;
}
+
+_HURD_H_EXTERN_INLINE int
+__hurd_fail_noerrno (error_t err)
+{
+ switch (err)
+ {
+ case EMACH_SEND_INVALID_DEST:
+ case EMIG_SERVER_DIED:
+ /* The server has disappeared! */
+ err = EIEIO;
+ break;
+
+ case KERN_NO_SPACE:
+ err = ENOMEM;
+ break;
+
+ case KERN_INVALID_ARGUMENT:
+ err = EINVAL;
+ break;
+
+ case 0:
+ return 0;
+
+ default:
+ break;
+ }
+
+ errno = err;
+ return -1;
+}
/* Basic ports and info, initialized by startup. */
diff --git a/include/unistd.h b/include/unistd.h
index d2802b2..6144f41 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -181,6 +181,12 @@ extern int __getlogin_r_loginuid (char *name, size_t namesize)
# include <dl-unistd.h>
# endif
+# if IS_IN (rtld) || !defined SHARED
+/* __access variant that does not set errno. Used in very early initialization
+ code in libc.a and ld.so. */
+extern __typeof (__access) __access_noerrno attribute_hidden;
+# endif
+
__END_DECLS
# endif
diff --git a/io/access.c b/io/access.c
index 4534704..68b49ca 100644
--- a/io/access.c
+++ b/io/access.c
@@ -19,6 +19,13 @@
#include <stddef.h>
#include <unistd.h>
+/* Test for access to FILE without setting errno. */
+int
+__access_noerrno (const char *file, int type)
+{
+ return -1;
+}
+
/* Test for access to FILE. */
int
__access (const char *file, int type)
@@ -33,5 +40,4 @@ __access (const char *file, int type)
return -1;
}
stub_warning (access)
-
weak_alias (__access, access)
diff --git a/sysdeps/mach/hurd/access.c b/sysdeps/mach/hurd/access.c
index c308340..620acea 100644
--- a/sysdeps/mach/hurd/access.c
+++ b/sysdeps/mach/hurd/access.c
@@ -22,9 +22,20 @@
#include <hurd/lookup.h>
#include <fcntl.h>
-/* Test for access to FILE by our real user and group IDs. */
-int
-__access (const char *file, int type)
+static int
+hurd_fail_seterrno (error_t err)
+{
+ return __hurd_fail (err);
+}
+
+static int
+hurd_fail_noerrno (error_t err)
+{
+ return __hurd_fail_noerrno (err);
+}
+
+static int
+access_common (const char *file, int type, int (*errfunc) (error_t))
{
error_t err;
file_t rcrdir, rcwdir, io;
@@ -120,13 +131,13 @@ __access (const char *file, int type)
if (rcwdir != MACH_PORT_NULL)
__mach_port_deallocate (__mach_task_self (), rcwdir);
if (err)
- return __hurd_fail (err);
+ return errfunc (err);
/* Find out what types of access we are allowed to this file. */
err = __file_check_access (io, &allowed);
__mach_port_deallocate (__mach_task_self (), io);
if (err)
- return __hurd_fail (err);
+ return errfunc (err);
flags = 0;
if (type & R_OK)
@@ -138,9 +149,23 @@ __access (const char *file, int type)
if (flags & ~allowed)
/* We are not allowed all the requested types of access. */
- return __hurd_fail (EACCES);
+ return errfunc (EACESS);
return 0;
}
+/* Test for access to FILE by our real user and group IDs without setting
+ errno. */
+int
+__access_noerrno (const char *file, int type)
+{
+ return access_common (file, type, hurd_fail_noerrno);
+}
+
+/* Test for access to FILE by our real user and group IDs. */
+int
+__access (const char *file, int type)
+{
+ return access_common (file, type, hurd_fail);
+}
weak_alias (__access, access)
diff --git a/sysdeps/nacl/access.c b/sysdeps/nacl/access.c
index 95a0fb7..4266d63 100644
--- a/sysdeps/nacl/access.c
+++ b/sysdeps/nacl/access.c
@@ -19,6 +19,13 @@
#include <unistd.h>
#include <nacl-interfaces.h>
+/* Test for access to FILE without setting errno. */
+int
+__access (const char *file, int type)
+{
+ return NACL_CALL_NOERRNO (__nacl_irt_dev_filename.access (file, type), 0);
+}
+
/* Test for access to FILE. */
int
__access (const char *file, int type)
diff --git a/sysdeps/nacl/nacl-interfaces.h b/sysdeps/nacl/nacl-interfaces.h
index b7b45bb..edd3217 100644
--- a/sysdeps/nacl/nacl-interfaces.h
+++ b/sysdeps/nacl/nacl-interfaces.h
@@ -113,4 +113,8 @@ __nacl_fail (int err)
#define NACL_CALL(err, val) \
({ int _err = (err); _err ? __nacl_fail (_err) : (val); })
+/* Same as NACL_CALL but without setting errno. */
+#define NACL_CALL_NOERRNO(err, val) \
+ ({ int _err = (err); _err ? _err : (val); })
+
#endif /* nacl-interfaces.h */
diff --git a/sysdeps/unix/sysv/linux/access.c b/sysdeps/unix/sysv/linux/access.c
index 8f003df..adefbca 100644
--- a/sysdeps/unix/sysv/linux/access.c
+++ b/sysdeps/unix/sysv/linux/access.c
@@ -21,6 +21,21 @@
#include <sysdep-cancel.h>
int
+__access_noerrno (const char *file, int type)
+{
+ int res;
+ INTERNAL_SYSCALL_DECL (err);
+#ifdef __NR_access
+ res = INTERNAL_SYSCALL_CALL (access, err, file, type);
+#else
+ res = INTERNAL_SYSCALL_CALL (faccessat, err, AT_FDCWD, file, type);
+#endif
+ if (INTERNAL_SYSCALL_ERROR_P (res, err))
+ return INTERNAL_SYSCALL_ERRNO (res, err);
+ return 0;
+}
+
+int
__access (const char *file, int type)
{
#ifdef __NR_access
-----------------------------------------------------------------------
hooks/post-receive
--
GNU C Library master sources