This is the mail archive of the
gdb-patches@sources.redhat.com
mailing list for the GDB project.
[commit] Prefer xfer_partial for memory xfers
- From: Andrew Cagney <cagney at gnu dot org>
- To: gdb-patches at sources dot redhat dot com
- Date: Thu, 30 Sep 2004 12:27:50 -0400
- Subject: [commit] Prefer xfer_partial for memory xfers
Hello,
This modifies the memory read/write functions so that they strongly
prefer the inferior's to_xfer_partial method over the older
to_xfer_memory method.
With this in place the need to implement xfer_memory is eliminated - I
deleted the function from inf-ptrace.c - inferiors (namely GNU/Linux)
can more easily overide the inherited xfer method.
committed,
Andrew
(and I thought getting GNU/Linux using inferior inheritance was be easy)
2004-09-30 Andrew Cagney <cagney@gnu.org>
* inf-ptrace.c (inf_ptrace_target): Do not set to_xfer_memory.
(inf_ptrace_xfer_memory): Delete.
* target.c (target_xfer_partial_p, xfer_using_stratum): New.
(target_read_memory, target_write_memory): Use xfer_using_stratum
when target_xfer_partial_p.
(debug_target): Move to start of file.
(target_read_memory_partial, target_write_memory_partial): Use
to_xfer_partial when target_xfer_partial_p.
Index: inf-ptrace.c
===================================================================
RCS file: /cvs/src/src/gdb/inf-ptrace.c,v
retrieving revision 1.7
diff -p -u -r1.7 inf-ptrace.c
--- inf-ptrace.c 30 Sep 2004 15:47:30 -0000 1.7
+++ inf-ptrace.c 30 Sep 2004 16:17:38 -0000
@@ -742,7 +742,6 @@ inf_ptrace_target (void)
t->to_resume = inf_ptrace_resume;
t->to_wait = inf_ptrace_wait;
t->to_prepare_to_store = inf_ptrace_prepare_to_store;
- t->to_xfer_memory = inf_ptrace_xfer_memory;
t->to_xfer_partial = inf_ptrace_xfer_partial;
t->to_files_info = inf_ptrace_files_info;
t->to_kill = inf_ptrace_kill_inferior;
Index: target.c
===================================================================
RCS file: /cvs/src/src/gdb/target.c,v
retrieving revision 1.83
diff -p -u -r1.83 target.c
--- target.c 30 Sep 2004 14:16:20 -0000 1.83
+++ target.c 30 Sep 2004 16:17:38 -0000
@@ -840,6 +840,89 @@ target_section_by_addr (struct target_op
return NULL;
}
+/* Return non-zero when the target vector has supplied an xfer_partial
+ method and it, rather than xfer_memory, should be used. */
+static int
+target_xfer_partial_p (void)
+{
+ return (target_stack != NULL
+ && target_stack->to_xfer_partial != default_xfer_partial);
+}
+
+/* Attempt a transfer all LEN bytes starting at OFFSET between the
+ inferior's KIND:ANNEX space and GDB's READBUF/WRITEBUF buffer. If
+ the transfer succeeds, return zero, otherwize the host ERRNO is
+ returned.
+
+ The inferior is formed from several layers. In the case of
+ corefiles, inf-corefile is layered above inf-exec and a request for
+ text (corefiles do not include text pages) will be first sent to
+ the core-stratum, fail, and then sent to the object-file where it
+ will succeed.
+
+ NOTE: cagney/2004-09-30:
+
+ The old code tried to use four separate mechanisms for mapping an
+ object:offset:len tuple onto an inferior and its address space: the
+ target stack; the inferior's TO_SECTIONS; solib's SO_LIST;
+ overlays.
+
+ This is stupid.
+
+ The code below is instead using a single mechanism (currently
+ strata). If that mechanism proves insufficient then re-factor it
+ implementing another singluar mechanism (for instance, a generic
+ object:annex onto inferior:object:annex say). */
+
+static int
+xfer_using_stratum (enum target_object object, const char *annex,
+ CORE_ADDR memaddr, int len, void *readbuf,
+ const void *writebuf)
+{
+ LONGEST xfered;
+ struct target_ops *target;
+
+ /* Always successful. */
+ if (len == 0)
+ return 0;
+ /* Never successful. */
+ if (target_stack == NULL)
+ return EIO;
+
+ target = target_stack;
+ while (1)
+ {
+ xfered = target->to_xfer_partial (target, object, annex,
+ readbuf, writebuf, memaddr, len);
+ if (xfered > 0)
+ {
+ /* The partial xfer succeeded, update the counts, check that
+ the xfer hasn't finished and if it hasn't set things up
+ for the next round. */
+ len -= xfered;
+ if (len <= 0)
+ return 0;
+ target = target_stack;
+ }
+ else if (xfered < 0)
+ {
+ /* Something totally screwed up, abandon the attempt to
+ xfer. */
+ if (errno)
+ return errno;
+ else
+ return EIO;
+ }
+ else
+ {
+ /* This "stratum" didn't work, try the next one down. */
+ target = target->beneath;
+ if (target == NULL)
+ return EIO;
+ }
+ }
+}
+
/* Read LEN bytes of target memory at address MEMADDR, placing the results in
GDB's memory at MYADDR. Returns either 0 for success or an errno value
if any error occurs.
@@ -853,13 +936,21 @@ target_section_by_addr (struct target_op
int
target_read_memory (CORE_ADDR memaddr, char *myaddr, int len)
{
- return target_xfer_memory (memaddr, myaddr, len, 0);
+ if (target_xfer_partial_p ())
+ return xfer_using_stratum (TARGET_OBJECT_MEMORY, NULL,
+ memaddr, len, myaddr, NULL);
+ else
+ return target_xfer_memory (memaddr, myaddr, len, 0);
}
int
target_write_memory (CORE_ADDR memaddr, char *myaddr, int len)
{
- return target_xfer_memory (memaddr, myaddr, len, 1);
+ if (target_xfer_partial_p ())
+ return xfer_using_stratum (TARGET_OBJECT_MEMORY, NULL,
+ memaddr, len, NULL, myaddr);
+ else
+ return target_xfer_memory (memaddr, myaddr, len, 1);
}
static int trust_readonly = 0;
@@ -1065,13 +1156,23 @@ target_xfer_memory_partial (CORE_ADDR me
int
target_read_memory_partial (CORE_ADDR memaddr, char *buf, int len, int *err)
{
- return target_xfer_memory_partial (memaddr, buf, len, 0, err);
+ if (target_xfer_partial_p ())
+ return target_stack->to_xfer_partial (target_stack,
+ TARGET_OBJECT_MEMORY, NULL,
+ buf, NULL, memaddr, len);
+ else
+ return target_xfer_memory_partial (memaddr, buf, len, 0, err);
}
int
target_write_memory_partial (CORE_ADDR memaddr, char *buf, int len, int *err)
{
- return target_xfer_memory_partial (memaddr, buf, len, 1, err);
+ if (target_xfer_partial_p ())
+ return target_stack->to_xfer_partial (target_stack,
+ TARGET_OBJECT_MEMORY, NULL,
+ NULL, buf, memaddr, len);
+ else
+ return target_xfer_memory_partial (memaddr, buf, len, 1, err);
}
/* More generic transfers. */