[PATCH v2] Add mman.h/.c for win32

[Ulf Hermann <ulf dot hermann at qt dot io>]

We cannot get mmap() and friends from gnulib and they don't exist on windows.
The functionality we need can be implemnted using native win32 functions, though.

(changelog entries were missing in V1)

Signed-off-by: Ulf Hermann <ulf.hermann@qt.io>
---
 ChangeLog               |   4 ++
 configure.ac            |   7 +++
 libgnu/ChangeLog        |   7 +++
 libgnu/Makefile.am      |  17 +++++-
 libgnu/mman_win32.c     | 140 ++++++++++++++++++++++++++++++++++++++++++++++++
 libgnu/sys_mman.win32.h |  63 ++++++++++++++++++++++
 6 files changed, 237 insertions(+), 1 deletion(-)
 create mode 100644 libgnu/mman_win32.c
 create mode 100644 libgnu/sys_mman.win32.h

diff --git a/ChangeLog b/ChangeLog
index 01f3197..2c0e34d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2017-05-04  Ulf Hermann  <ulf.hermann@qt.io>
+
+	* configure.ac: Check for sys/mman.h or alternatively MapViewOfFile().
+
 2017-05-03  Ulf Hermann  <ulf.hermann@qt.io>
 
 	* configure.ac: Check if endian.h and byteswap.h are available.
diff --git a/configure.ac b/configure.ac
index 1e6c844..6a2f991 100644
--- a/configure.ac
+++ b/configure.ac
@@ -550,6 +550,13 @@ AM_CONDITIONAL(HAVE_ENDIAN_H, [test "x$ac_cv_have_decl_BYTE_ORDER" = "xyes"])
 AC_CHECK_DECLS([bswap_32], [], [], [[#include <byteswap.h>]])
 AM_CONDITIONAL(HAVE_BYTESWAP_H, [test "x$ac_cv_have_decl_bswap_32" = "xyes"])
 
+AC_CHECK_HEADERS(sys/mman.h)
+AM_CONDITIONAL(HAVE_SYS_MMAN_H, [test "x$ac_cv_header_sys_mman_h" = "xyes"])
+if test "x$ac_cv_header_sys_mman_h" != "xyes"; then
+	AC_CHECK_DECLS([MapViewOfFile], [], [], [[#include <windows.h>]])
+fi
+AM_CONDITIONAL(USE_WIN32_MMAN, [test "x$ac_cv_have_decl_MapViewOfFile" = "xyes"])
+
 dnl Check if we have <linux/bpf.h> for EM_BPF disassembly.
 AC_CHECK_HEADERS(linux/bpf.h)
 AM_CONDITIONAL(HAVE_LINUX_BPF_H, [test "x$ac_cv_header_linux_bpf_h" = "xyes"])
diff --git a/libgnu/ChangeLog b/libgnu/ChangeLog
index ca38be2..60a049f 100644
--- a/libgnu/ChangeLog
+++ b/libgnu/ChangeLog
@@ -1,3 +1,10 @@
+2017-05-04  Ulf Hermann  <ulf.hermann@qt.io>
+
+	* Makefile.am: If sys/mman.h is unavailable, but MapViewOfFile is,
+	then use our own implementation of mmap and related functions.
+	* mman_win32.c: New file.
+	* sys_mman.win32.h: New file.
+
 2017-05-03  Ulf Hermann  <ulf.hermann@qt.io>
 
 	* Makefile.am: Make endian.h and byteswap.h available if they don't
diff --git a/libgnu/Makefile.am b/libgnu/Makefile.am
index 37fdb9c..5af121a 100644
--- a/libgnu/Makefile.am
+++ b/libgnu/Makefile.am
@@ -35,7 +35,7 @@ noinst_LIBRARIES =
 MOSTLYCLEANFILES =
 MOSTLYCLEANDIRS =
 BUILT_SOURCES =
-EXTRA_DIST = endian.in.h byteswap.in.h
+EXTRA_DIST = endian.in.h byteswap.in.h sys_mman.win32.h mman_win32.c
 CLEANFILES =
 SUFFIXES =
 
@@ -53,4 +53,19 @@ BUILT_SOURCES += byteswap.h
 MOSTLYCLEANFILES += byteswap.h
 endif
 
+if !HAVE_SYS_MMAN_H
+if USE_WIN32_MMAN
+sys/mman.h: sys_mman.win32.h
+	$(AM_V_GEN)rm -f $@ && mkdir -p sys && cat $< > $@
+BUILT_SOURCES += sys/mman.h
+MOSTLYCLEANFILES += sys/mman.h
+endif
+endif
+
 include gnulib.am
+
+if !HAVE_SYS_MMAN_H
+if USE_WIN32_MMAN
+libgnu_a_SOURCES += mman_win32.c
+endif
+endif
diff --git a/libgnu/mman_win32.c b/libgnu/mman_win32.c
new file mode 100644
index 0000000..78966c2
--- /dev/null
+++ b/libgnu/mman_win32.c
@@ -0,0 +1,140 @@
+/* Replacement for mmap(2) and friends on windows
+   Copyright (C) 2017 The Qt Company Ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils 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
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+#include <sys/mman.h>
+#include <windows.h>
+#include <io.h>
+
+void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
+{
+    if (fd == -1) {
+        errno = EBADF;
+        return MAP_FAILED;
+    }
+
+    HANDLE file = (HANDLE)_get_osfhandle(fd);
+    if (file == INVALID_HANDLE_VALUE) {
+        errno = EBADF;
+        return MAP_FAILED;
+    }
+
+    // Apparently there is no writeonly - we might get the write-copy mode to work, though.
+    DWORD flProtect = PROT_NONE;
+    if (prot & PROT_READ) {
+        if (prot & PROT_WRITE) {
+            if (prot & PROT_EXEC) {
+                if (flags & MAP_PRIVATE)
+                    flProtect = PAGE_EXECUTE_WRITECOPY;
+                else
+                    flProtect = PAGE_EXECUTE_READWRITE;
+            } else {
+                if (flags & MAP_PRIVATE)
+                    flProtect = PAGE_WRITECOPY;
+                else
+                    flProtect = PAGE_READWRITE;
+            }
+        } else if (prot & PROT_EXEC) {
+            flProtect = PAGE_EXECUTE_READ;
+        }
+    } else if (prot & PROT_EXEC) {
+        flProtect = PAGE_EXECUTE;
+    } else {
+        errno = EPERM;
+        return MAP_FAILED;
+    }
+
+    HANDLE fileMapping = CreateFileMapping(file, NULL, flProtect, 0, 0, NULL);
+    if (fileMapping == NULL) {
+        errno = EINVAL; // windows docs say this happens on disk full. EINVAL is close enough.
+        return MAP_FAILED;
+    }
+
+    // you can only have either read-only, read-write, copy-on-write access. Either can be combined
+    // with exec. We try to map the given flags and prot parameters as best as we can.
+    DWORD access = 0;
+    if (flags & MAP_PRIVATE)
+        access |= FILE_MAP_COPY;
+    else if (prot & PROT_WRITE)
+        access |= FILE_MAP_WRITE;
+    else
+        access |= FILE_MAP_READ;
+
+    if (prot & PROT_EXEC)
+        access |= FILE_MAP_EXECUTE;
+
+
+    void *viewMapping = MapViewOfFileEx(fileMapping, access, 0, offset, length, addr);
+    CloseHandle(fileMapping);
+
+    if (viewMapping == NULL) {
+        errno = EINVAL;
+        return MAP_FAILED;
+    }
+
+    return viewMapping;
+}
+
+int munmap(void *addr, size_t length) {
+    // We cannot honor length here. We just unmap everything
+    // That is enough for elfutils, though.
+    (void) length;
+
+    if (UnmapViewOfFile(addr))
+        return 0;
+
+    errno = EINVAL;
+    return -1;
+}
+
+int msync(void *addr, size_t length, int flags) {
+    (void) flags;
+
+    if (FlushViewOfFile(addr, length))
+        return 0;
+
+    errno = EINVAL;
+    return -1;
+}
+
+int posix_madvise(void *addr, size_t len, int advice)
+{
+    (void) addr;
+    (void) len;
+    (void) advice;
+    return 0;
+}
+
+int mprotect(void *addr, size_t len, int prot)
+{
+    (void) addr;
+    (void) len;
+    (void) prot;
+    errno = EACCES;
+    return -1;
+}
diff --git a/libgnu/sys_mman.win32.h b/libgnu/sys_mman.win32.h
new file mode 100644
index 0000000..9ad54af
--- /dev/null
+++ b/libgnu/sys_mman.win32.h
@@ -0,0 +1,63 @@
+/* Replacement for mmap(2) and friends on windows
+   Copyright (C) 2017 The Qt Company Ltd.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils 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
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef LIB_SYS_MMAN_H
+#define LIB_SYS_MMAN_H
+
+#include <stddef.h>
+#include <errno.h>
+#include <unistd.h>
+
+#define PROT_NONE    0x00
+#define PROT_READ    0x04
+#define PROT_WRITE   0x02
+#define PROT_EXEC    0x01
+
+#define MAP_FAILED  ((void *) -1)
+
+#define MAP_SHARED   0x01
+#define MAP_PRIVATE  0x02
+#define MAP_FIXED    0x10
+
+#define MS_ASYNC      1
+#define MS_INVALIDATE 2
+#define MS_SYNC       4
+
+#define POSIX_MADV_NORMAL     0
+#define POSIX_MADV_SEQUENTIAL 1
+#define POSIX_MADV_RANDOM     2
+#define POSIX_MADV_WILLNEED   3
+#define POSIX_MADV_DONTNEED   4
+
+void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset);
+int munmap(void *addr, size_t length);
+int msync(void *addr, size_t length, int flags);
+int posix_madvise(void *addr, size_t len, int advice);
+int mprotect(void *addr, size_t len, int prot);
+
+#endif // MMAN_H
-- 
2.1.4