From 6a730e10a76d1e03a9554292419201534c1521f1 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Fri, 22 Apr 2016 16:31:22 +0200 Subject: win32mmap: set errno appropriately It is not really helpful when a `git fetch` fails with the message: fatal: mmap failed: No error In the particular instance encountered by a colleague of yours truly, the Win32 error code was ERROR_COMMITMENT_LIMIT which means that the page file is not big enough. Let's make the message fatal: mmap failed: File too large instead, which is only marginally better, but which can be associated with the appropriate work-around: setting `core.packedGitWindowSize` to a relatively small value. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- compat/win32mmap.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'compat') diff --git a/compat/win32mmap.c b/compat/win32mmap.c index 80a8c9af4f..3a39f0fadc 100644 --- a/compat/win32mmap.c +++ b/compat/win32mmap.c @@ -24,15 +24,21 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t of hmap = CreateFileMapping((HANDLE)_get_osfhandle(fd), NULL, PAGE_WRITECOPY, 0, 0, NULL); - if (!hmap) + if (!hmap) { + errno = EINVAL; return MAP_FAILED; + } temp = MapViewOfFileEx(hmap, FILE_MAP_COPY, h, l, length, start); if (!CloseHandle(hmap)) warning("unable to close file mapping handle"); - return temp ? temp : MAP_FAILED; + if (temp) + return temp; + + errno = GetLastError() == ERROR_COMMITMENT_LIMIT ? EFBIG : EINVAL; + return MAP_FAILED; } int git_munmap(void *start, size_t length) -- cgit v1.2.1 From 7ce7ee2d8228a97f023c7e34488ed83a557d83fb Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Fri, 22 Apr 2016 16:31:26 +0200 Subject: mmap(win32): avoid copy-on-write when it is unnecessary Often we are mmap()ing read-only. In those cases, it is wasteful to map in copy-on-write mode. Even worse: it can cause errors where we run out of space in the page file. So let's be extra careful to map files in read-only mode whenever possible. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- compat/win32mmap.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'compat') diff --git a/compat/win32mmap.c b/compat/win32mmap.c index 3a39f0fadc..b836169b3c 100644 --- a/compat/win32mmap.c +++ b/compat/win32mmap.c @@ -22,14 +22,15 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t of die("Invalid usage of mmap when built with USE_WIN32_MMAP"); hmap = CreateFileMapping((HANDLE)_get_osfhandle(fd), NULL, - PAGE_WRITECOPY, 0, 0, NULL); + prot == PROT_READ ? PAGE_READONLY : PAGE_WRITECOPY, 0, 0, NULL); if (!hmap) { errno = EINVAL; return MAP_FAILED; } - temp = MapViewOfFileEx(hmap, FILE_MAP_COPY, h, l, length, start); + temp = MapViewOfFileEx(hmap, prot == PROT_READ ? + FILE_MAP_READ : FILE_MAP_COPY, h, l, length, start); if (!CloseHandle(hmap)) warning("unable to close file mapping handle"); -- cgit v1.2.1 From d5425d10ca68a297061f87f4460dd7e0b32b39a6 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Fri, 22 Apr 2016 16:31:32 +0200 Subject: mmap(win32): avoid expensive fstat() call On Windows, we have to emulate the fstat() call to fill out information that takes extra effort to obtain, such as the file permissions/type. If all we want is the file size, we can use the much cheaper GetFileSizeEx() function (available since Windows XP). Suggested by Philip Kelley. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- compat/win32mmap.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) (limited to 'compat') diff --git a/compat/win32mmap.c b/compat/win32mmap.c index b836169b3c..519d51f2b6 100644 --- a/compat/win32mmap.c +++ b/compat/win32mmap.c @@ -2,26 +2,24 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset) { - HANDLE hmap; + HANDLE osfhandle, hmap; void *temp; - off_t len; - struct stat st; + LARGE_INTEGER len; uint64_t o = offset; uint32_t l = o & 0xFFFFFFFF; uint32_t h = (o >> 32) & 0xFFFFFFFF; - if (!fstat(fd, &st)) - len = st.st_size; - else + osfhandle = (HANDLE)_get_osfhandle(fd); + if (!GetFileSizeEx(osfhandle, &len)) die("mmap: could not determine filesize"); - if ((length + offset) > len) - length = xsize_t(len - offset); + if ((length + offset) > len.QuadPart) + length = xsize_t(len.QuadPart - offset); if (!(flags & MAP_PRIVATE)) die("Invalid usage of mmap when built with USE_WIN32_MMAP"); - hmap = CreateFileMapping((HANDLE)_get_osfhandle(fd), NULL, + hmap = CreateFileMapping(osfhandle, NULL, prot == PROT_READ ? PAGE_READONLY : PAGE_WRITECOPY, 0, 0, NULL); if (!hmap) { -- cgit v1.2.1