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Merge branch 'js/win32-mmap'

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mmap emulation on Windows has been optimized and work better without
consuming paging store when not needed.

* js/win32-mmap:
  mmap(win32): avoid expensive fstat() call
  mmap(win32): avoid copy-on-write when it is unnecessary
  win32mmap: set errno appropriately
This commit is contained in:
Junio C Hamano
2016-04-29 12:59:08 -07:00
parent 175008d454 d5425d10ca
commit f9dd74134a
1 changed files with 18 additions and 13 deletions
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31
compat/win32mmap.c
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@ -2,37 +2,42 @@
void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset) void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset)
{ {
HANDLE hmap; HANDLE osfhandle, hmap;
void *temp; void *temp;
off_t len; LARGE_INTEGER len;
struct stat st;
uint64_t o = offset; uint64_t o = offset;
uint32_t l = o & 0xFFFFFFFF; uint32_t l = o & 0xFFFFFFFF;
uint32_t h = (o >> 32) & 0xFFFFFFFF; uint32_t h = (o >> 32) & 0xFFFFFFFF;
if (!fstat(fd, &st)) osfhandle = (HANDLE)_get_osfhandle(fd);
len = st.st_size; if (!GetFileSizeEx(osfhandle, &len))
else
die("mmap: could not determine filesize"); die("mmap: could not determine filesize");
if ((length + offset) > len) if ((length + offset) > len.QuadPart)
length = xsize_t(len - offset); length = xsize_t(len.QuadPart - offset);
if (!(flags & MAP_PRIVATE)) if (!(flags & MAP_PRIVATE))
die("Invalid usage of mmap when built with USE_WIN32_MMAP"); die("Invalid usage of mmap when built with USE_WIN32_MMAP");
hmap = CreateFileMapping((HANDLE)_get_osfhandle(fd), NULL, hmap = CreateFileMapping(osfhandle, NULL,
PAGE_WRITECOPY, 0, 0, NULL); prot == PROT_READ ? PAGE_READONLY : PAGE_WRITECOPY, 0, 0, NULL);
if (!hmap) if (!hmap) {
errno = EINVAL;
return MAP_FAILED; 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)) if (!CloseHandle(hmap))
warning("unable to close file mapping handle"); 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) int git_munmap(void *start, size_t length)