git/compat/win32mmap.c
Johannes Schindelin 6a730e10a7 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 <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-04-22 15:01:14 -07:00

48 lines
1,011 B
C

#include "../git-compat-util.h"
void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset)
{
HANDLE hmap;
void *temp;
off_t len;
struct stat st;
uint64_t o = offset;
uint32_t l = o & 0xFFFFFFFF;
uint32_t h = (o >> 32) & 0xFFFFFFFF;
if (!fstat(fd, &st))
len = st.st_size;
else
die("mmap: could not determine filesize");
if ((length + offset) > len)
length = xsize_t(len - offset);
if (!(flags & MAP_PRIVATE))
die("Invalid usage of mmap when built with USE_WIN32_MMAP");
hmap = CreateFileMapping((HANDLE)_get_osfhandle(fd), NULL,
PAGE_WRITECOPY, 0, 0, NULL);
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");
if (temp)
return temp;
errno = GetLastError() == ERROR_COMMITMENT_LIMIT ? EFBIG : EINVAL;
return MAP_FAILED;
}
int git_munmap(void *start, size_t length)
{
return !UnmapViewOfFile(start);
}