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>

diff --git a/compat/win32mmap.c b/compat/win32mmap.c
index 80a8c9af4f0ddcc883370fe05781337cef0d5ef0..3a39f0fadc7ecb9871a9a85fd6d07ee67419bca8 100644 (file)
--- 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)