wrapper.c: add xpread() similar to xread()

It is a common mistake to call read(2)/pread(2) and forget to
anticipate that they may return error with EAGAIN/EINTR when the
system call is interrupted.

We have xread() helper to relieve callers of read(2) from having to
worry about it; add xpread() helper to do the same for pread(2).

Update the caller in the builtin/index-pack.c and the mmap emulation
in compat/.

Signed-off-by: Yiannis Marangos <yiannis.marangos@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 3 deletions

diff --git a/compat/mmap.c b/compat/mmap.c
index c9d46d1..7f662fe 100644
--- a/compat/mmap.c
+++ b/compat/mmap.c
@@ -14,7 +14,7 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t of
 	}
 
 	while (n < length) {
-		ssize_t count = pread(fd, (char *)start + n, length - n, offset + n);
+		ssize_t count = xpread(fd, (char *)start + n, length - n, offset + n);
 
 		if (count == 0) {
 			memset((char *)start+n, 0, length-n);
@@ -22,8 +22,6 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t of
 		}
 
 		if (count < 0) {
-			if (errno == EAGAIN || errno == EINTR)
-				continue;
 			free(start);
 			errno = EACCES;
 			return MAP_FAILED;