[PATCH] Do not use errno when pread() returns 0

[Samuel Tardieu <sam@rfc1149.net>]

If we use pread() while at the end of the file, it will return 0, which is
not an error from the operating system point of view. In this case, errno
has not been set and must not be used.

Signed-off-by: Samuel Tardieu <sam@rfc1149.net>

---
 index-pack.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/index-pack.c b/index-pack.c
index 2e4c088..73860bf 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -365,8 +365,11 @@ static void *get_data_from_pack(struct object_entry *obj)
 	data = src;
 	do {
 		ssize_t n = pread(pack_fd, data + rdy, len - rdy, from + rdy);
-		if (n <= 0)
+		if (n < 0)
 			die("cannot pread pack file: %s", strerror(errno));
+		if (!n)
+			die("premature end of pack file, %lu bytes missing",
+			    len - rdy);
 		rdy += n;
 	} while (rdy < len);
 	data = xmalloc(obj->size);
-- 
tg: (395ff9b..) short-pread (depends on: spearce/next)