From dc49cd769b5fa6b7e0114b051c34a849828a7603 Mon Sep 17 00:00:00 2001 From: "Shawn O. Pearce" Date: Tue, 6 Mar 2007 20:44:37 -0500 Subject: Cast 64 bit off_t to 32 bit size_t Some systems have sizeof(off_t) == 8 while sizeof(size_t) == 4. This implies that we are able to access and work on files whose maximum length is around 2^63-1 bytes, but we can only malloc or mmap somewhat less than 2^32-1 bytes of memory. On such a system an implicit conversion of off_t to size_t can cause the size_t to wrap, resulting in unexpected and exciting behavior. Right now we are working around all gcc warnings generated by the -Wshorten-64-to-32 option by passing the off_t through xsize_t(). In the future we should make xsize_t on such problematic platforms detect the wrapping and die if such a file is accessed. Signed-off-by: Shawn O. Pearce Signed-off-by: Junio C Hamano --- git-compat-util.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'git-compat-util.h') diff --git a/git-compat-util.h b/git-compat-util.h index 33b68e463c..7534db1267 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -258,6 +258,11 @@ static inline ssize_t xwrite(int fd, const void *buf, size_t len) } } +static inline size_t xsize_t(off_t len) +{ + return (size_t)len; +} + static inline int has_extension(const char *filename, const char *ext) { size_t len = strlen(filename); -- cgit v1.2.3