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 --- diffcore-order.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'diffcore-order.c') diff --git a/diffcore-order.c b/diffcore-order.c index 7ad094618..2a4bd8232 100644 --- a/diffcore-order.c +++ b/diffcore-order.c @@ -14,6 +14,7 @@ static void prepare_order(const char *orderfile) void *map; char *cp, *endp; struct stat st; + size_t sz; if (order) return; @@ -25,11 +26,12 @@ static void prepare_order(const char *orderfile) close(fd); return; } - map = mmap(NULL, st.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); + sz = xsize_t(st.st_size); + map = mmap(NULL, sz, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); close(fd); if (map == MAP_FAILED) return; - endp = (char *) map + st.st_size; + endp = (char *) map + sz; for (pass = 0; pass < 2; pass++) { cnt = 0; cp = map; -- cgit v1.2.1