backtrace.c: Fix word cast to a pointer This patch fixes a compilation problem of Xorg + libunwind support when building it on MIPS variants with 32-bit pointers. Related: http://lists.busybox.net/pipermail/buildroot/2014-December/114404.html Patch submitted upstream: http://lists.x.org/archives/xorg-devel/2015-January/045226.html Patch reviewed by an Xorg developer: http://lists.x.org/archives/xorg-devel/2015-January/045383.html Signed-off-by: Vicente Olivert Riera From 84f04e0274661401a91efd4e9b21dccc1396e1d6 Mon Sep 17 00:00:00 2001 From: Vicente Olivert Riera Date: Wed, 3 Dec 2014 11:34:47 +0000 Subject: [PATCH] backtrace.c: Fix word cast to a pointer backtrace.c uses a word size provided by libunwind. In some architectures like MIPS, libunwind makes that word size 64-bit for all variants of the architecture. In the lines #90 and #98, backtrace.c tries to do a cast to a pointer, which fails in all MIPS variants with 32-bit pointers, like MIPS32 or MIPS64 n32, because it's trying to do a cast from a 64-bit wide variable to a 32-bit pointer: Making all in os make[2]: Entering directory `/home/test/test/1/output/build/xserver_xorg-server-1.15.1/os' CC WaitFor.lo CC access.lo CC auth.lo CC backtrace.lo backtrace.c: In function 'xorg_backtrace': backtrace.c:90:20: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast] if (dladdr((void *)(pip.start_ip + off), &dlinfo) && dlinfo.dli_fname && ^ backtrace.c:98:13: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast] (void *)(pip.start_ip + off)); ^ cc1: some warnings being treated as errors make[2]: *** [backtrace.lo] Error 1 make[2]: *** Waiting for unfinished jobs.... Making the cast to a pointer-sized integer, and then to a pointer fixes the problem. Related: https://bugs.freedesktop.org/show_bug.cgi?id=79939 Signed-off-by: Vicente Olivert Riera --- os/backtrace.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/os/backtrace.c b/os/backtrace.c index 3d1195b..fd129ef 100644 --- a/os/backtrace.c +++ b/os/backtrace.c @@ -87,7 +87,7 @@ xorg_backtrace(void) procname[1] = 0; } - if (dladdr((void *)(pip.start_ip + off), &dlinfo) && dlinfo.dli_fname && + if (dladdr((void *)(uintptr_t)(pip.start_ip + off), &dlinfo) && dlinfo.dli_fname && *dlinfo.dli_fname) filename = dlinfo.dli_fname; else @@ -95,7 +95,7 @@ xorg_backtrace(void) ErrorFSigSafe("%u: %s (%s%s+0x%x) [%p]\n", i++, filename, procname, ret == -UNW_ENOMEM ? "..." : "", (int)off, - (void *)(pip.start_ip + off)); + (void *)(uintptr_t)(pip.start_ip + off)); ret = unw_step(&cursor); if (ret < 0) -- 1.7.1