From 267668803ab0a24e57084df13dce132d4c007a89 Mon Sep 17 00:00:00 2001 From: Warner Losh Date: Sun, 27 Dec 2015 23:04:11 +0000 Subject: [PATCH] The FILE structure has a mbstate_t in it. This structure needs to be aligned on a int64_t boundary. However, when we allocate the array of these structures, we use ALIGNBYTES which defaults to sizeof(int) on arm, i386 and others. The i386 stuff can handle unaligned accesses seemlessly. However, arm cannot. Take this into account when creating the array of FILEs, and add some comments about why. Differential Revision: https://reviews.freebsd.org/D4708 --- lib/libc/stdio/findfp.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/lib/libc/stdio/findfp.c b/lib/libc/stdio/findfp.c index b8bb5afb551..6a68958d50f 100644 --- a/lib/libc/stdio/findfp.c +++ b/lib/libc/stdio/findfp.c @@ -41,6 +41,7 @@ __FBSDID("$FreeBSD$"); #include #include #include +#include #include #include @@ -96,11 +97,22 @@ moreglue(int n) struct glue *g; static FILE empty = { ._fl_mutex = PTHREAD_MUTEX_INITIALIZER }; FILE *p; + size_t align; - g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)); + /* + * FILE has a mbstate_t variable. This variable tries to be int64_t + * aligned through its definition. int64_t may be larger than void *, + * which is the size traditionally used for ALIGNBYTES. So, use our own + * rounding instead of the MI ALIGN macros. If for some reason + * ALIGNBYTES is larger than int64_t, respect that too. There appears to + * be no portable way to ask for FILE's alignment requirements other + * than just knowing here. + */ + align = MAX(ALIGNBYTES, sizeof(int64_t)); + g = (struct glue *)malloc(sizeof(*g) + align + n * sizeof(FILE)); if (g == NULL) return (NULL); - p = (FILE *)ALIGN(g + 1); + p = (FILE *)roundup((uintptr_t)(g + 1), align); g->next = NULL; g->niobs = n; g->iobs = p;