From 6e2978fe5ceadecd0cb8867051cff1244ce6638c Mon Sep 17 00:00:00 2001 From: Matthew Flatt Date: Sun, 9 Oct 2016 17:22:38 -0600 Subject: [PATCH] save errno in write barrier signal handler In case a write barrier happens between the set and use of `errno`, make sure the barrier doesn't cause the `errno` value to change in the process of making other system calls. --- racket/src/racket/gc2/newgc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/racket/src/racket/gc2/newgc.c b/racket/src/racket/gc2/newgc.c index 8caf3c530e..84883218c6 100644 --- a/racket/src/racket/gc2/newgc.c +++ b/racket/src/racket/gc2/newgc.c @@ -9,6 +9,7 @@ #include #include #include +#include #include "platforms.h" #include "../src/schpriv.h" #include "gc2.h" @@ -1004,6 +1005,7 @@ static void set_has_back_pointers(NewGC *gc, mpage *page) static int designate_modified_gc(NewGC *gc, void *p) { + int saved_errno = errno; /* in case signal happens between set and use of errno */ mpage *page = pagemap_find_page(gc->page_maps, p); if (gc->no_further_modifications) { @@ -1019,6 +1021,7 @@ static int designate_modified_gc(NewGC *gc, void *p) || (gc->doing_memory_accounting && gc->finished_incremental))) { check_incremental_unprotect(gc, page); gc->unprotected_page = 1; /* for using fuel */ + errno = saved_errno; return 1; } GCPRINT(GCOUTF, "Seg fault (internal error during gc) at %p\n", p); @@ -1031,6 +1034,7 @@ static int designate_modified_gc(NewGC *gc, void *p) if (!page->back_pointers) set_has_back_pointers(gc, page); gc->modified_unprotects++; + errno = saved_errno; return 1; } else { if (gc->primoridal_gc)