Add overflow detection

Origin: http://marc.info/?l=openbsd-ports&m=142090828929750&w=2

* main.c: Call exit(1) when out of memory to avoid dereferencing null
pointers when gc's malloc fails.

* alloc.h: Replacements for w3m's allocation macros which add
overflow detection and concentrate the macros in one file.

* indep.h, libwc/charset.c, libwc/status.c, matrix.c: Use the
overflow-detecting allocation macros from alloc.h.

1 files changed, 8 insertions, 0 deletions

diff --git a/main.c b/main.c
index 76256d6..cb15c9f 100644
--- a/main.c
+++ b/main.c
@@ -383,6 +383,13 @@ make_optional_header_string(char *s)
     return hs;
 }
 
+static void *
+die_oom(size_t bytes)
+{
+    fprintf(stderr, "Out of memory: %zu bytes unavailable!\n", bytes);
+    exit(1);
+}
+
 int
 main(int argc, char **argv, char **envp)
 {
@@ -412,6 +419,7 @@ main(int argc, char **argv, char **envp)
     char **getimage_args = NULL;
 #endif /* defined(DONT_CALL_GC_AFTER_FORK) && defined(USE_IMAGE) */
     GC_INIT();
+    GC_set_oom_fn(die_oom);
 #if defined(ENABLE_NLS) || (defined(USE_M17N) && defined(HAVE_LANGINFO_CODESET))
     setlocale(LC_ALL, "");
 #endif