text: safer temporary file creation

Set umask before calling mkstemp. According to POSIX 2008 this is
not necessary since the temporary file is guaranteed to be created
with permission restricted to the current user. However this is
more secure on non-conforming systems and safe as long as we do not
use multiple threads.

Fixes Coverity CID 101333.

1 files changed, 4 insertions, 1 deletions

diff --git a/text.c b/text.c
index f47ccbc..a77bc07 100644
--- a/text.c
+++ b/text.c
@@ -919,7 +919,10 @@ bool text_range_save(Text *txt, Filerange *range, const char *filename) {
 		 */
 		size_t size = txt->buf->size;
 		char tmpname[32] = "/tmp/vis-XXXXXX";
-		if ((newfd = mkstemp(tmpname)) == -1)
+		mode_t mask = umask(S_IXUSR | S_IRWXG | S_IRWXO);
+		newfd = mkstemp(tmpname);
+		umask(mask);
+		if (newfd == -1)
 			goto err;
 		if (unlink(tmpname) == -1)
 			goto err;