From: Kamil Dudka <kdudka@redhat.com>
Date: Wed, 23 Oct 2013 13:04:22 +0000 (+0200)
Subject: decode: avoid using a static buffer in th_get_pathname()
X-Git-Url: https://repo.or.cz/w/libtar.git/commitdiff_plain/ec613af2e9371d7a3e1f7c7a6822164a4255b4d1

decode: avoid using a static buffer in th_get_pathname()

A solution suggested by Chris Frey:
https://lists.feep.net:8080/pipermail/libtar/2013-October/000377.html

Note this can break programs that expect sizeof(TAR) to be fixed.
---

diff --git a/lib/decode.c b/lib/decode.c
index c16ea2d..edb2185 100644
--- a/lib/decode.c
+++ b/lib/decode.c
@@ -26,20 +26,30 @@
 char *
 th_get_pathname(TAR *t)
 {
-	static TLS_THREAD char filename[MAXPATHLEN];
-
 	if (t->th_buf.gnu_longname)
 		return t->th_buf.gnu_longname;
 
-	if (t->th_buf.prefix[0] != '\0')
+	/* allocate the th_pathname buffer if not already */
+	if (t->th_pathname == NULL)
+	{
+		t->th_pathname = malloc(MAXPATHLEN * sizeof(char));
+		if (t->th_pathname == NULL)
+			/* out of memory */
+			return NULL;
+	}
+
+	if (t->th_buf.prefix[0] == '\0')
+	{
+		snprintf(t->th_pathname, MAXPATHLEN, "%.100s", t->th_buf.name);
+	}
+	else
 	{
-		snprintf(filename, sizeof(filename), "%.155s/%.100s",
+		snprintf(t->th_pathname, MAXPATHLEN, "%.155s/%.100s",
 			 t->th_buf.prefix, t->th_buf.name);
-		return filename;
 	}
 
-	snprintf(filename, sizeof(filename), "%.100s", t->th_buf.name);
-	return filename;
+	/* will be deallocated in tar_close() */
+	return t->th_pathname;
 }
 
 
diff --git a/lib/handle.c b/lib/handle.c
index 002d23c..a19c046 100644
--- a/lib/handle.c
+++ b/lib/handle.c
@@ -122,6 +122,7 @@ tar_close(TAR *t)
 		libtar_hash_free(t->h, ((t->oflags & O_ACCMODE) == O_RDONLY
 					? free
 					: (libtar_freefunc_t)tar_dev_free));
+	free(t->th_pathname);
 	free(t);
 
 	return i;
diff --git a/lib/libtar.h b/lib/libtar.h
index 616ca8f..2fefee0 100644
--- a/lib/libtar.h
+++ b/lib/libtar.h
@@ -86,6 +86,9 @@ typedef struct
 	int options;
 	struct tar_header th_buf;
 	libtar_hash_t *h;
+
+	/* introduced in libtar 1.2.21 */
+	char *th_pathname;
 }
 TAR;