From: Kamil Dudka <kdudka@redhat.com>
Date: Wed, 23 Oct 2013 13:04:22 +0200
Subject: [PATCH] decode: avoid using a static buffer in th_get_pathname()

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.
---
 lib/decode.c |   25 ++++++++++++++++++-------
 lib/handle.c |    1 +
 lib/libtar.h |    3 +++
 3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/lib/decode.c b/lib/decode.c
index c16ea2d..35312be 100644
--- a/lib/decode.c
+++ b/lib/decode.c
@@ -13,6 +13,7 @@
 #include <internal.h>
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/param.h>
 #include <pwd.h>
 #include <grp.h>
@@ -26,20 +27,30 @@
 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 33a262c..9faf2ed 100644
--- a/lib/handle.c
+++ b/lib/handle.c
@@ -121,6 +121,7 @@ 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 55f509a..5993cd2 100644
--- a/lib/libtar.h
+++ b/lib/libtar.h
@@ -85,6 +85,9 @@ typedef struct
 	int options;
 	struct tar_header th_buf;
 	libtar_hash_t *h;
+
+	/* introduced in libtar 1.2.21 */
+	char *th_pathname;
 }
 TAR;