From: Tim Kientzle <kientzle@gmail.com>
Date: Sun, 19 Oct 2008 22:38:35 +0000 (-0400)
Subject: Make the end-of-archive detection work properly with the new
X-Git-Tag: v2.6.0~67
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b5287f57935fba77f636485b119ef41f00cb55dc;p=thirdparty%2Flibarchive.git

Make the end-of-archive detection work properly with the new
strict read_ahead() semantics, which return a failure instead of
a short read at end-of-file.  This seems to be one of the very
few cases where the short read is actually informative.

SVN-Revision: 226
---

diff --git a/libarchive/archive_read_support_format_tar.c b/libarchive/archive_read_support_format_tar.c
index 44952381f..0a649791a 100644
--- a/libarchive/archive_read_support_format_tar.c
+++ b/libarchive/archive_read_support_format_tar.c
@@ -555,15 +555,19 @@ tar_read_header(struct archive_read *a, struct tar *tar,
 	bytes = (a->decompressor->read_ahead)(a, &h, 512);
 	if (bytes < 0)
 		return (bytes);
-	if (bytes == 0) {
-		/*
-		 * An archive that just ends without a proper
-		 * end-of-archive marker.  Yes, there are tar programs
-		 * that do this; hold our nose and accept it.
-		 */
-		return (ARCHIVE_EOF);
-	}
-	if (bytes < 512) {
+	if (bytes < 512) {  /* Short read or EOF. */
+		/* Try requesting just one byte and see what happens. */
+		bytes = (a->decompressor->read_ahead)(a, &h, 1);
+		if (bytes == 0) {
+			/*
+			 * The archive ends at a 512-byte boundary but
+			 * without a proper end-of-archive marker.
+			 * Yes, there are tar writers that do this;
+			 * hold our nose and accept it.
+			 */
+			return (ARCHIVE_EOF);
+		}
+		/* Archive ends with a partial block; this is bad. */
 		archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
 		    "Truncated tar archive");
 		return (ARCHIVE_FATAL);