tar: use standard header prefix

APKs have been created with GNU tar so far, which uses the
GNU extensions for long names. In order to increase portability
support the standard header's 'prefix' portion in case
the GNU extensions are not present.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/archive.c b/src/archive.c
index 438eb94..b1f9c30 100644
--- a/src/archive.c
+++ b/src/archive.c
@@ -206,10 +206,12 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 	int end = 0, r;
 	size_t toskip, paxlen = 0;
 	apk_blob_t pax = APK_BLOB_NULL, longname = APK_BLOB_NULL;
+	char filename[sizeof buf.name + sizeof buf.prefix + 2];
 
 	odi = (struct apk_tar_digest_info *) &buf.linkname[3];
 	EVP_MD_CTX_init(&teis.mdctx);
 	memset(&entry, 0, sizeof(entry));
+	entry.name = buf.name;
 	while ((r = apk_istream_read(is, &buf, 512)) == 512) {
 		offset += 512;
 		if (buf.name[0] == '\0') {
@@ -224,13 +226,19 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 			.gid   = apk_resolve_gid(idc, buf.gname, GET_OCTAL(buf.gid)),
 			.mode  = GET_OCTAL(buf.mode) & 07777,
 			.mtime = GET_OCTAL(buf.mtime),
-			.name  = entry.name ?: buf.name,
+			.name  = entry.name,
 			.uname = buf.uname,
 			.gname = buf.gname,
 			.device = makedev(GET_OCTAL(buf.devmajor),
 					  GET_OCTAL(buf.devminor)),
 			.xattrs = entry.xattrs,
 		};
+		if (buf.prefix[0] && buf.typeflag != 'x' && buf.typeflag != 'g') {
+			snprintf(filename, sizeof filename, "%.*s/%.*s",
+				 (int) sizeof buf.prefix, buf.prefix,
+				 (int) sizeof buf.name, buf.name);
+			entry.name = filename;
+		}
 		buf.mode[0] = 0; /* to nul terminate 100-byte buf.name */
 		buf.magic[0] = 0; /* to nul terminate 100-byte buf.linkname */
 		teis.csum = NULL;