From: Marcus Tillmanns <maddimax@gmail.com>
Date: Thu, 15 May 2025 12:07:48 +0000 (+0200)
Subject: Allow setting the original filename for gzip compressed files (#2544)
X-Git-Tag: v3.8.0~21
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84ac71335fd7bc151be763dd525353c182b280b5;p=thirdparty%2Flibarchive.git

Allow setting the original filename for gzip compressed files (#2544)

Co-authored-by: Martin Matuška <martin@matuska.de>
---

diff --git a/libarchive/archive_write_add_filter_gzip.c b/libarchive/archive_write_add_filter_gzip.c
index 71d789126..5ef43c193 100644
--- a/libarchive/archive_write_add_filter_gzip.c
+++ b/libarchive/archive_write_add_filter_gzip.c
@@ -58,6 +58,7 @@ archive_write_set_compression_gzip(struct archive *a)
 struct private_data {
 	int		 compression_level;
 	int		 timestamp;
+	char	*original_filename;
 #ifdef HAVE_ZLIB_H
 	z_stream	 stream;
 	int64_t		 total_in;
@@ -113,6 +114,8 @@ archive_write_add_filter_gzip(struct archive *_a)
 	f->free = &archive_compressor_gzip_free;
 	f->code = ARCHIVE_FILTER_GZIP;
 	f->name = "gzip";
+
+	data->original_filename = NULL;
 #ifdef HAVE_ZLIB_H
 	data->compression_level = Z_DEFAULT_COMPRESSION;
 	return (ARCHIVE_OK);
@@ -140,6 +143,7 @@ archive_compressor_gzip_free(struct archive_write_filter *f)
 #else
 	__archive_write_program_free(data->pdata);
 #endif
+	free((void*)data->original_filename);
 	free(data);
 	f->data = NULL;
 	return (ARCHIVE_OK);
@@ -165,6 +169,13 @@ archive_compressor_gzip_options(struct archive_write_filter *f, const char *key,
 		data->timestamp = (value == NULL)?-1:1;
 		return (ARCHIVE_OK);
 	}
+	if (strcmp(key, "original-filename") == 0) {
+		free((void*)data->original_filename);
+		data->original_filename = NULL;
+		if (value)
+			data->original_filename = strdup(value);
+		return (ARCHIVE_OK);
+	}
 
 	/* Note: The "warn" return is just to inform the options
 	 * supervisor that we didn't handle it.  It will generate
@@ -210,7 +221,7 @@ archive_compressor_gzip_open(struct archive_write_filter *f)
 	data->compressed[0] = 0x1f; /* GZip signature bytes */
 	data->compressed[1] = 0x8b;
 	data->compressed[2] = 0x08; /* "Deflate" compression */
-	data->compressed[3] = 0; /* No options */
+	data->compressed[3] = data->original_filename == NULL ? 0 : 0x8;
 	if (data->timestamp >= 0) {
 		time_t t = time(NULL);
 		data->compressed[4] = (uint8_t)(t)&0xff;  /* Timestamp */
@@ -229,6 +240,12 @@ archive_compressor_gzip_open(struct archive_write_filter *f)
 	data->stream.next_out += 10;
 	data->stream.avail_out -= 10;
 
+	if (data->original_filename != NULL) {
+		strcpy((char*)data->compressed + 10, data->original_filename);
+		data->stream.next_out += strlen(data->original_filename) + 1;
+		data->stream.avail_out -= strlen(data->original_filename) + 1;
+	}
+
 	f->write = archive_compressor_gzip_write;
 
 	/* Initialize compression library. */
diff --git a/libarchive/test/test_write_filter_gzip.c b/libarchive/test/test_write_filter_gzip.c
index 14b14ecdd..8fbdbed09 100644
--- a/libarchive/test/test_write_filter_gzip.c
+++ b/libarchive/test/test_write_filter_gzip.c
@@ -145,6 +145,8 @@ DEFINE_TEST(test_write_filter_gzip)
 	    archive_write_set_filter_option(a, NULL, "compression-level", "99"));
 	assertEqualIntA(a, ARCHIVE_OK,
 	    archive_write_set_options(a, "gzip:compression-level=9"));
+	assertEqualIntA(a, ARCHIVE_OK,
+		archive_write_set_options(a, "gzip:original-filename=testorgfilename"));
 	assertEqualIntA(a, ARCHIVE_OK, archive_write_open_memory(a, buff, buffsize, &used2));
 	for (i = 0; i < 100; i++) {
 		snprintf(path, sizeof(path), "file%03d", i);
@@ -164,8 +166,9 @@ DEFINE_TEST(test_write_filter_gzip)
 	assertEqualInt(rbuff[0], 0x1f);
 	assertEqualInt(rbuff[1], 0x8b);
 	assertEqualInt(rbuff[2], 0x08);
-	assertEqualInt(rbuff[3], 0x00);
+	assertEqualInt(rbuff[3], 0x08);
 	assertEqualInt(rbuff[8], 2); /* RFC 1952 flag for compression level 9 */
+	assertEqualString((const char*)rbuff+10, "testorgfilename");
 
 	/* Curiously, this test fails; the test data above compresses
 	 * better at default compression than at level 9. */