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List:       busybox
Subject:    [PATCH] libarchive/get_header_ar.c: fix extraction of archives from binutils in deterministic mode
From:       Peter Korsgaard <peter () korsgaard ! com>
Date:       2021-11-26 15:38:57
Message-ID: 20211126153857.23988-1-peter () korsgaard ! com
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GNU binutils in deterministic mode (ar rD or built with
--enable-deterministic-archives) hard codes file mode to 0644 (NOT 0100644)
since https://github.com/bminor/binutils-gdb/commit/36e4dce69dd2

This confuses busybox ar x (data_extract_all):

touch a; ar rD a.ar a
ar: creating a.ar

busybox ar x a.ar
ar: unrecognized file type
hexdump -C a.ar
00000000  21 3c 61 72 63 68 3e 0a  61 2f 20 20 20 20 20 20  |!<arch>.a/      |
00000010  20 20 20 20 20 20 20 20  30 20 20 20 20 20 20 20  |        0       |
00000020  20 20 20 20 30 20 20 20  20 20 30 20 20 20 20 20  |    0     0     |
00000030  36 34 34 20 20 20 20 20  30 20 20 20 20 20 20 20  |644     0       |
00000040  20 20 60 0a                                       |  `.|

As a workaround, force the mode bits to S_IFREG, as nothing else makes sense
for ar.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
---
 archival/libarchive/get_header_ar.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/archival/libarchive/get_header_ar.c b/archival/libarchive/get_header_ar.c
index 3a19d6ff7..6bd897392 100644
--- a/archival/libarchive/get_header_ar.c
+++ b/archival/libarchive/get_header_ar.c
@@ -92,8 +92,12 @@ char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
 	/* Only size is always present, the rest may be missing in
 	 * long filename pseudo file. Thus we decode the rest
 	 * after dealing with long filename pseudo file.
+	 *
+	 * GNU binutils in deterministic mode hard codes mode to 0644 (NOT
+	 * 0100644). AR archives can only contain files, so force file
+	 * mode.
 	 */
-	typed->mode = read_num(ar.formatted.mode, 8, sizeof(ar.formatted.mode));
+	typed->mode = read_num(ar.formatted.mode, 8, sizeof(ar.formatted.mode)) | S_IFREG;
 	typed->gid = read_num(ar.formatted.gid, 10, sizeof(ar.formatted.gid));
 	typed->uid = read_num(ar.formatted.uid, 10, sizeof(ar.formatted.uid));
 	typed->mtime = read_num(ar.formatted.date, 10, sizeof(ar.formatted.date));
-- 
2.20.1

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