[PATCH 3/2] archive-zip: write extended timestamp
- From
René Scharfe <rene.scharfe@lsrfire.ath.cx>
- Date
- Sep 24, 2012, 15:56 UTC
- Message-ID
- <506082A7.4010108@lsrfire.ath.cx>
- In-Reply-To
- <5058CE49.3070108@lsrfire.ath.cx>
File modification times in ZIP files are encoded in DOS format: local time with a granularity of two seconds. Add an extra field to all archive entries to also record the mtime in Unix' fashion, as UTC with a granularity of one second.
This has the desirable side-effect of convincing Info-ZIP unzip 6.00 to respect general purpose flag 11, which is used to indicate that a file name is encoded in UTF-8. Any extra field would do, actually, but the extended timestamp is a reasonably small one (22 bytes per entry). Archives created by Info-ZIP zip 3.0 contain it, too (but with ctime and atime as well).
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> --- archive-zip.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-)
diff --git a/archive-zip.c b/archive-zip.c index 0f763e8..55f66b4 100644 --- a/archive-zip.c +++ b/archive-zip.c @@ -76,6 +76,14 @@ struct zip_dir_trailer { unsigned char _end[1]; }; +struct zip_extra_mtime { + unsigned char magic[2]; + unsigned char extra_size[2]; + unsigned char flags[1]; + unsigned char mtime[4]; + unsigned char _end[1]; +}; + /* * On ARM, padding is added at the end of the struct, so a simple * sizeof(struct ...) reports two bytes more than the payload size @@ -85,6 +93,9 @@ struct zip_dir_trailer { #define ZIP_DATA_DESC_SIZE offsetof(struct zip_data_desc, _end) #define ZIP_DIR_HEADER_SIZE offsetof(struct zip_dir_header, _end) #define ZIP_DIR_TRAILER_SIZE offsetof(struct zip_dir_trailer, _end) +#define ZIP_EXTRA_MTIME_SIZE offsetof(struct zip_extra_mtime, _end) +#define ZIP_EXTRA_MTIME_PAYLOAD_SIZE \ + (ZIP_EXTRA_MTIME_SIZE - offsetof(struct zip_extra_mtime, flags)) static void copy_le16(unsigned char *dest, unsigned int n) { @@ -186,6 +197,7 @@ static int write_zip_entry(struct archiver_args *args, { struct zip_local_header header; struct zip_dir_header dirent; + struct zip_extra_mtime extra; unsigned long attr2; unsigned long compressed_size; unsigned long crc; @@ -266,8 +278,13 @@ static int write_zip_entry(struct archiver_args *args, } } + copy_le16(extra.magic, 0x5455); + copy_le16(extra.extra_size, ZIP_EXTRA_MTIME_PAYLOAD_SIZE); + extra.flags[0] = 1; /* just mtime */ + copy_le32(extra.mtime, args->time); + /* make sure we have enough free space in the dictionary */ - direntsize = ZIP_DIR_HEADER_SIZE + pathlen; + direntsize = ZIP_DIR_HEADER_SIZE + pathlen + ZIP_EXTRA_MTIME_SIZE; while (zip_dir_size < zip_dir_offset + direntsize) { zip_dir_size += ZIP_DIRECTORY_MIN_SIZE; zip_dir = xrealloc(zip_dir, zip_dir_size); @@ -283,7 +300,7 @@ static int write_zip_entry(struct archiver_args *args, copy_le16(dirent.mdate, zip_date); set_zip_dir_data_desc(&dirent, size, compressed_size, crc); copy_le16(dirent.filename_length, pathlen); - copy_le16(dirent.extra_length, 0); + copy_le16(dirent.extra_length, ZIP_EXTRA_MTIME_SIZE); copy_le16(dirent.comment_length, 0); copy_le16(dirent.disk, 0); copy_le16(dirent.attr1, 0); @@ -301,11 +318,13 @@ static int write_zip_entry(struct archiver_args *args, else set_zip_header_data_desc(&header, size, compressed_size, crc); copy_le16(header.filename_length, pathlen); - copy_le16(header.extra_length, 0); + copy_le16(header.extra_length, ZIP_EXTRA_MTIME_SIZE); write_or_die(1, &header, ZIP_LOCAL_HEADER_SIZE); zip_offset += ZIP_LOCAL_HEADER_SIZE; write_or_die(1, path, pathlen); zip_offset += pathlen; + write_or_die(1, &extra, ZIP_EXTRA_MTIME_SIZE); + zip_offset += ZIP_EXTRA_MTIME_SIZE; if (stream && method == 0) { unsigned char buf[STREAM_BUFFER_SIZE]; ssize_t readlen; @@ -402,6 +421,8 @@ static int write_zip_entry(struct archiver_args *args, zip_dir_offset += ZIP_DIR_HEADER_SIZE; memcpy(zip_dir + zip_dir_offset, path, pathlen); zip_dir_offset += pathlen; + memcpy(zip_dir + zip_dir_offset, &extra, ZIP_EXTRA_MTIME_SIZE); + zip_dir_offset += ZIP_EXTRA_MTIME_SIZE; zip_dir_entries++; return 0;
-- 1.7.12