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archive-zip: write extended timestamp

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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1 parent 88182ba commit 227bf59806dc408d60f8f80a14d8dfe71b92c6d2 René Scharfe committed with Sep 24, 2012
Showing with 24 additions and 3 deletions.
  1. +24 −3 archive-zip.c
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@@ -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;

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