Den 06/10/2010 kl. 08.00 skrev Tim Kientzle:
>>
>> % diff mod.strings orig.strings
>> 2c2
>> < / 1286312209 0 0 0 958 `
>> ---
>>> / 1269146263 0 0 0 958 `
>
> That's the timestamp on the pseudo-entry used to store the archive
> symbol table. (GNU/SysV ar files use a pseudo-entry named "/" to
> store the symbol table. Since '/' is added to end of names in this
> format, this is essentially an entry with an empty name.)
>
> The current ar code generates this entry and sets the timestamp
> around line 624 of usr.bin/ar/write.c.
>
> As far as I can tell, ar itself doesn't care about the timestamp here;
> it's possible that ranlib or ld do care. If they don't, we could set
> this timestamp to zero always.
Is something like the following acceptable? Without risking changes to
buildworld/distribution just now, this would allow me to dump contents of an
archive and re-insert them with '0' for mtime, uid and gid before checking
checksums, without affecting normal ar behaviour.
erik% svn diff
Index: ar.1
===================================================================
--- ar.1 (revision 213478)
+++ ar.1 (working copy)
@@ -62,6 +62,7 @@
.Op Fl a Ar position-after
.Op Fl b Ar position-before
.Op Fl c
+.Op Fl D
.Op Fl i Ar position-before
.Op Fl j
.Op Fl s
@@ -179,6 +180,14 @@
.Ar archive .
The archive's symbol table, if present, is updated to reflect
the new contents of the archive.
+.It Fl D
+When used in combination with the
+.Fl r
+option, insterts 0's instead of the real mtime, uid and gid values
+from the members named by arguments
+.Ar files ... .
+This ensures that checksums on the resulting archives are reproducible
+when member contents are identical.
.It Fl f
Synonymous with option
.Fl T .
Index: ar.c
===================================================================
--- ar.c (revision 213478)
+++ ar.c (working copy)
@@ -154,7 +154,7 @@
}
}
- while ((opt = getopt_long(argc, argv, "abCcdfijlMmopqrSsTtuVvxz",
+ while ((opt = getopt_long(argc, argv, "abCcdDfijlMmopqrSsTtuVvxz",
longopts, NULL)) != -1) {
switch(opt) {
case 'a':
@@ -173,6 +173,9 @@
case 'd':
set_mode(bsdar, opt);
break;
+ case 'D':
+ bsdar->options |= AR_D;
+ break;
case 'f':
case 'T':
bsdar->options |= AR_TR;
@@ -357,8 +360,8 @@
(void)fprintf(stderr, "\tar -m [-Tabijsvz] position archive file
...\n");
(void)fprintf(stderr, "\tar -p [-Tv] archive [file ...]\n");
(void)fprintf(stderr, "\tar -q [-Tcjsvz] archive file ...\n");
- (void)fprintf(stderr, "\tar -r [-Tcjsuvz] archive file ...\n");
- (void)fprintf(stderr, "\tar -r [-Tabcijsuvz] position archive file
...\n");
+ (void)fprintf(stderr, "\tar -r [-TcDjsuvz] archive file ...\n");
+ (void)fprintf(stderr, "\tar -r [-TabcDijsuvz] position archive file
...\n");
(void)fprintf(stderr, "\tar -s [-jz] archive\n");
(void)fprintf(stderr, "\tar -t [-Tv] archive [file ...]\n");
(void)fprintf(stderr, "\tar -x [-CTouv] archive [file ...]\n");
Index: ar.h
===================================================================
--- ar.h (revision 213478)
+++ ar.h (working copy)
@@ -43,6 +43,7 @@
#define AR_U 0x0200 /* only extract or update newer members.*/
#define AR_V 0x0400 /* verbose mode */
#define AR_Z 0x0800 /* gzip compression */
+#define AR_D 0x1000 /* insert members with dummy mtime, uid and gid
*/
#define DEF_BLKSZ 10240 /* default block size */
Index: write.c
===================================================================
--- write.c (revision 213478)
+++ write.c (working copy)
@@ -163,11 +163,22 @@
if (mtime != 0 && bsdar->options & AR_U && sb.st_mtime <= mtime)
goto giveup;
- obj->uid = sb.st_uid;
- obj->gid = sb.st_gid;
+ /*
+ * When modifier -D is specified, mtime and UID / GID from the file
+ * will be replaced with 0. This ensures that checksums will match
+ * for two archives containing the exact same files.
+ */
+ if (bsdar->options & AR_D) {
+ obj->uid = 0;
+ obj->gid = 0;
+ obj->mtime = 0;
+ } else {
+ obj->uid = sb.st_uid;
+ obj->gid = sb.st_gid;
+ obj->mtime = sb.st_mtime;
+ }
obj->md = sb.st_mode;
obj->size = sb.st_size;
- obj->mtime = sb.st_mtime;
obj->dev = sb.st_dev;
obj->ino = sb.st_ino;
@@ -621,7 +632,10 @@
bsdar->options & AR_S) {
entry = archive_entry_new();
archive_entry_copy_pathname(entry, "/");
- archive_entry_set_mtime(entry, time(NULL), 0);
+ if (bsdar->options & AR_O)
+ archive_entry_set_mtime(entry, 0, 0);
+ else
+ archive_entry_set_mtime(entry, time(NULL), 0);
archive_entry_set_size(entry, (bsdar->s_cnt + 1) *
sizeof(uint32_t) + bsdar->s_sn_sz);
AC(archive_write_header(a, entry));
Thanks,
Erik
