[Bug-tar] [PATCH] tar: Fixed bug, tar always updates the archive when path ends with a trailing slash

[Andrey Arapov]

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Dear developers,

seems there is a bug which causes tar to always update the contents of an 
archive if the directory
ends with a slash in the FILE specified with "-T" flag,
see below the example of this unexpected behavior and a patch that I made:

- -- I've tried both version of tar

address@hidden:~$ tar --version
tar (GNU tar) 1.27.1
address@hidden:~/Downloads/src/tar-1.28$ ./src/tar --version
tar (GNU tar) 1.28

- -- Normal and expected behavior

address@hidden:~$ /bin/tar --create -vf archive.tar .ssh
.ssh/
.ssh/id_ed25519
.ssh/id_ed25519.pub
.ssh/known_hosts
address@hidden:~$ /bin/tar --update -vf archive.tar .ssh
address@hidden:~$ /bin/tar --update -vf archive.tar .ssh/

(with -v flag tar would output whether there is a "new" file go into an 
archive.tar)

- -- Normal and expected behavior (using file list)

address@hidden:~$ cat list.txt
.ssh
address@hidden:~$ /bin/tar --update -vf archive.tar -T list.txt
address@hidden:~$ /bin/tar --update -vf archive.tar -T list.txt

- -- BUG: Adding slash in the name of path (.ssh => .ssh/), causes tar to 
update the archive always

address@hidden:~$ vim list.txt
address@hidden:~$ cat list.txt
.ssh/
address@hidden:~$ /bin/tar --update -vf archive.tar -T list.txt
.ssh/
.ssh/id_ed25519
.ssh/id_ed25519.pub
.ssh/known_hosts
address@hidden:~$ /bin/tar --update -vf archive.tar -T list.txt
.ssh/
.ssh/id_ed25519
.ssh/id_ed25519.pub
.ssh/known_hosts
address@hidden:~$ tar -tvf archive.tar
drwx------ arno/arno 0 2015-10-12 23:48 .ssh/
- -rw------- arno/arno 444 2015-10-14 20:36 .ssh/id_ed25519
- -rw-r--r-- arno/arno 93 2015-07-29 21:59 .ssh/id_ed25519.pub
- -rw-r--r-- arno/arno 3842 2015-10-15 20:51 .ssh/known_hosts
drwx------ arno/arno 0 2015-10-12 23:48 .ssh/
- -rw------- arno/arno 444 2015-10-14 20:36 .ssh/id_ed25519
- -rw-r--r-- arno/arno 93 2015-07-29 21:59 .ssh/id_ed25519.pub
- -rw-r--r-- arno/arno 3842 2015-10-15 20:51 .ssh/known_hosts
drwx------ arno/arno 0 2015-10-12 23:48 .ssh/
- -rw------- arno/arno 444 2015-10-14 20:36 .ssh/id_ed25519
- -rw-r--r-- arno/arno 93 2015-07-29 21:59 .ssh/id_ed25519.pub
- -rw-r--r-- arno/arno 3842 2015-10-15 20:51 .ssh/known_hosts


- -- The patch

I have decided to try myself and make a patch, please review it carefully, I do 
not want to break anything :-)

Signed-off-by: Andrey Arapov <address@hidden>
diff -u src/names.c.orig src/names.c
- --- src/names.c.orig    2014-03-26 21:58:48.000000000 +0100
+++ src/names.c 2015-10-18 23:58:52.131318666 +0200
@@ -705,6 +705,10 @@
 
   for (p = namelist; p; p = p->next)
     {
+      /* only zap trailing a slash */
+      if (ISSLASH(p->name[length]))
+        p->name[length] = '\0';
+
       if (p->name[0]
      && exclude_fnmatch (p->name, file_name, p->matching_flags))
    return p;


kind regards,
Andrey Arapov

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