Re: Comments on the pax patch?

[Svante Signell <svante.signell@telia.com>]

On Wed, 2011-10-12 at 23:24 +0200, Guillem Jover wrote:
> On Wed, 2011-10-12 at 21:03:13 +0200, Svante Signell wrote:
> > Attached is a patch to make pax-20090728 build under GNU/Hurd. Function
> > calls changed are readlink()->xreadlink() (new, same as for psmisc) and
> 
> The same comment here, I've mentioned before the lstat/malloc/readlink
> combo before. I even sent a patch to the man-pages upstream to
> document it, now merged, please see:
> 
>   <http://man7.org/linux/man-pages/online/pages/man2/readlink.2.html>
> 
> > realpath()->canonicalize_file_name().
> 
> Does the code only support GNU based systems? Otherwise this cannot be

Attached is an updated patch using the already existing lstat call and
conditioning on __GNU__ for canonicalize_file_name. I hope I got the
free() calls at the right places.

Any thing left before submitting a bug report?


diff -ur pax-20090728/file_subs.c pax-20090728.modified/file_subs.c
--- pax-20090728/file_subs.c	2009-07-28 17:38:28.000000000 +0000
+++ pax-20090728.modified/file_subs.c	2011-10-13 14:02:04.000000000 +0000
@@ -351,7 +351,7 @@
 	int pass = 0;
 	mode_t file_mode;
 	struct stat sb;
-	char target[MAXPATHLEN];
+	char *target = NULL;
 	char *nm = arcn->name;
 	int len;
 
@@ -374,8 +374,15 @@
 			if (strcmp(NM_TAR, argv0) == 0 && Lflag) {
 				while (lstat(nm, &sb) == 0 &&
 				    S_ISLNK(sb.st_mode)) {
+					target = malloc(sb.st_size + 1);
+					if (target == NULL) {
+						oerrno = ENOMEM;
+						syswarn(1, oerrno,
+						    "Insufficient memory");
+						return(-1);
+					}
 					len = readlink(nm, target,
-					    sizeof target - 1);
+					    strlen(target));
 					if (len == -1) {
 						syswarn(0, errno,
 						   "cannot follow symlink %s in chain for %s",
@@ -388,6 +395,7 @@
 				}
 			}
 			res = mkdir(nm, file_mode);
+			free(target);
 
 badlink:
 			if (ign)
diff -ur pax-20090728/tables.c pax-20090728.modified/tables.c
--- pax-20090728/tables.c	2009-07-28 17:38:28.000000000 +0000
+++ pax-20090728.modified/tables.c	2011-10-13 13:40:37.000000000 +0000
@@ -1126,13 +1126,21 @@
 add_dir(char *name, struct stat *psb, int frc_mode)
 {
 	DIRDATA *dblk;
+#ifdef __GNU__
+	char *rp;
+#else
 	char realname[MAXPATHLEN], *rp;
+#endif
 
 	if (dirp == NULL)
 		return;
 
 	if (havechd && *name != '/') {
+#ifdef __GNU__
+		if ((rp = canonicalize_file_name(name)) == NULL) {
+#else
 		if ((rp = realpath(name, realname)) == NULL) {
+#endif
 			paxwarn(1, "Cannot canonicalize %s", name);
 			return;
 		}
@@ -1143,6 +1151,9 @@
 		if (dblk == NULL) {
 			paxwarn(1, "Unable to store mode and times for created"
 			    " directory: %s", name);
+#ifdef __GNU__
+			free(rp);
+#endif
 			return;
 		}
 		dirp = dblk;
@@ -1152,6 +1163,9 @@
 	if ((dblk->name = strdup(name)) == NULL) {
 		paxwarn(1, "Unable to store mode and times for created"
 		    " directory: %s", name);
+#ifdef __GNU__
+		free(rp);
+#endif
 		return;
 	}
 	dblk->mode = psb->st_mode & 0xffff;
@@ -1159,6 +1173,9 @@
 	dblk->atime = psb->st_atime;
 	dblk->frc_mode = frc_mode;
 	++dircnt;
+#ifdef __GNU__
+	free(rp);
+#endif
 }
 
 /*