>Number: 176136
>Category: bin
>Synopsis: cp(1) fails to overwrite a symlnk pointing to a directory
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Feb 14 08:00:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator: Akinori MUSHA
>Release: 9.1-STABLE
>Organization:
>Environment:
FreeBSD 9.1-STABLE/amd64
>Description:
Our implementation of cp(1) cannot overwrite a symlink pointing to an existing
directory.
This is because it always calls stat(2) on a destination file path even if -R
(with -P by default) is given, where lstat(2) should be used instead.
Dragonfly BSD, OS X and OpenBSD all share the same problem with us.
NetBSD cp(1) has once had this problem but fixed it in 2006 (bin/cp.c rev.1.42).
GNU cp does not have this problem.
Solaris/OpenIndiana's cp(1) (/usr/xpg4/bin/cp) seems to have this problem.
As far as I read, SUSv4 is not very clear as to how cp(1) should do about the
situation, but there should be no reason a symlink cannot be overwritten.
>How-To-Repeat:
% ln -s . foo
% mkdir bar
% ln -s .. bar/foo
Now we have <foo> and <bar/foo>.
Let's try copying <foo> to <bar/foo>.
% cp -RP foo bar/
cp: cannot overwrite directory bar/foo with non-directory foo
It failed!
% ls -l bar
total 1
lrwxr-xr-x 1 knu knu 2 Feb 14 16:18 foo -> ..
It seems cp(1) decided not to copy the source file just because the destination
symlink was resolved to a directory, but it is certainly not what you would
expect.
>Fix:
Index: cp.c
===================================================================
--- cp.c (revision 246770)
+++ cp.c (working copy)
@@ -262,7 +262,7 @@ copy(char *argv[], enum op type, int fts
struct stat to_stat;
FTS *ftsp;
FTSENT *curr;
- int base = 0, dne, badcp, rval;
+ int base = 0, dne, badcp, rval, sval;
size_t nlen;
char *p, *target_mid;
mode_t mask, mode;
@@ -383,8 +383,18 @@ copy(char *argv[], enum op type, int fts
continue;
}
+ /*
+ * lstat(2) should be used if neither -H or -L is
+ * given, or we will fail to overwrite an existing
+ * symlink pointing to a directory.
+ */
+ if (fts_options & (FTS_LOGICAL | FTS_COMFOLLOW))
+ sval = stat(to.p_path, &to_stat);
+ else
+ sval = lstat(to.p_path, &to_stat);
+
/* Not an error but need to remember it happened */
- if (stat(to.p_path, &to_stat) == -1)
+ if (sval == -1)
dne = 1;
else {
if (to_stat.st_dev == curr->fts_statp->st_dev &&
>Release-Note:
>Audit-Trail:
>Unformatted:
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