Chris Larson (kergoth) writes:

I was adding -s/--symbolic-link support to busybox cp when I noticed a
bug with -r/-a.  Test case:

mkdir -p test/out
cd test
busybox cp -a * out/

Will never return until we run out of open files or similar.
Coreutils cp on the other hand will error with "cannot copy a directory,
`out', into itself, `out'".  Patch attached.

1 files changed, 16 insertions, 0 deletions

diff --git a/libbb/copy_file.c b/libbb/copy_file.c
index 7ddb9a23f..637b8179b 100644
--- a/libbb/copy_file.c
+++ b/libbb/copy_file.c
@@ -65,12 +65,28 @@ int copy_file(const char *source, const char *dest, int flags)
                 DIR *dp;
                 struct dirent *d;
                 mode_t saved_umask = 0;
+                char *dstparent;
+                struct stat dstparent_stat;
 
                 if (!(flags & FILEUTILS_RECUR)) {
                         bb_error_msg("%s: omitting directory", source);
                         return -1;
                 }
 
+                dstparent = dirname(bb_xstrdup(dest));
+                if (lstat(dstparent, &dstparent_stat) < 0) {
+                        bb_perror_msg("unable to stat `%s'", dstparent);
+                        free(dstparent);
+                        return -1;
+                }
+                free(dstparent);
+
+                if (source_stat.st_dev == dstparent_stat.st_dev &&
+                        source_stat.st_ino == dstparent_stat.st_ino) {
+                        bb_error_msg("cannot copy a directory, `%s', into itself, `%s'", source, dest);
+                        return -1;
+                }
+
                 /* Create DEST.  */
                 if (dest_exists) {
                         if (!S_ISDIR(dest_stat.st_mode)) {