readlink,realpath: fix a case with a symplink, closes 11021

function                                             old     new   delta
xmalloc_realpath_coreutils                           125     201     +76

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
index ead30e499..a4e402b84 100644
--- a/libbb/xreadlink.c
+++ b/libbb/xreadlink.c
@@ -147,6 +147,35 @@ char* FAST_FUNC xmalloc_realpath_coreutils(const char *path)
                                 buf[len++] = '/';
                                 strcpy(buf + len, last_slash);
                         }
+                } else {
+                        char *link = xmalloc_readlink(path);
+                        if (link) {
+                                char *cwd;
+                                if (link[0] == '/') {
+                                        /*
+                                         * $ ln -s /bin/qwe symlink  # note: /bin is a link to /usr/bin
+                                         * $ readlink -f symlink
+                                         * /usr/bin/qwe/target_does_not_exist
+                                         * $ realpath symlink
+                                         * /usr/bin/qwe/target_does_not_exist
+                                         */
+                                        buf = xmalloc_realpath_coreutils(link);
+                                        free(link);
+                                        return buf;
+                                }
+                                /*
+                                 * $ ln -s target_does_not_exist symlink
+                                 * $ readlink -f symlink
+                                 * /CURDIR/target_does_not_exist
+                                 * $ realpath symlink
+                                 * /CURDIR/target_does_not_exist
+                                 */
+                                cwd = xrealloc_getcwd_or_warn(NULL);
+                                buf = concat_path_file(cwd, link);
+                                free(cwd);
+                                free(link);
+                                return buf;
+                        }
                 }
         }