realpath,readlink -f: coreutils compat, closes 11021

function                                             old     new   delta
xmalloc_realpath_coreutils                             -     121    +121

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

4 files changed, 33 insertions, 2 deletions

diff --git a/coreutils/readlink.c b/coreutils/readlink.c
index b8e327d11..49361cea0 100644
--- a/coreutils/readlink.c
+++ b/coreutils/readlink.c
@@ -86,7 +86,7 @@ int readlink_main(int argc UNUSED_PARAM, char **argv)
 
         /* NOFORK: only one alloc is allowed; must free */
         if (opt & 1) { /* -f */
-                buf = xmalloc_realpath(fname);
+                buf = xmalloc_realpath_coreutils(fname);
         } else {
                 buf = xmalloc_readlink_or_warn(fname);
         }
diff --git a/coreutils/realpath.c b/coreutils/realpath.c
index aa878fcd2..43923681c 100644
--- a/coreutils/realpath.c
+++ b/coreutils/realpath.c
@@ -38,7 +38,7 @@ int realpath_main(int argc UNUSED_PARAM, char **argv)
 
         do {
                 /* NOFORK: only one alloc is allowed; must free */
-                char *resolved_path = xmalloc_realpath(*argv);
+                char *resolved_path = xmalloc_realpath_coreutils(*argv);
                 if (resolved_path != NULL) {
                         puts(resolved_path);
                         free(resolved_path);
diff --git a/include/libbb.h b/include/libbb.h
index a605c7f03..d4ba031df 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -485,6 +485,7 @@ DIR *xopendir(const char *path) FAST_FUNC;
 DIR *warn_opendir(const char *path) FAST_FUNC;
 
 char *xmalloc_realpath(const char *path) FAST_FUNC RETURNS_MALLOC;
+char *xmalloc_realpath_coreutils(const char *path) FAST_FUNC RETURNS_MALLOC;
 char *xmalloc_readlink(const char *path) FAST_FUNC RETURNS_MALLOC;
 char *xmalloc_readlink_or_warn(const char *path) FAST_FUNC RETURNS_MALLOC;
 /* !RETURNS_MALLOC: it's a realloc-like function */
diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
index 9b62bcc43..6315033bb 100644
--- a/libbb/xreadlink.c
+++ b/libbb/xreadlink.c
@@ -122,3 +122,33 @@ char* FAST_FUNC xmalloc_realpath(const char *path)
         return xstrdup(realpath(path, buf));
 #endif
 }
+
+char* FAST_FUNC xmalloc_realpath_coreutils(const char *path)
+{
+        char *buf;
+
+        errno = 0;
+        buf = xmalloc_realpath(path);
+        /*
+         * There is one case when "readlink -f" and
+         * "realpath" from coreutils succeed,
+         * even though file does not exist, such as:
+         *     /tmp/file_does_not_exist
+         * (the directory must exist).
+         */
+        if (!buf && errno == ENOENT) {
+                char *last_slash = strrchr(path, '/');
+                if (last_slash) {
+                        *last_slash++ = '\0';
+                        buf = xmalloc_realpath(path);
+                        if (buf) {
+                                unsigned len = strlen(buf);
+                                buf = xrealloc(buf, len + strlen(last_slash) + 2);
+                                buf[len++] = '/';
+                                strcpy(buf + len, last_slash);
+                        }
+                }
+        }
+
+        return buf;
+}