tls: prepare for ECDH_anon ciphers

[oweals/busybox.git] / libbb / xreadlink.c

diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
index a5f7eb8bef5fac5e35076696e707f93eda9b4438..ead30e499cdb6d36464a3fd8bda53d0bb640135e 100644 (file)
--- a/libbb/xreadlink.c
+++ b/libbb/xreadlink.c
@@ -1,16 +1,23 @@
 /* vi: set sw=4 ts=4: */
 /*
- *  xreadlink.c - safe implementation of readlink.
- *  Returns a NULL on failure...
+ * xreadlink.c - safe implementation of readlink.
+ * Returns a NULL on failure.
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
-
 #include "libbb.h"
 
+/* Some systems (eg Hurd) do not have MAXSYMLINKS definition,
+ * set it to some reasonable value if it isn't defined */
+#ifndef MAXSYMLINKS
+# define MAXSYMLINKS 20
+#endif
+
 /*
  * NOTE: This function returns a malloced char* that you will have to free
- * yourself. You have been warned.
+ * yourself.
  */
-char *xmalloc_readlink(const char *path)
+char* FAST_FUNC xmalloc_readlink(const char *path)
 {
        enum { GROWBY = 80 }; /* how large we will grow strings by */
 
@@ -33,16 +40,16 @@ char *xmalloc_readlink(const char *path)
 }
 
 /*
- * this routine is not the same as realpath(), which
- * canonicalizes the given path completely.  this routine only
- * follows trailing symlinks until a real file is reached, and
- * returns its name.  if the path ends in a dangling link, or if
- * the target doesn't exist, the path is returned in any case. 
- * intermediate symlinks in the path are not expanded -- only
+ * This routine is not the same as realpath(), which
+ * canonicalizes the given path completely. This routine only
+ * follows trailing symlinks until a real file is reached and
+ * returns its name. If the path ends in a dangling link or if
+ * the target doesn't exist, the path is returned in any case.
+ * Intermediate symlinks in the path are not expanded -- only
  * those at the tail.
- * a malloced char* is returned, which must be freed by the caller.
+ * A malloced char* is returned, which must be freed by the caller.
  */
-char *xmalloc_follow_symlinks(const char *path)
+char* FAST_FUNC xmalloc_follow_symlinks(const char *path)
 {
        char *buf;
        char *lpc;
@@ -54,18 +61,17 @@ char *xmalloc_follow_symlinks(const char *path)
        goto jump_in;
 
        while (1) {
-
                linkpath = xmalloc_readlink(buf);
                if (!linkpath) {
                        /* not a symlink, or doesn't exist */
                        if (errno == EINVAL || errno == ENOENT)
                                return buf;
-                       free(buf);
-                       return NULL;
-               } 
+                       goto free_buf_ret_null;
+               }
 
                if (!--looping) {
                        free(linkpath);
+ free_buf_ret_null:
                        free(buf);
                        return NULL;
                }
@@ -85,28 +91,64 @@ char *xmalloc_follow_symlinks(const char *path)
        }
 }
 
-char *xmalloc_readlink_or_warn(const char *path)
+char* FAST_FUNC xmalloc_readlink_or_warn(const char *path)
 {
        char *buf = xmalloc_readlink(path);
        if (!buf) {
                /* EINVAL => "file: Invalid argument" => puzzled user */
-               bb_error_msg("%s: cannot read link (not a symlink?)", path);
+               const char *errmsg = "not a symlink";
+               int err = errno;
+               if (err != EINVAL)
+                       errmsg = strerror(err);
+               bb_error_msg("%s: cannot read link: %s", path, errmsg);
        }
        return buf;
 }
 
-/* UNUSED */
-#if 0
-char *xmalloc_realpath(const char *path)
+char* FAST_FUNC xmalloc_realpath(const char *path)
 {
-#if defined(__GLIBC__) && !defined(__UCLIBC__)
+/* NB: uclibc also defines __GLIBC__
+ * Therefore the test "if glibc, or uclibc >= 0.9.31" looks a bit weird:
+ */
+#if defined(__GLIBC__) && \
+    (!defined(__UCLIBC__) || UCLIBC_VERSION >= KERNEL_VERSION(0, 9, 31))
        /* glibc provides a non-standard extension */
+       /* new: POSIX.1-2008 specifies this behavior as well */
        return realpath(path, NULL);
 #else
        char buf[PATH_MAX+1];
 
-       /* on error returns NULL (xstrdup(NULL) ==NULL) */
+       /* on error returns NULL (xstrdup(NULL) == NULL) */
        return xstrdup(realpath(path, buf));
 #endif
 }
-#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;
+}