Introduce new static function real_path_internal()

It accepts a new parameter, die_on_error.  If die_on_error is false,
it simply cleans up after itself and returns NULL rather than dying.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jeff King <peff@peff.net>

diff --git a/abspath.c b/abspath.c
index 05f2d7934878a832f5a2efdf4222c16223050853..a7ab8e908f8188ae1b55fca15cc2fb8772f40096 100644 (file)
--- a/abspath.c
+++ b/abspath.c
@@ -15,15 +15,26 @@ int is_directory(const char *path)
 #define MAXDEPTH 5
 
 /*
- * Use this to get the real path, i.e. resolve links. If you want an
- * absolute path but don't mind links, use absolute_path.
+ * Return the real path (i.e., absolute path, with symlinks resolved
+ * and extra slashes removed) equivalent to the specified path.  (If
+ * you want an absolute path but don't mind links, use
+ * absolute_path().)  The return value is a pointer to a static
+ * buffer.
+ *
+ * The input and all intermediate paths must be shorter than MAX_PATH.
+ * The directory part of path (i.e., everything up to the last
+ * dir_sep) must denote a valid, existing directory, but the last
+ * component need not exist.  If die_on_error is set, then die with an
+ * informative error message if there is a problem.  Otherwise, return
+ * NULL on errors (without generating any output).
  *
  * If path is our buffer, then return path, as it's already what the
  * user wants.
  */
-const char *real_path(const char *path)
+static const char *real_path_internal(const char *path, int die_on_error)
 {
        static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
+       char *retval = NULL;
        char cwd[1024] = "";
        int buf_index = 1;
 
@@ -35,11 +46,19 @@ const char *real_path(const char *path)
        if (path == buf || path == next_buf)
                return path;
 
-       if (!*path)
-               die("The empty string is not a valid path");
+       if (!*path) {
+               if (die_on_error)
+                       die("The empty string is not a valid path");
+               else
+                       goto error_out;
+       }
 
-       if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
-               die ("Too long path: %.*s", 60, path);
+       if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX) {
+               if (die_on_error)
+                       die("Too long path: %.*s", 60, path);
+               else
+                       goto error_out;
+       }
 
        while (depth--) {
                if (!is_directory(buf)) {
@@ -54,20 +73,36 @@ const char *real_path(const char *path)
                }
 
                if (*buf) {
-                       if (!*cwd && !getcwd(cwd, sizeof(cwd)))
-                               die_errno ("Could not get current working directory");
+                       if (!*cwd && !getcwd(cwd, sizeof(cwd))) {
+                               if (die_on_error)
+                                       die_errno("Could not get current working directory");
+                               else
+                                       goto error_out;
+                       }
 
-                       if (chdir(buf))
-                               die_errno ("Could not switch to '%s'", buf);
+                       if (chdir(buf)) {
+                               if (die_on_error)
+                                       die_errno("Could not switch to '%s'", buf);
+                               else
+                                       goto error_out;
+                       }
+               }
+               if (!getcwd(buf, PATH_MAX)) {
+                       if (die_on_error)
+                               die_errno("Could not get current working directory");
+                       else
+                               goto error_out;
                }
-               if (!getcwd(buf, PATH_MAX))
-                       die_errno ("Could not get current working directory");
 
                if (last_elem) {
                        size_t len = strlen(buf);
-                       if (len + strlen(last_elem) + 2 > PATH_MAX)
-                               die ("Too long path name: '%s/%s'",
-                                               buf, last_elem);
+                       if (len + strlen(last_elem) + 2 > PATH_MAX) {
+                               if (die_on_error)
+                                       die("Too long path name: '%s/%s'",
+                                           buf, last_elem);
+                               else
+                                       goto error_out;
+                       }
                        if (len && !is_dir_sep(buf[len-1]))
                                buf[len++] = '/';
                        strcpy(buf + len, last_elem);
@@ -77,10 +112,18 @@ const char *real_path(const char *path)
 
                if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
                        ssize_t len = readlink(buf, next_buf, PATH_MAX);
-                       if (len < 0)
-                               die_errno ("Invalid symlink '%s'", buf);
-                       if (PATH_MAX <= len)
-                               die("symbolic link too long: %s", buf);
+                       if (len < 0) {
+                               if (die_on_error)
+                                       die_errno("Invalid symlink '%s'", buf);
+                               else
+                                       goto error_out;
+                       }
+                       if (PATH_MAX <= len) {
+                               if (die_on_error)
+                                       die("symbolic link too long: %s", buf);
+                               else
+                                       goto error_out;
+                       }
                        next_buf[len] = '\0';
                        buf = next_buf;
                        buf_index = 1 - buf_index;
@@ -89,10 +132,18 @@ const char *real_path(const char *path)
                        break;
        }
 
+       retval = buf;
+error_out:
+       free(last_elem);
        if (*cwd && chdir(cwd))
                die_errno ("Could not change back to '%s'", cwd);
 
-       return buf;
+       return retval;
+}
+
+const char *real_path(const char *path)
+{
+       return real_path_internal(path, 1);
 }
 
 static const char *get_pwd_cwd(void)