- if (!path || path[0] != '~')
- return NULL;
- path++;
- slash = strchr(path, '/');
- if (path[0] == '/' || !path[0]) {
- pw = getpwuid(getuid());
- }
- else {
- if (slash) {
- *slash = 0;
- pw = getpwnam(path);
- *slash = '/';
- }
- else
- pw = getpwnam(path);
- }
- if (!pw || !pw->pw_dir || sz <= strlen(pw->pw_dir))
- return NULL;
- baselen = strlen(pw->pw_dir);
- memcpy(buf, pw->pw_dir, baselen);
- while ((1 < baselen) && (buf[baselen-1] == '/')) {
- buf[baselen-1] = 0;
- baselen--;
- }
- if (slash && slash[1]) {
- len = strlen(slash);
- if (sz <= baselen + len)
- return NULL;
- memcpy(buf + baselen, slash, len + 1);
+/*
+ * Return a string with ~ and ~user expanded via getpw*. If buf != NULL,
+ * then it is a newly allocated string. Returns NULL on getpw failure or
+ * if path is NULL.
+ */
+char *expand_user_path(const char *path)
+{
+ struct strbuf user_path = STRBUF_INIT;
+ const char *first_slash = strchrnul(path, '/');
+ const char *to_copy = path;
+
+ if (path == NULL)
+ goto return_null;
+ if (path[0] == '~') {
+ const char *username = path + 1;
+ size_t username_len = first_slash - username;
+ struct passwd *pw = getpw_str(username, username_len);
+ if (!pw)
+ goto return_null;
+ strbuf_add(&user_path, pw->pw_dir, strlen(pw->pw_dir));
+ to_copy = first_slash;