Clarify commit-tree documentation

[thirdparty/git.git] / dir.c

diff --git a/dir.c b/dir.c
index 8d8faf5d788b402d5fd4f5d724954fd2ee178fdb..eb6c3abd30baefb9501c69b0e956ae1231f4b085 100644 (file)
--- a/dir.c
+++ b/dir.c
@@ -642,3 +642,46 @@ file_exists(const char *f)
   struct stat sb;
   return stat(f, &sb) == 0;
 }
+
+/*
+ * get_relative_cwd() gets the prefix of the current working directory
+ * relative to 'dir'.  If we are not inside 'dir', it returns NULL.
+ *
+ * As a convenience, it also returns NULL if 'dir' is already NULL.  The
+ * reason for this behaviour is that it is natural for functions returning
+ * directory names to return NULL to say "this directory does not exist"
+ * or "this directory is invalid".  These cases are usually handled the
+ * same as if the cwd is not inside 'dir' at all, so get_relative_cwd()
+ * returns NULL for both of them.
+ *
+ * Most notably, get_relative_cwd(buffer, size, get_git_work_tree())
+ * unifies the handling of "outside work tree" with "no work tree at all".
+ */
+char *get_relative_cwd(char *buffer, int size, const char *dir)
+{
+       char *cwd = buffer;
+
+       if (!dir)
+               return NULL;
+       if (!getcwd(buffer, size))
+               die("can't find the current directory: %s", strerror(errno));
+
+       if (!is_absolute_path(dir))
+               dir = make_absolute_path(dir);
+
+       while (*dir && *dir == *cwd) {
+               dir++;
+               cwd++;
+       }
+       if (*dir)
+               return NULL;
+       if (*cwd == '/')
+               return cwd + 1;
+       return cwd;
+}
+
+int is_inside_dir(const char *dir)
+{
+       char buffer[PATH_MAX];
+       return get_relative_cwd(buffer, sizeof(buffer), dir) != NULL;
+}