Merge branch 'bw/realpath-wo-chdir'

The implementation of "real_path()" was to go there with chdir(2)
and call getcwd(3), but this obviously wouldn't be usable in a
threaded environment.  Rewrite it to manually resolve relative
paths including symbolic links in path components.

* bw/realpath-wo-chdir:
  real_path: set errno when max number of symlinks is exceeded
  real_path: prevent redefinition of MAXSYMLINKS

abspath.c

@@ -62,7 +62,9 @@ static void get_root_part(struct strbuf *resolved, struct strbuf *remaining)
 }
 
 /* We allow "recursive" symbolic links. Only within reason, though. */
-#define MAXSYMLINKS 5
+#ifndef MAXSYMLINKS
+#define MAXSYMLINKS 32
+#endif
 
 /*
  * Return the real path (i.e., absolute path, with symlinks resolved
@@ -139,6 +141,8 @@ char *strbuf_realpath(struct strbuf *resolved, const char *path,
 			strbuf_reset(&symlink);
 
 			if (num_symlinks++ > MAXSYMLINKS) {
+				errno = ELOOP;
+
 				if (die_on_error)
 					die("More than %d nested symlinks "
 					    "on path '%s'", MAXSYMLINKS, path);

dir.c

@@ -2731,8 +2731,8 @@ void connect_work_tree_and_git_dir(const char *work_tree_, const char *git_dir_)
 {
 	struct strbuf file_name = STRBUF_INIT;
 	struct strbuf rel_path = STRBUF_INIT;
-	char *git_dir = xstrdup(real_path(git_dir_));
-	char *work_tree = xstrdup(real_path(work_tree_));
+	char *git_dir = real_pathdup(git_dir_);
+	char *work_tree = real_pathdup(work_tree_);
 
 	/* Update gitfile */
 	strbuf_addf(&file_name, "%s/.git", work_tree);