enter_repo: do not modify input

entr_repo(..., 0) currently modifies the input to strip away
trailing slashes. This means that we some times need to copy the
input to keep the original.

Change it to unconditionally copy it into the used_path buffer so
we can safely use the input without having to copy it. Also store
a working copy in validated_path up-front before we start
resolving anything.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Phil Hord <hordp@cisco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -734,7 +734,7 @@ int safe_create_leading_directories(char *path);
 int safe_create_leading_directories_const(const char *path);
 int mkdir_in_gitdir(const char *path);
 extern char *expand_user_path(const char *path);
-char *enter_repo(char *path, int strict);
+const char *enter_repo(const char *path, int strict);
 static inline int is_absolute_path(const char *path)
 {
 	return is_dir_sep(path[0]) || has_dos_drive_prefix(path);

daemon.c

@@ -108,11 +108,11 @@ static void NORETURN daemon_die(const char *err, va_list params)
 	exit(1);
 }
 
-static char *path_ok(char *directory)
+static const char *path_ok(char *directory)
 {
 	static char rpath[PATH_MAX];
 	static char interp_path[PATH_MAX];
-	char *path;
+	const char *path;
 	char *dir;
 
 	dir = directory;

path.c

@@ -283,7 +283,7 @@ return_null:
  * links.  User relative paths are also returned as they are given,
  * except DWIM suffixing.
  */
-char *enter_repo(char *path, int strict)
+const char *enter_repo(const char *path, int strict)
 {
 	static char used_path[PATH_MAX];
 	static char validated_path[PATH_MAX];
@@ -297,14 +297,16 @@ char *enter_repo(char *path, int strict)
 		};
 		int len = strlen(path);
 		int i;
-		while ((1 < len) && (path[len-1] == '/')) {
-			path[len-1] = 0;
+		while ((1 < len) && (path[len-1] == '/'))
 			len--;
-		}
+
 		if (PATH_MAX <= len)
 			return NULL;
-		if (path[0] == '~') {
-			char *newpath = expand_user_path(path);
+		strncpy(used_path, path, len); used_path[len] = 0 ;
+		strcpy(validated_path, used_path);
+
+		if (used_path[0] == '~') {
+			char *newpath = expand_user_path(used_path);
 			if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 				free(newpath);
 				return NULL;
@@ -316,24 +318,18 @@ char *enter_repo(char *path, int strict)
 			 * anyway.
 			 */
 			strcpy(used_path, newpath); free(newpath);
-			strcpy(validated_path, path);
-			path = used_path;
 		}
 		else if (PATH_MAX - 10 < len)
 			return NULL;
-		else {
-			path = strcpy(used_path, path);
-			strcpy(validated_path, path);
-		}
-		len = strlen(path);
+		len = strlen(used_path);
 		for (i = 0; suffix[i]; i++) {
-			strcpy(path + len, suffix[i]);
-			if (!access(path, F_OK)) {
+			strcpy(used_path + len, suffix[i]);
+			if (!access(used_path, F_OK)) {
 				strcat(validated_path, suffix[i]);
 				break;
 			}
 		}
-		if (!suffix[i] || chdir(path))
+		if (!suffix[i] || chdir(used_path))
 			return NULL;
 		path = validated_path;
 	}