[PATCH] get_sha1: support relative path "<obj>:<sth>" syntax

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Currently :path and ref:path can be used to refer to a specific object
in index or ref respectively. "path" component is absolute path. This
patch allows "path" to be written as "./path" or "../path", which is
relative to user's original cwd.

This does not work in commands that startup_info is NULL
(i.e. non-builtin ones).
---
 On Wed, Nov 10, 2010 at 07:26:20AM -0800, Jakub Narebski wrote:
 > The <obj>:<sth> is (with single exception of ':/<regexp>') about
 > selecting subitem (path): <tree-ish>:<path>, [:<stage>]:<path>

 I feel the urge of keeping ':./path' and ':../path' out of this
 competition.

 The idea is old although I don't remember if anybody has made any
 attempt to realize it: use './' and '../' to specify the given path
 is relative, not absolute.

 I don't remember either if the idea was rejected or nobody bothered
 to implement it. Anyway, here it is (for demostration only because it
 needs two minor patches to work). Comments?
 --
 Duy

 sha1_name.c |   30 +++++++++++++++++++++++++++---
 1 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/sha1_name.c b/sha1_name.c
index 484081d..791608d 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1060,25 +1060,35 @@ int get_sha1_with_context_1(const char *name, unsigned char *sha1,
 	if (!ret)
 		return ret;
 	/* sha1:path --> object name of path in ent sha1
-	 * :path -> object name of path in index
+	 * :path -> object name of absolute path in index
+	 * :./path -> object name of path relative to cwd in index
 	 * :[0-3]:path -> object name of path in index at stage
 	 * :/foo -> recent commit matching foo
 	 */
 	if (name[0] == ':') {
 		int stage = 0;
 		struct cache_entry *ce;
+		char *new_path = NULL;
 		int pos;
 		if (namelen > 2 && name[1] == '/')
 			return get_sha1_oneline(name + 2, sha1);
 		if (namelen < 3 ||
 		    name[2] != ':' ||
-		    name[1] < '0' || '3' < name[1])
+		    name[1] < '0' || '3' < name[1]) {
 			cp = name + 1;
+			if (startup_info && cp[0] == '.' &&
+			    (cp[1] == '/' || (cp[1] == '.' && cp[2] == '/'))) {
+				new_path = prefix_path(startup_info->prefix,
+						       strlen(startup_info->prefix),
+						       cp);
+				cp = new_path;
+			}
+		}
 		else {
 			stage = name[1] - '0';
 			cp = name + 3;
 		}
-		namelen = namelen - (cp - name);
+		namelen = strlen(cp);
 
 		strncpy(oc->path, cp,
 			sizeof(oc->path));
@@ -1096,12 +1106,14 @@ int get_sha1_with_context_1(const char *name, unsigned char *sha1,
 				break;
 			if (ce_stage(ce) == stage) {
 				hashcpy(sha1, ce->sha1);
+				free(new_path);
 				return 0;
 			}
 			pos++;
 		}
 		if (!gently)
 			diagnose_invalid_index_path(stage, prefix, cp);
+		free(new_path);
 		return -1;
 	}
 	for (cp = name, bracket_depth = 0; *cp; cp++) {
@@ -1122,6 +1134,17 @@ int get_sha1_with_context_1(const char *name, unsigned char *sha1,
 		}
 		if (!get_sha1_1(name, cp-name, tree_sha1)) {
 			const char *filename = cp+1;
+			char *new_filename = NULL;
+
+			if (startup_info &&
+			    filename[0] == '.' &&
+			    (filename[1] == '/' ||
+			     (filename[1] == '.' && filename[2] == '/'))) {
+				new_filename = prefix_path(startup_info->prefix,
+							   strlen(startup_info->prefix),
+							   filename);
+				filename = new_filename;
+			}
 			ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
 			if (!gently) {
 				diagnose_invalid_sha1_path(prefix, filename,
@@ -1133,6 +1156,7 @@ int get_sha1_with_context_1(const char *name, unsigned char *sha1,
 				sizeof(oc->path));
 			oc->path[sizeof(oc->path)-1] = '\0';
 
+			free(new_filename);
 			return ret;
 		} else {
 			if (!gently)
-- 
1.7.3.2.210.g045198