Merge branch 'lt/gitlink'

* lt/gitlink:
  Tests for core subproject support
  Expose subprojects as special files to "git diff" machinery
  Fix some "git ls-files -o" fallout from gitlinks
  Teach "git-read-tree -u" to check out submodules as a directory
  Teach git list-objects logic to not follow gitlinks
  Fix gitlink index entry filesystem matching
  Teach "git-read-tree -u" to check out submodules as a directory
  Teach git list-objects logic not to follow gitlinks
  Don't show gitlink directories when we want "other" files
  Teach git-update-index about gitlinks
  Teach directory traversal about subprojects
  Fix thinko in subproject entry sorting
  Teach core object handling functions about gitlinks
  Teach "fsck" not to follow subproject links
  Add "S_IFDIRLNK" file mode infrastructure for git links
  Add 'resolve_gitlink_ref()' helper function
  Avoid overflowing name buffer in deep directory structures
  diff-lib: use ce_mode_from_stat() rather than messing with modes manually

1 files changed, 138 insertions, 62 deletions

diff --git a/builtin-update-index.c b/builtin-update-index.c
index e5541df284..8f9899178b 100644
--- a/builtin-update-index.c
+++ b/builtin-update-index.c
@@ -9,6 +9,7 @@
 #include "cache-tree.h"
 #include "tree-walk.h"
 #include "builtin.h"
+#include "refs.h"
 
 /*
  * Default to not allowing changes to the list of files. The
@@ -60,78 +61,153 @@ static int mark_valid(const char *path)
 	return -1;
 }
 
-static int process_file(const char *path)
+static int remove_one_path(const char *path)
 {
-	int size, namelen, option, status;
-	struct cache_entry *ce;
-	struct stat st;
-
-	status = lstat(path, &st);
-
-	/* We probably want to do this in remove_file_from_cache() and
-	 * add_cache_entry() instead...
-	 */
-	cache_tree_invalidate_path(active_cache_tree, path);
+	if (!allow_remove)
+		return error("%s: does not exist and --remove not passed", path);
+	if (remove_file_from_cache(path))
+		return error("%s: cannot remove from the index", path);
+	return 0;
+}
 
-	if (status < 0 || S_ISDIR(st.st_mode)) {
-		/* When we used to have "path" and now we want to add
-		 * "path/file", we need a way to remove "path" before
-		 * being able to add "path/file".  However,
-		 * "git-update-index --remove path" would not work.
-		 * --force-remove can be used but this is more user
-		 * friendly, especially since we can do the opposite
-		 * case just fine without --force-remove.
-		 */
-		if (status == 0 || (errno == ENOENT || errno == ENOTDIR)) {
-			if (allow_remove) {
-				if (remove_file_from_cache(path))
-					return error("%s: cannot remove from the index",
-					             path);
-				else
-					return 0;
-			} else if (status < 0) {
-				return error("%s: does not exist and --remove not passed",
-				             path);
-			}
-		}
-		if (0 == status)
-			return error("%s: is a directory - add files inside instead",
-			             path);
-		else
-			return error("lstat(\"%s\"): %s", path,
-				     strerror(errno));
-	}
+/*
+ * Handle a path that couldn't be lstat'ed. It's either:
+ *  - missing file (ENOENT or ENOTDIR). That's ok if we're
+ *    supposed to be removing it and the removal actually
+ *    succeeds.
+ *  - permission error. That's never ok.
+ */
+static int process_lstat_error(const char *path, int err)
+{
+	if (err == ENOENT || err == ENOTDIR)
+		return remove_one_path(path);
+	return error("lstat(\"%s\"): %s", path, strerror(errno));
+}
 
-	namelen = strlen(path);
-	size = cache_entry_size(namelen);
-	ce = xcalloc(1, size);
-	memcpy(ce->name, path, namelen);
-	ce->ce_flags = htons(namelen);
-	fill_stat_cache_info(ce, &st);
-
-	if (trust_executable_bit && has_symlinks)
-		ce->ce_mode = create_ce_mode(st.st_mode);
-	else {
-		/* If there is an existing entry, pick the mode bits and type
-		 * from it, otherwise assume unexecutable regular file.
-		 */
-		struct cache_entry *ent;
-		int pos = cache_name_pos(path, namelen);
+static int add_one_path(struct cache_entry *old, const char *path, int len, struct stat *st)
+{
+	int option, size = cache_entry_size(len);
+	struct cache_entry *ce = xcalloc(1, size);
 
-		ent = (0 <= pos) ? active_cache[pos] : NULL;
-		ce->ce_mode = ce_mode_from_stat(ent, st.st_mode);
-	}
+	memcpy(ce->name, path, len);
+	ce->ce_flags = htons(len);
+	fill_stat_cache_info(ce, st);
+	ce->ce_mode = ce_mode_from_stat(old, st->st_mode);
 
-	if (index_path(ce->sha1, path, &st, !info_only))
+	if (index_path(ce->sha1, path, st, !info_only))
 		return -1;
 	option = allow_add ? ADD_CACHE_OK_TO_ADD : 0;
 	option |= allow_replace ? ADD_CACHE_OK_TO_REPLACE : 0;
 	if (add_cache_entry(ce, option))
-		return error("%s: cannot add to the index - missing --add option?",
-			     path);
+		return error("%s: cannot add to the index - missing --add option?", path);
 	return 0;
 }
 
+/*
+ * Handle a path that was a directory. Four cases:
+ *
+ *  - it's already a gitlink in the index, and we keep it that
+ *    way, and update it if we can (if we cannot find the HEAD,
+ *    we're going to keep it unchanged in the index!)
+ *
+ *  - it's a *file* in the index, in which case it should be
+ *    removed as a file if removal is allowed, since it doesn't
+ *    exist as such any more. If removal isn't allowed, it's
+ *    an error.
+ *
+ *    (NOTE! This is old and arguably fairly strange behaviour.
+ *    We might want to make this an error unconditionally, and
+ *    use "--force-remove" if you actually want to force removal).
+ *
+ *  - it used to exist as a subdirectory (ie multiple files with
+ *    this particular prefix) in the index, in which case it's wrong
+ *    to try to update it as a directory.
+ *
+ *  - it doesn't exist at all in the index, but it is a valid
+ *    git directory, and it should be *added* as a gitlink.
+ */
+static int process_directory(const char *path, int len, struct stat *st)
+{
+	unsigned char sha1[20];
+	int pos = cache_name_pos(path, len);
+
+	/* Exact match: file or existing gitlink */
+	if (pos >= 0) {
+		struct cache_entry *ce = active_cache[pos];
+		if (S_ISDIRLNK(ntohl(ce->ce_mode))) {
+
+			/* Do nothing to the index if there is no HEAD! */
+			if (resolve_gitlink_ref(path, "HEAD", sha1) < 0)
+				return 0;
+
+			return add_one_path(ce, path, len, st);
+		}
+		/* Should this be an unconditional error? */
+		return remove_one_path(path);
+	}
+
+	/* Inexact match: is there perhaps a subdirectory match? */
+	pos = -pos-1;
+	while (pos < active_nr) {
+		struct cache_entry *ce = active_cache[pos++];
+
+		if (strncmp(ce->name, path, len))
+			break;
+		if (ce->name[len] > '/')
+			break;
+		if (ce->name[len] < '/')
+			continue;
+
+		/* Subdirectory match - error out */
+		return error("%s: is a directory - add individual files instead", path);
+	}
+
+	/* No match - should we add it as a gitlink? */
+	if (!resolve_gitlink_ref(path, "HEAD", sha1))
+		return add_one_path(NULL, path, len, st);
+
+	/* Error out. */
+	return error("%s: is a directory - add files inside instead", path);
+}
+
+/*
+ * Process a regular file
+ */
+static int process_file(const char *path, int len, struct stat *st)
+{
+	int pos = cache_name_pos(path, len);
+	struct cache_entry *ce = pos < 0 ? NULL : active_cache[pos];
+
+	if (ce && S_ISDIRLNK(ntohl(ce->ce_mode)))
+		return error("%s is already a gitlink, not replacing", path);
+
+	return add_one_path(ce, path, len, st);
+}
+
+static int process_path(const char *path)
+{
+	int len;
+	struct stat st;
+
+	/* We probably want to do this in remove_file_from_cache() and
+	 * add_cache_entry() instead...
+	 */
+	cache_tree_invalidate_path(active_cache_tree, path);
+
+	/*
+	 * First things first: get the stat information, to decide
+	 * what to do about the pathname!
+	 */
+	if (lstat(path, &st) < 0)
+		return process_lstat_error(path, errno);
+
+	len = strlen(path);
+	if (S_ISDIR(st.st_mode))
+		return process_directory(path, len, &st);
+
+	return process_file(path, len, &st);
+}
+
 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 			 const char *path, int stage)
 {
@@ -210,8 +286,8 @@ static void update_one(const char *path, const char *prefix, int prefix_length)
 		report("remove '%s'", path);
 		goto free_return;
 	}
-	if (process_file(p))
-		die("Unable to process file %s", path);
+	if (process_path(p))
+		die("Unable to process path %s", path);
 	report("add '%s'", path);
  free_return:
 	if (p < path || p > path + strlen(path))