[PATCH v7 0/3]

[PATCH v7 0/3]

[dturner]

This version of the patch adds improved error outputs for various
weird situations that can come up during symlink resolution.  It
also improves the documentation, following suggestions by Junio Hamano.

[PATCH v7 1/3] tree-walk: learn get_tree_entry_follow_symlinks

[dturner]

From: David Turner <dturner@twitter.com>

Add a new function, get_tree_entry_follow_symlinks, to tree-walk.[ch].
The function is not yet used.  It will be used to implement git
cat-file --batch --follow-symlinks.

The function locates an object by path, following symlinks in the
repository.  If the symlinks lead outside the repository, the function
reports this to the caller.

Signed-off-by: David Turner <dturner@twitter.com>
---
 tree-walk.c | 206 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tree-walk.h |  18 ++++++
 2 files changed, 224 insertions(+)

diff --git a/tree-walk.c b/tree-walk.c
index 5dd9a71..81d6604 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -415,6 +415,12 @@ int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
 	return error;
 }
 
+struct dir_state {
+	void *tree;
+	unsigned long size;
+	unsigned char sha1[20];
+};
+
 static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
 {
 	int namelen = strlen(name);
@@ -478,6 +484,206 @@ int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned ch
 	return retval;
 }
 
+/*
+ * This is Linux's built-in max for the number of symlinks to follow.
+ * That limit, of course, does not affect git, but it's a reasonable
+ * choice.
+ */
+#define GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS 40
+
+/**
+ * Find a tree entry by following symlinks in tree_sha (which is
+ * assumed to be the root of the repository).  In the event that a
+ * symlink points outside the repository (e.g. a link to /foo or a
+ * root-level link to ../foo), the portion of the link which is
+ * outside the repository will be returned in result_path, and *mode
+ * will be set to 0.  It is assumed that result_path is uninitialized.
+ * If there are no symlinks, or the end result of the symlink chain
+ * points to an object inside the repository, result will be filled in
+ * with the sha1 of the found object, and *mode will hold the mode of
+ * the object.
+ *
+ * See the code for enum follow_symlink_result for a description of
+ * the return values.
+ */
+enum follow_symlinks_result get_tree_entry_follow_symlinks(unsigned char *tree_sha1, const char *name, unsigned char *result, struct strbuf *result_path, unsigned *mode)
+{
+	int retval = MISSING_OBJECT;
+	struct dir_state *parents = NULL;
+	size_t parents_alloc = 0;
+	ssize_t parents_nr = 0;
+	unsigned char current_tree_sha1[20];
+	struct strbuf namebuf = STRBUF_INIT;
+	struct tree_desc t = {0};
+	int follows_remaining = GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS;
+	int i;
+
+	result_path->buf = 0;
+	result_path->alloc = 0;
+	result_path->len = 0;
+	strbuf_addstr(&namebuf, name);
+	hashcpy(current_tree_sha1, tree_sha1);
+
+	while (1) {
+		int find_result;
+		char *first_slash;
+		char *remainder = NULL;
+
+		if (!t.buffer) {
+			void *tree;
+			unsigned char root[20];
+			unsigned long size;
+			tree = read_object_with_reference(current_tree_sha1,
+							  tree_type, &size,
+							  root);
+			if (!tree)
+				goto done;
+
+			ALLOC_GROW(parents, parents_nr + 1, parents_alloc);
+			parents[parents_nr].tree = tree;
+			parents[parents_nr].size = size;
+			hashcpy(parents[parents_nr].sha1, root);
+			parents_nr++;
+
+			if (namebuf.buf[0] == '\0') {
+				hashcpy(result, root);
+				retval = FOUND;
+				goto done;
+			}
+
+			if (!size)
+				goto done;
+
+			/* descend */
+			init_tree_desc(&t, tree, size);
+		}
+
+		/* Handle symlinks to e.g. a//b by removing leading slashes */
+		while (namebuf.buf[0] == '/') {
+			strbuf_remove(&namebuf, 0, 1);
+		}
+
+		/* Split namebuf into a first component and a remainder */
+		if ((first_slash = strchr(namebuf.buf, '/'))) {
+			*first_slash = 0;
+			remainder = first_slash + 1;
+		}
+
+		if (!strcmp(namebuf.buf, "..")) {
+			struct dir_state *parent;
+			/*
+			 * We could end up with .. in the namebuf if it
+			 * appears in a symlink.
+			 */
+
+			if (parents_nr == 1) {
+				if (remainder)
+					*first_slash = '/';
+				strbuf_add(result_path, namebuf.buf,
+					   namebuf.len);
+				*mode = 0;
+				retval = FOUND;
+				goto done;
+			}
+			parent = &parents[parents_nr - 1];
+			free(parent->tree);
+			parents_nr--;
+			parent = &parents[parents_nr - 1];
+			init_tree_desc(&t, parent->tree, parent->size);
+			strbuf_remove(&namebuf, 0, remainder ? 3 : 2);
+			continue;
+		}
+
+		/* We could end up here via a symlink to dir/.. */
+		if (namebuf.buf[0] == '\0') {
+			hashcpy(result, parents[parents_nr - 1].sha1);
+			retval = FOUND;
+			goto done;
+		}
+
+		/* Look up the first (or only) path component in the tree. */
+		find_result = find_tree_entry(&t, namebuf.buf,
+					      current_tree_sha1, mode);
+		if (find_result) {
+			goto done;
+		}
+
+		if (S_ISDIR(*mode)) {
+			if (!remainder) {
+				hashcpy(result, current_tree_sha1);
+				retval = FOUND;
+				goto done;
+			}
+			/* Descend the tree */
+			t.buffer = NULL;
+			strbuf_remove(&namebuf, 0,
+				      1 + first_slash - namebuf.buf);
+		} else if (S_ISREG(*mode)) {
+			if (!remainder) {
+				hashcpy(result, current_tree_sha1);
+				retval = FOUND;
+			} else {
+				retval = NOT_DIR;
+			}
+			goto done;
+		} else if (S_ISLNK(*mode)) {
+			/* Follow a symlink */
+			unsigned long link_len;
+			size_t len;
+			char *contents, *contents_start;
+			struct dir_state *parent;
+			enum object_type type;
+
+			if (follows_remaining-- == 0) {
+				/* Too many symlinks followed */
+				retval = SYMLINK_LOOP;
+				goto done;
+			}
+
+			/*
+			 * At this point, we have followed at a least
+			 * one symlink, so on error we need to report this.
+			 */
+			retval = DANGLING_SYMLINK;
+
+			contents = read_sha1_file(current_tree_sha1, &type,
+						  &link_len);
+
+			if (!contents)
+				goto done;
+
+			if (contents[0] == '/') {
+				strbuf_addstr(result_path, contents);
+				*mode = 0;
+				retval = FOUND;
+				goto done;
+			}
+
+			if (remainder)
+				len = first_slash - namebuf.buf;
+			else
+				len = namebuf.len;
+
+			contents_start = contents;
+
+			parent = &parents[parents_nr - 1];
+			init_tree_desc(&t, parent->tree, parent->size);
+			strbuf_splice(&namebuf, 0, len,
+				      contents_start, link_len);
+			if (remainder)
+				namebuf.buf[link_len] = '/';
+			free(contents);
+		}
+	}
+done:
+	for (i = 0; i < parents_nr; i++)
+		free(parents[i].tree);
+	free(parents);
+
+	strbuf_release(&namebuf);
+	return retval;
+}
+
 static int match_entry(const struct pathspec_item *item,
 		       const struct name_entry *entry, int pathlen,
 		       const char *match, int matchlen,
diff --git a/tree-walk.h b/tree-walk.h
index ae7fb3a..3b2f7bf 100644
--- a/tree-walk.h
+++ b/tree-walk.h
@@ -40,6 +40,24 @@ struct traverse_info;
 typedef int (*traverse_callback_t)(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *);
 int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info);
 
+enum follow_symlinks_result {
+	FOUND = 0, /* This includes out-of-tree links */
+	MISSING_OBJECT = -1, /* The initial symlink is missing */
+	DANGLING_SYMLINK = -2, /*
+				* The initial symlink is there, but
+				* (transitively) points to a missing
+				* in-tree file
+				*/
+	SYMLINK_LOOP = -3,
+	NOT_DIR = -4, /*
+		       * Somewhere along the symlink chain, a path is
+		       * requested which contains a file as a
+		       * non-final element.
+		       */
+};
+
+enum follow_symlinks_result get_tree_entry_follow_symlinks(unsigned char *tree_sha1, const char *name, unsigned char *result, struct strbuf *result_path, unsigned *mode);
+
 struct traverse_info {
 	struct traverse_info *prev;
 	struct name_entry name;
-- 
2.0.4.315.gad8727a-twtrsrc

[PATCH v7 2/3] sha1_name: get_sha1_with_context learns to follow symlinks

[dturner]

From: David Turner <dturner@twitter.com>

Wire up get_sha1_with_context to call get_tree_entry_follow_symlinks
when GET_SHA1_FOLLOW_SYMLINKS is passed in flags. G_S_FOLLOW_SYMLINKS
is incompatible with G_S_ONLY_TO_DIE because the diagnosis
that ONLY_TO_DIE triggers does not at present consider symlinks, and
it would be a significant amount of additional code to allow it to
do so.

Signed-off-by: David Turner <dturner@twitter.com>
---
 cache.h     | 20 +++++++++++++-------
 sha1_name.c | 20 +++++++++++++++-----
 2 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/cache.h b/cache.h
index 3d3244b..65505d1 100644
--- a/cache.h
+++ b/cache.h
@@ -922,15 +922,21 @@ struct object_context {
 	unsigned char tree[20];
 	char path[PATH_MAX];
 	unsigned mode;
+	/*
+	 * symlink_path is only used by get_tree_entry_follow_symlinks,
+	 * and only for symlinks that point outside the repository.
+	 */
+	struct strbuf symlink_path;
 };
 
-#define GET_SHA1_QUIETLY        01
-#define GET_SHA1_COMMIT         02
-#define GET_SHA1_COMMITTISH     04
-#define GET_SHA1_TREE          010
-#define GET_SHA1_TREEISH       020
-#define GET_SHA1_BLOB	       040
-#define GET_SHA1_ONLY_TO_DIE 04000
+#define GET_SHA1_QUIETLY           01
+#define GET_SHA1_COMMIT            02
+#define GET_SHA1_COMMITTISH        04
+#define GET_SHA1_TREE             010
+#define GET_SHA1_TREEISH          020
+#define GET_SHA1_BLOB             040
+#define GET_SHA1_FOLLOW_SYMLINKS 0100
+#define GET_SHA1_ONLY_TO_DIE    04000
 
 extern int get_sha1(const char *str, unsigned char *sha1);
 extern int get_sha1_commit(const char *str, unsigned char *sha1);
diff --git a/sha1_name.c b/sha1_name.c
index 6d10f05..0c26515 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1434,11 +1434,19 @@ static int get_sha1_with_context_1(const char *name,
 			new_filename = resolve_relative_path(filename);
 			if (new_filename)
 				filename = new_filename;
-			ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
-			if (ret && only_to_die) {
-				diagnose_invalid_sha1_path(prefix, filename,
-							   tree_sha1,
-							   name, len);
+			if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
+				ret = get_tree_entry_follow_symlinks(tree_sha1,
+					filename, sha1, &oc->symlink_path,
+					&oc->mode);
+			} else {
+				ret = get_tree_entry(tree_sha1, filename,
+						     sha1, &oc->mode);
+				if (ret && only_to_die) {
+					diagnose_invalid_sha1_path(prefix,
+								   filename,
+								   tree_sha1,
+								   name, len);
+				}
 			}
 			hashcpy(oc->tree, tree_sha1);
 			strlcpy(oc->path, filename, sizeof(oc->path));
@@ -1469,5 +1477,7 @@ void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
 
 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
 {
+	if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
+		die("BUG: incompatible flags for get_sha1_with_context");
 	return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
 }
-- 
2.0.4.315.gad8727a-twtrsrc

[PATCH v7 3/3] cat-file: add --follow-symlinks to --batch

[dturner]

From: David Turner <dturner@twitter.com>

This wires the in-repo-symlink following code through to the cat-file
builtin.  In the event of an out-of-repo link, cat-file will print
the link in a new format.

Signed-off-by: David Turner <dturner@twitter.com>
---
 Documentation/git-cat-file.txt |  98 +++++++++++++++++++-
 builtin/cat-file.c             |  46 ++++++++-
 t/t1006-cat-file.sh            | 205 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 343 insertions(+), 6 deletions(-)

diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index f6a16f4..f4e3590 100644
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt
@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git cat-file' (-t | -s | -e | -p | <type> | --textconv ) <object>
-'git cat-file' (--batch | --batch-check) < <list-of-objects>
+'git cat-file' (--batch | --batch-check) [--follow-symlinks] < <list-of-objects>
 
 DESCRIPTION
 -----------
@@ -69,6 +69,61 @@ OPTIONS
 	not be combined with any other options or arguments.  See the
 	section `BATCH OUTPUT` below for details.
 
+--follow-symlinks::
+	With --batch or --batch-check, follow symlinks inside the
+	repository when requesting objects with extended SHA-1
+	expressions of the form tree-ish:path-in-tree.  Instead of
+	providing output about the link itself, provide output about
+	the linked-to object.  If a symlink points outside the
+	tree-ish (e.g. a link to /foo or a root-level link to ../foo),
+	the portion of the link which is outside the tree will be
+	printed.
+[normal]
+	This option does not (currently) work correctly when an
+	object in the index is specified (e.g. `:link` instead of
+	`HEAD:link`) rather than one in the tree.
+[normal]
+	This option cannot be used unless `--batch` or `--batch-check`
+	is used, because it would be impossible to distinguish between
+	the output for an out-of-repo symlink, and the contents of a
+	blob.
+
+For example, consider a git repository containing:
+
+--
+	f: a file containing "hello\n"
+	link: a symlink to f
+	dir/link: a symlink to ../f
+	plink: a symlink to ../f
+	alink: a symlink to /etc/passwd
+--
+For a regular file `f`, `echo HEAD:f | git cat-file --batch` would print
+--
+	ce013625030ba8dba906f756967f9e9ca394464a blob 6
+--
+
+And `echo HEAD:link | git cat-file --batch --follow-symlinks` would print
+the same thing, as would `HEAD:dir/link`, as they both point at `HEAD:f`.
+
+Without `--follow-symlinks`, these would print data about the
+symlink itself.  In the case of `HEAD:link`, you would see
+
+--
+	4d1ae35ba2c8ec712fa2a379db44ad639ca277bd blob 1
+--
+
+Both `plink` and `alink` point outside the tree, so they would
+respectively print:
+
+--
+	symlink 4
+	../f
+
+	symlink 11
+	/etc/passwd
+--
+
+
 OUTPUT
 ------
 If '-t' is specified, one of the <type>.
@@ -148,6 +203,47 @@ the repository, then `cat-file` will ignore any custom format and print:
 <object> SP missing LF
 ------------
 
+If --follow-symlinks is used, and a symlink in the repository points
+outside the repository, then `cat-file` will ignore any custom format
+and print:
+
+------------
+symlink SP <size> LF
+<symlink> LF
+------------
+
+The symlink will either be absolute (beginning with a /), or relative
+to the tree root.  For instance, if dir/link points to ../../foo, then
+<symlink> will be ../foo.  <size> is the size of the symlink in bytes.
+
+If --follow-symlinks is used, the following error messages will be
+displayed:
+
+------------
+<object> SP missing LF
+------------
+is printed when the initial symlink requested does not exist.
+
+------------
+dangling SP <size> LF
+<object> LF
+------------
+is printed when the initial symlink exists, but something that
+it (transitive-of) points to does not.
+
+------------
+loop SP <size> LF
+<object> LF
+------------
+is printed for symlink loops (or any symlinks that
+require more than 40 link resolutions to resolve).
+
+------------
+notdir SP <size> LF
+<object> LF
+------------
+is printed when, during symlink resolution, a file is used as a
+directory name.
 
 CAVEATS
 -------
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index df99df4..6ed4807 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -8,6 +8,7 @@
 #include "parse-options.h"
 #include "userdiff.h"
 #include "streaming.h"
+#include "tree-walk.h"
 
 static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 {
@@ -224,6 +225,7 @@ static void print_object_or_die(int fd, struct expand_data *data)
 
 struct batch_options {
 	int enabled;
+	int follow_symlinks;
 	int print_contents;
 	const char *format;
 };
@@ -232,12 +234,40 @@ static int batch_one_object(const char *obj_name, struct batch_options *opt,
 			    struct expand_data *data)
 {
 	struct strbuf buf = STRBUF_INIT;
+	struct object_context ctx;
+	int flags = opt->follow_symlinks ? GET_SHA1_FOLLOW_SYMLINKS : 0;
+	enum follow_symlinks_result result;
 
 	if (!obj_name)
 	   return 1;
 
-	if (get_sha1(obj_name, data->sha1)) {
-		printf("%s missing\n", obj_name);
+	result = get_sha1_with_context(obj_name, flags, data->sha1, &ctx);
+	if (result != FOUND) {
+		switch(result) {
+		case MISSING_OBJECT:
+			printf("%s missing\n", obj_name);
+			break;
+		case DANGLING_SYMLINK:
+			printf("dangling %"PRIuMAX"\n%s\n", strlen(obj_name),
+			       obj_name);
+			break;
+		case SYMLINK_LOOP:
+			printf("loop %"PRIuMAX"\n%s\n", strlen(obj_name),
+			       obj_name);
+			break;
+		case NOT_DIR:
+			printf("notdir %"PRIuMAX"\n%s\n", strlen(obj_name),
+			       obj_name);
+			break;
+		}
+		fflush(stdout);
+		return 0;
+	}
+
+	if (ctx.mode == 0) {
+		printf("symlink %"PRIuMAX"\n%s\n",
+		       (uintmax_t)ctx.symlink_path.len,
+		       ctx.symlink_path.buf);
 		fflush(stdout);
 		return 0;
 	}
@@ -342,9 +372,8 @@ static int batch_option_callback(const struct option *opt,
 {
 	struct batch_options *bo = opt->value;
 
-	if (unset) {
-		memset(bo, 0, sizeof(*bo));
-		return 0;
+	if (bo->enabled) {
+		return 1;
 	}
 
 	bo->enabled = 1;
@@ -369,6 +398,9 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 		OPT_SET_INT('p', NULL, &opt, N_("pretty-print object's content"), 'p'),
 		OPT_SET_INT(0, "textconv", &opt,
 			    N_("for blob objects, run textconv on object's content"), 'c'),
+		OPT_SET_INT(0, "follow-symlinks", &batch.follow_symlinks,
+			N_("follow in-repo symlinks; report out-of-repo symlinks (requires --batch or --batch-check)"),
+			    1),
 		{ OPTION_CALLBACK, 0, "batch", &batch, "format",
 			N_("show info and content of objects fed from the standard input"),
 			PARSE_OPT_OPTARG, batch_option_callback },
@@ -402,6 +434,10 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
 		usage_with_options(cat_file_usage, options);
 	}
 
+	if (batch.follow_symlinks && !batch.enabled) {
+		usage_with_options(cat_file_usage, options);
+	}
+
 	if (batch.enabled)
 		return batch_objects(&batch);
 
diff --git a/t/t1006-cat-file.sh b/t/t1006-cat-file.sh
index ab36b1e..a494013 100755
--- a/t/t1006-cat-file.sh
+++ b/t/t1006-cat-file.sh
@@ -189,6 +189,13 @@ do
     '
 done
 
+for opt in t s e p
+do
+    test_expect_success "Passing -$opt with --follow-symlinks fails" '
+	    test_must_fail git cat-file --follow-symlinks -$opt $hello_sha1
+	'
+done
+
 test_expect_success "--batch-check for a non-existent named object" '
     test "foobar42 missing
 foobar84 missing" = \
@@ -296,4 +303,202 @@ test_expect_success '%(deltabase) reports packed delta bases' '
 	}
 '
 
+# Tests for git cat-file --follow-symlinks
+test_expect_success 'prep for symlink tests' '
+	echo_without_newline "$hello_content" >morx &&
+	test_ln_s_add morx same-dir-link &&
+	test_ln_s_add dir link-to-dir &&
+	test_ln_s_add ../fleem out-of-repo-link &&
+	test_ln_s_add .. out-of-repo-link-dir &&
+	test_ln_s_add same-dir-link link-to-link &&
+	test_ln_s_add nope broken-same-dir-link &&
+	mkdir dir &&
+	test_ln_s_add ../morx dir/parent-dir-link &&
+	test_ln_s_add .. dir/link-dir &&
+	test_ln_s_add ../../escape dir/out-of-repo-link &&
+	test_ln_s_add ../.. dir/out-of-repo-link-dir &&
+	test_ln_s_add nope dir/broken-link-in-dir &&
+	mkdir dir/subdir &&
+	test_ln_s_add ../../morx dir/subdir/grandparent-dir-link &&
+	test_ln_s_add ../../../great-escape dir/subdir/out-of-repo-link &&
+	test_ln_s_add ../../.. dir/subdir/out-of-repo-link-dir &&
+	test_ln_s_add ../../../ dir/subdir/out-of-repo-link-dir-trailing &&
+	test_ln_s_add ../parent-dir-link dir/subdir/parent-dir-link-to-link &&
+	echo_without_newline "$hello_content" >dir/subdir/ind2 &&
+	echo_without_newline "$hello_content" >dir/ind1 &&
+	test_ln_s_add dir dirlink &&
+	test_ln_s_add dir/subdir subdirlink &&
+	test_ln_s_add subdir/ind2 dir/link-to-child &&
+	test_ln_s_add dir/link-to-child link-to-down-link &&
+	test_ln_s_add dir/.. up-down &&
+	test_ln_s_add dir/../ up-down-trailing &&
+	test_ln_s_add dir/../morx up-down-file &&
+	test_ln_s_add dir/../../morx up-up-down-file &&
+	test_ln_s_add subdirlink/../../morx up-two-down-file &&
+	test_ln_s_add loop1 loop2 &&
+	test_ln_s_add loop2 loop1 &&
+	git add morx dir/subdir/ind2 dir/ind1 &&
+	git commit -am "test" &&
+	echo $hello_sha1 blob $hello_size >found
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for non-links' '
+	echo HEAD:morx | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual &&
+	echo HEAD:nope missing >expect &&
+	echo HEAD:nope | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for in-repo, same-dir links' '
+	echo HEAD:same-dir-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for in-repo, links to dirs' '
+	echo HEAD:link-to-dir/ind1 | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual
+'
+
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for broken in-repo, same-dir links' '
+	echo dangling 25 >expect &&
+	echo HEAD:broken-same-dir-link >>expect &&
+	echo HEAD:broken-same-dir-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for same-dir links-to-links' '
+	echo HEAD:link-to-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for parent-dir links' '
+	echo HEAD:dir/parent-dir-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual &&
+	echo notdir 29 >expect &&
+	echo HEAD:dir/parent-dir-link/nope >>expect &&
+	echo HEAD:dir/parent-dir-link/nope | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for .. links' '
+	echo dangling 22 >expect &&
+	echo HEAD:dir/link-dir/nope >>expect &&
+	echo HEAD:dir/link-dir/nope | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo HEAD:dir/link-dir/morx | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual &&
+	echo dangling 27 >expect &&
+	echo HEAD:dir/broken-link-in-dir >>expect &&
+	echo HEAD:dir/broken-link-in-dir | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for ../.. links' '
+	echo notdir 41 >expect &&
+	echo HEAD:dir/subdir/grandparent-dir-link/nope >>expect &&
+	echo HEAD:dir/subdir/grandparent-dir-link/nope | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo HEAD:dir/subdir/grandparent-dir-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual &&
+	echo HEAD:dir/subdir/parent-dir-link-to-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for dir/ links' '
+	echo dangling 17 >expect &&
+	echo HEAD:dirlink/morx >>expect &&
+	echo HEAD:dirlink/morx | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo $hello_sha1 blob $hello_size >expect &&
+	echo HEAD:dirlink/ind1 | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for dir/subdir links' '
+	echo dangling 20 >expect &&
+	echo HEAD:subdirlink/morx >>expect &&
+	echo HEAD:subdirlink/morx | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo HEAD:subdirlink/ind2 | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for dir ->subdir links' '
+	echo notdir 27 >expect &&
+	echo HEAD:dir/link-to-child/morx >>expect &&
+	echo HEAD:dir/link-to-child/morx | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo HEAD:dir/link-to-child | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual &&
+	echo HEAD:link-to-down-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for out-of-repo symlinks' '
+	echo symlink 8 >expect &&
+	echo ../fleem >>expect &&
+	echo HEAD:out-of-repo-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo symlink 2 >expect &&
+	echo .. >>expect &&
+	echo HEAD:out-of-repo-link-dir | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for out-of-repo symlinks in dirs' '
+	echo symlink 9 >expect &&
+	echo ../escape >>expect &&
+	echo HEAD:dir/out-of-repo-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo symlink 2 >expect &&
+	echo .. >>expect &&
+	echo HEAD:dir/out-of-repo-link-dir | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for out-of-repo symlinks in subdirs' '
+	echo symlink 15 >expect &&
+	echo ../great-escape >>expect &&
+	echo HEAD:dir/subdir/out-of-repo-link | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo symlink 2 >expect &&
+	echo .. >>expect &&
+	echo HEAD:dir/subdir/out-of-repo-link-dir | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo symlink 3 >expect &&
+	echo ../ >>expect &&
+	echo HEAD:dir/subdir/out-of-repo-link-dir-trailing | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlinks works for symlinks with internal ..' '
+	echo HEAD: | git cat-file --batch-check >expect &&
+	echo HEAD:up-down | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo HEAD:up-down-trailing | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo HEAD:up-down-file | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual &&
+	echo symlink 7 >expect &&
+	echo ../morx >>expect &&
+	echo HEAD:up-up-down-file | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual &&
+	echo HEAD:up-two-down-file | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp found actual
+'
+
+test_expect_success 'git cat-file --batch-check --follow-symlink breaks loops' '
+	echo loop 10 >expect &&
+	echo HEAD:loop1 >>expect &&
+	echo HEAD:loop1 | git cat-file --batch-check --follow-symlinks >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git cat-file --batch --follow-symlink returns correct sha and mode' '
+	echo HEAD:morx | git cat-file --batch >expect &&
+	echo HEAD:morx | git cat-file --batch --follow-symlinks >actual &&
+	test_cmp expect actual
+'
 test_done
-- 
2.0.4.315.gad8727a-twtrsrc

Re: [PATCH v7 3/3] cat-file: add --follow-symlinks to --batch

[Junio C Hamano]

dturner@twopensource.com writes:

> From: David Turner <dturner@twitter.com>
>
> This wires the in-repo-symlink following code through to the cat-file
> builtin.  In the event of an out-of-repo link, cat-file will print
> the link in a new format.
>
> Signed-off-by: David Turner <dturner@twitter.com>
> ---

Thanks.

> +--follow-symlinks::
> +	With --batch or --batch-check, follow symlinks inside the
> +	repository when requesting objects with extended SHA-1
> +...
> +	printed.
> +[normal]
> +	This option does not (currently) work correctly when an

Nice; didn't realize that "[normal]" trick would work, but why not.

> +	object in the index is specified (e.g. `:link` instead of
> +	`HEAD:link`) rather than one in the tree.
> +[normal]
> +	This option cannot be used unless `--batch` or `--batch-check`
> +	is used, because it would be impossible to distinguish between
> +	the output for an out-of-repo symlink, and the contents of a
> +	blob.
> +
> +For example, consider a git repository containing:

... but I am not sure about this paragraph.  Does it align and look
to be at the same level as the first paragraph that begins with
"With `--batch` or `--batch-check`" (asking because I do not have an
access to a good environment to check the resulting HTML easily
right now)?

> +	result = get_sha1_with_context(obj_name, flags, data->sha1, &ctx);
> +	if (result != FOUND) {
> +		switch(result) {

	switch (result) {

> +		case MISSING_OBJECT:
> +			printf("%s missing\n", obj_name);
> +			break;
> +		case DANGLING_SYMLINK:
> +			printf("dangling %"PRIuMAX"\n%s\n", strlen(obj_name),
> +			       obj_name);
> +			break;
> +		case SYMLINK_LOOP:
> +			printf("loop %"PRIuMAX"\n%s\n", strlen(obj_name),
> +			       obj_name);
> +			break;
> +		case NOT_DIR:
> +			printf("notdir %"PRIuMAX"\n%s\n", strlen(obj_name),
> +			       obj_name);
> +			break;

Don't all these lengths need to be cast to uintmax_t, like the
"symlink" one below?

By the way, I noticed that my compiler is so stupid that it does not
realize this "switch (result)" is inside "if (result != FOUND)" and
missing "case FOUND:" is perfectly fine.  The remainder of the code
I have been compiling with -Wswitch, but this one makes me to drop
it.

> +		}
> +		fflush(stdout);
> +		return 0;
> +	}
> +
> +	if (ctx.mode == 0) {
> +		printf("symlink %"PRIuMAX"\n%s\n",
> +		       (uintmax_t)ctx.symlink_path.len,
> +		       ctx.symlink_path.buf);
>  		fflush(stdout);
>  		return 0;

Re: [PATCH v7 0/3]

[Junio C Hamano]

dturner@twopensource.com writes:

> This version of the patch adds improved error outputs for various
> weird situations that can come up during symlink resolution.

Overall these looked sensible.  I have been resisting the temptation
to merge this to my tree since around v5, primarily because I did
not want to resolve merge conflicts with kn/cat-file-literally more
than once, but I think this version looks solid enough that whatever
rerere will remember will be applicable to later iteration if one is
ever needed.

Hence I queued it on 'pu' for now; I haven't checked how the doc
formats, though.

Thanks.

Re: [PATCH v7 1/3] tree-walk: learn get_tree_entry_follow_symlinks

[Jeff King]

On Tue, May 12, 2015 at 09:49:57PM -0400, dturner@twopensource.com wrote:

> +		} else if (S_ISLNK(*mode)) {
> +			/* Follow a symlink */
> +			unsigned long link_len;
> +			size_t len;
> +			char *contents, *contents_start;
> [...]
> +			contents = read_sha1_file(current_tree_sha1, &type,
> +						  &link_len);

Here we have potentially allocated a buffer for contents...

> +
> +			if (!contents)
> +				goto done;

No need to free here, it's NULL...

> +
> +			if (contents[0] == '/') {
> +				strbuf_addstr(result_path, contents);
> +				*mode = 0;
> +				retval = FOUND;
> +				goto done;
> +			}

But here we leak it on "goto done".

> +			if (remainder)
> +				len = first_slash - namebuf.buf;
> +			else
> +				len = namebuf.len;
> +
> +			contents_start = contents;
> +
> +			parent = &parents[parents_nr - 1];
> +			init_tree_desc(&t, parent->tree, parent->size);
> +			strbuf_splice(&namebuf, 0, len,
> +				      contents_start, link_len);
> +			if (remainder)
> +				namebuf.buf[link_len] = '/';
> +			free(contents);
> +		}

And this code path calls free(), so it is good.

So I think you just need a free() in the conditional above.

-Peff

Re: [PATCH v7 0/3]

[Nickolai Belakovski]

On Fri, Feb 1, 2019 at 2:54 PM Junio C Hamano <gitster@pobox.com> wrote:
>
>
> As you can see in "git shortlog --no-merges", later two patches
> would look quite out of place by having overlong title and starting
> the description(i.e. after "<area>: ") in a capital letter.

Hadn't looked at it that way. OK, will shorten/uncapitalize.

>
> It is still not clear why we would want 2/3, even though I think 3/3
> is a good idea.
>
It's interesting to me that you like 3/3 but not 2/3 :)

My apologies for restating the commit message, but the point of 2/3 is
to communicate to the user that highlighted/marked branches will
behave differently from unhighlighted/unmarked branches for commands
to check out or delete. I think this is useful since it gives the user
actionable information ahead of time, as opposed to providing that
information upon failure of checkout/delete. It also makes sense since
'git branch' is already highlighting the current branch, i.e. this is
just an extension of that idea.

As we've stated earlier in this thread, 1/3 allows for users to
implement this on their own with a custom git branch format.
Personally I think there's value in making it default, since it's
adding information in a minimally intrusive way. I do believe that
merely adding information isn't a good enough reason to change things,
as information overload is a real thing, but in this case the output
isn't changed for anyone not using a worktree (same goes for 3/3), and
for someone using a worktree this provides useful and actionable
information, IMO.

Does that change your mind at all?

Re: [PATCH v7 0/3]

[Junio C Hamano]

nbelakovski@gmail.com writes:

>   ref-filter: add worktreepath atom
>   branch: Mark and color a branch differently if it is checked out in a
>     linked worktree
>   branch: Add an extra verbose output displaying worktree path for refs
>     checked out in a linked worktree

As you can see in "git shortlog --no-merges", later two patches
would look quite out of place by having overlong title and starting
the description(i.e. after "<area>: ") in a capital letter.

It is still not clear why we would want 2/3, even though I think 3/3
is a good idea.

This round signs off all the three patches, which is a great
improvement ;-)

[PATCH v7 0/3]

[nbelakovski]

From: Nickolai Belakovski <nbelakovski@gmail.com>


Moved initialization of ref_to_worktree_map outside of atom parser. Other minor fixes.

Put the hashmap and the worktree struct in the same struct, to make it more obvious that
they are to be initialized and free'd together.

Travis CI results: https://travis-ci.org/nbelakovski/git/builds/487642061

Nickolai Belakovski (3):
  ref-filter: add worktreepath atom
  branch: Mark and color a branch differently if it is checked out in a
    linked worktree
  branch: Add an extra verbose output displaying worktree path for refs
    checked out in a linked worktree

 Documentation/git-branch.txt       | 21 +++++-----
 Documentation/git-for-each-ref.txt |  5 +++
 builtin/branch.c                   | 16 ++++++--
 ref-filter.c                       | 78 ++++++++++++++++++++++++++++++++++++++
 t/t3200-branch.sh                  |  8 ++--
 t/t3203-branch-output.sh           | 21 ++++++++++
 t/t6302-for-each-ref-filter.sh     | 15 ++++++++
 7 files changed, 147 insertions(+), 17 deletions(-)

-- 
2.14.2