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authorJunio C Hamano <gitster@pobox.com>2015-06-01 19:45:16 (GMT)
committerJunio C Hamano <gitster@pobox.com>2015-06-01 19:45:16 (GMT)
commit67f0b6f3b2226ea858c616028375dcc3c46ccc37 (patch)
tree598a4db2b8e80916be9c2074490070bdd15e4df4
parent4ba5bb5531c6ec64a57ae2754ba51ce477eebaf0 (diff)
parent122d53464b29d3ac20891c5ee2f75ac5ecbb7b20 (diff)
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Merge branch 'dt/cat-file-follow-symlinks'
"git cat-file --batch(-check)" learned the "--follow-symlinks" option that follows an in-tree symbolic link when asked about an object via extended SHA-1 syntax, e.g. HEAD:RelNotes that points at Documentation/RelNotes/2.5.0.txt. With the new option, the command behaves as if HEAD:Documentation/RelNotes/2.5.0.txt was given as input instead. * dt/cat-file-follow-symlinks: cat-file: add --follow-symlinks to --batch sha1_name: get_sha1_with_context learns to follow symlinks tree-walk: learn get_tree_entry_follow_symlinks
-rw-r--r--Documentation/git-cat-file.txt99
-rw-r--r--builtin/cat-file.c51
-rw-r--r--cache.h20
-rw-r--r--sha1_name.c20
-rwxr-xr-xt/t1006-cat-file.sh206
-rw-r--r--tree-walk.c206
-rw-r--r--tree-walk.h18
7 files changed, 601 insertions, 19 deletions
diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index 499ae7b..319ab4c 100644
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt
@@ -10,7 +10,7 @@ SYNOPSIS
--------
[verse]
'git cat-file' (-t [--allow-unknown-type]| -s [--allow-unknown-type]| -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
-----------
@@ -72,6 +72,62 @@ OPTIONS
--allow-unknown-type::
Allow -s or -t to query broken/corrupt objects of unknown type.
+--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.
++
+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.
++
+This option cannot (currently) be used unless `--batch` or
+`--batch-check` is used.
++
+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>.
@@ -151,6 +207,47 @@ 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 ecb4888..049a95f 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,
int unknown_type)
@@ -233,6 +234,7 @@ 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;
};
@@ -241,12 +243,44 @@ 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",
+ (uintmax_t)strlen(obj_name), obj_name);
+ break;
+ case SYMLINK_LOOP:
+ printf("loop %"PRIuMAX"\n%s\n",
+ (uintmax_t)strlen(obj_name), obj_name);
+ break;
+ case NOT_DIR:
+ printf("notdir %"PRIuMAX"\n%s\n",
+ (uintmax_t)strlen(obj_name), obj_name);
+ break;
+ default:
+ die("BUG: unknown get_sha1_with_context result %d\n",
+ result);
+ 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;
}
@@ -333,7 +367,7 @@ static int batch_objects(struct batch_options *opt)
static const char * const cat_file_usage[] = {
N_("git cat-file (-t [--allow-unknown-type]|-s [--allow-unknown-type]|-e|-p|<type>|--textconv) <object>"),
- N_("git cat-file (--batch | --batch-check) < <list-of-objects>"),
+ N_("git cat-file (--batch | --batch-check) [--follow-symlinks] < <list-of-objects>"),
NULL
};
@@ -351,9 +385,8 @@ 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;
@@ -387,6 +420,8 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
{ OPTION_CALLBACK, 0, "batch-check", &batch, "format",
N_("show info about objects fed from the standard input"),
PARSE_OPT_OPTARG, batch_option_callback },
+ OPT_BOOL(0, "follow-symlinks", &batch.follow_symlinks,
+ N_("follow in-tree symlinks (used with --batch or --batch-check)")),
OPT_END()
};
@@ -411,6 +446,10 @@ 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/cache.h b/cache.h
index 9da9784..571c98f 100644
--- a/cache.h
+++ b/cache.h
@@ -971,15 +971,21 @@ 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 6de8c87..46218ba 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1433,11 +1433,19 @@ 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));
@@ -1468,5 +1476,7 @@ 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);
}
diff --git a/t/t1006-cat-file.sh b/t/t1006-cat-file.sh
index 4f225db..93a4794 100755
--- a/t/t1006-cat-file.sh
+++ b/t/t1006-cat-file.sh
@@ -201,6 +201,13 @@ 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 $hello_sha1
+ '
+done
+
test_expect_success "--batch-check for a non-existent named object" '
test "foobar42 missing
foobar84 missing" = \
@@ -341,4 +348,203 @@ test_expect_success "Size of large broken object is correct when type is large"
test_cmp expect actual
'
+# Tests for git cat-file --follow-symlinks
+test_expect_success 'prep for symlink tests' '
+ echo_without_newline "$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
diff --git a/tree-walk.c b/tree-walk.c
index 5dd9a71..6dccd2d 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;
+ int follows_remaining = GET_TREE_ENTRY_FOLLOW_SYMLINKS_MAX_LINKS;
+ int i;
+
+ init_tree_desc(&t, NULL, 0UL);
+ strbuf_init(result_path, 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);
+ free(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;