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setup: improve error diagnosis for invalid .git files
'read_gitfile_gently()' treats any non-regular file as 'READ_GITFILE_ERR_NOT_A_FILE' and fails to discern between 'ENOENT' and other stat failures. This flawed error reporting is noted by two 'NEEDSWORK' comments. Address these comments by introducing two new error codes: 'READ_GITFILE_ERR_MISSING'(which groups the "file missing" scenarios together) and 'READ_GITFILE_ERR_IS_A_DIR'. To preserve the original intent of the setup process: 1. Update 'read_gitfile_error_die()' to treat both 'IS_A_DIR' and 'MISSING' as no-ops, while continuing to call 'die()' on true 'NOT_A_FILE' errors to prevent security hazards (like FIFOs). 2. Unconditionally pass '&error_code' to 'read_gitfile_gently()'. 3. Only invoke 'is_git_directory()' when we explicitly receive 'READ_GITFILE_ERR_IS_A_DIR', avoiding redundant filesystem checks. 4. Correctly return 'GIT_DIR_INVALID_GITFILE' on unrecognized errors when 'die_on_error' is false. Additionally, audit external callers of 'read_gitfile_gently()' in 'submodule.c' and 'worktree.c' to accommodate the refined error codes. Signed-off-by: Tian Yuchen <a3205153416@gmail.com>
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6 files changed

+125
-14
lines changed

6 files changed

+125
-14
lines changed

‎setup.c‎

Lines changed: 40 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -897,8 +897,10 @@ int verify_repository_format(const struct repository_format *format,
897897
void read_gitfile_error_die(int error_code, const char *path, const char *dir)
898898
{
899899
switch (error_code) {
900-
case READ_GITFILE_ERR_STAT_FAILED:
901900
case READ_GITFILE_ERR_NOT_A_FILE:
901+
case READ_GITFILE_ERR_STAT_FAILED:
902+
case READ_GITFILE_ERR_MISSING:
903+
case READ_GITFILE_ERR_IS_A_DIR:
902904
/* non-fatal; follow return path */
903905
break;
904906
case READ_GITFILE_ERR_OPEN_FAILED:
@@ -941,8 +943,14 @@ const char *read_gitfile_gently(const char *path, int *return_error_code)
941943
static struct strbuf realpath = STRBUF_INIT;
942944

943945
if (stat(path, &st)) {
944-
/* NEEDSWORK: discern between ENOENT vs other errors */
945-
error_code = READ_GITFILE_ERR_STAT_FAILED;
946+
if (errno == ENOENT || errno == ENOTDIR)
947+
error_code = READ_GITFILE_ERR_MISSING;
948+
else
949+
error_code = READ_GITFILE_ERR_STAT_FAILED;
950+
goto cleanup_return;
951+
}
952+
if (S_ISDIR(st.st_mode)) {
953+
error_code = READ_GITFILE_ERR_IS_A_DIR;
946954
goto cleanup_return;
947955
}
948956
if (!S_ISREG(st.st_mode)) {
@@ -1578,20 +1586,41 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
15781586
if (offset > min_offset)
15791587
strbuf_addch(dir, '/');
15801588
strbuf_addstr(dir, DEFAULT_GIT_DIR_ENVIRONMENT);
1581-
gitdirenv = read_gitfile_gently(dir->buf, die_on_error ?
1582-
NULL : &error_code);
1589+
gitdirenv = read_gitfile_gently(dir->buf, &error_code);
15831590
if (!gitdirenv) {
1584-
if (die_on_error ||
1585-
error_code == READ_GITFILE_ERR_NOT_A_FILE) {
1586-
/* NEEDSWORK: fail if .git is not file nor dir */
1591+
switch (error_code) {
1592+
case READ_GITFILE_ERR_MISSING:
1593+
/* no .git in this directory, move on */
1594+
break;
1595+
case READ_GITFILE_ERR_IS_A_DIR:
15871596
if (is_git_directory(dir->buf)) {
15881597
gitdirenv = DEFAULT_GIT_DIR_ENVIRONMENT;
15891598
gitdir_path = xstrdup(dir->buf);
15901599
}
1591-
} else if (error_code != READ_GITFILE_ERR_STAT_FAILED)
1592-
return GIT_DIR_INVALID_GITFILE;
1593-
} else
1600+
/*
1601+
* NEEDSWORK: should we catch a directory .git
1602+
* that is not a git directory here?
1603+
*/
1604+
break;
1605+
case READ_GITFILE_ERR_STAT_FAILED:
1606+
if (die_on_error)
1607+
die(_("error reading '%s'"), dir->buf);
1608+
else
1609+
return GIT_DIR_INVALID_GITFILE;
1610+
case READ_GITFILE_ERR_NOT_A_FILE:
1611+
if (die_on_error)
1612+
die(_("not a regular file: '%s'"), dir->buf);
1613+
else
1614+
return GIT_DIR_INVALID_GITFILE;
1615+
default:
1616+
if (die_on_error || error_code == READ_GITFILE_ERR_NOT_A_FILE)
1617+
read_gitfile_error_die(error_code, dir->buf, NULL);
1618+
else
1619+
return GIT_DIR_INVALID_GITFILE;
1620+
}
1621+
} else {
15941622
gitfile = xstrdup(dir->buf);
1623+
}
15951624
/*
15961625
* Earlier, we tentatively added DEFAULT_GIT_DIR_ENVIRONMENT
15971626
* to check that directory for a repository.

‎setup.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -36,6 +36,8 @@ int is_nonbare_repository_dir(struct strbuf *path);
3636
#define READ_GITFILE_ERR_NO_PATH 6
3737
#define READ_GITFILE_ERR_NOT_A_REPO 7
3838
#define READ_GITFILE_ERR_TOO_LARGE 8
39+
#define READ_GITFILE_ERR_MISSING 9
40+
#define READ_GITFILE_ERR_IS_A_DIR 10
3941
void read_gitfile_error_die(int error_code, const char *path, const char *dir);
4042
const char *read_gitfile_gently(const char *path, int *return_error_code);
4143
#define read_gitfile(path) read_gitfile_gently((path), NULL)

‎submodule.c‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2559,7 +2559,7 @@ void absorb_git_dir_into_superproject(const char *path,
25592559
const struct submodule *sub;
25602560
struct strbuf sub_gitdir = STRBUF_INIT;
25612561

2562-
if (err_code == READ_GITFILE_ERR_STAT_FAILED) {
2562+
if (err_code == READ_GITFILE_ERR_MISSING) {
25632563
/* unpopulated as expected */
25642564
strbuf_release(&gitdir);
25652565
return;

‎t/meson.build‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -80,6 +80,7 @@ integration_tests = [
8080
't0006-date.sh',
8181
't0007-git-var.sh',
8282
't0008-ignores.sh',
83+
't0009-git-dir-validation.sh',
8384
't0010-racy-git.sh',
8485
't0012-help.sh',
8586
't0013-sha1dc.sh',

‎t/t0009-git-dir-validation.sh‎

Lines changed: 77 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,77 @@
1+
#!/bin/sh
2+
3+
test_description='setup: validation of .git file/directory types
4+
5+
Verify that setup_git_directory() correctly handles:
6+
1. Valid .git directories (including symlinks to them).
7+
2. Invalid .git files (FIFOs, sockets) by erroring out.
8+
3. Invalid .git files (garbage) by erroring out.
9+
'
10+
11+
. ./test-lib.sh
12+
13+
test_expect_success 'setup: create parent git repository' '
14+
git init parent &&
15+
test_commit -C parent "root-commit"
16+
'
17+
18+
test_expect_success SYMLINKS 'setup: .git as a symlink to a directory is valid' '
19+
test_when_finished "rm -rf parent/link-to-dir" &&
20+
mkdir -p parent/link-to-dir &&
21+
(
22+
cd parent/link-to-dir &&
23+
git init real-repo &&
24+
ln -s real-repo/.git .git &&
25+
git rev-parse --git-dir >actual &&
26+
echo .git >expect &&
27+
test_cmp expect actual
28+
)
29+
'
30+
31+
test_expect_success PIPE 'setup: .git as a FIFO (named pipe) is rejected' '
32+
test_when_finished "rm -rf parent/fifo-trap" &&
33+
mkdir -p parent/fifo-trap &&
34+
(
35+
cd parent/fifo-trap &&
36+
mkfifo .git &&
37+
test_must_fail git rev-parse --git-dir 2>stderr &&
38+
grep "not a regular file" stderr
39+
)
40+
'
41+
42+
test_expect_success SYMLINKS,PIPE 'setup: .git as a symlink to a FIFO is rejected' '
43+
test_when_finished "rm -rf parent/symlink-fifo-trap" &&
44+
mkdir -p parent/symlink-fifo-trap &&
45+
(
46+
cd parent/symlink-fifo-trap &&
47+
mkfifo target-fifo &&
48+
ln -s target-fifo .git &&
49+
test_must_fail git rev-parse --git-dir 2>stderr &&
50+
grep "not a regular file" stderr
51+
)
52+
'
53+
54+
test_expect_success 'setup: .git with garbage content is rejected' '
55+
test_when_finished "rm -rf parent/garbage-trap" &&
56+
mkdir -p parent/garbage-trap &&
57+
(
58+
cd parent/garbage-trap &&
59+
echo "garbage" >.git &&
60+
test_must_fail git rev-parse --git-dir 2>stderr &&
61+
grep "invalid gitfile format" stderr
62+
)
63+
'
64+
65+
test_expect_success 'setup: .git as an empty directory is ignored' '
66+
test_when_finished "rm -rf parent/empty-dir" &&
67+
mkdir -p parent/empty-dir &&
68+
(
69+
cd parent/empty-dir &&
70+
mkdir .git &&
71+
git rev-parse --git-dir >actual &&
72+
echo "$TRASH_DIRECTORY/parent/.git" >expect &&
73+
test_cmp expect actual
74+
)
75+
'
76+
77+
test_done

‎worktree.c‎

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -653,7 +653,8 @@ static void repair_gitfile(struct worktree *wt,
653653
}
654654
}
655655

656-
if (err == READ_GITFILE_ERR_NOT_A_FILE)
656+
if (err == READ_GITFILE_ERR_NOT_A_FILE ||
657+
err == READ_GITFILE_ERR_IS_A_DIR)
657658
fn(1, wt->path, _(".git is not a file"), cb_data);
658659
else if (err)
659660
repair = _(".git file broken");
@@ -833,7 +834,8 @@ void repair_worktree_at_path(const char *path,
833834
strbuf_addstr(&backlink, dotgit_contents);
834835
strbuf_realpath_forgiving(&backlink, backlink.buf, 0);
835836
}
836-
} else if (err == READ_GITFILE_ERR_NOT_A_FILE) {
837+
} else if (err == READ_GITFILE_ERR_NOT_A_FILE ||
838+
err == READ_GITFILE_ERR_IS_A_DIR) {
837839
fn(1, dotgit.buf, _("unable to locate repository; .git is not a file"), cb_data);
838840
goto done;
839841
} else if (err == READ_GITFILE_ERR_NOT_A_REPO) {

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