merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 177 insertions, 97 deletions

diff --git a/third_party/git/path.c b/third_party/git/path.c
index 25e97b8c3f..7b385e5eb2 100644
--- a/third_party/git/path.c
+++ b/third_party/git/path.c
@@ -11,6 +11,7 @@
 #include "path.h"
 #include "packfile.h"
 #include "object-store.h"
+#include "lockfile.h"
 
 static int get_st_mode_bits(const char *path, int *mode)
 {
@@ -101,36 +102,36 @@ struct common_dir {
 	/* Not considered garbage for report_linked_checkout_garbage */
 	unsigned ignore_garbage:1;
 	unsigned is_dir:1;
-	/* Not common even though its parent is */
-	unsigned exclude:1;
-	const char *dirname;
+	/* Belongs to the common dir, though it may contain paths that don't */
+	unsigned is_common:1;
+	const char *path;
 };
 
 static struct common_dir common_list[] = {
-	{ 0, 1, 0, "branches" },
-	{ 0, 1, 0, "common" },
-	{ 0, 1, 0, "hooks" },
-	{ 0, 1, 0, "info" },
-	{ 0, 0, 1, "info/sparse-checkout" },
-	{ 1, 1, 0, "logs" },
-	{ 1, 1, 1, "logs/HEAD" },
-	{ 0, 1, 1, "logs/refs/bisect" },
-	{ 0, 1, 1, "logs/refs/rewritten" },
-	{ 0, 1, 1, "logs/refs/worktree" },
-	{ 0, 1, 0, "lost-found" },
-	{ 0, 1, 0, "objects" },
-	{ 0, 1, 0, "refs" },
-	{ 0, 1, 1, "refs/bisect" },
-	{ 0, 1, 1, "refs/rewritten" },
-	{ 0, 1, 1, "refs/worktree" },
-	{ 0, 1, 0, "remotes" },
-	{ 0, 1, 0, "worktrees" },
-	{ 0, 1, 0, "rr-cache" },
-	{ 0, 1, 0, "svn" },
-	{ 0, 0, 0, "config" },
-	{ 1, 0, 0, "gc.pid" },
-	{ 0, 0, 0, "packed-refs" },
-	{ 0, 0, 0, "shallow" },
+	{ 0, 1, 1, "branches" },
+	{ 0, 1, 1, "common" },
+	{ 0, 1, 1, "hooks" },
+	{ 0, 1, 1, "info" },
+	{ 0, 0, 0, "info/sparse-checkout" },
+	{ 1, 1, 1, "logs" },
+	{ 1, 0, 0, "logs/HEAD" },
+	{ 0, 1, 0, "logs/refs/bisect" },
+	{ 0, 1, 0, "logs/refs/rewritten" },
+	{ 0, 1, 0, "logs/refs/worktree" },
+	{ 0, 1, 1, "lost-found" },
+	{ 0, 1, 1, "objects" },
+	{ 0, 1, 1, "refs" },
+	{ 0, 1, 0, "refs/bisect" },
+	{ 0, 1, 0, "refs/rewritten" },
+	{ 0, 1, 0, "refs/worktree" },
+	{ 0, 1, 1, "remotes" },
+	{ 0, 1, 1, "worktrees" },
+	{ 0, 1, 1, "rr-cache" },
+	{ 0, 1, 1, "svn" },
+	{ 0, 0, 1, "config" },
+	{ 1, 0, 1, "gc.pid" },
+	{ 0, 0, 1, "packed-refs" },
+	{ 0, 0, 1, "shallow" },
 	{ 0, 0, 0, NULL }
 };
 
@@ -236,30 +237,41 @@ static void *add_to_trie(struct trie *root, const char *key, void *value)
 	return old;
 }
 
-typedef int (*match_fn)(const char *unmatched, void *data, void *baton);
+typedef int (*match_fn)(const char *unmatched, void *value, void *baton);
 
 /*
  * Search a trie for some key.  Find the longest /-or-\0-terminated
- * prefix of the key for which the trie contains a value.  Call fn
- * with the unmatched portion of the key and the found value, and
- * return its return value.  If there is no such prefix, return -1.
+ * prefix of the key for which the trie contains a value.  If there is
+ * no such prefix, return -1.  Otherwise call fn with the unmatched
+ * portion of the key and the found value.  If fn returns 0 or
+ * positive, then return its return value.  If fn returns negative,
+ * then call fn with the next-longest /-terminated prefix of the key
+ * (i.e. a parent directory) for which the trie contains a value, and
+ * handle its return value the same way.  If there is no shorter
+ * /-terminated prefix with a value left, then return the negative
+ * return value of the most recent fn invocation.
  *
  * The key is partially normalized: consecutive slashes are skipped.
  *
- * For example, consider the trie containing only [refs,
- * refs/worktree] (both with values).
- *
- * | key             | unmatched  | val from node | return value |
- * |-----------------|------------|---------------|--------------|
- * | a               | not called | n/a           | -1           |
- * | refs            | \0         | refs          | as per fn    |
- * | refs/           | /          | refs          | as per fn    |
- * | refs/w          | /w         | refs          | as per fn    |
- * | refs/worktree   | \0         | refs/worktree | as per fn    |
- * | refs/worktree/  | /          | refs/worktree | as per fn    |
- * | refs/worktree/a | /a         | refs/worktree | as per fn    |
- * |-----------------|------------|---------------|--------------|
+ * For example, consider the trie containing only [logs,
+ * logs/refs/bisect], both with values, but not logs/refs.
  *
+ * | key                | unmatched      | prefix to node   | return value |
+ * |--------------------|----------------|------------------|--------------|
+ * | a                  | not called     | n/a              | -1           |
+ * | logstore           | not called     | n/a              | -1           |
+ * | logs               | \0             | logs             | as per fn    |
+ * | logs/              | /              | logs             | as per fn    |
+ * | logs/refs          | /refs          | logs             | as per fn    |
+ * | logs/refs/         | /refs/         | logs             | as per fn    |
+ * | logs/refs/b        | /refs/b        | logs             | as per fn    |
+ * | logs/refs/bisected | /refs/bisected | logs             | as per fn    |
+ * | logs/refs/bisect   | \0             | logs/refs/bisect | as per fn    |
+ * | logs/refs/bisect/  | /              | logs/refs/bisect | as per fn    |
+ * | logs/refs/bisect/a | /a             | logs/refs/bisect | as per fn    |
+ * | (If fn in the previous line returns -1, then fn is called once more:) |
+ * | logs/refs/bisect/a | /refs/bisect/a | logs             | as per fn    |
+ * |--------------------|----------------|------------------|--------------|
  */
 static int trie_find(struct trie *root, const char *key, match_fn fn,
 		     void *baton)
@@ -288,9 +300,13 @@ static int trie_find(struct trie *root, const char *key, match_fn fn,
 
 	/* Matched the entire compressed section */
 	key += i;
-	if (!*key)
+	if (!*key) {
 		/* End of key */
-		return fn(key, root->value, baton);
+		if (root->value)
+			return fn(key, root->value, baton);
+		else
+			return -1;
+	}
 
 	/* Partial path normalization: skip consecutive slashes */
 	while (key[0] == '/' && key[1] == '/')
@@ -320,8 +336,8 @@ static void init_common_trie(void)
 	if (common_trie_done_setup)
 		return;
 
-	for (p = common_list; p->dirname; p++)
-		add_to_trie(&common_trie, p->dirname, p);
+	for (p = common_list; p->path; p++)
+		add_to_trie(&common_trie, p->path, p);
 
 	common_trie_done_setup = 1;
 }
@@ -334,14 +350,11 @@ static int check_common(const char *unmatched, void *value, void *baton)
 {
 	struct common_dir *dir = value;
 
-	if (!dir)
-		return 0;
-
 	if (dir->is_dir && (unmatched[0] == 0 || unmatched[0] == '/'))
-		return !dir->exclude;
+		return dir->is_common;
 
 	if (!dir->is_dir && unmatched[0] == 0)
-		return !dir->exclude;
+		return dir->is_common;
 
 	return 0;
 }
@@ -350,9 +363,14 @@ static void update_common_dir(struct strbuf *buf, int git_dir_len,
 			      const char *common_dir)
 {
 	char *base = buf->buf + git_dir_len;
+	int has_lock_suffix = strbuf_strip_suffix(buf, LOCK_SUFFIX);
+
 	init_common_trie();
 	if (trie_find(&common_trie, base, check_common, NULL) > 0)
 		replace_dir(buf, git_dir_len, common_dir);
+
+	if (has_lock_suffix)
+		strbuf_addstr(buf, LOCK_SUFFIX);
 }
 
 void report_linked_checkout_garbage(void)
@@ -365,8 +383,8 @@ void report_linked_checkout_garbage(void)
 		return;
 	strbuf_addf(&sb, "%s/", get_git_dir());
 	len = sb.len;
-	for (p = common_list; p->dirname; p++) {
-		const char *path = p->dirname;
+	for (p = common_list; p->path; p++) {
+		const char *path = p->path;
 		if (p->ignore_garbage)
 			continue;
 		strbuf_setlen(&sb, len);
@@ -705,7 +723,7 @@ static struct passwd *getpw_str(const char *username, size_t len)
  * then it is a newly allocated string. Returns NULL on getpw failure or
  * if path is NULL.
  *
- * If real_home is true, real_path($HOME) is used in the expansion.
+ * If real_home is true, strbuf_realpath($HOME) is used in the expansion.
  */
 char *expand_user_path(const char *path, int real_home)
 {
@@ -832,8 +850,8 @@ const char *enter_repo(const char *path, int strict)
 	}
 
 	if (is_git_directory(".")) {
-		set_git_dir(".");
-		check_repository_format();
+		set_git_dir(".", 0);
+		check_repository_format(NULL);
 		return path;
 	}
 
@@ -1059,6 +1077,8 @@ const char *remove_leading_path(const char *in, const char *prefix)
 
 /*
  * It is okay if dst == src, but they should not overlap otherwise.
+ * The "dst" buffer must be at least as long as "src"; normalizing may shrink
+ * the size of the path, but will never grow it.
  *
  * Performs the following normalizations on src, storing the result in dst:
  * - Ensures that components are separated by '/' (Windows only)
@@ -1221,31 +1241,52 @@ static inline int chomp_trailing_dir_sep(const char *path, int len)
 }
 
 /*
- * If path ends with suffix (complete path components), returns the
- * part before suffix (sans trailing directory separators).
- * Otherwise returns NULL.
+ * If path ends with suffix (complete path components), returns the offset of
+ * the last character in the path before the suffix (sans trailing directory
+ * separators), and -1 otherwise.
  */
-char *strip_path_suffix(const char *path, const char *suffix)
+static ssize_t stripped_path_suffix_offset(const char *path, const char *suffix)
 {
 	int path_len = strlen(path), suffix_len = strlen(suffix);
 
 	while (suffix_len) {
 		if (!path_len)
-			return NULL;
+			return -1;
 
 		if (is_dir_sep(path[path_len - 1])) {
 			if (!is_dir_sep(suffix[suffix_len - 1]))
-				return NULL;
+				return -1;
 			path_len = chomp_trailing_dir_sep(path, path_len);
 			suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 		}
 		else if (path[--path_len] != suffix[--suffix_len])
-			return NULL;
+			return -1;
 	}
 
 	if (path_len && !is_dir_sep(path[path_len - 1]))
-		return NULL;
-	return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
+		return -1;
+	return chomp_trailing_dir_sep(path, path_len);
+}
+
+/*
+ * Returns true if the path ends with components, considering only complete path
+ * components, and false otherwise.
+ */
+int ends_with_path_components(const char *path, const char *components)
+{
+	return stripped_path_suffix_offset(path, components) != -1;
+}
+
+/*
+ * If path ends with suffix (complete path components), returns the
+ * part before suffix (sans trailing directory separators).
+ * Otherwise returns NULL.
+ */
+char *strip_path_suffix(const char *path, const char *suffix)
+{
+	ssize_t offset = stripped_path_suffix_offset(path, suffix);
+
+	return offset == -1 ? NULL : xstrndup(path, offset);
 }
 
 int daemon_avoid_alias(const char *p)
@@ -1295,37 +1336,77 @@ int daemon_avoid_alias(const char *p)
 	}
 }
 
-static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
+/*
+ * On NTFS, we need to be careful to disallow certain synonyms of the `.git/`
+ * directory:
+ *
+ * - For historical reasons, file names that end in spaces or periods are
+ *   automatically trimmed. Therefore, `.git . . ./` is a valid way to refer
+ *   to `.git/`.
+ *
+ * - For other historical reasons, file names that do not conform to the 8.3
+ *   format (up to eight characters for the basename, three for the file
+ *   extension, certain characters not allowed such as `+`, etc) are associated
+ *   with a so-called "short name", at least on the `C:` drive by default.
+ *   Which means that `git~1/` is a valid way to refer to `.git/`.
+ *
+ *   Note: Technically, `.git/` could receive the short name `git~2` if the
+ *   short name `git~1` were already used. In Git, however, we guarantee that
+ *   `.git` is the first item in a directory, therefore it will be associated
+ *   with the short name `git~1` (unless short names are disabled).
+ *
+ * - For yet other historical reasons, NTFS supports so-called "Alternate Data
+ *   Streams", i.e. metadata associated with a given file, referred to via
+ *   `<filename>:<stream-name>:<stream-type>`. There exists a default stream
+ *   type for directories, allowing `.git/` to be accessed via
+ *   `.git::$INDEX_ALLOCATION/`.
+ *
+ * When this function returns 1, it indicates that the specified file/directory
+ * name refers to a `.git` file or directory, or to any of these synonyms, and
+ * Git should therefore not track it.
+ *
+ * For performance reasons, _all_ Alternate Data Streams of `.git/` are
+ * forbidden, not just `::$INDEX_ALLOCATION`.
+ *
+ * This function is intended to be used by `git fsck` even on platforms where
+ * the backslash is a regular filename character, therefore it needs to handle
+ * backlash characters in the provided `name` specially: they are interpreted
+ * as directory separators.
+ */
+int is_ntfs_dotgit(const char *name)
 {
-	if (len < skip)
+	char c;
+
+	/*
+	 * Note that when we don't find `.git` or `git~1` we end up with `name`
+	 * advanced partway through the string. That's okay, though, as we
+	 * return immediately in those cases, without looking at `name` any
+	 * further.
+	 */
+	c = *(name++);
+	if (c == '.') {
+		/* .git */
+		if (((c = *(name++)) != 'g' && c != 'G') ||
+		    ((c = *(name++)) != 'i' && c != 'I') ||
+		    ((c = *(name++)) != 't' && c != 'T'))
+			return 0;
+	} else if (c == 'g' || c == 'G') {
+		/* git ~1 */
+		if (((c = *(name++)) != 'i' && c != 'I') ||
+		    ((c = *(name++)) != 't' && c != 'T') ||
+		    *(name++) != '~' ||
+		    *(name++) != '1')
+			return 0;
+	} else
 		return 0;
-	len -= skip;
-	path += skip;
-	while (len-- > 0) {
-		char c = *(path++);
-		if (c != ' ' && c != '.')
+
+	for (;;) {
+		c = *(name++);
+		if (!c || c == '\\' || c == '/' || c == ':')
+			return 1;
+		if (c != '.' && c != ' ')
 			return 0;
 	}
-	return 1;
-}
-
-int is_ntfs_dotgit(const char *name)
-{
-	size_t len;
-
-	for (len = 0; ; len++)
-		if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
-			if (only_spaces_and_periods(name, len, 4) &&
-					!strncasecmp(name, ".git", 4))
-				return 1;
-			if (only_spaces_and_periods(name, len, 5) &&
-					!strncasecmp(name, "git~1", 5))
-				return 1;
-			if (name[len] != '\\')
-				return 0;
-			name += len + 1;
-			len = -1;
-		}
 }
 
 static int is_ntfs_dot_generic(const char *name,
@@ -1341,7 +1422,7 @@ static int is_ntfs_dot_generic(const char *name,
 only_spaces_and_periods:
 		for (;;) {
 			char c = name[i++];
-			if (!c)
+			if (!c || c == ':')
 				return 1;
 			if (c != ' ' && c != '.')
 				return 0;
@@ -1447,12 +1528,11 @@ char *xdg_cache_home(const char *filename)
 	return NULL;
 }
 
-REPO_GIT_PATH_FUNC(cherry_pick_head, "CHERRY_PICK_HEAD")
-REPO_GIT_PATH_FUNC(revert_head, "REVERT_HEAD")
 REPO_GIT_PATH_FUNC(squash_msg, "SQUASH_MSG")
 REPO_GIT_PATH_FUNC(merge_msg, "MERGE_MSG")
 REPO_GIT_PATH_FUNC(merge_rr, "MERGE_RR")
 REPO_GIT_PATH_FUNC(merge_mode, "MERGE_MODE")
 REPO_GIT_PATH_FUNC(merge_head, "MERGE_HEAD")
+REPO_GIT_PATH_FUNC(merge_autostash, "MERGE_AUTOSTASH")
 REPO_GIT_PATH_FUNC(fetch_head, "FETCH_HEAD")
 REPO_GIT_PATH_FUNC(shallow, "shallow")