/src/git/path.c

Source
/*
 * Utilities for paths and pathnames
 */

#include "git-compat-util.h"
#include "abspath.h"
#include "gettext.h"
#include "repository.h"
#include "strbuf.h"
#include "string-list.h"
#include "dir.h"
#include "worktree.h"
#include "setup.h"
#include "submodule-config.h"
#include "path.h"
#include "packfile.h"
#include "odb.h"
#include "lockfile.h"
#include "exec-cmd.h"

static int get_st_mode_bits(const char *path, int *mode)
{
  struct stat st;
  if (lstat(path, &st) < 0)
    return -1;
  *mode = st.st_mode;
  return 0;
}

static struct strbuf *get_pathname(void)
{
  static struct strbuf pathname_array[4] = {
    STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
  };
  static int index;
  struct strbuf *sb = &pathname_array[index];
  index = (index + 1) % ARRAY_SIZE(pathname_array);
  strbuf_reset(sb);
  return sb;
}

static const char *cleanup_path(const char *path)
{
  /* Clean it up */
  if (skip_prefix(path, "./", &path)) {
    while (*path == '/')
      path++;
  }
  return path;
}

static void strbuf_cleanup_path(struct strbuf *sb)
{
  const char *path = cleanup_path(sb->buf);
  if (path > sb->buf)
    strbuf_remove(sb, 0, path - sb->buf);
}

int dir_prefix(const char *buf, const char *dir)
{
  size_t len = strlen(dir);
  return !strncmp(buf, dir, len) &&
    (is_dir_sep(buf[len]) || buf[len] == '\0');
}

/* $buf =~ m|$dir/+$file| but without regex */
static int is_dir_file(const char *buf, const char *dir, const char *file)
{
  int len = strlen(dir);
  if (strncmp(buf, dir, len) || !is_dir_sep(buf[len]))
    return 0;
  while (is_dir_sep(buf[len]))
    len++;
  return !strcmp(buf + len, file);
}

static void replace_dir(struct strbuf *buf, int len, const char *newdir)
{
  int newlen = strlen(newdir);
  int need_sep = (buf->buf[len] && !is_dir_sep(buf->buf[len])) &&
    !is_dir_sep(newdir[newlen - 1]);
  if (need_sep)
    len--;  /* keep one char, to be replaced with '/'  */
  strbuf_splice(buf, 0, len, newdir, newlen);
  if (need_sep)
    buf->buf[newlen] = '/';
}

struct common_dir {
  /* Not considered garbage for report_linked_checkout_garbage */
  unsigned ignore_garbage:1;
  unsigned is_dir:1;
  /* 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, 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 }
};

/*
 * A compressed trie.  A trie node consists of zero or more characters that
 * are common to all elements with this prefix, optionally followed by some
 * children.  If value is not NULL, the trie node is a terminal node.
 *
 * For example, consider the following set of strings:
 * abc
 * def
 * definite
 * definition
 *
 * The trie would look like:
 * root: len = 0, children a and d non-NULL, value = NULL.
 *    a: len = 2, contents = bc, value = (data for "abc")
 *    d: len = 2, contents = ef, children i non-NULL, value = (data for "def")
 *       i: len = 3, contents = nit, children e and i non-NULL, value = NULL
 *           e: len = 0, children all NULL, value = (data for "definite")
 *           i: len = 2, contents = on, children all NULL,
 *              value = (data for "definition")
 */
struct trie {
  struct trie *children[256];
  int len;
  char *contents;
  void *value;
};

static struct trie *make_trie_node(const char *key, void *value)
{
  struct trie *new_node = xcalloc(1, sizeof(*new_node));
  new_node->len = strlen(key);
  if (new_node->len) {
    new_node->contents = xmalloc(new_node->len);
    memcpy(new_node->contents, key, new_node->len);
  }
  new_node->value = value;
  return new_node;
}

/*
 * Add a key/value pair to a trie.  The key is assumed to be \0-terminated.
 * If there was an existing value for this key, return it.
 */
static void *add_to_trie(struct trie *root, const char *key, void *value)
{
  struct trie *child;
  void *old;
  int i;

  if (!*key) {
    /* we have reached the end of the key */
    old = root->value;
    root->value = value;
    return old;
  }

  for (i = 0; i < root->len; i++) {
    if (root->contents[i] == key[i])
      continue;

    /*
     * Split this node: child will contain this node's
     * existing children.
     */
    child = xmalloc(sizeof(*child));
    memcpy(child->children, root->children, sizeof(root->children));

    child->len = root->len - i - 1;
    if (child->len) {
      child->contents = xstrndup(root->contents + i + 1,
               child->len);
    }
    child->value = root->value;
    root->value = NULL;
    root->len = i;

    memset(root->children, 0, sizeof(root->children));
    root->children[(unsigned char)root->contents[i]] = child;

    /* This is the newly-added child. */
    root->children[(unsigned char)key[i]] =
      make_trie_node(key + i + 1, value);
    return NULL;
  }

  /* We have matched the entire compressed section */
  if (key[i]) {
    child = root->children[(unsigned char)key[root->len]];
    if (child) {
      return add_to_trie(child, key + root->len + 1, value);
    } else {
      child = make_trie_node(key + root->len + 1, value);
      root->children[(unsigned char)key[root->len]] = child;
      return NULL;
    }
  }

  old = root->value;
  root->value = value;
  return old;
}

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.  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 [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)
{
  int i;
  int result;
  struct trie *child;

  if (!*key) {
    /* we have reached the end of the key */
    if (root->value && !root->len)
      return fn(key, root->value, baton);
    else
      return -1;
  }

  for (i = 0; i < root->len; i++) {
    /* Partial path normalization: skip consecutive slashes. */
    if (key[i] == '/' && key[i+1] == '/') {
      key++;
      continue;
    }
    if (root->contents[i] != key[i])
      return -1;
  }

  /* Matched the entire compressed section */
  key += i;
  if (!*key) {
    /* End of key */
    if (root->value)
      return fn(key, root->value, baton);
    else
      return -1;
  }

  /* Partial path normalization: skip consecutive slashes */
  while (key[0] == '/' && key[1] == '/')
    key++;

  child = root->children[(unsigned char)*key];
  if (child)
    result = trie_find(child, key + 1, fn, baton);
  else
    result = -1;

  if (result >= 0 || (*key != '/' && *key != 0))
    return result;
  if (root->value)
    return fn(key, root->value, baton);
  else
    return -1;
}

static struct trie common_trie;
static int common_trie_done_setup;

static void init_common_trie(void)
{
  struct common_dir *p;

  if (common_trie_done_setup)
    return;

  for (p = common_list; p->path; p++)
    add_to_trie(&common_trie, p->path, p);

  common_trie_done_setup = 1;
}

/*
 * Helper function for update_common_dir: returns 1 if the dir
 * prefix is common.
 */
static int check_common(const char *unmatched, void *value,
      void *baton UNUSED)
{
  struct common_dir *dir = value;

  if (dir->is_dir && (unmatched[0] == 0 || unmatched[0] == '/'))
    return dir->is_common;

  if (!dir->is_dir && unmatched[0] == 0)
    return dir->is_common;

  return 0;
}

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(struct repository *r)
{
  struct strbuf sb = STRBUF_INIT;
  const struct common_dir *p;
  int len;

  if (!r->different_commondir)
    return;
  strbuf_addf(&sb, "%s/", r->gitdir);
  len = sb.len;
  for (p = common_list; p->path; p++) {
    const char *path = p->path;
    if (p->ignore_garbage)
      continue;
    strbuf_setlen(&sb, len);
    strbuf_addstr(&sb, path);
    if (file_exists(sb.buf))
      report_garbage(PACKDIR_FILE_GARBAGE, sb.buf);
  }
  strbuf_release(&sb);
}

static void adjust_git_path(struct repository *repo,
          struct strbuf *buf, int git_dir_len)
{
  const char *base = buf->buf + git_dir_len;

  if (is_dir_file(base, "info", "grafts"))
    strbuf_splice(buf, 0, buf->len,
            repo->graft_file, strlen(repo->graft_file));
  else if (!strcmp(base, "index"))
    strbuf_splice(buf, 0, buf->len,
            repo->index_file, strlen(repo->index_file));
  else if (dir_prefix(base, "objects"))
    replace_dir(buf, git_dir_len + 7, repo->objects->source->path);
  else if (repo_settings_get_hooks_path(repo) && dir_prefix(base, "hooks"))
    replace_dir(buf, git_dir_len + 5, repo_settings_get_hooks_path(repo));
  else if (repo->different_commondir)
    update_common_dir(buf, git_dir_len, repo->commondir);
}

static void strbuf_worktree_gitdir(struct strbuf *buf,
           const struct repository *repo,
           const struct worktree *wt)
{
  if (!wt)
    strbuf_addstr(buf, repo->gitdir);
  else if (!wt->id)
    strbuf_addstr(buf, repo->commondir);
  else
    repo_common_path_append(repo, buf, "worktrees/%s", wt->id);
}

static void repo_git_pathv(struct repository *repo,
         const struct worktree *wt, struct strbuf *buf,
         const char *fmt, va_list args)
{
  int gitdir_len;
  strbuf_worktree_gitdir(buf, repo, wt);
  if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
    strbuf_addch(buf, '/');
  gitdir_len = buf->len;
  strbuf_vaddf(buf, fmt, args);
  if (!wt)
    adjust_git_path(repo, buf, gitdir_len);
  strbuf_cleanup_path(buf);
}

char *repo_git_path(struct repository *repo,
        const char *fmt, ...)
{
  struct strbuf path = STRBUF_INIT;
  va_list args;
  va_start(args, fmt);
  repo_git_pathv(repo, NULL, &path, fmt, args);
  va_end(args);
  return strbuf_detach(&path, NULL);
}

const char *repo_git_path_append(struct repository *repo,
         struct strbuf *sb,
         const char *fmt, ...)
{
  va_list args;
  va_start(args, fmt);
  repo_git_pathv(repo, NULL, sb, fmt, args);
  va_end(args);
  return sb->buf;
}

const char *repo_git_path_replace(struct repository *repo,
          struct strbuf *sb,
          const char *fmt, ...)
{
  va_list args;
  strbuf_reset(sb);
  va_start(args, fmt);
  repo_git_pathv(repo, NULL, sb, fmt, args);
  va_end(args);
  return sb->buf;
}

char *mkpathdup(const char *fmt, ...)
{
  struct strbuf sb = STRBUF_INIT;
  va_list args;
  va_start(args, fmt);
  strbuf_vaddf(&sb, fmt, args);
  va_end(args);
  strbuf_cleanup_path(&sb);
  return strbuf_detach(&sb, NULL);
}

const char *mkpath(const char *fmt, ...)
{
  va_list args;
  struct strbuf *pathname = get_pathname();
  va_start(args, fmt);
  strbuf_vaddf(pathname, fmt, args);
  va_end(args);
  return cleanup_path(pathname->buf);
}

const char *worktree_git_path(const struct worktree *wt, const char *fmt, ...)
{
  struct strbuf *pathname = get_pathname();
  va_list args;

  if (!wt)
    BUG("%s() called with NULL worktree", __func__);

  va_start(args, fmt);
  repo_git_pathv(wt->repo, wt, pathname, fmt, args);
  va_end(args);
  return pathname->buf;
}

static void do_worktree_path(const struct repository *repo,
           struct strbuf *buf,
           const char *fmt, va_list args)
{
  strbuf_addstr(buf, repo->worktree);
  if(buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
    strbuf_addch(buf, '/');

  strbuf_vaddf(buf, fmt, args);
  strbuf_cleanup_path(buf);
}

char *repo_worktree_path(const struct repository *repo, const char *fmt, ...)
{
  struct strbuf path = STRBUF_INIT;
  va_list args;

  va_start(args, fmt);
  do_worktree_path(repo, &path, fmt, args);
  va_end(args);

  return strbuf_detach(&path, NULL);
}

const char *repo_worktree_path_append(const struct repository *repo,
              struct strbuf *sb,
              const char *fmt, ...)
{
  va_list args;

  if (!repo->worktree)
    return NULL;

  va_start(args, fmt);
  do_worktree_path(repo, sb, fmt, args);
  va_end(args);

  return sb->buf;
}

const char *repo_worktree_path_replace(const struct repository *repo,
               struct strbuf *sb,
               const char *fmt, ...)
{
  va_list args;

  strbuf_reset(sb);
  if (!repo->worktree)
    return NULL;

  va_start(args, fmt);
  do_worktree_path(repo, sb, fmt, args);
  va_end(args);

  return sb->buf;
}

/* Returns 0 on success, negative on failure. */
static int do_submodule_path(struct repository *repo,
           struct strbuf *buf, const char *path,
           const char *fmt, va_list args)
{
  struct strbuf git_submodule_common_dir = STRBUF_INIT;
  struct strbuf git_submodule_dir = STRBUF_INIT;
  int ret;

  ret = submodule_to_gitdir(repo, &git_submodule_dir, path);
  if (ret)
    goto cleanup;

  strbuf_complete(&git_submodule_dir, '/');
  strbuf_addbuf(buf, &git_submodule_dir);
  strbuf_vaddf(buf, fmt, args);

  if (get_common_dir_noenv(&git_submodule_common_dir, git_submodule_dir.buf))
    update_common_dir(buf, git_submodule_dir.len, git_submodule_common_dir.buf);

  strbuf_cleanup_path(buf);

cleanup:
  strbuf_release(&git_submodule_dir);
  strbuf_release(&git_submodule_common_dir);
  return ret;
}

char *repo_submodule_path(struct repository *repo,
        const char *path, const char *fmt, ...)
{
  int err;
  va_list args;
  struct strbuf buf = STRBUF_INIT;
  va_start(args, fmt);
  err = do_submodule_path(repo, &buf, path, fmt, args);
  va_end(args);
  if (err) {
    strbuf_release(&buf);
    return NULL;
  }
  return strbuf_detach(&buf, NULL);
}

const char *repo_submodule_path_append(struct repository *repo,
               struct strbuf *buf,
               const char *path,
               const char *fmt, ...)
{
  int err;
  va_list args;
  va_start(args, fmt);
  err = do_submodule_path(repo, buf, path, fmt, args);
  va_end(args);
  if (err)
    return NULL;
  return buf->buf;
}

const char *repo_submodule_path_replace(struct repository *repo,
          struct strbuf *buf,
          const char *path,
          const char *fmt, ...)
{
  int err;
  va_list args;
  strbuf_reset(buf);
  va_start(args, fmt);
  err = do_submodule_path(repo, buf, path, fmt, args);
  va_end(args);
  if (err)
    return NULL;
  return buf->buf;
}

static void repo_common_pathv(const struct repository *repo,
            struct strbuf *sb,
            const char *fmt,
            va_list args)
{
  strbuf_addstr(sb, repo->commondir);
  if (sb->len && !is_dir_sep(sb->buf[sb->len - 1]))
    strbuf_addch(sb, '/');
  strbuf_vaddf(sb, fmt, args);
  strbuf_cleanup_path(sb);
}

char *repo_common_path(const struct repository *repo,
           const char *fmt, ...)
{
  struct strbuf sb = STRBUF_INIT;
  va_list args;
  va_start(args, fmt);
  repo_common_pathv(repo, &sb, fmt, args);
  va_end(args);
  return strbuf_detach(&sb, NULL);
}

const char *repo_common_path_append(const struct repository *repo,
            struct strbuf *sb,
            const char *fmt, ...)
{
  va_list args;
  va_start(args, fmt);
  repo_common_pathv(repo, sb, fmt, args);
  va_end(args);
  return sb->buf;
}

const char *repo_common_path_replace(const struct repository *repo,
             struct strbuf *sb,
             const char *fmt, ...)
{
  va_list args;
  strbuf_reset(sb);
  va_start(args, fmt);
  repo_common_pathv(repo, sb, fmt, args);
  va_end(args);
  return sb->buf;
}

static struct passwd *getpw_str(const char *username, size_t len)
{
  struct passwd *pw;
  char *username_z = xmemdupz(username, len);
  pw = getpwnam(username_z);
  free(username_z);
  return pw;
}

/*
 * Return a string with ~ and ~user expanded via getpw*. Returns NULL on getpw
 * failure or if path is NULL.
 *
 * If real_home is true, strbuf_realpath($HOME) is used in the `~/` expansion.
 *
 * If the path starts with `%(prefix)/`, the remainder is interpreted as
 * relative to where Git is installed, and expanded to the absolute path.
 */
char *interpolate_path(const char *path, int real_home)
{
  struct strbuf user_path = STRBUF_INIT;
  const char *to_copy = path;

  if (!path)
    goto return_null;

  if (skip_prefix(path, "%(prefix)/", &path))
    return system_path(path);

  if (path[0] == '~') {
    const char *first_slash = strchrnul(path, '/');
    const char *username = path + 1;
    size_t username_len = first_slash - username;
    if (username_len == 0) {
      const char *home = getenv("HOME");
      if (!home)
        goto return_null;
      if (real_home)
        strbuf_add_real_path(&user_path, home);
      else
        strbuf_addstr(&user_path, home);
#ifdef GIT_WINDOWS_NATIVE
      convert_slashes(user_path.buf);
#endif
    } else {
      struct passwd *pw = getpw_str(username, username_len);
      if (!pw)
        goto return_null;
      strbuf_addstr(&user_path, pw->pw_dir);
    }
    to_copy = first_slash;
  }
  strbuf_addstr(&user_path, to_copy);
  return strbuf_detach(&user_path, NULL);
return_null:
  strbuf_release(&user_path);
  return NULL;
}

int calc_shared_perm(struct repository *repo,
         int mode)
{
  int tweak;
  int shared_repo = repo_settings_get_shared_repository(repo);
  if (shared_repo < 0)
    tweak = -shared_repo;
  else
    tweak = shared_repo;

  if (!(mode & S_IWUSR))
    tweak &= ~0222;
  if (mode & S_IXUSR)
    /* Copy read bits to execute bits */
    tweak |= (tweak & 0444) >> 2;
  if (shared_repo < 0)
    mode = (mode & ~0777) | tweak;
  else
    mode |= tweak;

  return mode;
}

int adjust_shared_perm(struct repository *repo,
           const char *path)
{
  int old_mode, new_mode;

  if (!repo_settings_get_shared_repository(repo))
    return 0;
  if (get_st_mode_bits(path, &old_mode) < 0)
    return -1;

  new_mode = calc_shared_perm(repo, old_mode);
  if (S_ISDIR(old_mode)) {
    /* Copy read bits to execute bits */
    new_mode |= (new_mode & 0444) >> 2;

    /*
     * g+s matters only if any extra access is granted
     * based on group membership.
     */
    if (FORCE_DIR_SET_GID && (new_mode & 060))
      new_mode |= FORCE_DIR_SET_GID;
  }

  if (((old_mode ^ new_mode) & ~S_IFMT) &&
      chmod(path, (new_mode & ~S_IFMT)) < 0)
    return -2;
  return 0;
}

void safe_create_dir(struct repository *repo, const char *dir, int share)
{
  if (mkdir(dir, 0777) < 0) {
    if (errno != EEXIST) {
      perror(dir);
      exit(1);
    }
  }
  else if (share && adjust_shared_perm(repo, dir))
    die(_("Could not make %s writable by group"), dir);
}

int safe_create_dir_in_gitdir(struct repository *repo, const char *path)
{
  if (mkdir(path, 0777)) {
    int saved_errno = errno;
    struct stat st;
    struct strbuf sb = STRBUF_INIT;

    if (errno != EEXIST)
      return -1;
    /*
     * Are we looking at a path in a symlinked worktree
     * whose original repository does not yet have it?
     * e.g. .git/rr-cache pointing at its original
     * repository in which the user hasn't performed any
     * conflict resolution yet?
     */
    if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
        strbuf_readlink(&sb, path, st.st_size) ||
        !is_absolute_path(sb.buf) ||
        mkdir(sb.buf, 0777)) {
      strbuf_release(&sb);
      errno = saved_errno;
      return -1;
    }
    strbuf_release(&sb);
  }
  return adjust_shared_perm(repo, path);
}

enum scld_error safe_create_leading_directories(struct repository *repo,
            char *path)
{
  char *next_component = path + offset_1st_component(path);
  enum scld_error ret = SCLD_OK;

  while (ret == SCLD_OK && next_component) {
    struct stat st;
    char *slash = next_component, slash_character;

    while (*slash && !is_dir_sep(*slash))
      slash++;

    if (!*slash)
      break;

    next_component = slash + 1;
    while (is_dir_sep(*next_component))
      next_component++;
    if (!*next_component)
      break;

    slash_character = *slash;
    *slash = '\0';
    if (!stat(path, &st)) {
      /* path exists */
      if (!S_ISDIR(st.st_mode)) {
        errno = ENOTDIR;
        ret = SCLD_EXISTS;
      }
    } else if (mkdir(path, 0777)) {
      if (errno == EEXIST &&
          !stat(path, &st) && S_ISDIR(st.st_mode))
        ; /* somebody created it since we checked */
      else if (errno == ENOENT)
        /*
         * Either mkdir() failed because
         * somebody just pruned the containing
         * directory, or stat() failed because
         * the file that was in our way was
         * just removed.  Either way, inform
         * the caller that it might be worth
         * trying again:
         */
        ret = SCLD_VANISHED;
      else
        ret = SCLD_FAILED;
    } else if (repo && adjust_shared_perm(repo, path)) {
      ret = SCLD_PERMS;
    }
    *slash = slash_character;
  }
  return ret;
}

enum scld_error safe_create_leading_directories_no_share(char *path)
{
  return safe_create_leading_directories(NULL, path);
}

enum scld_error safe_create_leading_directories_no_share_const(const char *path)
{
  return safe_create_leading_directories_const(NULL, path);
}

enum scld_error safe_create_leading_directories_const(struct repository *repo,
                  const char *path)
{
  int save_errno;
  /* path points to cache entries, so xstrdup before messing with it */
  char *buf = xstrdup(path);
  enum scld_error result = safe_create_leading_directories(repo, buf);

  save_errno = errno;
  free(buf);
  errno = save_errno;
  return result;
}

int safe_create_file_with_leading_directories(struct repository *repo,
                const char *path)
{
  int fd;

  fd = open(path, O_RDWR|O_CREAT|O_EXCL, 0600);
  if (0 <= fd)
    return fd;

  /* slow path */
  safe_create_leading_directories_const(repo, path);
  return open(path, O_RDWR|O_CREAT|O_EXCL, 0600);
}

static int have_same_root(const char *path1, const char *path2)
{
  int is_abs1, is_abs2;

  is_abs1 = is_absolute_path(path1);
  is_abs2 = is_absolute_path(path2);
  return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
         (!is_abs1 && !is_abs2);
}

/*
 * Give path as relative to prefix.
 *
 * The strbuf may or may not be used, so do not assume it contains the
 * returned path.
 */
const char *relative_path(const char *in, const char *prefix,
        struct strbuf *sb)
{
  int in_len = in ? strlen(in) : 0;
  int prefix_len = prefix ? strlen(prefix) : 0;
  int in_off = 0;
  int prefix_off = 0;
  int i = 0, j = 0;

  if (!in_len)
    return "./";
  else if (!prefix_len)
    return in;

  if (have_same_root(in, prefix))
    /* bypass dos_drive, for "c:" is identical to "C:" */
    i = j = has_dos_drive_prefix(in);
  else {
    return in;
  }

  while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
    if (is_dir_sep(prefix[i])) {
      while (is_dir_sep(prefix[i]))
        i++;
      while (is_dir_sep(in[j]))
        j++;
      prefix_off = i;
      in_off = j;
    } else {
      i++;
      j++;
    }
  }

  if (
      /* "prefix" seems like prefix of "in" */
      i >= prefix_len &&
      /*
       * but "/foo" is not a prefix of "/foobar"
       * (i.e. prefix not end with '/')
       */
      prefix_off < prefix_len) {
    if (j >= in_len) {
      /* in="/a/b", prefix="/a/b" */
      in_off = in_len;
    } else if (is_dir_sep(in[j])) {
      /* in="/a/b/c", prefix="/a/b" */
      while (is_dir_sep(in[j]))
        j++;
      in_off = j;
    } else {
      /* in="/a/bbb/c", prefix="/a/b" */
      i = prefix_off;
    }
  } else if (
       /* "in" is short than "prefix" */
       j >= in_len &&
       /* "in" not end with '/' */
       in_off < in_len) {
    if (is_dir_sep(prefix[i])) {
      /* in="/a/b", prefix="/a/b/c/" */
      while (is_dir_sep(prefix[i]))
        i++;
      in_off = in_len;
    }
  }
  in += in_off;
  in_len -= in_off;

  if (i >= prefix_len) {
    if (!in_len)
      return "./";
    else
      return in;
  }

  strbuf_reset(sb);
  strbuf_grow(sb, in_len);

  while (i < prefix_len) {
    if (is_dir_sep(prefix[i])) {
      strbuf_addstr(sb, "../");
      while (is_dir_sep(prefix[i]))
        i++;
      continue;
    }
    i++;
  }
  if (!is_dir_sep(prefix[prefix_len - 1]))
    strbuf_addstr(sb, "../");

  strbuf_addstr(sb, in);

  return sb->buf;
}

/*
 * A simpler implementation of relative_path
 *
 * Get relative path by removing "prefix" from "in". This function
 * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 * to increase performance when traversing the path to work_tree.
 */
const char *remove_leading_path(const char *in, const char *prefix)
{
  static struct strbuf buf = STRBUF_INIT;
  int i = 0, j = 0;

  if (!prefix || !prefix[0])
    return in;
  while (prefix[i]) {
    if (is_dir_sep(prefix[i])) {
      if (!is_dir_sep(in[j]))
        return in;
      while (is_dir_sep(prefix[i]))
        i++;
      while (is_dir_sep(in[j]))
        j++;
      continue;
    } else if (in[j] != prefix[i]) {
      return in;
    }
    i++;
    j++;
  }
  if (
      /* "/foo" is a prefix of "/foo" */
      in[j] &&
      /* "/foo" is not a prefix of "/foobar" */
      !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
     )
    return in;
  while (is_dir_sep(in[j]))
    j++;

  strbuf_reset(&buf);
  if (!in[j])
    strbuf_addstr(&buf, ".");
  else
    strbuf_addstr(&buf, in + j);
  return buf.buf;
}

/*
 * 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)
 * - Squashes sequences of '/' except "//server/share" on Windows
 * - Removes "." components.
 * - Removes ".." components, and the components the precede them.
 * Returns failure (non-zero) if a ".." component appears as first path
 * component anytime during the normalization. Otherwise, returns success (0).
 *
 * Note that this function is purely textual.  It does not follow symlinks,
 * verify the existence of the path, or make any system calls.
 *
 * prefix_len != NULL is for a specific case of prefix_pathspec():
 * assume that src == dst and src[0..prefix_len-1] is already
 * normalized, any time "../" eats up to the prefix_len part,
 * prefix_len is reduced. In the end prefix_len is the remaining
 * prefix that has not been overridden by user pathspec.
 *
 * NEEDSWORK: This function doesn't perform normalization w.r.t. trailing '/'.
 * For everything but the root folder itself, the normalized path should not
 * end with a '/', then the callers need to be fixed up accordingly.
 *
 */

static const char *skip_slashes(const char *p)
{
  while (is_dir_sep(*p))
    p++;
  return p;
}

int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
{
  char *dst0;
  const char *end;

  /*
   * Copy initial part of absolute path: "/", "C:/", "//server/share/".
   */
  end = src + offset_1st_component(src);
  while (src < end) {
    char c = *src++;
    if (is_dir_sep(c))
      c = '/';
    *dst++ = c;
  }
  dst0 = dst;

  src = skip_slashes(src);

  for (;;) {
    char c = *src;

    /*
     * A path component that begins with . could be
     * special:
     * (1) "." and ends   -- ignore and terminate.
     * (2) "./"           -- ignore them, eat slash and continue.
     * (3) ".." and ends  -- strip one and terminate.
     * (4) "../"          -- strip one, eat slash and continue.
     */
    if (c == '.') {
      if (!src[1]) {
        /* (1) */
        src++;
      } else if (is_dir_sep(src[1])) {
        /* (2) */
        src += 2;
        src = skip_slashes(src);
        continue;
      } else if (src[1] == '.') {
        if (!src[2]) {
          /* (3) */
          src += 2;
          goto up_one;
        } else if (is_dir_sep(src[2])) {
          /* (4) */
          src += 3;
          src = skip_slashes(src);
          goto up_one;
        }
      }
    }

    /* copy up to the next '/', and eat all '/' */
    while ((c = *src++) != '\0' && !is_dir_sep(c))
      *dst++ = c;
    if (is_dir_sep(c)) {
      *dst++ = '/';
      while (is_dir_sep(c))
        c = *src++;
      src--;
    } else if (!c)
      break;
    continue;

  up_one:
    /*
     * strip the last component
     *
     * dst0..dst is prefix portion, and dst[-1] is '/';
     * go up one level.
     */
    dst--;  /* go to trailing '/' */
    if (dst <= dst0)
      return -1;
    /* Windows: dst[-1] cannot be backslash anymore */
    while (dst0 < dst && dst[-1] != '/')
      dst--;
    if (prefix_len && *prefix_len > dst - dst0)
      *prefix_len = dst - dst0;
  }
  *dst = '\0';
  return 0;
}

int normalize_path_copy(char *dst, const char *src)
{
  return normalize_path_copy_len(dst, src, NULL);
}

int strbuf_normalize_path(struct strbuf *src)
{
  struct strbuf dst = STRBUF_INIT;

  strbuf_grow(&dst, src->len);
  if (normalize_path_copy(dst.buf, src->buf) < 0) {
    strbuf_release(&dst);
    return -1;
  }

  /*
   * normalize_path does not tell us the new length, so we have to
   * compute it by looking for the new NUL it placed
   */
  strbuf_setlen(&dst, strlen(dst.buf));
  strbuf_swap(src, &dst);
  strbuf_release(&dst);
  return 0;
}

/*
 * path = Canonical absolute path
 * prefixes = string_list containing normalized, absolute paths without
 * trailing slashes (except for the root directory, which is denoted by "/").
 *
 * Determines, for each path in prefixes, whether the "prefix"
 * is an ancestor directory of path.  Returns the length of the longest
 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 * is an ancestor.  (Note that this means 0 is returned if prefixes is
 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 * are not considered to be their own ancestors.  path must be in a
 * canonical form: empty components, or "." or ".." components are not
 * allowed.
 */
int longest_ancestor_length(const char *path, struct string_list *prefixes)
{
  int max_len = -1;

  if (!strcmp(path, "/"))
    return -1;

  for (size_t i = 0; i < prefixes->nr; i++) {
    const char *ceil = prefixes->items[i].string;
    int len = strlen(ceil);

    /*
     * For root directories (`/`, `C:/`, `//server/share/`)
     * adjust the length to exclude the trailing slash.
     */
    if (len > 0 && ceil[len - 1] == '/')
      len--;

    if (strncmp(path, ceil, len) ||
        path[len] != '/' || !path[len + 1])
      continue; /* no match */

    if (len > max_len)
      max_len = len;
  }

  return max_len;
}

/* strip arbitrary amount of directory separators at end of path */
static inline int chomp_trailing_dir_sep(const char *path, int len)
{
  while (len && is_dir_sep(path[len - 1]))
    len--;
  return len;
}

/*
 * 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.
 */
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 -1;

    if (is_dir_sep(path[path_len - 1])) {
      if (!is_dir_sep(suffix[suffix_len - 1]))
        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 -1;
  }

  if (path_len && !is_dir_sep(path[path_len - 1]))
    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)
{
  int sl, ndot;

  /*
   * This resurrects the belts and suspenders paranoia check by HPA
   * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
   * does not do getcwd() based path canonicalization.
   *
   * sl becomes true immediately after seeing '/' and continues to
   * be true as long as dots continue after that without intervening
   * non-dot character.
   */
  if (!p || (*p != '/' && *p != '~'))
    return -1;
  sl = 1; ndot = 0;
  p++;

  while (1) {
    char ch = *p++;
    if (sl) {
      if (ch == '.')
        ndot++;
      else if (ch == '/') {
        if (ndot < 3)
          /* reject //, /./ and /../ */
          return -1;
        ndot = 0;
      }
      else if (ch == 0) {
        if (0 < ndot && ndot < 3)
          /* reject /.$ and /..$ */
          return -1;
        return 0;
      }
      else
        sl = ndot = 0;
    }
    else if (ch == 0)
      return 0;
    else if (ch == '/') {
      sl = 1;
      ndot = 0;
    }
  }
}

/*
 * 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)
{
  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;

  for (;;) {
    c = *(name++);
    if (!c || is_xplatform_dir_sep(c) || c == ':')
      return 1;
    if (c != '.' && c != ' ')
      return 0;
  }
}

static int is_ntfs_dot_generic(const char *name,
             const char *dotgit_name,
             size_t len,
             const char *dotgit_ntfs_shortname_prefix)
{
  int saw_tilde;
  size_t i;

  if ((name[0] == '.' && !strncasecmp(name + 1, dotgit_name, len))) {
    i = len + 1;
only_spaces_and_periods:
    for (;;) {
      char c = name[i++];
      if (!c || c == ':')
        return 1;
      if (c != ' ' && c != '.')
        return 0;
    }
  }

  /*
   * Is it a regular NTFS short name, i.e. shortened to 6 characters,
   * followed by ~1, ... ~4?
   */
  if (!strncasecmp(name, dotgit_name, 6) && name[6] == '~' &&
      name[7] >= '1' && name[7] <= '4') {
    i = 8;
    goto only_spaces_and_periods;
  }

  /*
   * Is it a fall-back NTFS short name (for details, see
   * https://en.wikipedia.org/wiki/8.3_filename?
   */
  for (i = 0, saw_tilde = 0; i < 8; i++)
    if (name[i] == '\0')
      return 0;
    else if (saw_tilde) {
      if (name[i] < '0' || name[i] > '9')
        return 0;
    } else if (name[i] == '~') {
      if (name[++i] < '1' || name[i] > '9')
        return 0;
      saw_tilde = 1;
    } else if (i >= 6)
      return 0;
    else if (name[i] & 0x80) {
      /*
       * We know our needles contain only ASCII, so we clamp
       * here to make the results of tolower() sane.
       */
      return 0;
    } else if (tolower(name[i]) != dotgit_ntfs_shortname_prefix[i])
      return 0;

  goto only_spaces_and_periods;
}

/*
 * Inline helper to make sure compiler resolves strlen() on literals at
 * compile time.
 */
static inline int is_ntfs_dot_str(const char *name, const char *dotgit_name,
          const char *dotgit_ntfs_shortname_prefix)
{
  return is_ntfs_dot_generic(name, dotgit_name, strlen(dotgit_name),
           dotgit_ntfs_shortname_prefix);
}

int is_ntfs_dotgitmodules(const char *name)
{
  return is_ntfs_dot_str(name, "gitmodules", "gi7eba");
}

int is_ntfs_dotgitignore(const char *name)
{
  return is_ntfs_dot_str(name, "gitignore", "gi250a");
}

int is_ntfs_dotgitattributes(const char *name)
{
  return is_ntfs_dot_str(name, "gitattributes", "gi7d29");
}

int is_ntfs_dotmailmap(const char *name)
{
  return is_ntfs_dot_str(name, "mailmap", "maba30");
}

int looks_like_command_line_option(const char *str)
{
  return str && str[0] == '-';
}

char *xdg_config_home_for(const char *subdir, const char *filename)
{
  const char *home, *config_home;

  assert(subdir);
  assert(filename);
  config_home = getenv("XDG_CONFIG_HOME");
  if (config_home && *config_home)
    return mkpathdup("%s/%s/%s", config_home, subdir, filename);

  home = getenv("HOME");
  if (home)
    return mkpathdup("%s/.config/%s/%s", home, subdir, filename);

  return NULL;
}

char *xdg_config_home(const char *filename)
{
  return xdg_config_home_for("git", filename);
}

char *xdg_cache_home(const char *filename)
{
  const char *home, *cache_home;

  assert(filename);
  cache_home = getenv("XDG_CACHE_HOME");
  if (cache_home && *cache_home)
    return mkpathdup("%s/git/%s", cache_home, filename);

  home = getenv("HOME");
  if (home)
    return mkpathdup("%s/.cache/git/%s", home, filename);
  return NULL;
}

void format_path(struct strbuf *dest, const char *path,
     const char *prefix, enum path_format format)
{
  strbuf_reset(dest);

  switch (format) {
  case PATH_FORMAT_UNMODIFIED:
    strbuf_addstr(dest, path);
    break;

  case PATH_FORMAT_RELATIVE: {
    struct strbuf relative_buf = STRBUF_INIT;
    struct strbuf real_path = STRBUF_INIT;
    struct strbuf real_prefix = STRBUF_INIT;
    char *cwd = NULL;

    /*
     * We don't ever produce a relative path if prefix is NULL,
     * so set the prefix to the current directory so that we can
     * produce a relative path whenever possible.
     */
    if (!prefix)
      prefix = cwd = xgetcwd();

    if (!is_absolute_path(path)) {
      strbuf_realpath_forgiving(&real_path, path, 1);
      path = real_path.buf;
    }
    if (!is_absolute_path(prefix)) {
      strbuf_realpath_forgiving(&real_prefix, prefix, 1);
      prefix = real_prefix.buf;
    }

    strbuf_addstr(dest, relative_path(path, prefix, &relative_buf));

    strbuf_release(&relative_buf);
    strbuf_release(&real_path);
    strbuf_release(&real_prefix);
    free(cwd);
    break;
  }

  case PATH_FORMAT_RELATIVE_IF_SHARED: {
    struct strbuf relative_buf = STRBUF_INIT;

    /*
     * If we're using RELATIVE_IF_SHARED mode, then we want an
     * absolute path unless the two share a common prefix, so don't
     * default the prefix to the current working directory. Doing so
     * would cause a relative path to always be produced if possible.
     */
    strbuf_addstr(dest, relative_path(path, prefix, &relative_buf));
    strbuf_release(&relative_buf);
    break;
  }

  case PATH_FORMAT_CANONICAL:
    /*
     * strbuf_realpath_forgiving inherently resets the destination
     * buffer, safely aligning with our replace semantics.
     */
    strbuf_realpath_forgiving(dest, path, 1);
    break;

  default:
    BUG("unknown path_format value %d", format);
  }
}

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(fetch_head, "FETCH_HEAD")
REPO_GIT_PATH_FUNC(shallow, "shallow")
REPO_GIT_PATH_FUNC(merge_labels, "MERGE_LABELS")

Coverage Report

Created: 2026-11-12 06:03