From d99270c450d8f9ef3ecfbcbeeb99b581f36c9175 Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Thu, 24 May 2012 18:01:11 -0400 Subject: [PATCH] new: Centralize file type stat-ing logic This moves our logic to get a file's type into one function. This has several benefits: we can support OSes and file systems that do not provide dirent.d_type or always return DT_UNKNOWN, complex symlink-handling logic has been replaced by a simple stat fall-through in one place, and the error message for un-stat-able file is more accurate (previously, the error always mentioned directories, even though a broken symlink is not a directory). --- notmuch-new.c | 103 ++++++++++++++++++++++++++++++-------------------- test/new | 2 +- 2 files changed, 64 insertions(+), 41 deletions(-) diff --git a/notmuch-new.c b/notmuch-new.c index 72dd558d..c64f1a77 100644 --- a/notmuch-new.c +++ b/notmuch-new.c @@ -154,6 +154,48 @@ dirent_sort_strcmp_name (const struct dirent **a, const struct dirent **b) return strcmp ((*a)->d_name, (*b)->d_name); } +/* Return the type of a directory entry relative to path as a stat(2) + * mode. Like stat, this follows symlinks. Returns -1 and sets errno + * if the file's type cannot be determined (which includes dangling + * symlinks). + */ +static int +dirent_type (const char *path, const struct dirent *entry) +{ + struct stat statbuf; + char *abspath; + int err, saved_errno; + +#ifdef _DIRENT_HAVE_D_TYPE + /* Mapping from d_type to stat mode_t. We omit DT_LNK so that + * we'll fall through to stat and get the real file type. */ + static const mode_t modes[] = { + [DT_BLK] = S_IFBLK, + [DT_CHR] = S_IFCHR, + [DT_DIR] = S_IFDIR, + [DT_FIFO] = S_IFIFO, + [DT_REG] = S_IFREG, + [DT_SOCK] = S_IFSOCK + }; + if (entry->d_type < ARRAY_SIZE(modes) && modes[entry->d_type]) + return modes[entry->d_type]; +#endif + + abspath = talloc_asprintf (NULL, "%s/%s", path, entry->d_name); + if (!abspath) { + errno = ENOMEM; + return -1; + } + err = stat(abspath, &statbuf); + saved_errno = errno; + talloc_free (abspath); + if (err < 0) { + errno = saved_errno; + return -1; + } + return statbuf.st_mode & S_IFMT; +} + /* Test if the directory looks like a Maildir directory. * * Search through the array of directory entries to see if we can find all @@ -162,12 +204,12 @@ dirent_sort_strcmp_name (const struct dirent **a, const struct dirent **b) * Return 1 if the directory looks like a Maildir and 0 otherwise. */ static int -_entries_resemble_maildir (struct dirent **entries, int count) +_entries_resemble_maildir (const char *path, struct dirent **entries, int count) { int i, found = 0; for (i = 0; i < count; i++) { - if (entries[i]->d_type != DT_DIR && entries[i]->d_type != DT_UNKNOWN) + if (dirent_type (path, entries[i]) != S_IFDIR) continue; if (strcmp(entries[i]->d_name, "new") == 0 || @@ -250,7 +292,7 @@ add_files_recursive (notmuch_database_t *notmuch, notmuch_status_t status, ret = NOTMUCH_STATUS_SUCCESS; notmuch_message_t *message = NULL; struct dirent **fs_entries = NULL; - int i, num_fs_entries = 0; + int i, num_fs_entries = 0, entry_type; notmuch_directory_t *directory; notmuch_filenames_t *db_files = NULL; notmuch_filenames_t *db_subdirs = NULL; @@ -300,7 +342,7 @@ add_files_recursive (notmuch_database_t *notmuch, } /* Pass 1: Recurse into all sub-directories. */ - is_maildir = _entries_resemble_maildir (fs_entries, num_fs_entries); + is_maildir = _entries_resemble_maildir (path, fs_entries, num_fs_entries); for (i = 0; i < num_fs_entries; i++) { if (interrupted) @@ -308,17 +350,16 @@ add_files_recursive (notmuch_database_t *notmuch, entry = fs_entries[i]; - /* We only want to descend into directories. - * But symlinks can be to directories too, of course. - * - * And if the filesystem doesn't tell us the file type in the - * scandir results, then it might be a directory (and if not, - * then we'll stat and return immediately in the next level of - * recursion). */ - if (entry->d_type != DT_DIR && - entry->d_type != DT_LNK && - entry->d_type != DT_UNKNOWN) - { + /* We only want to descend into directories (and symlinks to + * directories). */ + entry_type = dirent_type (path, entry); + if (entry_type == -1) { + /* Be pessimistic, e.g. so we don't lose lots of mail just + * because a user broke a symlink. */ + fprintf (stderr, "Error reading file %s/%s: %s\n", + path, entry->d_name, strerror (errno)); + return NOTMUCH_STATUS_FILE_ERROR; + } else if (entry_type != S_IFDIR) { continue; } @@ -407,31 +448,13 @@ add_files_recursive (notmuch_database_t *notmuch, notmuch_filenames_move_to_next (db_subdirs); } - /* If we're looking at a symlink, we only want to add it if it - * links to a regular file, (and not to a directory, say). - * - * Similarly, if the file is of unknown type (due to filesystem - * limitations), then we also need to look closer. - * - * In either case, a stat does the trick. - */ - if (entry->d_type == DT_LNK || entry->d_type == DT_UNKNOWN) { - int err; - - next = talloc_asprintf (notmuch, "%s/%s", path, entry->d_name); - err = stat (next, &st); - talloc_free (next); - next = NULL; - - /* Don't emit an error for a link pointing nowhere, since - * the directory-traversal pass will have already done - * that. */ - if (err) - continue; - - if (! S_ISREG (st.st_mode)) - continue; - } else if (entry->d_type != DT_REG) { + /* Only add regular files (and symlinks to regular files). */ + entry_type = dirent_type (path, entry); + if (entry_type == -1) { + fprintf (stderr, "Error reading file %s/%s: %s\n", + path, entry->d_name, strerror (errno)); + return NOTMUCH_STATUS_FILE_ERROR; + } else if (entry_type != S_IFREG) { continue; } diff --git a/test/new b/test/new index a7bc1462..cab7c016 100755 --- a/test/new +++ b/test/new @@ -140,7 +140,7 @@ test_begin_subtest "Broken symlink aborts" ln -s does-not-exist "${MAIL_DIR}/broken" output=$(NOTMUCH_NEW 2>&1) test_expect_equal "$output" \ -"Error reading directory ${MAIL_DIR}/broken: No such file or directory +"Error reading file ${MAIL_DIR}/broken: No such file or directory Note: A fatal error was encountered: Something went wrong trying to read or write a file No new mail." rm "${MAIL_DIR}/broken"