[PATCH v2 2/2] new: Centralize file type stat-ing logic
Austin Clements
amdragon at MIT.EDU
Mon May 7 15:20:40 PDT 2012
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symlink-handling logic has been replaced by a simple stat fall-through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 cb720cc..8955677 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;
+ int i, num_fs_entries, entry_type;
notmuch_directory_t *directory;
notmuch_filenames_t *db_files = NULL;
notmuch_filenames_t *db_subdirs = NULL;
@@ -317,7 +359,7 @@ 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)
@@ -325,17 +367,16 @@ 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;
}
@@ -425,31 +466,13 @@ 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 26253db..e3900f5 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 "$output" \
-"Error reading directory /run/shm/nm/tmp.new/mail/broken: No such file or directory
+"Error reading file /run/shm/nm/tmp.new/mail/broken: No such file or directory
Note: A fatal error was encountered: Something went wrong trying to read or write a file
No new mail."
rm "${MAIL_DIR}/broken"
--
1.7.10
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