Quoth Jani Nikula on May 08 at 12:08 am:
> On May 7, 2012 9:10 PM, "Austin Clements" <[1]amdragon at mit.edu> wrote:
> >
> > 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 symlink-handling logic has been replaced by a simple stat fall-through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).
>
> Please find some quick drive-by-review below.
Thanks for the review! New version on its way...
> J.
>
> > ---
> > ?notmuch-new.c | ? 99
> ++++++++++++++++++++++++++++++++++-----------------------
> > ?test/new ? ? ?| ? ?2 +-
> > ?2 files changed, 60 insertions(+), 41 deletions(-)
> >
> > diff --git a/notmuch-new.c b/notmuch-new.c
> > index cb720cc..cf2580e 100644
> > --- a/notmuch-new.c
> > +++ b/notmuch-new.c
> > @@ -154,6 +154,44 @@ 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;
> > +
> > +#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 < sizeof(modes)/sizeof(modes[0]) &&
>
> ARRAY_SIZE()
Huh. I went looking for that. I wonder how I missed it.
> > + ? ? ? modes[entry->d_type])
> > + ? ? ? return modes[entry->d_type];
> > +#endif
> > +
> > + ? ?abspath = talloc_asprintf (NULL, "%s/%s", path, entry->d_name);
> > + ? ?if (!abspath)
> > + ? ? ? return -1;
>
> Does talloc set errno in this case? I suspect not.
>
> > + ? ?err = stat(abspath, &statbuf);
> > + ? ?talloc_free (abspath);
>
> This likely breaks your promise about errno. You can't trust talloc_free()
> not calling some function that sets errno.
Setting errno was a late and apparently not well thought-out addition.
The new patch should set it on all of the error paths and save it
around things that may modify it.
> > + ? ?if (err < 0)
> > + ? ? ? 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 +200,12 @@ 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 +288,7 @@ 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 +355,7 @@ 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 +363,16 @@ 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 loose lots of mail
>
> s/loose/lose/ ?
Oops.
> > + ? ? ? ? ? ?* just because a user broke a symlink. */
> > + ? ? ? ? ? fprintf (stderr, "Error reading file %s/%s: %s\n",
> > + ? ? ? ? ? ? ? ? ? ?path, entry->d_name, strerror (errno));
>
> You can't trust errno here, as explained above.
Fixed above.
> > + ? ? ? ? ? return NOTMUCH_STATUS_FILE_ERROR;
> > + ? ? ? } else if (entry_type != S_IFDIR) {
> > ? ? ? ? ? ?continue;
> > ? ? ? ?}
> >
> > @@ -425,31 +462,13 @@ 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));
>
> Ditto.
>
> > + ? ? ? ? ? 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"
> >
> > _______________________________________________
> > notmuch mailing list
> > [2]notmuch at notmuchmail.org
> > [3]http://notmuchmail.org/mailman/listinfo/notmuch
