maildir: Don't waste time stat()ing if generated filename is in tmp/.

diff --git a/src/lib-storage/index/maildir/maildir-save.c b/src/lib-storage/index/maildir/maildir-save.c
index 130f9066c2acfac2651baed5c737152267aedb26..eae063251379a37e706052fa6d74df882b884281 100644 (file)
--- a/src/lib-storage/index/maildir/maildir-save.c
+++ b/src/lib-storage/index/maildir/maildir-save.c
@@ -316,10 +316,10 @@ static int maildir_create_tmp(struct maildir_mailbox *mbox, const char *dir,
                              const char **fname_r)
 {
        struct mailbox *box = &mbox->box;
-       struct stat st;
        unsigned int prefix_len;
        const char *tmp_fname;
        string_t *path;
+       mode_t old_mask;
        int fd;
 
        path = t_str_new(256);
@@ -327,34 +327,20 @@ static int maildir_create_tmp(struct maildir_mailbox *mbox, const char *dir,
        str_append_c(path, '/');
        prefix_len = str_len(path);
 
-       for (;;) {
+       do {
                tmp_fname = maildir_filename_generate();
                str_truncate(path, prefix_len);
                str_append(path, tmp_fname);
 
-               /* stat() first to see if it exists. pretty much the only
-                  possibility of that happening is if time had moved
-                  backwards, but even then it's highly unlikely. */
-               if (stat(str_c(path), &st) == 0) {
-                       /* try another file name */
-               } else if (errno != ENOENT) {
-                       mail_storage_set_critical(box->storage,
-                               "stat(%s) failed: %m", str_c(path));
-                       return -1;
-               } else {
-                       /* doesn't exist */
-                       mode_t old_mask = umask(0777 & ~box->file_create_mode);
-                       fd = open(str_c(path),
-                                 O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 0777);
-                       umask(old_mask);
-
-                       if (fd != -1 || errno != EEXIST)
-                               break;
-                       /* race condition between stat() and open().
-                          highly unlikely. */
-               }
-               tmp_fname = NULL;
-       }
+               /* the generated filename is unique. the only reason why it
+                  might return an existing filename is if the time moved
+                  backwards. so we'll use O_EXCL anyway, although it's mostly
+                  useless. */
+               old_mask = umask(0777 & ~box->file_create_mode);
+               fd = open(str_c(path),
+                         O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 0777);
+               umask(old_mask);
+       } while (fd == -1 && errno == EEXIST);
 
        *fname_r = tmp_fname;
        if (fd == -1) {