Use openat() and unlinkat() instead of chdir()ing to the recovery dir.

Since we use flock() and not fcntl() locking we can open the recovery
file read-only.  OK martijn@

diff --git a/usr.bin/vi/common/recover.c b/usr.bin/vi/common/recover.c
index 3a43b2a..3545df8 100644 (file)
--- a/usr.bin/vi/common/recover.c
+++ b/usr.bin/vi/common/recover.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: recover.c,v 1.25 2016/06/29 20:38:39 tb Exp $ */
+/*     $OpenBSD: recover.c,v 1.26 2017/06/12 18:38:57 millert Exp $    */
 
 /*-
  * Copyright (c) 1993, 1994
@@ -465,6 +465,7 @@ rcv_list(SCR *sp)
        struct dirent *dp;
        struct stat sb;
        DIR *dirp;
+       int fd;
        FILE *fp;
        int found;
        char *p, *t, file[PATH_MAX], path[PATH_MAX];
@@ -473,7 +474,7 @@ rcv_list(SCR *sp)
        if (opts_empty(sp, O_RECDIR, 0))
                return (1);
        p = O_STR(sp, O_RECDIR);
-       if (chdir(p) || (dirp = opendir(".")) == NULL) {
+       if ((dirp = opendir(p)) == NULL) {
                msgq_str(sp, M_SYSERR, p, "recdir: %s");
                return (1);
        }
@@ -485,16 +486,11 @@ rcv_list(SCR *sp)
 
                /*
                 * If it's readable, it's recoverable.
-                *
-                * XXX
-                * Should be "r", we don't want to write the file.  However,
-                * if we're using fcntl(2), there's no way to lock a file
-                * descriptor that's not open for writing.
                 */
-               if ((fp = fopen(dp->d_name, "r+")) == NULL)
+               if ((fd = openat(dirfd(dirp), dp->d_name, O_RDONLY)) == -1)
                        continue;
 
-               switch (file_lock(sp, NULL, NULL, fileno(fp), 1)) {
+               switch (file_lock(sp, NULL, NULL, fd, 1)) {
                case LOCK_FAILED:
                        /*
                         * XXX
@@ -508,11 +504,15 @@ rcv_list(SCR *sp)
                        break;
                case LOCK_UNAVAIL:
                        /* If it's locked, it's live. */
-                       (void)fclose(fp);
+                       close(fd);
                        continue;
                }
 
                /* Check the headers. */
+               if ((fp = fdopen(fd, "r")) == NULL) {
+                       close(fd);
+                       continue;
+               }
                if (fgets(file, sizeof(file), fp) == NULL ||
                    strncmp(file, VI_FHEADER, sizeof(VI_FHEADER) - 1) ||
                    (p = strchr(file, '\n')) == NULL ||
@@ -536,12 +536,12 @@ rcv_list(SCR *sp)
                errno = 0;
                if (stat(path + sizeof(VI_PHEADER) - 1, &sb) &&
                    errno == ENOENT) {
-                       (void)unlink(dp->d_name);
+                       (void)unlinkat(dirfd(dirp), dp->d_name, 0);
                        goto next;
                }
 
                /* Get the last modification time and display. */
-               (void)fstat(fileno(fp), &sb);
+               (void)fstat(fd, &sb);
                (void)printf("%.24s: %s\n",
                    ctime(&sb.st_mtime), file + sizeof(VI_FHEADER) - 1);
                found = 1;