scrub/scrub-2.6.1-symlinks-to-block-device.patch

From 499a491c21b5a18be79334282dfa11fd4f408c49 Mon Sep 17 00:00:00 2001
From: Sergio Correia <scorreia@redhat.com>
Date: Wed, 27 Jan 2021 09:42:15 -0300
Subject: [PATCH] scrub should work for symlinks pointing to block devices

In [1] (add -L option to avoid scrubbing symlink target [Tim
Boronczyk]), scrub introduced a -L (--no-link) option so that it would
not scrub the target, if it was a link and this new option was set.

A side-effect of that change is that scrub stopped working for links
pointing to a block device, whereas it would still work for links
pointing to regular files -- it is not clear from the commit changelog
and the added documentation for this new option that this was an
intended change.

In this commit we fix this regression, and scrub works again for links
pointing to block devices. -L/--no-link option also works for these
links.

[1] https://github.com/chaos/scrub/commit/01915c442288b4b274261fa07e42e116fb9d6b60
---
 src/scrub.c | 13 ++++++++-----
 src/util.c  | 13 +++++++++----
 src/util.h  |  2 +-
 3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/scrub.c b/src/scrub.c
index 1dada28..178dfe7 100644
--- a/src/scrub.c
+++ b/src/scrub.c
@@ -334,6 +334,10 @@ static int scrub_object(char *filename, const struct opt_struct *opt,
                 fprintf(stderr, "%s: %s already scrubbed? (-f to force)\n",
                         prog, filename);
                 errcount++;
+            } else if (is_symlink(filename) && opt->nofollow) {
+                fprintf(stderr, "%s: skipping symlink %s because --no-link (-L) option was set\n",
+                        prog, filename);
+                errcount++;
             } else if (!noexec) {
                 if (dryrun) {
                     printf("%s: (dryrun) scrub special file %s\n",
@@ -343,8 +347,8 @@ static int scrub_object(char *filename, const struct opt_struct *opt,
                 }
             }
             break;
-        case FILE_LINK:
-            if (opt->nofollow) {
+        case FILE_REGULAR:
+            if (is_symlink(filename) && opt->nofollow) {
                 if (opt->remove && !noexec) {
                     if (dryrun) {
                         printf("%s: (dryrun) unlink %s\n", prog, filename);
@@ -359,8 +363,7 @@ static int scrub_object(char *filename, const struct opt_struct *opt,
                 }
                 break;
             }
-            /* FALL THRU */
-        case FILE_REGULAR:
+
             if (access(filename, R_OK|W_OK) < 0) {
                 fprintf(stderr, "%s: no rw access to %s\n", prog, filename);
                 errcount++;
@@ -670,7 +673,7 @@ scrub_file(char *path, const struct opt_struct *opt)
     filetype_t ftype = filetype(path);
     off_t size = opt->devsize;
 
-    assert(ftype == FILE_REGULAR || ftype == FILE_LINK);
+    assert(ftype == FILE_REGULAR);
 
     if (stat(path, &sb) < 0) {
         fprintf(stderr, "%s: stat %s: %s\n", prog, path, strerror(errno));
diff --git a/src/util.c b/src/util.c
index 96dd59b..fb85368 100644
--- a/src/util.c
+++ b/src/util.c
@@ -71,6 +71,15 @@ write_all(int fd, const unsigned char *buf, int count)
     return n;
 }
 
+/* Indicates whether the file represented by 'path' is a symlink.
+ */
+int
+is_symlink(char *path)
+{
+    struct stat sb;
+    return lstat(path, &sb) == 0 && S_ISLNK(sb.st_mode);
+}
+
 /* Return the type of file represented by 'path'.
  */
 filetype_t
@@ -80,10 +89,6 @@ filetype(char *path)
 
     filetype_t res = FILE_NOEXIST;
 
-    if (lstat(path, &sb) == 0 && S_ISLNK(sb.st_mode)) {
-        return FILE_LINK;
-    }
-
     if (stat(path, &sb) == 0) {
         if (S_ISREG(sb.st_mode))
             res = FILE_REGULAR;
diff --git a/src/util.h b/src/util.h
index 513ae48..04246df 100644
--- a/src/util.h
+++ b/src/util.h
@@ -13,7 +13,6 @@ typedef enum {
     FILE_REGULAR,
     FILE_CHAR,
     FILE_BLOCK,
-    FILE_LINK,
     FILE_OTHER,
 } filetype_t;
 
@@ -21,6 +20,7 @@ typedef enum { UP, DOWN } round_t;
 
 int         read_all(int fd, unsigned char *buf, int count);
 int         write_all(int fd, const unsigned char *buf, int count);
+int         is_symlink(char *path);
 filetype_t  filetype(char *path);
 off_t       blkalign(off_t offset, int blocksize, round_t rtype);
 void *      alloc_buffer(int bufsize);