path-util: rework find_binary(), fsck_exists() and mkfs_exists()

Modernize the code a bit:

- Get rid of FOREACH_WORD_SEPARATOR() loop in favour of a
  extract_first_word() loop.

- Remove find_binary()'s "local" flag. It's not reasonably possible to
  look for binaries on remote systems, we hence should not pretend we
  could.

- When we cannot find a suitable binary, return the last error returned
  from access() rather than ENOENT unconditionally.

- Rework fsck_exists() and mkfs_exists() to return 1 on success, 0 if
  the implementation is missing and negative on real errors. This is
  more like we do it in other functions.

- Make sure we also detect direct fsck symlinks to "true", rather than
  just absolute ones to /bin/true.

1 files changed, 11 insertions, 5 deletions

diff --git a/src/run/run.c b/src/run/run.c
index 93d8cd1d08..25ef04a7d2 100644
--- a/src/run/run.c
+++ b/src/run/run.c
@@ -1153,14 +1153,20 @@ int main(int argc, char* argv[]) {
         if (r <= 0)
                 goto finish;
 
-        if (argc > optind) {
-                r = find_binary(argv[optind], arg_transport == BUS_TRANSPORT_LOCAL, &command);
+        if (argc > optind && arg_transport == BUS_TRANSPORT_LOCAL) {
+                /* Patch in an absolute path */
+
+                r = find_binary(argv[optind], &command);
                 if (r < 0) {
-                        log_error_errno(r, "Failed to find executable %s%s: %m",
-                                        argv[optind],
-                                        arg_transport == BUS_TRANSPORT_LOCAL ? "" : " on local system");
+                        log_error_errno(r, "Failed to find executable %s: %m", argv[optind]);
+                        goto finish;
+                }
+                if (r == 0) {
+                        log_error("Couldn't find executable %s.", argv[optind]);
+                        r = -ENOENT;
                         goto finish;
                 }
+
                 argv[optind] = command;
         }