[pacman-dev] [PATCH] Give better error messages on database locking failures

[Dan McGee]

This was noted when trying to perform an operation on a pacman database
on a read-only file system. Print the actual underlying errno string,
and only show the "you can remove" message if the lock file actually
exists.

Before:
    $ pacman -Su
    error: failed to init transaction (unable to lock database)
      if you're sure a package manager is not already
      running, you can remove /e/db.lck

After:
    $ pacman -Su
    error: failed to init transaction (unable to lock database)
    error: could not lock database: Read-only file system

Signed-off-by: Dan McGee <d...@archlinux.org>
---
 src/pacman/util.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/pacman/util.c b/src/pacman/util.c
index 0b076d9..f7f8ecf 100644
--- a/src/pacman/util.c
+++ b/src/pacman/util.c
@@ -69,9 +69,13 @@ void trans_init_error(void)
        pm_printf(ALPM_LOG_ERROR, _("failed to init transaction (%s)\n"),
                        alpm_strerror(err));
        if(err == ALPM_ERR_HANDLE_LOCK) {
-               fprintf(stderr, _("  if you're sure a package manager is not 
already\n"
-                                       "  running, you can remove %s\n"),
-                               alpm_option_get_lockfile(config->handle));
+               const char *lockfile = alpm_option_get_lockfile(config->handle);
+               pm_printf(ALPM_LOG_ERROR, _("could not lock database: %s\n"),
+                                       strerror(errno));
+               if(access(lockfile, F_OK) == 0) {
+                       fprintf(stderr, _("  if you're sure a package manager 
is not already\n"
+                                               "  running, you can remove 
%s\n"), lockfile);
+               }
        }
 }
 
-- 
1.7.9.1