journalctl: when we fail to open a journal file, print why

When we enumerate journal files and encounter an invalid one, remember
which this, and show it to the user.

Note the possibly slightly surprising logic here: we store only one path
per error code. This means we show all error kinds but not every actual
error we encounter. This has the benefit of not requiring us to keep a
potentially unbounded list of errors with their sources around, but can
still provide a pretty complete overview on the errors we encountered.

Fixes #1669.

1 files changed, 22 insertions, 5 deletions

diff --git a/src/journal/journalctl.c b/src/journal/journalctl.c
index 30ae6e39c3..98a852cb50 100644
--- a/src/journal/journalctl.c
+++ b/src/journal/journalctl.c
@@ -1708,33 +1708,50 @@ static int access_check_var_log_journal(sd_journal *j) {
 static int access_check(sd_journal *j) {
         Iterator it;
         void *code;
+        char *path;
         int r = 0;
 
         assert(j);
 
-        if (set_isempty(j->errors)) {
+        if (hashmap_isempty(j->errors)) {
                 if (ordered_hashmap_isempty(j->files))
                         log_notice("No journal files were found.");
 
                 return 0;
         }
 
-        if (set_contains(j->errors, INT_TO_PTR(-EACCES))) {
+        if (hashmap_contains(j->errors, INT_TO_PTR(-EACCES))) {
                 (void) access_check_var_log_journal(j);
 
                 if (ordered_hashmap_isempty(j->files))
                         r = log_error_errno(EACCES, "No journal files were opened due to insufficient permissions.");
         }
 
-        SET_FOREACH(code, j->errors, it) {
+        HASHMAP_FOREACH_KEY(path, code, j->errors, it) {
                 int err;
 
                 err = abs(PTR_TO_INT(code));
 
-                if (err == EACCES)
+                switch (err) {
+                case EACCES:
                         continue;
 
-                log_warning_errno(err, "An error was encountered while opening journal files, ignoring: %m");
+                case ENODATA:
+                        log_warning_errno(err, "Journal file %s is truncated, ignoring file.", path);
+                        break;
+
+                case EPROTONOSUPPORT:
+                        log_warning_errno(err, "Journal file %s uses an unsupported feature, ignoring file.", path);
+                        break;
+
+                case EBADMSG:
+                        log_warning_errno(err, "Journal file %s corrupted, ignoring file.", path);
+                        break;
+
+                default:
+                        log_warning_errno(err, "An error was encountered while opening journal file %s, ignoring file.", path);
+                        break;
+                }
         }
 
         return r;