logs-show: skip journal entry with an invalid timestamp (#35774)

Fixes #35737.

src/journal-remote/fuzz-journal-remote.c

@@ -16,6 +16,7 @@
 #include "path-util.h"
 #include "rm-rf.h"
 #include "strv.h"
+#include "tests.h"
 #include "tmpfile-util.h"
 
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
@@ -50,14 +51,11 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
                 return r;
         }
 
-        r = journal_remote_add_source(&s, fdin, (char*) "fuzz-data", false);
-        if (r < 0)
-                return r;
+        ASSERT_OK_POSITIVE(journal_remote_add_source(&s, fdin, (char*) "fuzz-data", false));
         TAKE_FD(fdin_close);
-        assert(r > 0);
 
         while (s.active)
-                assert_se(journal_remote_handle_raw_source(NULL, fdin, 0, &s) >= 0);
+                ASSERT_OK(journal_remote_handle_raw_source(NULL, fdin, 0, &s));
 
         assert_se(close(fdin) < 0 && errno == EBADF); /* Check that the fd is closed already */
 
@@ -80,11 +78,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         for (OutputMode mode = 0; mode < _OUTPUT_MODE_MAX; mode++) {
                 if (!dev_null)
                         log_info("/* %s */", output_mode_to_string(mode));
-                r = show_journal(dev_null ?: stdout, j, mode, 0, 0, -1, 0, NULL);
-                assert_se(r >= 0);
-
-                r = sd_journal_seek_head(j);
-                assert_se(r >= 0);
+                ASSERT_OK(show_journal(dev_null ?: stdout, j, mode, 0, 0, -1, 0, NULL));
+                ASSERT_OK(sd_journal_seek_head(j));
         }
 
         return 0;

src/shared/logs-show.c

@@ -335,7 +335,7 @@ static int output_timestamp_monotonic(
         assert(previous_boot_id);
 
         if (!VALID_MONOTONIC(display_ts->monotonic))
-                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "No valid monotonic timestamp available");
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "No valid monotonic timestamp available, skipping showing journal entry.");
 
         written_chars += fprintf(f, "[%5"PRI_USEC".%06"PRI_USEC, display_ts->monotonic / USEC_PER_SEC, display_ts->monotonic % USEC_PER_SEC);
 
@@ -375,15 +375,14 @@ static int output_timestamp_realtime(
         assert(j);
 
         if (!VALID_REALTIME(usec))
-                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "No valid realtime timestamp available.");
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "No valid realtime timestamp available, skipping showing journal entry.");
 
         switch (mode) {
 
         case OUTPUT_SHORT_FULL:
         case OUTPUT_WITH_UNIT: {
                 if (!format_timestamp_style(buf, sizeof(buf), usec, flags & OUTPUT_UTC ? TIMESTAMP_UTC : TIMESTAMP_PRETTY))
-                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
-                                               "Failed to format timestamp: %" PRIu64, usec);
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to format timestamp (%"PRIu64"), skipping showing journal entry.", usec);
                 break;
         }
 
@@ -623,6 +622,8 @@ static int output_short(
                 parse_display_realtime(j, realtime, monotonic, &usec);
                 r = output_timestamp_realtime(f, j, mode, flags, usec);
         }
+        if (r == -EINVAL)
+                return 0;
         if (r < 0)
                 return r;
         n += r;