journalctl: fix verbose output when no logs are found

$ journalctl -o verbose _EXE=/quiet/binary -f
-- Logs begin at Sun 2013-03-17 17:28:22 EDT. --
Failed to get realtime timestamp: Cannot assign requested address

JOURNAL_FOREACH_DATA_RETVAL is added, which allows the caller
to get the return value from sd_journal_enumerate_data. I think
we might want to expose this macro like SD_JOURNAL_FOREACH_DATA,
but for now it is in journal-internal.h.

There's a change in behaviour for output_*, not only in
output_verbose, that errors in sd_j_enumerate_data are not silently
ignored anymore.

https://bugs.freedesktop.org/show_bug.cgi?id=56459

src/journal/journal-internal.h

@@ -139,3 +139,6 @@ static inline void journal_closep(sd_journal **j) {
 }
 
 #define _cleanup_journal_close_ _cleanup_(journal_closep)
+
+#define JOURNAL_FOREACH_DATA_RETVAL(j, data, l, retval)                     \
+        for (sd_journal_restart_data(j); ((retval) = sd_journal_enumerate_data((j), &(data), &(l))) > 0; )

src/journal/journalctl.c

@@ -1288,11 +1288,10 @@ int main(int argc, char *argv[]) {
                                         log_error("Failed to iterate through journal: %s", strerror(-r));
                                         goto finish;
                                 }
+                                if (r == 0)
+                                        break;
                         }
 
-                        if (r == 0)
-                                break;
-
                         if (arg_until_set && !arg_reverse) {
                                 usec_t usec;
 
@@ -1338,10 +1337,12 @@ int main(int argc, char *argv[]) {
                                 arg_catalog * OUTPUT_CATALOG;
 
                         r = output_journal(stdout, j, arg_output, 0, flags);
-                        if (r < 0 || ferror(stdout))
+                        need_seek = true;
+                        if (r == -EADDRNOTAVAIL)
+                                break;
+                        else if (r < 0 || ferror(stdout))
                                 goto finish;
 
-                        need_seek = true;
                         n_shown++;
                 }
 

src/shared/logs-show.c

@@ -163,7 +163,7 @@ static int output_short(
 
         sd_journal_set_data_threshold(j, flags & OUTPUT_SHOW_ALL ? 0 : PRINT_THRESHOLD);
 
-        SD_JOURNAL_FOREACH_DATA(j, data, length) {
+        JOURNAL_FOREACH_DATA_RETVAL(j, data, length, r) {
 
                 r = parse_field(data, length, "PRIORITY=", &priority, &priority_len);
                 if (r < 0)
@@ -218,6 +218,9 @@ static int output_short(
                         return r;
         }
 
+        if (r < 0)
+                return r;
+
         if (!message)
                 return 0;
 
@@ -240,7 +243,7 @@ static int output_short(
                         r = sd_journal_get_monotonic_usec(j, &t, &boot_id);
 
                 if (r < 0) {
-                        log_error("Failed to get monotonic: %s", strerror(-r));
+                        log_error("Failed to get monotonic timestamp: %s", strerror(-r));
                         return r;
                 }
 
@@ -265,7 +268,7 @@ static int output_short(
                         r = sd_journal_get_realtime_usec(j, &x);
 
                 if (r < 0) {
-                        log_error("Failed to get realtime: %s", strerror(-r));
+                        log_error("Failed to get realtime timestamp: %s", strerror(-r));
                         return r;
                 }
 
@@ -336,7 +339,8 @@ static int output_verbose(
 
         r = sd_journal_get_realtime_usec(j, &realtime);
         if (r < 0) {
-                log_error("Failed to get realtime timestamp: %s", strerror(-r));
+                log_full(r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_ERR,
+                         "Failed to get realtime timestamp: %s", strerror(-r));
                 return r;
         }
 
@@ -350,7 +354,7 @@ static int output_verbose(
                 format_timestamp(ts, sizeof(ts), realtime),
                 cursor);
 
-        SD_JOURNAL_FOREACH_DATA(j, data, length) {
+        JOURNAL_FOREACH_DATA_RETVAL(j, data, length, r) {
                 const char *c;
                 int fieldlen;
                 c = memchr(data, '=', length);
@@ -373,6 +377,9 @@ static int output_verbose(
                 }
         }
 
+        if (r < 0)
+                return r;
+
         if (flags & OUTPUT_CATALOG)
                 print_catalog(f, j);
 
@@ -426,7 +433,7 @@ static int output_export(
                 (unsigned long long) monotonic,
                 sd_id128_to_string(boot_id, sid));
 
-        SD_JOURNAL_FOREACH_DATA(j, data, length) {
+        JOURNAL_FOREACH_DATA_RETVAL(j, data, length, r) {
 
                 /* We already printed the boot id, from the data in
                  * the header, hence let's suppress it here */
@@ -455,6 +462,9 @@ static int output_export(
                 fputc('\n', f);
         }
 
+        if (r < 0)
+                return r;
+
         fputc('\n', f);
 
         return 0;
@@ -583,7 +593,7 @@ static int output_json(
                 return -ENOMEM;
 
         /* First round, iterate through the entry and count how often each field appears */
-        SD_JOURNAL_FOREACH_DATA(j, data, length) {
+        JOURNAL_FOREACH_DATA_RETVAL(j, data, length, r) {
                 const char *eq;
                 char *n;
                 unsigned u;
@@ -617,6 +627,9 @@ static int output_json(
                 }
         }
 
+        if (r < 0)
+                return r;
+
         separator = true;
         do {
                 done = true;