lvmpolld: improve syscal errors logging

2 files changed, 27 insertions, 9 deletions

diff --git a/daemons/lvmpolld/lvmpolld-core.c b/daemons/lvmpolld/lvmpolld-core.c
index 9461ac23e..4c1977fb5 100644
--- a/daemons/lvmpolld/lvmpolld-core.c
+++ b/daemons/lvmpolld/lvmpolld-core.c
@@ -59,6 +59,18 @@ typedef struct lvmpolld_state {
 
 static pthread_key_t key;
 
+static const char *_strerror_r(int errnum, lvmpolld_thread_data_t *data)
+{
+#ifdef _GNU_SOURCE
+	return strerror_r(errnum, data->buf, sizeof(data->buf));
+#elif (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
+	return strerror_r(errnum, data->buf, sizeof(data->buf)) ? NULL : data->buf;
+#else
+#	warning "Can't decide strerror_r implementation to use. lvmpolld will not issue more specific error messages"
+	return NULL;
+#endif
+}
+
 static void usage(const char *prog, FILE *file)
 {
 	fprintf(file, "Usage:\n"
@@ -216,7 +228,8 @@ static int poll_for_output(lvmpolld_lv_t *pdlv, lvmpolld_thread_data_t *data)
 				{ .fd = data->errpipe[0], .events = POLLIN } };
 
 	if (!(data->fout = fdopen(data->outpipe[0], "r")) || !(data->ferr = fdopen(data->errpipe[0], "r"))) {
-		ERROR(pdlv->ls, "%s: %s", PD_LOG_PREFIX, "failed to open file stream");
+		ERROR(pdlv->ls, "%s: %s: (%d) %s", PD_LOG_PREFIX, "failed to open file stream",
+		      errno, _strerror_r(errno, data) ?: "");
 		goto out;
 	}
 
@@ -227,9 +240,9 @@ static int poll_for_output(lvmpolld_lv_t *pdlv, lvmpolld_thread_data_t *data)
 
 		DEBUGLOG(pdlv->ls, "%s: %s %d", PD_LOG_PREFIX, "poll() returned", r);
 		if (r < 0) {
-			ERROR(pdlv->ls, "%s: %s (PID %d) %s (%d): %s",
+			ERROR(pdlv->ls, "%s: %s (PID %d) failed: (%d) %s",
 			      PD_LOG_PREFIX, "poll() for LVM2 cmd", pdlv->cmd_pid,
-			      "ended with error", errno, "(strerror())");
+			      errno, _strerror_r(errno, data) ?: "");
 			goto out;
 		} else if (!r) {
 			timeout++;
@@ -295,9 +308,10 @@ static int poll_for_output(lvmpolld_lv_t *pdlv, lvmpolld_thread_data_t *data)
 
 		if (wait4) {
 			if (wait4 < 0) {
-				ERROR(pdlv->ls, "%s: %s (PID %d) %s", PD_LOG_PREFIX,
-				      "waitpid() for lvm2 cmd", pdlv->cmd_pid,
-				      "resulted in error");
+				ERROR(pdlv->ls, "%s: %s (PID %d) failed: (%d) %s",
+				      PD_LOG_PREFIX, "waitpid() for lvm2 cmd",
+				      pdlv->cmd_pid, errno,
+				      _strerror_r(errno, data) ?: "");
 				goto out;
 			}
 			DEBUGLOG(pdlv->ls, "%s: %s", PD_LOG_PREFIX, "child exited");
@@ -395,7 +409,8 @@ static void *fork_and_poll(void *args)
 	} else {
 		/* parent */
 		if (r == -1) {
-			ERROR(ls, "%s: %s", PD_LOG_PREFIX, "fork failed");
+			ERROR(ls, "%s: %s: (%d) %s", PD_LOG_PREFIX, "fork failed",
+			      errno, _strerror_r(errno, data) ?: "");
 			goto err;
 		}
 
@@ -405,13 +420,15 @@ static void *fork_and_poll(void *args)
 
 		/* failure to close write end of any pipe will result in broken polling */
 		if (close(data->outpipe[1])) {
-			ERROR(ls, "%s: %s", PD_LOG_PREFIX, "failed to close write end of pipe");
+			ERROR(ls, "%s: %s: (%d) %s", PD_LOG_PREFIX, "failed to close write end of pipe",
+			      errno, _strerror_r(errno, data) ?: "");
 			goto err;
 		}
 		data->outpipe[1] = -1;
 
 		if (close(data->errpipe[1])) {
-			ERROR(ls, "%s: %s", PD_LOG_PREFIX, "failed to close write end of err pipe");
+			ERROR(ls, "%s: %s: (%d) %s", PD_LOG_PREFIX, "failed to close write end of err pipe",
+			      errno, _strerror_r(errno, data) ?: "");
 			goto err;
 		}
 		data->errpipe[1] = -1;
diff --git a/daemons/lvmpolld/lvmpolld-data-utils.h b/daemons/lvmpolld/lvmpolld-data-utils.h
index 834b6ab58..3940fee6d 100644
--- a/daemons/lvmpolld/lvmpolld-data-utils.h
+++ b/daemons/lvmpolld/lvmpolld-data-utils.h
@@ -89,6 +89,7 @@ typedef struct {
 	int errpipe[2];
 	FILE *fout;
 	FILE *ferr;
+	char buf[1024];
 	lvmpolld_lv_t *pdlv;
 } lvmpolld_thread_data_t;