tools: add 'lvm lastlog' command for interactive query and display of last command's log

If we're running in lvm shell, we can keep last command's log report
for further query with possible different selection criteria for easy
log lookup.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.158 - 
 =================================
+  Add lvm lastlog command for query and display of last cmd's log in lvm shell.
   Report per-object return codes via cmd log while processing multiple objects.
   Annotate processing code with log report hooks for per-object command log.
   Also pass common printed messages (besides warnings and errors) to log report.

lib/commands/toolcontext.c

@@ -2247,6 +2247,9 @@ void destroy_toolcontext(struct cmd_context *cmd)
 	if (cmd->cft_def_hash)
 		dm_hash_destroy(cmd->cft_def_hash);
 
+	if (cmd->log_rh)
+		dm_report_free(cmd->log_rh);
+
 	if (cmd->libmem)
 		dm_pool_destroy(cmd->libmem);
 

lib/commands/toolcontext.h

@@ -185,6 +185,11 @@ struct cmd_context {
 	char dev_dir[PATH_MAX];
 	char proc_dir[PATH_MAX];
 
+	/*
+	 * Command log reporting.
+	 */
+	struct dm_report *log_rh;		/* keep log report of last cmd for further queries if cmd line is interactive (e.g. lvm shell) */
+
 	/*
 	 * Buffers.
 	 */

tools/Makefile.in

@@ -168,7 +168,7 @@ liblvm2cmd.$(LIB_SUFFIX).$(LIB_VERSION): liblvm2cmd.$(LIB_SUFFIX)
 
 .commands: $(srcdir)/commands.h $(srcdir)/cmdnames.h Makefile
 	$(CC) -E -P $(srcdir)/cmdnames.h 2> /dev/null | \
-		egrep -v '^ *(|#.*|config|devtypes|dumpconfig|formats|fullreport|help|lvpoll|pvdata|segtypes|systemid|tags|version) *$$' > .commands
+		egrep -v '^ *(|#.*|config|devtypes|dumpconfig|formats|fullreport|help|lastlog|lvpoll|pvdata|segtypes|systemid|tags|version) *$$' > .commands
 
 ifneq ("$(CFLOW_CMD)", "")
 CFLOW_SOURCES = $(addprefix $(srcdir)/, $(SOURCES))

tools/commands.h

@@ -174,6 +174,15 @@ xx(fullreport,
    rows_ARG, select_ARG, separator_ARG, shared_ARG, sort_ARG, trustcache_ARG,
    unbuffered_ARG, units_ARG, unquoted_ARG)
 
+xx(lastlog,
+   "Display last command's log report",
+   PERMITTED_READ_ONLY | NO_METADATA_PROCESSING,
+   "log\n"
+   "\t[--reportformat {json}]\n"
+   "\t[-S|--select Selection]\n",
+
+   reportformat_ARG, select_ARG)
+
 xx(lvchange,
    "Change the attributes of logical volume(s)",
    CACHE_VGMETADATA | PERMITTED_READ_ONLY,

tools/lvm.c

@@ -235,6 +235,12 @@ int lvm_shell(struct cmd_context *cmd, struct cmdline_context *cmdline)
 			break;
 		}
 
+		if (cmd->log_rh && strcmp(argv[0], "lastlog")) {
+			/* drop old log report */
+			dm_report_free(cmd->log_rh);
+			cmd->log_rh = NULL;
+		}
+
 		ret = lvm_run_command(cmd, argc, argv);
 		if (ret == ENO_SUCH_CMD)
 			log_error("No such command '%s'.  Try 'help'.",

tools/reporter.c

@@ -1497,3 +1497,38 @@ bad:
 		dm_report_free(tmp_log_rh);
 	return 0;
 }
+
+int lastlog(struct cmd_context *cmd, int argc, char **argv)
+{
+	static report_idx_t expected_idxs[] = {REPORT_IDX_SINGLE, REPORT_IDX_LOG, REPORT_IDX_NULL};
+	struct dm_report_group *report_group = NULL;
+	const char *selection = NULL;
+	int r = ECMD_FAILED;
+
+	if (!cmd->log_rh) {
+		log_error("No log report stored.");
+		goto out;
+	}
+
+	if (!report_format_init(cmd, NULL, &report_group, &cmd->log_rh, NULL))
+		goto_out;
+
+	if (arg_count(cmd, select_ARG) &&
+	    !_do_report_get_selection(cmd, NULL, NULL, expected_idxs, &selection))
+		goto_out;
+
+	if (!dm_report_set_selection(cmd->log_rh, selection)) {
+		log_error("Failed to set selection for log report.");
+		goto out;
+	}
+
+	if (!dm_report_output(cmd->log_rh) ||
+	    !dm_report_group_pop(report_group))
+		goto_out;
+
+	r = ECMD_PROCESSED;
+out:
+	if (!dm_report_group_destroy(report_group))
+		stack;
+	return r;
+}

tools/toollib.c

@@ -1778,8 +1778,16 @@ void destroy_processing_handle(struct cmd_context *cmd, struct processing_handle
 
 		if (!dm_report_group_destroy(handle->report_group))
 			stack;
-		if (handle->log_rh)
-			dm_report_free(handle->log_rh);
+		if (handle->log_rh) {
+			if (cmd->is_interactive) {
+				/*
+				 * Keep log report if we're interactive so
+				 * we can do further queries on this report.
+				 */
+				cmd->log_rh = handle->log_rh;
+			} else
+				dm_report_free(handle->log_rh);
+		}
 		/*
 		 * TODO: think about better alternatives:
 		 * handle mempool, dm_alloc for handle memory...