perf tools: Suggest inbuilt commands for unknown command

The existing unknown command code looks for perf scripts like
perf-archive.sh and perf-iostat.sh, however, inbuilt commands aren't
suggested. Add the inbuilt commands so they may be suggested too.

Before:

  $ perf reccord
  perf: 'reccord' is not a perf-command. See 'perf --help'.
  $

After:

  $ perf reccord
  perf: 'reccord' is not a perf-command. See 'perf --help'.

  Did you mean this?
          record
  $
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240301201306.2680986-1-irogers@google.com
[ Added some fixes from Ian to problems I noticed while testing ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin.h

@@ -2,8 +2,10 @@
 #ifndef BUILTIN_H
 #define BUILTIN_H
 
+struct cmdnames;
+
 void list_common_cmds_help(void);
-const char *help_unknown_cmd(const char *cmd);
+const char *help_unknown_cmd(const char *cmd, struct cmdnames *main_cmds);
 
 int cmd_annotate(int argc, const char **argv);
 int cmd_bench(int argc, const char **argv);

tools/perf/perf.c

@@ -18,6 +18,7 @@
 #include <subcmd/run-command.h>
 #include "util/parse-events.h"
 #include <subcmd/parse-options.h>
+#include <subcmd/help.h>
 #include "util/debug.h"
 #include "util/event.h"
 #include "util/util.h" // usage()
@@ -458,7 +459,7 @@ static int libperf_print(enum libperf_print_level level,
 
 int main(int argc, const char **argv)
 {
-	int err;
+	int err, done_help = 0;
 	const char *cmd;
 	char sbuf[STRERR_BUFSIZE];
 
@@ -557,22 +558,32 @@ int main(int argc, const char **argv)
 	pthread__block_sigwinch();
 
 	while (1) {
-		static int done_help;
-
 		run_argv(&argc, &argv);
 
 		if (errno != ENOENT)
 			break;
 
 		if (!done_help) {
-			cmd = argv[0] = help_unknown_cmd(cmd);
+			struct cmdnames main_cmds = {};
+
+			for (unsigned int i = 0; i < ARRAY_SIZE(commands); i++) {
+				add_cmdname(&main_cmds,
+					    commands[i].cmd,
+					    strlen(commands[i].cmd));
+			}
+			cmd = argv[0] = help_unknown_cmd(cmd, &main_cmds);
+			clean_cmdnames(&main_cmds);
 			done_help = 1;
+			if (!cmd)
+				break;
 		} else
 			break;
 	}
 
+	if (cmd) {
 		fprintf(stderr, "Failed to run command '%s': %s\n",
 			cmd, str_error_r(errno, sbuf, sizeof(sbuf)));
+	}
 out:
 	if (debug_fp)
 		fclose(debug_fp);

tools/perf/util/help-unknown-cmd.c

@@ -52,46 +52,44 @@ static int add_cmd_list(struct cmdnames *cmds, struct cmdnames *old)
 	return 0;
 }
 
-const char *help_unknown_cmd(const char *cmd)
+const char *help_unknown_cmd(const char *cmd, struct cmdnames *main_cmds)
 {
 	unsigned int i, n = 0, best_similarity = 0;
-	struct cmdnames main_cmds, other_cmds;
+	struct cmdnames other_cmds;
 
-	memset(&main_cmds, 0, sizeof(main_cmds));
-	memset(&other_cmds, 0, sizeof(main_cmds));
+	memset(&other_cmds, 0, sizeof(other_cmds));
 
 	perf_config(perf_unknown_cmd_config, NULL);
 
-	load_command_list("perf-", &main_cmds, &other_cmds);
+	load_command_list("perf-", main_cmds, &other_cmds);
 
-	if (add_cmd_list(&main_cmds, &other_cmds) < 0) {
+	if (add_cmd_list(main_cmds, &other_cmds) < 0) {
 		fprintf(stderr, "ERROR: Failed to allocate command list for unknown command.\n");
 		goto end;
 	}
-	qsort(main_cmds.names, main_cmds.cnt,
-	      sizeof(main_cmds.names), cmdname_compare);
-	uniq(&main_cmds);
+	qsort(main_cmds->names, main_cmds->cnt,
+	      sizeof(main_cmds->names), cmdname_compare);
+	uniq(main_cmds);
 
-	if (main_cmds.cnt) {
+	if (main_cmds->cnt) {
 		/* This reuses cmdname->len for similarity index */
-		for (i = 0; i < main_cmds.cnt; ++i)
-			main_cmds.names[i]->len =
-				levenshtein(cmd, main_cmds.names[i]->name, 0, 2, 1, 4);
+		for (i = 0; i < main_cmds->cnt; ++i)
+			main_cmds->names[i]->len =
+				levenshtein(cmd, main_cmds->names[i]->name, 0, 2, 1, 4);
 
-		qsort(main_cmds.names, main_cmds.cnt,
-		      sizeof(*main_cmds.names), levenshtein_compare);
+		qsort(main_cmds->names, main_cmds->cnt,
+		      sizeof(*main_cmds->names), levenshtein_compare);
 
-		best_similarity = main_cmds.names[0]->len;
+		best_similarity = main_cmds->names[0]->len;
 		n = 1;
-		while (n < main_cmds.cnt && best_similarity == main_cmds.names[n]->len)
+		while (n < main_cmds->cnt && best_similarity == main_cmds->names[n]->len)
 			++n;
 	}
 
 	if (autocorrect && n == 1) {
-		const char *assumed = main_cmds.names[0]->name;
+		const char *assumed = main_cmds->names[0]->name;
 
-		main_cmds.names[0] = NULL;
-		clean_cmdnames(&main_cmds);
+		main_cmds->names[0] = NULL;
 		clean_cmdnames(&other_cmds);
 		fprintf(stderr, "WARNING: You called a perf program named '%s', "
 			"which does not exist.\n"
@@ -107,15 +105,14 @@ const char *help_unknown_cmd(const char *cmd)
 
 	fprintf(stderr, "perf: '%s' is not a perf-command. See 'perf --help'.\n", cmd);
 
-	if (main_cmds.cnt && best_similarity < 6) {
+	if (main_cmds->cnt && best_similarity < 6) {
 		fprintf(stderr, "\nDid you mean %s?\n",
 			n < 2 ? "this": "one of these");
 
 		for (i = 0; i < n; i++)
-			fprintf(stderr, "\t%s\n", main_cmds.names[i]->name);
+			fprintf(stderr, "\t%s\n", main_cmds->names[i]->name);
 	}
 end:
-	clean_cmdnames(&main_cmds);
 	clean_cmdnames(&other_cmds);
-	exit(1);
+	return NULL;
 }