1// SPDX-License-Identifier: GPL-2.0
2/*
3 * builtin-help.c
4 *
5 * Builtin help command
6 */
7#include "util/cache.h"
8#include "util/config.h"
9#include "util/strbuf.h"
10#include "builtin.h"
11#include <subcmd/exec-cmd.h>
12#include "common-cmds.h"
13#include <subcmd/parse-options.h>
14#include <subcmd/run-command.h>
15#include <subcmd/help.h>
16#include "util/debug.h"
17#include "util/util.h"
18#include <linux/kernel.h>
19#include <linux/string.h>
20#include <linux/zalloc.h>
21#include <errno.h>
22#include <limits.h>
23#include <stdio.h>
24#include <stdlib.h>
25#include <string.h>
26#include <sys/types.h>
27#include <sys/stat.h>
28#include <unistd.h>
29
30static struct man_viewer_list {
31	struct man_viewer_list *next;
32	char name[0];
33} *man_viewer_list;
34
35static struct man_viewer_info_list {
36	struct man_viewer_info_list *next;
37	const char *info;
38	char name[0];
39} *man_viewer_info_list;
40
41enum help_format {
42	HELP_FORMAT_NONE,
43	HELP_FORMAT_MAN,
44	HELP_FORMAT_INFO,
45	HELP_FORMAT_WEB,
46};
47
48static enum help_format parse_help_format(const char *format)
49{
50	if (!strcmp(format, "man"))
51		return HELP_FORMAT_MAN;
52	if (!strcmp(format, "info"))
53		return HELP_FORMAT_INFO;
54	if (!strcmp(format, "web") || !strcmp(format, "html"))
55		return HELP_FORMAT_WEB;
56
57	pr_err("unrecognized help format '%s'", format);
58	return HELP_FORMAT_NONE;
59}
60
61static const char *get_man_viewer_info(const char *name)
62{
63	struct man_viewer_info_list *viewer;
64
65	for (viewer = man_viewer_info_list; viewer; viewer = viewer->next) {
66		if (!strcasecmp(name, viewer->name))
67			return viewer->info;
68	}
69	return NULL;
70}
71
72static int check_emacsclient_version(void)
73{
74	struct strbuf buffer = STRBUF_INIT;
75	struct child_process ec_process;
76	const char *argv_ec[] = { "emacsclient", "--version", NULL };
77	int version;
78	int ret = -1;
79
80	/* emacsclient prints its version number on stderr */
81	memset(&ec_process, 0, sizeof(ec_process));
82	ec_process.argv = argv_ec;
83	ec_process.err = -1;
84	ec_process.stdout_to_stderr = 1;
85	if (start_command(&ec_process)) {
86		fprintf(stderr, "Failed to start emacsclient.\n");
87		return -1;
88	}
89	if (strbuf_read(&buffer, ec_process.err, 20) < 0) {
90		fprintf(stderr, "Failed to read emacsclient version\n");
91		goto out;
92	}
93	close(ec_process.err);
94
95	/*
96	 * Don't bother checking return value, because "emacsclient --version"
97	 * seems to always exits with code 1.
98	 */
99	finish_command(&ec_process);
100
101	if (!strstarts(buffer.buf, "emacsclient")) {
102		fprintf(stderr, "Failed to parse emacsclient version.\n");
103		goto out;
104	}
105
106	version = atoi(buffer.buf + strlen("emacsclient"));
107
108	if (version < 22) {
109		fprintf(stderr,
110			"emacsclient version '%d' too old (< 22).\n",
111			version);
112	} else
113		ret = 0;
114out:
115	strbuf_release(&buffer);
116	return ret;
117}
118
119static void exec_failed(const char *cmd)
120{
121	char sbuf[STRERR_BUFSIZE];
122	pr_warning("failed to exec '%s': %s", cmd, str_error_r(errno, sbuf, sizeof(sbuf)));
123}
124
125static void exec_woman_emacs(const char *path, const char *page)
126{
127	if (!check_emacsclient_version()) {
128		/* This works only with emacsclient version >= 22. */
129		char *man_page;
130
131		if (!path)
132			path = "emacsclient";
133		if (asprintf(&man_page, "(woman \"%s\")", page) > 0) {
134			execlp(path, "emacsclient", "-e", man_page, NULL);
135			free(man_page);
136		}
137		exec_failed(path);
138	}
139}
140
141static void exec_man_konqueror(const char *path, const char *page)
142{
143	const char *display = getenv("DISPLAY");
144
145	if (display && *display) {
146		char *man_page;
147		const char *filename = "kfmclient";
148
149		/* It's simpler to launch konqueror using kfmclient. */
150		if (path) {
151			const char *file = strrchr(path, '/');
152			if (file && !strcmp(file + 1, "konqueror")) {
153				char *new = strdup(path);
154				char *dest = strrchr(new, '/');
155
156				/* strlen("konqueror") == strlen("kfmclient") */
157				strcpy(dest + 1, "kfmclient");
158				path = new;
159			}
160			if (file)
161				filename = file;
162		} else
163			path = "kfmclient";
164		if (asprintf(&man_page, "man:%s(1)", page) > 0) {
165			execlp(path, filename, "newTab", man_page, NULL);
166			free(man_page);
167		}
168		exec_failed(path);
169	}
170}
171
172static void exec_man_man(const char *path, const char *page)
173{
174	if (!path)
175		path = "man";
176	execlp(path, "man", page, NULL);
177	exec_failed(path);
178}
179
180static void exec_man_cmd(const char *cmd, const char *page)
181{
182	char *shell_cmd;
183
184	if (asprintf(&shell_cmd, "%s %s", cmd, page) > 0) {
185		execl("/bin/sh", "sh", "-c", shell_cmd, NULL);
186		free(shell_cmd);
187	}
188	exec_failed(cmd);
189}
190
191static void add_man_viewer(const char *name)
192{
193	struct man_viewer_list **p = &man_viewer_list;
194	size_t len = strlen(name);
195
196	while (*p)
197		p = &((*p)->next);
198	*p = zalloc(sizeof(**p) + len + 1);
199	strcpy((*p)->name, name);
200}
201
202static int supported_man_viewer(const char *name, size_t len)
203{
204	return (!strncasecmp("man", name, len) ||
205		!strncasecmp("woman", name, len) ||
206		!strncasecmp("konqueror", name, len));
207}
208
209static void do_add_man_viewer_info(const char *name,
210				   size_t len,
211				   const char *value)
212{
213	struct man_viewer_info_list *new = zalloc(sizeof(*new) + len + 1);
214
215	strncpy(new->name, name, len);
216	new->info = strdup(value);
217	new->next = man_viewer_info_list;
218	man_viewer_info_list = new;
219}
220
221static void unsupported_man_viewer(const char *name, const char *var)
222{
223	pr_warning("'%s': path for unsupported man viewer.\n"
224		   "Please consider using 'man.<tool>.%s' instead.", name, var);
225}
226
227static int add_man_viewer_path(const char *name,
228			       size_t len,
229			       const char *value)
230{
231	if (supported_man_viewer(name, len))
232		do_add_man_viewer_info(name, len, value);
233	else
234		unsupported_man_viewer(name, "cmd");
235
236	return 0;
237}
238
239static int add_man_viewer_cmd(const char *name,
240			      size_t len,
241			      const char *value)
242{
243	if (supported_man_viewer(name, len))
244		unsupported_man_viewer(name, "path");
245	else
246		do_add_man_viewer_info(name, len, value);
247
248	return 0;
249}
250
251static int add_man_viewer_info(const char *var, const char *value)
252{
253	const char *name = var + 4;
254	const char *subkey = strrchr(name, '.');
255
256	if (!subkey) {
257		pr_err("Config with no key for man viewer: %s", name);
258		return -1;
259	}
260
261	if (!strcmp(subkey, ".path")) {
262		if (!value)
263			return config_error_nonbool(var);
264		return add_man_viewer_path(name, subkey - name, value);
265	}
266	if (!strcmp(subkey, ".cmd")) {
267		if (!value)
268			return config_error_nonbool(var);
269		return add_man_viewer_cmd(name, subkey - name, value);
270	}
271
272	pr_warning("'%s': unsupported man viewer sub key.", subkey);
273	return 0;
274}
275
276static int perf_help_config(const char *var, const char *value, void *cb)
277{
278	enum help_format *help_formatp = cb;
279
280	if (!strcmp(var, "help.format")) {
281		if (!value)
282			return config_error_nonbool(var);
283		*help_formatp = parse_help_format(value);
284		if (*help_formatp == HELP_FORMAT_NONE)
285			return -1;
286		return 0;
287	}
288	if (!strcmp(var, "man.viewer")) {
289		if (!value)
290			return config_error_nonbool(var);
291		add_man_viewer(value);
292		return 0;
293	}
294	if (strstarts(var, "man."))
295		return add_man_viewer_info(var, value);
296
297	return 0;
298}
299
300static struct cmdnames main_cmds, other_cmds;
301
302void list_common_cmds_help(void)
303{
304	unsigned int i, longest = 0;
305
306	for (i = 0; i < ARRAY_SIZE(common_cmds); i++) {
307		if (longest < strlen(common_cmds[i].name))
308			longest = strlen(common_cmds[i].name);
309	}
310
311	puts(" The most commonly used perf commands are:");
312	for (i = 0; i < ARRAY_SIZE(common_cmds); i++) {
313		printf("   %-*s   ", longest, common_cmds[i].name);
314		puts(common_cmds[i].help);
315	}
316}
317
318static const char *cmd_to_page(const char *perf_cmd)
319{
320	char *s;
321
322	if (!perf_cmd)
323		return "perf";
324	else if (strstarts(perf_cmd, "perf"))
325		return perf_cmd;
326
327	return asprintf(&s, "perf-%s", perf_cmd) < 0 ? NULL : s;
328}
329
330static void setup_man_path(void)
331{
332	char *new_path;
333	const char *old_path = getenv("MANPATH");
334
335	/* We should always put ':' after our path. If there is no
336	 * old_path, the ':' at the end will let 'man' to try
337	 * system-wide paths after ours to find the manual page. If
338	 * there is old_path, we need ':' as delimiter. */
339	if (asprintf(&new_path, "%s:%s", system_path(PERF_MAN_PATH), old_path ?: "") > 0) {
340		setenv("MANPATH", new_path, 1);
341		free(new_path);
342	} else {
343		pr_err("Unable to setup man path");
344	}
345}
346
347static void exec_viewer(const char *name, const char *page)
348{
349	const char *info = get_man_viewer_info(name);
350
351	if (!strcasecmp(name, "man"))
352		exec_man_man(info, page);
353	else if (!strcasecmp(name, "woman"))
354		exec_woman_emacs(info, page);
355	else if (!strcasecmp(name, "konqueror"))
356		exec_man_konqueror(info, page);
357	else if (info)
358		exec_man_cmd(info, page);
359	else
360		pr_warning("'%s': unknown man viewer.", name);
361}
362
363static int show_man_page(const char *perf_cmd)
364{
365	struct man_viewer_list *viewer;
366	const char *page = cmd_to_page(perf_cmd);
367	const char *fallback = getenv("PERF_MAN_VIEWER");
368
369	setup_man_path();
370	for (viewer = man_viewer_list; viewer; viewer = viewer->next)
371		exec_viewer(viewer->name, page); /* will return when unable */
372
373	if (fallback)
374		exec_viewer(fallback, page);
375	exec_viewer("man", page);
376
377	pr_err("no man viewer handled the request");
378	return -1;
379}
380
381static int show_info_page(const char *perf_cmd)
382{
383	const char *page = cmd_to_page(perf_cmd);
384	setenv("INFOPATH", system_path(PERF_INFO_PATH), 1);
385	execlp("info", "info", "perfman", page, NULL);
386	return -1;
387}
388
389static int get_html_page_path(char **page_path, const char *page)
390{
391	struct stat st;
392	const char *html_path = system_path(PERF_HTML_PATH);
393	char path[PATH_MAX];
394
395	/* Check that we have a perf documentation directory. */
396	if (stat(mkpath(path, sizeof(path), "%s/perf.html", html_path), &st)
397	    || !S_ISREG(st.st_mode)) {
398		pr_err("'%s': not a documentation directory.", html_path);
399		return -1;
400	}
401
402	return asprintf(page_path, "%s/%s.html", html_path, page);
403}
404
405/*
406 * If open_html is not defined in a platform-specific way (see for
407 * example compat/mingw.h), we use the script web--browse to display
408 * HTML.
409 */
410#ifndef open_html
411static void open_html(const char *path)
412{
413	execl_cmd("web--browse", "-c", "help.browser", path, NULL);
414}
415#endif
416
417static int show_html_page(const char *perf_cmd)
418{
419	const char *page = cmd_to_page(perf_cmd);
420	char *page_path; /* it leaks but we exec bellow */
421
422	if (get_html_page_path(&page_path, page) < 0)
423		return -1;
424
425	open_html(page_path);
426
427	return 0;
428}
429
430int cmd_help(int argc, const char **argv)
431{
432	bool show_all = false;
433	enum help_format help_format = HELP_FORMAT_MAN;
434	struct option builtin_help_options[] = {
435	OPT_BOOLEAN('a', "all", &show_all, "print all available commands"),
436	OPT_SET_UINT('m', "man", &help_format, "show man page", HELP_FORMAT_MAN),
437	OPT_SET_UINT('w', "web", &help_format, "show manual in web browser",
438			HELP_FORMAT_WEB),
439	OPT_SET_UINT('i', "info", &help_format, "show info page",
440			HELP_FORMAT_INFO),
441	OPT_END(),
442	};
443	const char * const builtin_help_subcommands[] = {
444		"buildid-cache", "buildid-list", "diff", "evlist", "help", "list",
445		"record", "report", "bench", "stat", "timechart", "top", "annotate",
446		"script", "sched", "kallsyms", "kmem", "lock", "kvm", "test", "inject", "mem", "data",
447#ifdef HAVE_LIBELF_SUPPORT
448		"probe",
449#endif
450#if defined(HAVE_LIBAUDIT_SUPPORT) || defined(HAVE_SYSCALL_TABLE_SUPPORT)
451		"trace",
452#endif
453	NULL };
454	const char *builtin_help_usage[] = {
455		"perf help [--all] [--man|--web|--info] [command]",
456		NULL
457	};
458	int rc;
459
460	load_command_list("perf-", &main_cmds, &other_cmds);
461
462	rc = perf_config(perf_help_config, &help_format);
463	if (rc)
464		return rc;
465
466	argc = parse_options_subcommand(argc, argv, builtin_help_options,
467			builtin_help_subcommands, builtin_help_usage, 0);
468
469	if (show_all) {
470		printf("\n Usage: %s\n\n", perf_usage_string);
471		list_commands("perf commands", &main_cmds, &other_cmds);
472		printf(" %s\n\n", perf_more_info_string);
473		return 0;
474	}
475
476	if (!argv[0]) {
477		printf("\n usage: %s\n\n", perf_usage_string);
478		list_common_cmds_help();
479		printf("\n %s\n\n", perf_more_info_string);
480		return 0;
481	}
482
483	switch (help_format) {
484	case HELP_FORMAT_MAN:
485		rc = show_man_page(argv[0]);
486		break;
487	case HELP_FORMAT_INFO:
488		rc = show_info_page(argv[0]);
489		break;
490	case HELP_FORMAT_WEB:
491		rc = show_html_page(argv[0]);
492		break;
493	case HELP_FORMAT_NONE:
494		/* fall-through */
495	default:
496		rc = -1;
497		break;
498	}
499
500	return rc;
501}
502