perf help: Use asprintf instead of adhoc equivalents

That doesn't chekcs malloc return and that, when using strbuf, if it
can't grow, just explodes away via die().

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-vr8qsjbwub7e892hpa9msz95@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-help.c

@@ -106,12 +106,14 @@ static void exec_woman_emacs(const char *path, const char *page)
 
 	if (!check_emacsclient_version()) {
 		/* This works only with emacsclient version >= 22. */
-		struct strbuf man_page = STRBUF_INIT;
+		char *man_page;
 
 		if (!path)
 			path = "emacsclient";
-		strbuf_addf(&man_page, "(woman \"%s\")", page);
-		execlp(path, "emacsclient", "-e", man_page.buf, NULL);
+		if (asprintf(&man_page, "(woman \"%s\")", page) > 0) {
+			execlp(path, "emacsclient", "-e", man_page, NULL);
+			free(man_page);
+		}
 		warning("failed to exec '%s': %s", path,
 			strerror_r(errno, sbuf, sizeof(sbuf)));
 	}
@@ -122,7 +124,7 @@ static void exec_man_konqueror(const char *path, const char *page)
 	const char *display = getenv("DISPLAY");
 
 	if (display && *display) {
-		struct strbuf man_page = STRBUF_INIT;
+		char *man_page;
 		const char *filename = "kfmclient";
 		char sbuf[STRERR_BUFSIZE];
 
@@ -141,8 +143,10 @@ static void exec_man_konqueror(const char *path, const char *page)
 				filename = file;
 		} else
 			path = "kfmclient";
-		strbuf_addf(&man_page, "man:%s(1)", page);
-		execlp(path, filename, "newTab", man_page.buf, NULL);
+		if (asprintf(&man_page, "man:%s(1)", page) > 0) {
+			execlp(path, filename, "newTab", man_page, NULL);
+			free(man_page);
+		}
 		warning("failed to exec '%s': %s", path,
 			strerror_r(errno, sbuf, sizeof(sbuf)));
 	}
@@ -161,11 +165,13 @@ static void exec_man_man(const char *path, const char *page)
 
 static void exec_man_cmd(const char *cmd, const char *page)
 {
-	struct strbuf shell_cmd = STRBUF_INIT;
 	char sbuf[STRERR_BUFSIZE];
+	char *shell_cmd;
 
-	strbuf_addf(&shell_cmd, "%s %s", cmd, page);
-	execl("/bin/sh", "sh", "-c", shell_cmd.buf, NULL);
+	if (asprintf(&shell_cmd, "%s %s", cmd, page) > 0) {
+		execl("/bin/sh", "sh", "-c", shell_cmd, NULL);
+		free(shell_cmd);
+	}
 	warning("failed to exec '%s': %s", cmd,
 		strerror_r(errno, sbuf, sizeof(sbuf)));
 }
@@ -299,43 +305,33 @@ static int is_perf_command(const char *s)
 		is_in_cmdlist(&other_cmds, s);
 }
 
-static const char *prepend(const char *prefix, const char *cmd)
-{
-	size_t pre_len = strlen(prefix);
-	size_t cmd_len = strlen(cmd);
-	char *p = malloc(pre_len + cmd_len + 1);
-	memcpy(p, prefix, pre_len);
-	strcpy(p + pre_len, cmd);
-	return p;
-}
-
 static const char *cmd_to_page(const char *perf_cmd)
 {
+	char *s;
+
 	if (!perf_cmd)
 		return "perf";
 	else if (!prefixcmp(perf_cmd, "perf"))
 		return perf_cmd;
-	else
-		return prepend("perf-", perf_cmd);
+
+	return asprintf(&s, "perf-%s", perf_cmd) < 0 ? NULL : s;
 }
 
 static void setup_man_path(void)
 {
-	struct strbuf new_path = STRBUF_INIT;
+	char *new_path;
 	const char *old_path = getenv("MANPATH");
 
 	/* We should always put ':' after our path. If there is no
 	 * old_path, the ':' at the end will let 'man' to try
 	 * system-wide paths after ours to find the manual page. If
 	 * there is old_path, we need ':' as delimiter. */
-	strbuf_addstr(&new_path, system_path(PERF_MAN_PATH));
-	strbuf_addch(&new_path, ':');
-	if (old_path)
-		strbuf_addstr(&new_path, old_path);
-
-	setenv("MANPATH", new_path.buf, 1);
-
-	strbuf_release(&new_path);
+	if (asprintf(&new_path, "%s:%s", system_path(PERF_MAN_PATH), old_path ?: "") > 0) {
+		setenv("MANPATH", new_path, 1);
+		free(new_path);
+	} else {
+		error("Unable to setup man path");
+	}
 }
 
 static void exec_viewer(const char *name, const char *page)
@@ -380,7 +376,7 @@ static int show_info_page(const char *perf_cmd)
 	return -1;
 }
 
-static int get_html_page_path(struct strbuf *page_path, const char *page)
+static int get_html_page_path(char **page_path, const char *page)
 {
 	struct stat st;
 	const char *html_path = system_path(PERF_HTML_PATH);
@@ -392,10 +388,7 @@ static int get_html_page_path(struct strbuf *page_path, const char *page)
 		return -1;
 	}
 
-	strbuf_init(page_path, 0);
-	strbuf_addf(page_path, "%s/%s.html", html_path, page);
-
-	return 0;
+	return asprintf(page_path, "%s/%s.html", html_path, page);
 }
 
 /*
@@ -413,12 +406,12 @@ static void open_html(const char *path)
 static int show_html_page(const char *perf_cmd)
 {
 	const char *page = cmd_to_page(perf_cmd);
-	struct strbuf page_path; /* it leaks but we exec bellow */
+	char *page_path; /* it leaks but we exec bellow */
 
-	if (get_html_page_path(&page_path, page) != 0)
+	if (get_html_page_path(&page_path, page) < 0)
 		return -1;
 
-	open_html(page_path.buf);
+	open_html(page_path);
 
 	return 0;
 }