tools: Introduce str_error_r()

The tools so far have been using the strerror_r() GNU variant, that
returns a string, be it the buffer passed or something else.

But that, besides being tricky in cases where we expect that the
function using strerror_r() returns the error formatted in a provided
buffer (we have to check if it returned something else and copy that
instead), breaks the build on systems not using glibc, like Alpine
Linux, where musl libc is used.

So, introduce yet another wrapper, str_error_r(), that has the GNU
interface, but uses the portable XSI variant of strerror_r(), so that
users rest asured that the provided buffer is used and it is what is
returned.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.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-d4t42fnf48ytlk8rjxs822tf@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/linux/string.h

@@ -12,4 +12,6 @@ int strtobool(const char *s, bool *res);
 extern size_t strlcpy(char *dest, const char *src, size_t size);
 #endif
 
+char *str_error_r(int errnum, char *buf, size_t buflen);
+
 #endif /* _LINUX_STRING_H_ */

tools/lib/str_error_r.c

@@ -0,0 +1,26 @@
+#undef _GNU_SOURCE
+#include <string.h>
+#include <stdio.h>
+#include <linux/string.h>
+
+/*
+ * The tools so far have been using the strerror_r() GNU variant, that returns
+ * a string, be it the buffer passed or something else.
+ *
+ * But that, besides being tricky in cases where we expect that the function
+ * using strerror_r() returns the error formatted in a provided buffer (we have
+ * to check if it returned something else and copy that instead), breaks the
+ * build on systems not using glibc, like Alpine Linux, where musl libc is
+ * used.
+ *
+ * So, introduce yet another wrapper, str_error_r(), that has the GNU
+ * interface, but uses the portable XSI variant of strerror_r(), so that users
+ * rest asured that the provided buffer is used and it is what is returned.
+ */
+char *str_error_r(int errnum, char *buf, size_t buflen)
+{
+	int err = strerror_r(errnum, buf, buflen);
+	if (err)
+		snprintf(buf, buflen, "INTERNAL ERROR: strerror_r(%d, %p, %zd)=%d", errnum, buf, buflen, err);
+	return buf;
+}

tools/perf/MANIFEST

@@ -29,6 +29,7 @@ tools/lib/symbol/kallsyms.c
 tools/lib/symbol/kallsyms.h
 tools/lib/find_bit.c
 tools/lib/bitmap.c
+tools/lib/str_error_r.c
 tools/include/asm/atomic.h
 tools/include/asm/barrier.h
 tools/include/asm/bug.h

tools/perf/arch/x86/tests/rdpmc.c

@@ -111,14 +111,14 @@ static int __test__rdpmc(void)
 	if (fd < 0) {
 		pr_err("Error: sys_perf_event_open() syscall returned "
 		       "with %d (%s)\n", fd,
-		       strerror_r(errno, sbuf, sizeof(sbuf)));
+		       str_error_r(errno, sbuf, sizeof(sbuf)));
 		return -1;
 	}
 
 	addr = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
 	if (addr == (void *)(-1)) {
 		pr_err("Error: mmap() syscall returned with (%s)\n",
-		       strerror_r(errno, sbuf, sizeof(sbuf)));
+		       str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_close;
 	}
 

tools/perf/builtin-buildid-cache.c

@@ -351,7 +351,7 @@ int cmd_buildid_cache(int argc, const char **argv,
 						continue;
 					}
 					pr_warning("Couldn't add %s: %s\n",
-						   pos->s, strerror_r(errno, sbuf, sizeof(sbuf)));
+						   pos->s, str_error_r(errno, sbuf, sizeof(sbuf)));
 				}
 
 			strlist__delete(list);
@@ -369,7 +369,7 @@ int cmd_buildid_cache(int argc, const char **argv,
 						continue;
 					}
 					pr_warning("Couldn't remove %s: %s\n",
-						   pos->s, strerror_r(errno, sbuf, sizeof(sbuf)));
+						   pos->s, str_error_r(errno, sbuf, sizeof(sbuf)));
 				}
 
 			strlist__delete(list);
@@ -387,7 +387,7 @@ int cmd_buildid_cache(int argc, const char **argv,
 						continue;
 					}
 					pr_warning("Couldn't remove %s: %s\n",
-						   pos->s, strerror_r(errno, sbuf, sizeof(sbuf)));
+						   pos->s, str_error_r(errno, sbuf, sizeof(sbuf)));
 				}
 
 			strlist__delete(list);
@@ -408,7 +408,7 @@ int cmd_buildid_cache(int argc, const char **argv,
 						continue;
 					}
 					pr_warning("Couldn't update %s: %s\n",
-						   pos->s, strerror_r(errno, sbuf, sizeof(sbuf)));
+						   pos->s, str_error_r(errno, sbuf, sizeof(sbuf)));
 				}
 
 			strlist__delete(list);

tools/perf/builtin-help.c

@@ -117,7 +117,7 @@ static void exec_woman_emacs(const char *path, const char *page)
 			free(man_page);
 		}
 		warning("failed to exec '%s': %s", path,
-			strerror_r(errno, sbuf, sizeof(sbuf)));
+			str_error_r(errno, sbuf, sizeof(sbuf)));
 	}
 }
 
@@ -150,7 +150,7 @@ static void exec_man_konqueror(const char *path, const char *page)
 			free(man_page);
 		}
 		warning("failed to exec '%s': %s", path,
-			strerror_r(errno, sbuf, sizeof(sbuf)));
+			str_error_r(errno, sbuf, sizeof(sbuf)));
 	}
 }
 
@@ -162,7 +162,7 @@ static void exec_man_man(const char *path, const char *page)
 		path = "man";
 	execlp(path, "man", page, NULL);
 	warning("failed to exec '%s': %s", path,
-		strerror_r(errno, sbuf, sizeof(sbuf)));
+		str_error_r(errno, sbuf, sizeof(sbuf)));
 }
 
 static void exec_man_cmd(const char *cmd, const char *page)
@@ -175,7 +175,7 @@ static void exec_man_cmd(const char *cmd, const char *page)
 		free(shell_cmd);
 	}
 	warning("failed to exec '%s': %s", cmd,
-		strerror_r(errno, sbuf, sizeof(sbuf)));
+		str_error_r(errno, sbuf, sizeof(sbuf)));
 }
 
 static void add_man_viewer(const char *name)

tools/perf/builtin-kvm.c

@@ -1018,13 +1018,13 @@ static int kvm_live_open_events(struct perf_kvm_stat *kvm)
 	err = perf_evlist__open(evlist);
 	if (err < 0) {
 		printf("Couldn't create the events: %s\n",
-		       strerror_r(errno, sbuf, sizeof(sbuf)));
+		       str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out;
 	}
 
 	if (perf_evlist__mmap(evlist, kvm->opts.mmap_pages, false) < 0) {
 		ui__error("Failed to mmap the events: %s\n",
-			  strerror_r(errno, sbuf, sizeof(sbuf)));
+			  str_error_r(errno, sbuf, sizeof(sbuf)));
 		perf_evlist__close(evlist);
 		goto out;
 	}

tools/perf/builtin-probe.c

@@ -308,7 +308,7 @@ static void pr_err_with_code(const char *msg, int err)
 
 	pr_err("%s", msg);
 	pr_debug(" Reason: %s (Code: %d)",
-		 strerror_r(-err, sbuf, sizeof(sbuf)), err);
+		 str_error_r(-err, sbuf, sizeof(sbuf)), err);
 	pr_err("\n");
 }
 

tools/perf/builtin-record.c

@@ -361,7 +361,7 @@ static int record__mmap_evlist(struct record *rec,
 			return -errno;
 		} else {
 			pr_err("failed to mmap with %d (%s)\n", errno,
-				strerror_r(errno, msg, sizeof(msg)));
+				str_error_r(errno, msg, sizeof(msg)));
 			if (errno)
 				return -errno;
 			else
@@ -407,7 +407,7 @@ try_again:
 	if (perf_evlist__apply_filters(evlist, &pos)) {
 		error("failed to set filter \"%s\" on event %s with %d (%s)\n",
 			pos->filter, perf_evsel__name(pos), errno,
-			strerror_r(errno, msg, sizeof(msg)));
+			str_error_r(errno, msg, sizeof(msg)));
 		rc = -1;
 		goto out;
 	}
@@ -1003,7 +1003,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 
 	if (forks && workload_exec_errno) {
 		char msg[STRERR_BUFSIZE];
-		const char *emsg = strerror_r(workload_exec_errno, msg, sizeof(msg));
+		const char *emsg = str_error_r(workload_exec_errno, msg, sizeof(msg));
 		pr_err("Workload failed: %s\n", emsg);
 		err = -1;
 		goto out_child;

tools/perf/builtin-sched.c

@@ -494,7 +494,7 @@ force_again:
 		}
 		pr_err("Error: sys_perf_event_open() syscall returned "
 		       "with %d (%s)\n%s", fd,
-		       strerror_r(errno, sbuf, sizeof(sbuf)), info);
+		       str_error_r(errno, sbuf, sizeof(sbuf)), info);
 		exit(EXIT_FAILURE);
 	}
 	return fd;

tools/perf/builtin-stat.c

@@ -596,7 +596,7 @@ try_again:
 	if (perf_evlist__apply_filters(evsel_list, &counter)) {
 		error("failed to set filter \"%s\" on event %s with %d (%s)\n",
 			counter->filter, perf_evsel__name(counter), errno,
-			strerror_r(errno, msg, sizeof(msg)));
+			str_error_r(errno, msg, sizeof(msg)));
 		return -1;
 	}
 
@@ -637,7 +637,7 @@ try_again:
 		wait(&status);
 
 		if (workload_exec_errno) {
-			const char *emsg = strerror_r(workload_exec_errno, msg, sizeof(msg));
+			const char *emsg = str_error_r(workload_exec_errno, msg, sizeof(msg));
 			pr_err("Workload failed: %s\n", emsg);
 			return -1;
 		}

tools/perf/builtin-top.c

@@ -907,7 +907,7 @@ try_again:
 
 	if (perf_evlist__mmap(evlist, opts->mmap_pages, false) < 0) {
 		ui__error("Failed to mmap with %d (%s)\n",
-			    errno, strerror_r(errno, msg, sizeof(msg)));
+			    errno, str_error_r(errno, msg, sizeof(msg)));
 		goto out_err;
 	}
 
@@ -1028,7 +1028,7 @@ out_delete:
 
 out_err_cpu_topo: {
 	char errbuf[BUFSIZ];
-	const char *err = strerror_r(-ret, errbuf, sizeof(errbuf));
+	const char *err = str_error_r(-ret, errbuf, sizeof(errbuf));
 
 	ui__error("Could not read the CPU topology map: %s\n", err);
 	goto out_delete;
@@ -1295,7 +1295,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused)
 
 	if (perf_evlist__create_maps(top.evlist, target) < 0) {
 		ui__error("Couldn't create thread/CPU maps: %s\n",
-			  errno == ENOENT ? "No such process" : strerror_r(errno, errbuf, sizeof(errbuf)));
+			  errno == ENOENT ? "No such process" : str_error_r(errno, errbuf, sizeof(errbuf)));
 		goto out_delete_evlist;
 	}
 

tools/perf/builtin-trace.c

@@ -1601,7 +1601,7 @@ signed_print:
 		fprintf(trace->output, ") = %ld", ret);
 	} else if (ret < 0 && (sc->fmt->errmsg || sc->fmt->errpid)) {
 		char bf[STRERR_BUFSIZE];
-		const char *emsg = strerror_r(-ret, bf, sizeof(bf)),
+		const char *emsg = str_error_r(-ret, bf, sizeof(bf)),
 			   *e = audit_errno_to_name(-ret);
 
 		fprintf(trace->output, ") = -1 %s %s", e, emsg);
@@ -2402,7 +2402,7 @@ out_error_apply_filters:
 	fprintf(trace->output,
 		"Failed to set filter \"%s\" on event %s with %d (%s)\n",
 		evsel->filter, perf_evsel__name(evsel), errno,
-		strerror_r(errno, errbuf, sizeof(errbuf)));
+		str_error_r(errno, errbuf, sizeof(errbuf)));
 	goto out_delete_evlist;
 }
 out_error_mem:

tools/perf/perf.c

@@ -374,7 +374,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 	/* Check for ENOSPC and EIO errors.. */
 	if (fflush(stdout)) {
 		fprintf(stderr, "write failure on standard output: %s",
-			strerror_r(errno, sbuf, sizeof(sbuf)));
+			str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out;
 	}
 	if (ferror(stdout)) {
@@ -383,7 +383,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 	}
 	if (fclose(stdout)) {
 		fprintf(stderr, "close failed on standard output: %s",
-			strerror_r(errno, sbuf, sizeof(sbuf)));
+			str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out;
 	}
 	status = 0;
@@ -615,7 +615,7 @@ int main(int argc, const char **argv)
 	}
 
 	fprintf(stderr, "Failed to run command '%s': %s\n",
-		cmd, strerror_r(errno, sbuf, sizeof(sbuf)));
+		cmd, str_error_r(errno, sbuf, sizeof(sbuf)));
 out:
 	return 1;
 }

tools/perf/tests/backward-ring-buffer.c

@@ -60,7 +60,7 @@ static int do_test(struct perf_evlist *evlist, int mmap_pages,
 	err = perf_evlist__mmap(evlist, mmap_pages, true);
 	if (err < 0) {
 		pr_debug("perf_evlist__mmap: %s\n",
-			 strerror_r(errno, sbuf, sizeof(sbuf)));
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		return TEST_FAIL;
 	}
 
@@ -124,7 +124,7 @@ int test__backward_ring_buffer(int subtest __maybe_unused)
 	err = perf_evlist__open(evlist);
 	if (err < 0) {
 		pr_debug("perf_evlist__open: %s\n",
-			 strerror_r(errno, sbuf, sizeof(sbuf)));
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;
 	}
 

tools/perf/tests/bpf.c

@@ -143,14 +143,14 @@ static int do_test(struct bpf_object *obj, int (*func)(void),
 	err = perf_evlist__open(evlist);
 	if (err < 0) {
 		pr_debug("perf_evlist__open: %s\n",
-			 strerror_r(errno, sbuf, sizeof(sbuf)));
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;
 	}
 
 	err = perf_evlist__mmap(evlist, opts.mmap_pages, false);
 	if (err < 0) {
 		pr_debug("perf_evlist__mmap: %s\n",
-			 strerror_r(errno, sbuf, sizeof(sbuf)));
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;
 	}
 

tools/perf/tests/builtin-test.c

@@ -258,7 +258,7 @@ static int run_test(struct test *test, int subtest)
 
 	if (child < 0) {
 		pr_err("failed to fork test: %s\n",
-			strerror_r(errno, sbuf, sizeof(sbuf)));
+			str_error_r(errno, sbuf, sizeof(sbuf)));
 		return -1;
 	}
 

tools/perf/tests/event-times.c

@@ -37,7 +37,7 @@ static int attach__enable_on_exec(struct perf_evlist *evlist)
 	err = perf_evlist__open(evlist);
 	if (err < 0) {
 		pr_debug("perf_evlist__open: %s\n",
-			 strerror_r(errno, sbuf, sizeof(sbuf)));
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		return err;
 	}
 

tools/perf/tests/mmap-basic.c

@@ -49,7 +49,7 @@ int test__basic_mmap(int subtest __maybe_unused)
 	sched_setaffinity(0, sizeof(cpu_set), &cpu_set);
 	if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) < 0) {
 		pr_debug("sched_setaffinity() failed on CPU %d: %s ",
-			 cpus->map[0], strerror_r(errno, sbuf, sizeof(sbuf)));
+			 cpus->map[0], str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_free_cpus;
 	}
 
@@ -79,7 +79,7 @@ int test__basic_mmap(int subtest __maybe_unused)
 		if (perf_evsel__open(evsels[i], cpus, threads) < 0) {
 			pr_debug("failed to open counter: %s, "
 				 "tweak /proc/sys/kernel/perf_event_paranoid?\n",
-				 strerror_r(errno, sbuf, sizeof(sbuf)));
+				 str_error_r(errno, sbuf, sizeof(sbuf)));
 			goto out_delete_evlist;
 		}
 
@@ -89,7 +89,7 @@ int test__basic_mmap(int subtest __maybe_unused)
 
 	if (perf_evlist__mmap(evlist, 128, true) < 0) {
 		pr_debug("failed to mmap events: %d (%s)\n", errno,
-			 strerror_r(errno, sbuf, sizeof(sbuf)));
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_delete_evlist;
 	}
 

tools/perf/tests/openat-syscall-all-cpus.c

@@ -41,7 +41,7 @@ int test__openat_syscall_event_on_all_cpus(int subtest __maybe_unused)
 	if (perf_evsel__open(evsel, cpus, threads) < 0) {
 		pr_debug("failed to open counter: %s, "
 			 "tweak /proc/sys/kernel/perf_event_paranoid?\n",
-			 strerror_r(errno, sbuf, sizeof(sbuf)));
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
 		goto out_evsel_delete;
 	}
 
@@ -62,7 +62,7 @@ int test__openat_syscall_event_on_all_cpus(int subtest __maybe_unused)
 		if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) < 0) {
 			pr_debug("sched_setaffinity() failed on CPU %d: %s ",
 				 cpus->map[cpu],
-				 strerror_r(errno, sbuf, sizeof(sbuf)));
+				 str_error_r(errno, sbuf, sizeof(sbuf)));
 			goto out_close_fd;
 		}
 		for (i = 0; i < ncalls; ++i) {