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 <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Wang Nan <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: acmel

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 @@ static int record__open(struct record *rec)
 	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 @@ static int self_open_counters(struct perf_sched *sched, unsigned long cur_task)
 		}
 		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;