From: "Kirill A. Shutemov" <kir...@shutemov.name>
Perf uses GNU-specific version of strerror_r(). The GNU-specific
strerror_r() returns a pointer to a string containing the error message.
This may be either a pointer to a string that the function stores in
buf, or a pointer to some (immutable) static string (in which case buf
is unused).
In glibc-2.16 GNU version was marked with attribute warn_unused_result.
It triggers few warnings in perf:
util/target.c: In function ‘perf_target__strerror’:
util/target.c:114:13: error: ignoring return value of ‘strerror_r’, declared
with attribute warn_unused_result [-Werror=unused-result]
ui/browsers/hists.c: In function ‘hist_browser__dump’:
ui/browsers/hists.c:981:13: error: ignoring return value of ‘strerror_r’,
declared with attribute warn_unused_result [-Werror=unused-result]
They are bugs.
The right way to fix it is to switch to XSI-compliant version.
Unfortunately, glibc doesn't allow to get XSI-complaint strerror_r() and
_GNU_SOURCE at the same time.
Let's bundle XSI-complaint version to perf and use it.
Signed-off-by: Kirill A. Shutemov <kir...@shutemov.name>
---
tools/perf/ui/browsers/hists.c | 2 +-
tools/perf/util/string.c | 25 +++++++++++++++++++++++++
tools/perf/util/target.c | 3 ++-
tools/perf/util/util.h | 1 +
4 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 482f051..8bd1780 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -978,7 +978,7 @@ static int hist_browser__dump(struct hist_browser *browser)
fp = fopen(filename, "w");
if (fp == NULL) {
char bf[64];
- strerror_r(errno, bf, sizeof(bf));
+ xsi_strerror_r(errno, bf, sizeof(bf));
ui_helpline__fpush("Couldn't write to %s: %s", filename, bf);
return -1;
}
diff --git a/tools/perf/util/string.c b/tools/perf/util/string.c
index 199bc4d..71b68b9 100644
--- a/tools/perf/util/string.c
+++ b/tools/perf/util/string.c
@@ -1,5 +1,6 @@
#include "util.h"
#include "string.h"
+#include <linux/kernel.h>
#define K 1024LL
/*
@@ -335,3 +336,27 @@ char *rtrim(char *s)
return s;
}
+
+/**
+ * xsi_strerror_r() - XSI-compliant version of strerror_r()
+ */
+int xsi_strerror_r(int errnum, char *buf, size_t buflen)
+{
+ const char *p;
+ size_t len;
+
+ /* GNU-specific version of strerror_r() */
+ p = strerror_r(errnum, buf, buflen);
+
+ /* glibc use the buffer only if errnum is not correct */
+ if (p == buf)
+ return EINVAL;
+
+ len = strlen(p);
+ if (buflen > 0) {
+ char *c = mempcpy(buf, p, min(buflen - 1, len));
+ *c = '\0';
+ }
+
+ return buflen > len ? 0 : ERANGE;
+}
diff --git a/tools/perf/util/target.c b/tools/perf/util/target.c
index 1064d5b..0ec1a30 100644
--- a/tools/perf/util/target.c
+++ b/tools/perf/util/target.c
@@ -8,6 +8,7 @@
#include "target.h"
#include "debug.h"
+#include "util.h"
#include <pwd.h>
#include <string.h>
@@ -111,7 +112,7 @@ int perf_target__strerror(struct perf_target *target, int
errnum,
const char *msg;
if (errnum >= 0) {
- strerror_r(errnum, buf, buflen);
+ xsi_strerror_r(errnum, buf, buflen);
return 0;
}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index b13c733..3e85d63 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -265,5 +265,6 @@ bool is_power_of_2(unsigned long n)
size_t hex_width(u64 v);
char *rtrim(char *s);
+int xsi_strerror_r(int errnum, char *buf, size_t buflen);
#endif
--
1.7.11.2
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