On Mon, Jul 23, 2012 at 04:48:22PM -0400, Ulrich Drepper wrote:
> On Mon, Jul 23, 2012 at 4:31 PM, Kirill A. Shutemov
> <kir...@shutemov.name> wrote:
> > + const char *err = strerror_r(errnum, buf, buflen);
> > +
> > + if (err != buf && buflen > 0) {
> > + size_t len = strlen(err);
> > + char *c = mempcpy(buf, err, min(buflen - 1, len));
> > + *c = '\0';
> > + }
>
> No need to check for err == NULL.
There's no such check.
> buflen == 0 is a possibility given
> the interface but I'd say this is an error and should be tested for at
> the beginning of the function and the call should fail or even abort
> the program.
>From 11d62205ee3c534aa9b0e9a24a312438ac726ffb Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kir...@shutemov.name>
Date: Mon, 23 Jul 2012 17:41:05 +0300
Subject: [PATCH 2/2] perf: fix strerror_r() usage
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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.
Let's fix strerror_r() usage.
Signed-off-by: Kirill A. Shutemov <kir...@shutemov.name>
---
tools/perf/ui/browsers/hists.c | 4 ++--
tools/perf/util/target.c | 12 +++++++++++-
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 482f051..413bd62 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -978,8 +978,8 @@ 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));
- ui_helpline__fpush("Couldn't write to %s: %s", filename, bf);
+ const char *err = strerror_r(errno, bf, sizeof(bf));
+ ui_helpline__fpush("Couldn't write to %s: %s", filename, err);
return -1;
}
diff --git a/tools/perf/util/target.c b/tools/perf/util/target.c
index 1064d5b..5c4b3b1 100644
--- a/tools/perf/util/target.c
+++ b/tools/perf/util/target.c
@@ -9,6 +9,7 @@
#include "target.h"
#include "debug.h"
+#include <assert.h>
#include <pwd.h>
#include <string.h>
@@ -110,8 +111,17 @@ int perf_target__strerror(struct perf_target *target, int
errnum,
int idx;
const char *msg;
+ assert(buflen > 0);
+
if (errnum >= 0) {
- strerror_r(errnum, buf, buflen);
+ const char *err = strerror_r(errnum, buf, buflen);
+
+ if (err != buf) {
+ size_t len = strlen(err);
+ char *c = mempcpy(buf, err, min(buflen - 1, len));
+ *c = '\0';
+ }
+
return 0;
}
--
Kirill A. Shutemov
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