* Arnaldo Carvalho de Melo <a...@ghostprotocols.net> wrote:
> Em Fri, Nov 22, 2013 at 03:24:26PM +0100, Jiri Olsa escreveu:
> > }
> > +
> > +ssize_t perf_data_file__write(struct perf_data_file *file,
> > + void *buf, size_t size)
> > +{
> > + ssize_t total = size;
> > +
> > + while (size) {
> > + ssize_t ret = write(file->fd, buf, size);
> > +
> > + if (ret < 0) {
> > + pr_err("failed to write perf data, error: %m\n");
> > + return -1;
> > + }
> > +
> > + size -= ret;
> > + buf += ret;
> > + }
> > +
> > + return total;
>
> So this is the functional equivalent of "readn", so please move it to
> just after "readn" and make this just a simple wrapper.
Btw., would be nice to add a small comment to readn() that describes
its semantics, it looks like a useful helper.
I also added a check for the input parameter 'n', plus I added a
'left' variable to make the flow clearer, and added a debug check for
the return value - I think returning 'n' is more obvious.
Totally untested though.
Thanks,
Ingo
Signed-off-by: Ingo Molnar <mi...@kernel.org>
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 28a0a89..4789081 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -6,6 +6,7 @@
#endif
#include <stdio.h>
#include <stdlib.h>
+#include <linux/kernel.h>
/*
* XXX We need to find a better place for these things...
@@ -151,21 +152,29 @@ unsigned long convert_unit(unsigned long value, char
*unit)
return value;
}
-int readn(int fd, void *buf, size_t n)
+/*
+ * Read exactly 'n' bytes or return an error:
+ */
+int readn(int fd, void *buf, ssize_t n)
{
void *buf_start = buf;
+ size_t left = n;
+
+ BUG_ON(n <= 0);
- while (n) {
- int ret = read(fd, buf, n);
+ while (left) {
+ int ret = read(fd, buf, left);
if (ret <= 0)
return ret;
- n -= ret;
+ left -= ret;
buf += ret;
}
- return buf - buf_start;
+ BUG_ON(buf-buf_start != n);
+
+ return n;
}
size_t hex_width(u64 v)
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index c8f362d..bb0a336 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -253,7 +253,7 @@ bool strlazymatch(const char *str, const char *pat);
int strtailcmp(const char *s1, const char *s2);
char *strxfrchar(char *s, char from, char to);
unsigned long convert_unit(unsigned long value, char *unit);
-int readn(int fd, void *buf, size_t size);
+int readn(int fd, void *buf, ssize_t size);
struct perf_event_attr;
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