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perf tools: Fine tune readn function

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Added a 'left' variable to make the flow clearer, and added a debug
check for the return value - returning 'n' is more obvious.

Added small comment for readn.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Original-patch-by: Ingo Molnar <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1385634619-8129-4-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Jiri Olsa 2013-11-28 11:30:15 +01:00 committed by Arnaldo Carvalho de Melo
parent 727ebd544f
commit 838d145202
1 changed files with 11 additions and 5 deletions
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16
tools/perf/util/util.c
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@ -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 +152,26 @@ unsigned long convert_unit(unsigned long value, char *unit)
return value;
}
/*
* Read exactly 'n' bytes or return an error.
*/
ssize_t readn(int fd, void *buf, size_t n)
{
void *buf_start = buf;
size_t left = n;
while (n) {
ssize_t ret = read(fd, buf, n);
while (left) {
ssize_t ret = read(fd, buf, left);
if (ret <= 0)
return ret;
n -= ret;
buf += ret;
left -= ret;
buf += ret;
}
return buf - buf_start;
BUG_ON((size_t)(buf - buf_start) != n);
return n;
}
size_t hex_width(u64 v)