[tip:perf/core] perf tools: Add writen function

[tip-bot for Jiri Olsa <tipbot@zytor.com>]

Commit-ID:  bc3a502bc2bc78d03526d6abcc5697aab18d5ae9
Gitweb:     http://git.kernel.org/tip/bc3a502bc2bc78d03526d6abcc5697aab18d5ae9
Author:     Jiri Olsa <jolsa@redhat.com>
AuthorDate: Thu, 28 Nov 2013 11:30:16 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 2 Dec 2013 09:22:46 -0300

perf tools: Add writen function

Adding 'writen' function as a synchronous wrapper for write syscall with
following prototype:

  ssize_t writen(int fd, void *buf, size_t n)

Returns the number of bytes written on success or -1 in case of err.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Requested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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/1385634619-8129-5-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/util.c | 24 +++++++++++++++++++-----
 tools/perf/util/util.h |  1 +
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 6ea0b4a..b1d5376 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -152,16 +152,14 @@ 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)
+static ssize_t ion(bool is_read, int fd, void *buf, size_t n)
 {
 	void *buf_start = buf;
 	size_t left = n;
 
 	while (left) {
-		ssize_t ret = read(fd, buf, left);
+		ssize_t ret = is_read ? read(fd, buf, left) :
+					write(fd, buf, left);
 
 		if (ret <= 0)
 			return ret;
@@ -174,6 +172,22 @@ ssize_t readn(int fd, void *buf, size_t n)
 	return n;
 }
 
+/*
+ * Read exactly 'n' bytes or return an error.
+ */
+ssize_t readn(int fd, void *buf, size_t n)
+{
+	return ion(true, fd, buf, n);
+}
+
+/*
+ * Write exactly 'n' bytes or return an error.
+ */
+ssize_t writen(int fd, void *buf, size_t n)
+{
+	return ion(false, fd, buf, n);
+}
+
 size_t hex_width(u64 v)
 {
 	size_t n = 1;
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 9f6b928..ce0f73d 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -254,6 +254,7 @@ 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);
 ssize_t readn(int fd, void *buf, size_t n);
+ssize_t writen(int fd, void *buf, size_t n);
 
 struct perf_event_attr;