[tip:perf/core] tools lib api fs: Add sysfs__read_str function

[tip-bot for Jiri Olsa]

Commit-ID:  51c0396c600f49de9c3ff8f6fd83055de3709c3d
Gitweb:     http://git.kernel.org/tip/51c0396c600f49de9c3ff8f6fd83055de3709c3d
Author:     Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate: Sun, 14 Feb 2016 17:03:44 +0100
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 16 Feb 2016 17:12:57 -0300

tools lib api fs: Add sysfs__read_str function

Adding sysfs__read_str function to ease up reading string files from
sysfs. New interface is:

  int sysfs__read_str(const char *entry, char **buf, size_t *sizep);

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1455465826-8426-4-git-send-email-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/lib/api/fs/fs.c | 13 +++++++++++++
 tools/lib/api/fs/fs.h |  1 +
 2 files changed, 14 insertions(+)

diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
index 2cbf677..ef78c22 100644
--- a/tools/lib/api/fs/fs.c
+++ b/tools/lib/api/fs/fs.c
@@ -377,6 +377,19 @@ int sysfs__read_int(const char *entry, int *value)
 	return filename__read_int(path, value);
 }
 
+int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
+{
+	char path[PATH_MAX];
+	const char *sysfs = sysfs__mountpoint();
+
+	if (!sysfs)
+		return -1;
+
+	snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+	return filename__read_str(path, buf, sizep);
+}
+
 int sysctl__read_int(const char *sysctl, int *value)
 {
 	char path[PATH_MAX];
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 858922b..9f65980 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -32,4 +32,5 @@ int filename__read_str(const char *filename, char **buf, size_t *sizep);
 int sysctl__read_int(const char *sysctl, int *value);
 int sysfs__read_int(const char *entry, int *value);
 int sysfs__read_ull(const char *entry, unsigned long long *value);
+int sysfs__read_str(const char *entry, char **buf, size_t *sizep);
 #endif /* __API_FS__ */