[tip:perf/core] tools lib api fs: Introduce sysfs__read_bool

[tip-bot for Alexander Shishkin <tipbot@zytor.com>]

Commit-ID:  b9835a90084bd3cc45d7ab80c37f282046bc13d3
Gitweb:     http://git.kernel.org/tip/b9835a90084bd3cc45d7ab80c37f282046bc13d3
Author:     Alexander Shishkin <alexander.shishkin@linux.intel.com>
AuthorDate: Thu, 16 Mar 2017 18:41:59 +0200
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 17 Mar 2017 11:49:09 -0300

tools lib api fs: Introduce sysfs__read_bool

Will be used in a upcoming patch warning about PERF_RECORD_AUX data
gaps, reading the "module/kvm_intel/parameters/vmm_exclusive" sysfs
entry.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vince@deater.net>
Link: http://lkml.kernel.org/r/8760j941ig.fsf@ashishki-desk.ger.corp.intel.com
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/lib/api/fs/fs.c | 29 +++++++++++++++++++++++++++++
 tools/lib/api/fs/fs.h |  1 +
 2 files changed, 30 insertions(+)

diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
index 4b6bfc4..809c772 100644
--- a/tools/lib/api/fs/fs.c
+++ b/tools/lib/api/fs/fs.c
@@ -439,6 +439,35 @@ int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
 	return filename__read_str(path, buf, sizep);
 }
 
+int sysfs__read_bool(const char *entry, bool *value)
+{
+	char *buf;
+	size_t size;
+	int ret;
+
+	ret = sysfs__read_str(entry, &buf, &size);
+	if (ret < 0)
+		return ret;
+
+	switch (buf[0]) {
+	case '1':
+	case 'y':
+	case 'Y':
+		*value = true;
+		break;
+	case '0':
+	case 'n':
+	case 'N':
+		*value = false;
+		break;
+	default:
+		ret = -1;
+	}
+
+	free(buf);
+
+	return ret;
+}
 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 6b332dc..956c211 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -37,4 +37,5 @@ 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);
+int sysfs__read_bool(const char *entry, bool *value);
 #endif /* __API_FS__ */