[PATCH 2/3] tools lib api fs: Add sysfs__write_int function

[kan . liang]

From: Kan Liang <kan.li...@intel.com>

Adding sysfs__write_int function to ease up writing int to sysfs.
New interface is:

  int sysfs__write_int(const char *entry, int value);

Also, introducing filename__write_int which is useful for new helpers to
write sysctl values.

Signed-off-by: Kan Liang <kan.li...@intel.com>
---
 tools/lib/api/fs/fs.c | 29 +++++++++++++++++++++++++++++
 tools/lib/api/fs/fs.h |  4 ++++
 2 files changed, 33 insertions(+)

diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
index 809c772..de4f74e 100644
--- a/tools/lib/api/fs/fs.c
+++ b/tools/lib/api/fs/fs.c
@@ -387,6 +387,22 @@ int filename__read_str(const char *filename, char **buf, 
size_t *sizep)
        return err;
 }
 
+int filename__write_int(const char *filename, int value)
+{
+       int fd = open(filename, O_WRONLY), err = -1;
+       char buf[64];
+
+       if (fd < 0)
+               return err;
+
+       sprintf(buf, "%d", value);
+       if (write(fd, buf, sizeof(buf)) == sizeof(buf))
+               err = 0;
+
+       close(fd);
+       return err;
+}
+
 int procfs__read_str(const char *entry, char **buf, size_t *sizep)
 {
        char path[PATH_MAX];
@@ -480,3 +496,16 @@ int sysctl__read_int(const char *sysctl, int *value)
 
        return filename__read_int(path, value);
 }
+
+int sysfs__write_int(const char *entry, int value)
+{
+       char path[PATH_MAX];
+       const char *sysfs = sysfs__mountpoint();
+
+       if (!sysfs)
+               return -1;
+
+       snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+       return filename__write_int(path, value);
+}
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 956c211..4560534 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -31,6 +31,8 @@ int filename__read_int(const char *filename, int *value);
 int filename__read_ull(const char *filename, unsigned long long *value);
 int filename__read_str(const char *filename, char **buf, size_t *sizep);
 
+int filename__write_int(const char *filename, int value);
+
 int procfs__read_str(const char *entry, char **buf, size_t *sizep);
 
 int sysctl__read_int(const char *sysctl, int *value);
@@ -38,4 +40,6 @@ 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);
+
+int sysfs__write_int(const char *entry, int value);
 #endif /* __API_FS__ */
-- 
2.7.4