tools lib api fs: Introduce sysfs__read_{int,ull}()

To read either an int or an unsigned long long value from the given
file.

E.g.:

  $ cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
  3200000
  $ ./sysfs__read_ull
  devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
  /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq=3200000
  $

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-4a12m4d5k8m4qgc1vguocvei@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 49 insertions, 0 deletions

diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
index 791509346178..732dbef588b0 100644
--- a/tools/lib/api/fs/fs.c
+++ b/tools/lib/api/fs/fs.c
@@ -1,5 +1,6 @@
 #include <ctype.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -281,6 +282,50 @@ int filename__read_int(const char *filename, int *value)
         return err;
 }
 
+int filename__read_ull(const char *filename, unsigned long long *value)
+{
+        char line[64];
+        int fd = open(filename, O_RDONLY), err = -1;
+
+        if (fd < 0)
+                return -1;
+
+        if (read(fd, line, sizeof(line)) > 0) {
+                *value = strtoull(line, NULL, 10);
+                if (*value != ULLONG_MAX)
+                        err = 0;
+        }
+
+        close(fd);
+        return err;
+}
+
+int sysfs__read_ull(const char *entry, unsigned long long *value)
+{
+        char path[PATH_MAX];
+        const char *sysfs = sysfs__mountpoint();
+
+        if (!sysfs)
+                return -1;
+
+        snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+        return filename__read_ull(path, value);
+}
+
+int sysfs__read_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__read_int(path, value);
+}
+
 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 f654bcb99d1e..d024a7f682f6 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -25,5 +25,9 @@ FS(tracefs)
 
 
 int filename__read_int(const char *filename, int *value);
+int filename__read_ull(const char *filename, unsigned long long *value);
+
 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);
 #endif /* __API_FS__ */