zte's code,first commit
Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/os/linux/linux-3.4.x/tools/perf/util/sysfs.c b/ap/os/linux/linux-3.4.x/tools/perf/util/sysfs.c
new file mode 100644
index 0000000..48c6902
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/tools/perf/util/sysfs.c
@@ -0,0 +1,60 @@
+
+#include "util.h"
+#include "sysfs.h"
+
+static const char * const sysfs_known_mountpoints[] = {
+ "/sys",
+ 0,
+};
+
+static int sysfs_found;
+char sysfs_mountpoint[PATH_MAX];
+
+static int sysfs_valid_mountpoint(const char *sysfs)
+{
+ struct statfs st_fs;
+
+ if (statfs(sysfs, &st_fs) < 0)
+ return -ENOENT;
+ else if (st_fs.f_type != (long) SYSFS_MAGIC)
+ return -ENOENT;
+
+ return 0;
+}
+
+const char *sysfs_find_mountpoint(void)
+{
+ const char * const *ptr;
+ char type[100];
+ FILE *fp;
+
+ if (sysfs_found)
+ return (const char *) sysfs_mountpoint;
+
+ ptr = sysfs_known_mountpoints;
+ while (*ptr) {
+ if (sysfs_valid_mountpoint(*ptr) == 0) {
+ sysfs_found = 1;
+ strcpy(sysfs_mountpoint, *ptr);
+ return sysfs_mountpoint;
+ }
+ ptr++;
+ }
+
+ /* give up and parse /proc/mounts */
+ fp = fopen("/proc/mounts", "r");
+ if (fp == NULL)
+ return NULL;
+
+ while (!sysfs_found &&
+ fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
+ sysfs_mountpoint, type) == 2) {
+
+ if (strcmp(type, "sysfs") == 0)
+ sysfs_found = 1;
+ }
+
+ fclose(fp);
+
+ return sysfs_found ? sysfs_mountpoint : NULL;
+}