+ return __max(sysconf(_SC_NPROCESSORS_CONF), count);
+}
+#endif
+
+/*
+ * Get the CPU possible mask string from sysfs.
+ *
+ * buf: the buffer where the mask will be read.
+ * max_bytes: the maximum number of bytes to write in the buffer.
+ *
+ * Returns the number of bytes read or -1 on error.
+ */
+int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes)
+{
+ ssize_t bytes_read = 0;
+ size_t total_bytes_read = 0;
+ int fd = -1, ret = -1;
+
+ if (buf == NULL)
+ goto end;
+
+ fd = open("/sys/devices/system/cpu/possible", O_RDONLY);
+ if (fd < 0)
+ goto end;
+
+ do {
+ bytes_read = read(fd, buf + total_bytes_read,
+ max_bytes - total_bytes_read);
+
+ if (bytes_read < 0) {
+ if (errno == EINTR) {
+ continue; /* retry operation */
+ } else {
+ goto end;
+ }
+ }
+
+ total_bytes_read += bytes_read;
+ assert(total_bytes_read <= max_bytes);
+ } while (max_bytes > total_bytes_read && bytes_read > 0);
+
+ /*
+ * Make sure the mask read is a null terminated string.
+ */
+ if (total_bytes_read < max_bytes)
+ buf[total_bytes_read] = '\0';
+ else
+ buf[max_bytes - 1] = '\0';
+
+ if (total_bytes_read > INT_MAX)
+ goto end;
+ ret = (int) total_bytes_read;
+end:
+ if (fd >= 0 && close(fd) < 0)
+ PERROR("close");
+ return ret;
+}
+
+/*
+ * Get the number of CPUs from the possible cpu mask.
+ *
+ * pmask: the mask to parse.
+ * len: the len of the mask excluding '\0'.
+ *
+ * Returns the number of possible CPUs from the mask or 0 on error.
+ */
+int get_num_possible_cpus_from_mask(const char *pmask, size_t len)
+{
+ ssize_t i;
+ unsigned long cpu_index;
+ char *endptr;
+
+ /* We need at least one char to read */
+ if (len < 1)
+ goto error;
+
+ /* Start from the end to read the last CPU index. */
+ for (i = len - 1; i > 0; i--) {
+ /* Break when we hit the first separator. */
+ if ((pmask[i] == ',') || (pmask[i] == '-')) {
+ i++;
+ break;
+ }
+ }
+
+ cpu_index = strtoul(&pmask[i], &endptr, 10);