Second commit

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 73 insertions, 0 deletions

diff --git a/proc.c b/proc.c
new file mode 100644
index 0000000..08e9252
--- /dev/null
+++ b/proc.c
@@ -0,0 +1,73 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+size_t
+getnproc(size_t default_count)
+{
+	char buf[128];
+	int fd, num = 0;
+	size_t n = 0, off = 0, len = 0;
+	size_t nums[] = {0, 0};
+	ssize_t r;
+	size_t last = 0;
+
+	fd = open("/sys/devices/system/cpu/online", O_RDONLY);
+	if (fd < 0)
+		return default_count;
+
+	for (;; off++) {
+		if (off == len) {
+			r = read(fd, buf, sizeof(buf));
+			if (r <= 0) {
+				if (!r)
+					break;
+				if (errno == EINTR)
+					continue;
+			error:
+				n = default_count;
+				goto out;
+			}
+			len = (size_t)r;
+			off = 0;
+		}
+
+		if (buf[off] == '-') {
+			if (num++ == 1)
+				goto error;
+		} else if (buf[off] == ',' || buf[off] == '\n') {
+			if (num == 0) {
+				nums[1] = nums[0];
+			} else {
+				num = 0;
+				if (nums[1] < nums[0])
+					goto error;
+			}
+			if (nums[0] < last)
+				goto error;
+			last = nums[0];
+			if (nums[1] - nums[0] + 1U > SIZE_MAX - n)
+				goto error;
+			n += nums[1] - nums[0] + 1U;
+		} else if (isdigit(buf[off])) {
+			if (nums[num] > (SIZE_MAX - (size_t)(buf[off] & 15)) / 10U)
+				goto error;
+			nums[num] = nums[num] * 10U + (size_t)(buf[off] & 15);
+		} else {
+			goto error;
+		}
+	}
+
+	n = n ? n : default_count;
+out:
+	close(fd);
+	return n;
+}
+
+
+size_t
+getautonthreads(void)
+{
+	size_t n = getnproc(8U);
+	return n < 3U ? 1U : n - 2U;
+}