toolbox: swap utils
Add swap utilities (mkswap, swapon, swapoff) to the toolbox
Change-Id: If5ed6981670a1cdda6b528b587dbc1be7ccdf832
Signed-off-by: Rom Lemarchand <romlem@google.com>
diff --git a/toolbox/mkswap.c b/toolbox/mkswap.c
new file mode 100644
index 0000000..1710ef6
--- /dev/null
+++ b/toolbox/mkswap.c
@@ -0,0 +1,94 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <asm/page.h>
+#include <sys/swap.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+/* XXX This needs to be obtained from kernel headers. See b/9336527 */
+struct linux_swap_header {
+ char bootbits[1024]; /* Space for disklabel etc. */
+ uint32_t version;
+ uint32_t last_page;
+ uint32_t nr_badpages;
+ unsigned char sws_uuid[16];
+ unsigned char sws_volume[16];
+ uint32_t padding[117];
+ uint32_t badpages[1];
+};
+
+#define MAGIC_SWAP_HEADER "SWAPSPACE2"
+#define MAGIC_SWAP_HEADER_LEN 10
+#define MIN_PAGES 10
+
+int mkswap_main(int argc, char **argv)
+{
+ int err = 0;
+ int fd;
+ ssize_t len;
+ off_t swap_size;
+ int pagesize;
+ struct linux_swap_header sw_hdr;
+
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
+ return -EINVAL;
+ }
+
+ fd = open(argv[1], O_WRONLY);
+ if (fd < 0) {
+ err = errno;
+ fprintf(stderr, "Cannot open %s\n", argv[1]);
+ return err;
+ }
+
+ pagesize = getpagesize();
+ /* Determine the length of the swap file */
+ swap_size = lseek(fd, 0, SEEK_END);
+ if (swap_size < MIN_PAGES * pagesize) {
+ fprintf(stderr, "Swap file needs to be at least %dkB\n",
+ (MIN_PAGES * pagesize) >> 10);
+ err = -ENOSPC;
+ goto err;
+ }
+ if (lseek(fd, 0, SEEK_SET)) {
+ err = errno;
+ fprintf(stderr, "Can't seek to the beginning of the file\n");
+ goto err;
+ }
+
+ memset(&sw_hdr, 0, sizeof(sw_hdr));
+ sw_hdr.version = 1;
+ sw_hdr.last_page = (swap_size / pagesize) - 1;
+
+ len = write(fd, &sw_hdr, sizeof(sw_hdr));
+ if (len != sizeof(sw_hdr)) {
+ err = errno;
+ fprintf(stderr, "Failed to write swap header into %s\n", argv[1]);
+ goto err;
+ }
+
+ /* Write the magic header */
+ if (lseek(fd, pagesize - MAGIC_SWAP_HEADER_LEN, SEEK_SET) < 0) {
+ err = errno;
+ fprintf(stderr, "Failed to seek into %s\n", argv[1]);
+ goto err;
+ }
+
+ len = write(fd, MAGIC_SWAP_HEADER, MAGIC_SWAP_HEADER_LEN);
+ if (len != MAGIC_SWAP_HEADER_LEN) {
+ err = errno;
+ fprintf(stderr, "Failed to write magic swap header into %s\n", argv[1]);
+ goto err;
+ }
+
+ if (fsync(fd) < 0) {
+ err = errno;
+ fprintf(stderr, "Failed to sync %s\n", argv[1]);
+ goto err;
+ }
+err:
+ close(fd);
+ return err;
+}