- Add a utility to remove the S1SUSPEND stamp from a swap device.

1 files changed, 167 insertions, 0 deletions

diff --git a/src/pm-reset-swap.c b/src/pm-reset-swap.c
new file mode 100644
index 0000000..2f372ea
--- /dev/null
+++ b/src/pm-reset-swap.c
@@ -0,0 +1,167 @@
+/*
+ * mark a swap device as not usable for thaw
+ *
+ * Copyright 2006 Red Hat, Inc.
+ *
+ * Authors:
+ *   Peter Jones <pjones@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#define _GNU_SOURCE 1
+
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+
+/* XXX this is a total hack for bad system headers. */
+typedef u_int32_t __u32;
+#include <linux/pmu.h>
+
+typedef u_int64_t sector_t;
+
+/*
+ * Here's what the disk looks like after a successful hibernate:
+
+ 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+ *
+ 00000400  01 00 00 00 ff df 03 00  00 00 00 00 00 00 00 00  |................|
+ 00000410  00 00 00 00 00 00 00 00  00 00 00 00 73 77 61 70  |............swap|
+ 00000420  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+ *
+ 00000fe0  00 00 00 00 01 00 00 00  00 00 00 00 53 57 41 50  |............SWAP|
+ 00000ff0  53 50 41 43 45 32 53 31  53 55 53 50 45 4e 44 00  |SPACE2S1SUSPEND.|
+
+ * And here's what it looks like if you haven't hibernated to it:
+
+ 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+ *
+ 00000400  01 00 00 00 ff df 03 00  00 00 00 00 00 00 00 00  |................|
+ 00000410  00 00 00 00 00 00 00 00  00 00 00 00 73 77 61 70  |............swap|
+ 00000420  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+ *
+ 00000ff0  00 00 00 00 00 00 53 57  41 50 53 50 41 43 45 32  |......SWAPSPACE2|
+
+ *
+ */
+
+/* The signature offset is annoying.  The struct is:
+ * struct swsusp_header {
+ *     char reserved[PAGE_SIZE - 20 - sizeof(sector_t)];
+ *     sector_t image;
+ *     char orig_sig[10];
+ *     char sig[10];
+ * }
+ */
+off_t get_sig_offset(int orig)
+{
+    int pagesize = sysconf(_SC_PAGESIZE);
+
+    return (off_t)((sizeof (char) * pagesize) - (orig ? 20 : 10));
+}
+
+static inline int
+print_usage(FILE *output, int retval)
+{
+    fprintf(output, "usage: pm-reset-swap <device node>\n");
+    return retval;
+}
+
+int check_resume_block(FILE *dev, off_t offset)
+{
+    char buf[11] = {0,};
+    off_t location = offset + get_sig_offset(0);
+
+    if (fseek(dev, location, SEEK_SET) < 0)
+        return -1;
+    if (fread(buf, sizeof (char), 10, dev) != 10)
+        return -1;
+
+    if (!strncmp(buf, "S1SUSPEND", 9))
+        return 1;
+
+    return 0;
+}
+
+int clear_resume_block(FILE *dev, off_t offset)
+{
+    char buf[21] = {0,};
+    off_t location = offset + get_sig_offset(1);
+
+    if (fseek(dev, location, SEEK_SET) < 0)
+        return -1;
+
+    if (fread(buf, sizeof (char), 20, dev) != 20)
+        return -1;
+
+    if (fseek(dev, location, SEEK_SET) < 0)
+        return -1;
+
+    memmove(buf+10, buf, 10);
+    memset(buf, '\0', 10);
+
+    if (fwrite(buf, sizeof (char), 20, dev) != 20)
+        return -1;
+
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    FILE *dev = NULL;
+    int rc;
+
+    if (argc != 2)
+        return print_usage(stderr, 1);
+
+    if (!strcmp(argv[1], "--help")) {
+        return print_usage(stdout, 0);
+    }
+
+    if (!(dev = fopen(argv[1], "r+b"))) {
+        fprintf(stderr, "Could not open \"%s\": %m\n", argv[1]);
+        return 1;
+    }
+
+    rc = check_resume_block(dev, 0);
+    if (rc < 0) {
+        fprintf(stderr, "Could not check \"%s\" for swap signature: %m\n",
+                argv[1]);
+        fclose(dev);
+        return 2;
+    }
+    rc = 1;
+    if (rc == 1) {
+        if (clear_resume_block(dev, 0)) {
+            fprintf(stderr, "Could not clear swap signature on \"%s\": %m\n",
+                    argv[1]);
+            fclose(dev);
+            return 1;
+        }
+    }
+        
+    fclose(dev);
+    return 0;
+}
+
+/*
+ * vim:ts=8:sw=4:sts=4:et
+ */