Comment and whitespace tweaks.

[oweals/busybox.git] / util-linux / mkswap.c

diff --git a/util-linux/mkswap.c b/util-linux/mkswap.c
index af4cc10f74732453628c420673b7018558a4f6c5..11c411b6ac14043f3ce2f0bfcb83b740c235638d 100644 (file)
--- a/util-linux/mkswap.c
+++ b/util-linux/mkswap.c
@@ -8,12 +8,90 @@
 
 #include "libbb.h"
 
+#if ENABLE_SELINUX
+static void mkswap_selinux_setcontext(int fd, const char *path)
+{
+       struct stat stbuf;
+
+       if (!is_selinux_enabled())
+               return;
+
+       if (fstat(fd, &stbuf) < 0)
+               bb_perror_msg_and_die("fstat failed");
+       if (S_ISREG(stbuf.st_mode)) {
+               security_context_t newcon;
+               security_context_t oldcon = NULL;
+               context_t context;
+
+               if (fgetfilecon(fd, &oldcon) < 0) {
+                       if (errno != ENODATA)
+                               goto error;
+                       if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0)
+                               goto error;
+               }
+               context = context_new(oldcon);
+               if (!context || context_type_set(context, "swapfile_t"))
+                       goto error;
+               newcon = context_str(context);
+               if (!newcon)
+                       goto error;
+               /* fsetfilecon_raw is hidden */
+               if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0)
+                       goto error;
+               if (ENABLE_FEATURE_CLEAN_UP) {
+                       context_free(context);
+                       freecon(oldcon);
+               }
+       }
+       return;
+ error:
+       bb_perror_msg_and_die("SELinux relabeling failed");
+}
+#else
+#define mkswap_selinux_setcontext(fd, path) ((void)0)
+#endif
+
+#if 0 /* from Linux 2.6.23 */
+/*
+ * Magic header for a swap area. The first part of the union is
+ * what the swap magic looks like for the old (limited to 128MB)
+ * swap area format, the second part of the union adds - in the
+ * old reserved area - some extra information. Note that the first
+ * kilobyte is reserved for boot loader or disk label stuff...
+ */
+union swap_header {
+       struct {
+               char reserved[PAGE_SIZE - 10];
+               char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
+       } magic;
+       struct {
+               char            bootbits[1024]; /* Space for disklabel etc. */
+               __u32           version;        /* second kbyte, word 0 */
+               __u32           last_page;      /* 1 */
+               __u32           nr_badpages;    /* 2 */
+               unsigned char   sws_uuid[16];   /* 3,4,5,6 */
+               unsigned char   sws_volume[16]; /* 7,8,9,10  */
+               __u32           padding[117];   /* 11..127 */
+               __u32           badpages[1];    /* 128, total 129 32-bit words */
+       } info;
+};
+#endif
+
+#define NWORDS 129
+#define hdr ((uint32_t*)(&bb_common_bufsiz1))
+
+struct BUG_bufsiz1_is_too_small {
+       char BUG_bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1];
+};
+
+/* Stored without terminating NUL */
+static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2";
+
 int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int mkswap_main(int argc, char **argv)
 {
        int fd, pagesize;
        off_t len;
-       unsigned int hdr[129];
 
        // No options supported.
 
@@ -22,14 +100,17 @@ int mkswap_main(int argc, char **argv)
        // Figure out how big the device is and announce our intentions.
 
        fd = xopen(argv[1], O_RDWR);
-       len = fdlength(fd);
+       /* fdlength was reported to be unreliable - use seek */
+       len = xlseek(fd, 0, SEEK_END);
+#if ENABLE_SELINUX
+       xlseek(fd, 0, SEEK_SET);
+#endif
        pagesize = getpagesize();
-       printf("Setting up swapspace version 1, size = %"OFF_FMT"d bytes\n",
+       printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n",
                        len - pagesize);
+       mkswap_selinux_setcontext(fd, argv[1]);
 
-       // Make a header.
-
-       memset(hdr, 0, sizeof(hdr));
+       // Make a header. hdr is zero-filled so far...
        hdr[0] = 1;
        hdr[1] = (len / pagesize) - 1;
 
@@ -37,9 +118,9 @@ int mkswap_main(int argc, char **argv)
        // signature on disk (not in cache) during swapon.
 
        xlseek(fd, 1024, SEEK_SET);
-       xwrite(fd, hdr, sizeof(hdr));
-       xlseek(fd, pagesize-10, SEEK_SET);
-       xwrite(fd, "SWAPSPACE2", 10);
+       xwrite(fd, hdr, NWORDS * 4);
+       xlseek(fd, pagesize - 10, SEEK_SET);
+       xwrite(fd, SWAPSPACE2, 10);
        fsync(fd);
 
        if (ENABLE_FEATURE_CLEAN_UP) close(fd);