dynamic_pager.tproj/dynamic_pager.c

   1 #define mig_external
   2
   3 #include <sys/mount.h>
   4 #include <sys/stat.h>
   5 #include <sys/sysctl.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <unistd.h>
  10 #include <dirent.h>
  11
  12 /*
  13  * We don't exit with a non-zero status anywhere here for 2 reasons:
  14  * - the kernel can continue to create swapfiles in "/private/var/vm/swapfile<index>"
  15  * - we want this job to run only once at boot and exit regardless of whether:
  16  *      -- it could clean up the swap directory
  17  *      -- it could set the prefix for the swapfile name.
  18  */
  19
  20 static void
  21 clean_swap_directory(const char *path)
  22 {
  23         DIR *dir;
  24         struct dirent *entry;
  25         char buf[1024];
  26
  27         dir = opendir(path);
  28         if (dir == NULL) {
  29                 fprintf(stderr,"dynamic_pager: cannot open swap directory %s\n", path);
  30                 exit(0);
  31         }
  32
  33         while ((entry = readdir(dir)) != NULL) {
  34                 if (entry->d_namlen>= 4 && strncmp(entry->d_name, "swap", 4) == 0) {
  35                         snprintf(buf, sizeof buf, "%s/%s", path, entry->d_name);
  36                         unlink(buf);
  37                 }
  38         }
  39
  40         closedir(dir);
  41 }
  42
  43 int
  44 main(int argc, char **argv)
  45 {
  46         char default_filename[] = "/private/var/vm/swapfile";
  47         int ch;
  48         int err=0;
  49         static char tmp[1024];
  50         struct statfs sfs;
  51         char *q;
  52         char fileroot[512];
  53
  54         seteuid(getuid());
  55         strcpy(fileroot, default_filename);
  56
  57         while ((ch = getopt(argc, argv, "F:")) != EOF) {
  58                 switch((char)ch) {
  59
  60                 case 'F':
  61                         strncpy(fileroot, optarg, 500);
  62                         break;
  63
  64                 default:
  65                         (void)fprintf(stderr,
  66                             "usage: dynamic_pager [-F filename]\n");
  67                         exit(0);
  68                 }
  69         }
  70
  71         /*
  72          * get rid of the filename at the end of the swap file specification
  73          * we only want the portion of the pathname that should already exist
  74          */
  75         strcpy(tmp, fileroot);
  76         if ((q = strrchr(tmp, '/')))
  77                 *q = 0;
  78
  79         /*
  80          * Remove all files in the swap directory.
  81          */
  82         clean_swap_directory(tmp);
  83
  84         if (statfs(tmp, &sfs) == -1) {
  85                 /*
  86                  * Setup the swap directory.
  87                  */
  88
  89                 if (mkdir(tmp, 0755) == -1) {
  90                         (void)fprintf(stderr, "dynamic_pager: cannot create swap directory %s\n", tmp);
  91                 }
  92         }
  93
  94         chown(tmp, 0, 0);
  95
  96         err = sysctlbyname("vm.swapfileprefix", NULL, 0, fileroot, sizeof(fileroot));
  97         if (err) {
  98                 (void)fprintf(stderr, "Failed to set swapfile name prefix with error: %d\n", err);
  99         }
 100
 101         return (0);
 102 }