dynamic_pager.tproj/dynamic_pager.c

   1
   2 #define mig_external
   3
   4 #include <sys/mount.h>
   5 #include <sys/stat.h>
   6 #include <sys/sysctl.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <unistd.h>
  11 #include <dirent.h>
  12
  13 /*
  14  * We don't exit with a non-zero status anywhere here for 2 reasons:
  15  * - the kernel can continue to create swapfiles in "/private/var/vm/swapfile<index>"
  16  * - we want this job to run only once at boot and exit regardless of whether:
  17  *      -- it could clean up the swap directory
  18  *      -- it could set the prefix for the swapfile name.
  19  */
  20
  21
  22 static void
  23 clean_swap_directory(const char *path)
  24 {
  25         DIR *dir;
  26         struct dirent *entry;
  27         char buf[1024];
  28
  29         dir = opendir(path);
  30         if (dir == NULL) {
  31                 fprintf(stderr,"dynamic_pager: cannot open swap directory %s\n", path);
  32                 exit(0);
  33         }
  34
  35         while ((entry = readdir(dir)) != NULL) {
  36                 if (entry->d_namlen>= 4 && strncmp(entry->d_name, "swap", 4) == 0) {
  37                         snprintf(buf, sizeof buf, "%s/%s", path, entry->d_name);
  38                         unlink(buf);
  39                 }
  40         }
  41
  42         closedir(dir);
  43 }
  44
  45 int
  46 main(int argc, char **argv)
  47 {
  48         char default_filename[] = "/private/var/vm/swapfile";
  49         int ch;
  50         int err=0;
  51         static char tmp[1024];
  52         struct statfs sfs;
  53         char *q;
  54         char fileroot[512];
  55
  56         seteuid(getuid());
  57         strcpy(fileroot, default_filename);
  58
  59         while ((ch = getopt(argc, argv, "F:")) != EOF) {
  60                 switch((char)ch) {
  61
  62                 case 'F':
  63                         strncpy(fileroot, optarg, 500);
  64                         break;
  65
  66                 default:
  67                         (void)fprintf(stderr,
  68                             "usage: dynamic_pager [-F filename]\n");
  69                         exit(0);
  70                 }
  71         }
  72
  73         /*
  74          * get rid of the filename at the end of the swap file specification
  75          * we only want the portion of the pathname that should already exist
  76          */
  77         strcpy(tmp, fileroot);
  78         if ((q = strrchr(tmp, '/')))
  79                 *q = 0;
  80
  81         /*
  82          * Remove all files in the swap directory.
  83          */
  84         clean_swap_directory(tmp);
  85
  86         if (statfs(tmp, &sfs) == -1) {
  87                 /*
  88                  * Setup the swap directory.
  89                  */
  90
  91                 if (mkdir(tmp, 0755) == -1) {
  92                         (void)fprintf(stderr, "dynamic_pager: cannot create swap directory %s\n", tmp);
  93                 }
  94         }
  95
  96         chown(tmp, 0, 0);
  97
  98         err = sysctlbyname("vm.swapfileprefix", NULL, 0, fileroot, sizeof(fileroot));
  99         if (err) {
 100                 (void)fprintf(stderr, "Failed to set swapfile name prefix with error: %d\n", err);
 101         }
 102
 103         return (0);
 104 }