splice-cp.c

   1 /*
   2  * Splice cp a file
   3  */
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <unistd.h>
   7 #include <fcntl.h>
   8 #include <errno.h>
   9 #include <sys/types.h>
  10 #include <sys/stat.h>
  11
  12 #include "splice.h"
  13
  14 #define BS      SPLICE_SIZE
  15
  16 static int splice_flags;
  17
  18 static int usage(char *name)
  19 {
  20         fprintf(stderr, "%s: [-m] in_file out_file\n", name);
  21         return 1;
  22 }
  23
  24 static int parse_options(int argc, char *argv[])
  25 {
  26         int c, index = 1;
  27
  28         while ((c = getopt(argc, argv, "m")) != -1) {
  29                 switch (c) {
  30                 case 'm':
  31                         splice_flags = SPLICE_F_MOVE;
  32                         index++;
  33                         break;
  34                 default:
  35                         return -1;
  36                 }
  37         }
  38
  39         return index;
  40 }
  41
  42 int main(int argc, char *argv[])
  43 {
  44         int in_fd, out_fd, pfds[2], index;
  45         struct stat sb;
  46
  47         index = parse_options(argc, argv);
  48         if (index == -1 || index + 2 > argc)
  49                 return usage(argv[0]);
  50
  51         in_fd = open(argv[index], O_RDONLY);
  52         if (in_fd < 0)
  53                 return error("open input");
  54
  55         if (fstat(in_fd, &sb) < 0)
  56                 return error("stat input");
  57
  58         out_fd = open(argv[index + 1], O_WRONLY | O_CREAT | O_TRUNC, 0644);
  59         if (out_fd < 0)
  60                 return error("open output");
  61
  62         if (pipe(pfds) < 0)
  63                 return error("pipe");
  64
  65         do {
  66                 int this_len = min((off_t) BS, sb.st_size);
  67                 int ret = ssplice(in_fd, NULL, pfds[1], NULL, this_len, 0);
  68
  69                 if (ret < 0)
  70                         return error("splice-in");
  71                 else if (!ret)
  72                         break;
  73
  74                 sb.st_size -= ret;
  75                 while (ret > 0) {
  76                         int written = ssplice(pfds[0], NULL, out_fd, NULL, ret, splice_flags);
  77                         if (written <= 0)
  78                                 return error("splice-out");
  79                         ret -= written;
  80                 }
  81         } while (sb.st_size);
  82
  83         close(in_fd);
  84         close(pfds[1]);
  85         close(out_fd);
  86         close(pfds[0]);
  87         return 0;
  88 }