ktee.c

   1 /*
   2  * A tee implementation using sys_tee. Stores stdin input in the given file
   3  * and duplicates that to stdout.
   4  */
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8 #include <string.h>
   9 #include <fcntl.h>
  10 #include <string.h>
  11 #include <sys/types.h>
  12 #include <errno.h>
  13 #include <assert.h>
  14 #include <limits.h>
  15
  16 #include "splice.h"
  17
  18 static int splice_flags;
  19
  20 static int do_splice(int infd, int outfd, unsigned int len, char *msg)
  21 {
  22         while (len) {
  23                 int written = ssplice(infd, NULL, outfd, NULL, len, splice_flags);
  24
  25                 if (written <= 0)
  26                         return error(msg);
  27
  28                 len -= written;
  29         }
  30
  31         return 0;
  32 }
  33
  34 static int usage(char *name)
  35 {
  36         fprintf(stderr, "... | %s: [-m(ove)] outfile\n", name);
  37         return 1;
  38 }
  39
  40 static int parse_options(int argc, char *argv[])
  41 {
  42         int c, index = 1;
  43
  44         while ((c = getopt(argc, argv, "m")) != -1) {
  45                 switch (c) {
  46                 case 'm':
  47                         splice_flags = SPLICE_F_MOVE;
  48                         index++;
  49                         break;
  50                 default:
  51                         return -1;
  52                 }
  53         }
  54
  55         return index;
  56 }
  57
  58 int main(int argc, char *argv[])
  59 {
  60         int fd, index;
  61
  62         if (argc < 2)
  63                 return usage(argv[0]);
  64
  65         if (check_input_pipe())
  66                 return usage(argv[0]);
  67
  68         index = parse_options(argc, argv);
  69         if (index == -1 || index + 1 > argc)
  70                 return usage(argv[0]);
  71
  72         fd = open(argv[index], O_WRONLY | O_CREAT | O_TRUNC, 0644);
  73         if (fd < 0)
  74                 return error("open output");
  75
  76         do {
  77                 int tee_len = stee(STDIN_FILENO, STDOUT_FILENO, INT_MAX, 0);
  78
  79                 if (tee_len < 0) {
  80                         if (errno == EAGAIN) {
  81                                 usleep(1000);
  82                                 continue;
  83                         }
  84                         return error("tee");
  85                 } else if (!tee_len)
  86                         break;
  87
  88                 /*
  89                  * Send output to file, also consumes input pipe.
  90                  */
  91                 if (do_splice(STDIN_FILENO, fd, tee_len, "splice-file"))
  92                         break;
  93         } while (1);
  94
  95         return 0;
  96 }