sponge.c

   1 /*
   2  *  sponge.c - read in all available info from stdin, then output it to
   3  *  file named on the command line
   4  *
   5  *  Copyright ©  2006  Tollef Fog Heen
   6  *
   7  *  This program is free software; you can redistribute it and/or
   8  *  modify it under the terms of the GNU General Public License
   9  *  version 2 as published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  *  General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19  * USA
  20  *
  21  */
  22
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <unistd.h>
  26 #include <sys/types.h>
  27 #include <sys/stat.h>
  28 #include <fcntl.h>
  29 #include <errno.h>
  30 #include <string.h>
  31
  32 void usage() {
  33         printf("sponge <file>: suck in all input from stdin and write it to <file>");
  34         exit(0);
  35 }
  36
  37 int main(int argc, char **argv) {
  38         char *buf, *bufstart;
  39         size_t bufsize = 8192;
  40         size_t bufused = 0;
  41         ssize_t i = 0;
  42         int outfd;
  43
  44         if (argc != 2) {
  45                 usage();
  46         }
  47
  48         bufstart = buf = malloc(bufsize);
  49         if (!buf) {
  50                 perror("malloc");
  51                 exit(1);
  52         }
  53
  54         while ((i = read(0, buf, bufsize - bufused)) > 0) {
  55                 bufused = bufused+i;
  56                 if (bufused == bufsize) {
  57                         bufsize *= 2;
  58                         bufstart = realloc(bufstart, bufsize);
  59                         if (!bufstart) {
  60                                 perror("realloc");
  61                                 exit(1);
  62                         }
  63
  64                         buf = bufstart + bufused;
  65                 }
  66         }
  67         if (i == -1) {
  68                 perror("read");
  69                 exit(1);
  70         }
  71
  72         outfd = open(argv[1], O_CREAT | O_TRUNC | O_WRONLY, 0666);
  73         if (outfd == -1) {
  74                 fprintf(stderr, "Can't open %s: %s\n", argv[1], strerror(errno));
  75                 exit(1);
  76         }
  77
  78         i = write(outfd, bufstart, bufused);
  79         if (i == -1) {
  80                 perror("write");
  81                 exit(1);
  82         }
  83
  84         i = close(outfd);
  85         if (i == -1) {
  86                 perror("close");
  87                 exit(1);
  88         }
  89
  90         return 0;
  91 }