sample/zread.c

   1 #include <config.h>
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4
   5 /* Trivial example of reading a gzip'ed file or gzip'ed standard input
   6  * using stdio functions fread(), getc(), etc... fseek() is not supported.
   7  * Modify according to your needs. You can easily construct the symmetric
   8  * zwrite program.
   9  *
  10  * Usage: zread [file[.gz]]
  11  * This programs assumes that gzip is somewhere in your path.
  12  */
  13 int main(argc, argv)
  14     int argc;
  15     char **argv;
  16 {
  17     FILE *infile;
  18     char cmd[256];
  19     char buf[BUFSIZ];
  20     int n;
  21
  22     if (argc < 1 || argc > 2) {
  23         fprintf(stderr, "usage: %s [file[.gz]]\n", argv[0]);
  24         exit(EXIT_FAILURE);
  25     }
  26     strcpy(cmd, "gzip -dc ");  /* use "gzip -c" for zwrite */
  27     if (argc == 2) {
  28         strncat(cmd, argv[1], sizeof(cmd)-strlen(cmd));
  29     }
  30     infile = popen(cmd, "r");  /* use "w" for zwrite */
  31     if (infile == NULL) {
  32         fprintf(stderr, "%s: popen('%s', 'r') failed\n", argv[0], cmd);
  33         exit(EXIT_FAILURE);
  34     }
  35     /* Read one byte using getc: */
  36     n = getc(infile);
  37     if (n == EOF) {
  38         pclose(infile);
  39         exit(EXIT_SUCCESS);
  40     }
  41     putchar(n);
  42
  43     /* Read the rest using fread: */
  44     for (;;) {
  45         n = fread(buf, 1, BUFSIZ, infile);
  46         if (n <= 0) break;
  47         fwrite(buf, 1, n, stdout);
  48     }
  49     if (pclose(infile) != 0) {
  50         fprintf(stderr, "%s: pclose failed\n", argv[0]);
  51         exit(EXIT_FAILURE);
  52     }
  53     exit(EXIT_SUCCESS);
  54     return 0; /* just to make compiler happy */
  55 }