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   1 #include "config.h"
   2 #include <stdio.h>
   3 #include <string.h>
   4
   5 /**
   6  * pushpull - simple marshalling/unmarshalling routines
   7  *
   8  * This code lets you clearly add simple types into a buffer (the push
   9  * functions) and remove them (the pull functions).  The buffer stores
  10  * the values as little-endian for machine portability.  The pull functions
  11  * don't need to be checked on every call, but error state is kept so you
  12  * can check if there was an error at the end.
  13  *
  14  * The normal way to use this is to create your own higher-level marshal
  15  * and unmarshal functions in terms of these.
  16  *
  17  * Author: Rusty Russell <rusty@rustcorp.com.au>
  18  * License: CC0 (Public domain)
  19  *
  20  * Example:
  21  *      #include <ccan/pushpull/push.h>
  22  *      #include <ccan/pushpull/pull.h>
  23  *      #include <ccan/err/err.h>
  24  *      #include <string.h>
  25  *      #include <stdio.h>
  26  *      #include <unistd.h>
  27  *
  28  *      int main(int argc, char *argv[])
  29  *      {
  30  *              if (argv[1] && !strcmp(argv[1], "push")) {
  31  *                      int i;
  32  *                      char *buf = malloc(1);
  33  *                      size_t len = 0;
  34  *
  35  *                      // We ignore allocation failure!
  36  *                      for (i = 2; i < argc; i++)
  37  *                              push_u32(&buf, &len, atol(argv[i]));
  38  *
  39  *                      write(STDOUT_FILENO, buf, len);
  40  *              } else if (argc == 2 && !strcmp(argv[1], "pull")) {
  41  *                      int r, max = 32;
  42  *                      size_t len = 0;
  43  *                      char *buf = malloc(max);
  44  *                      const char *p;
  45  *                      uint32_t val;
  46  *
  47  *                      while ((r = read(STDIN_FILENO, buf+len, max-len)) > 0) {
  48  *                              len += r;
  49  *                              if (len == max) {
  50  *                                      max *= 2;
  51  *                                      // We crash on allocation failure
  52  *                                      buf = realloc(buf, max);
  53  *                              }
  54  *                      }
  55  *
  56  *                      p = buf;
  57  *                      while (pull_u32(&p, &len, &val))
  58  *                              printf("%u ", val);
  59  *              } else
  60  *                      errx(1, "Usage: %s [push|pull] [<number>...]", argv[0]);
  61  *              return 0;
  62  *      }
  63  */
  64 int main(int argc, char *argv[])
  65 {
  66         /* Expect exactly one argument */
  67         if (argc != 2)
  68                 return 1;
  69
  70         if (strcmp(argv[1], "depends") == 0) {
  71                 printf("ccan/endian\n");
  72                 return 0;
  73         }
  74
  75         return 1;
  76 }