Simple testcase

libtester.c (text/x-csrc), 768 bytes, created by Malte S. Stretz on 2004-11-21 13:55:51 UTC

#define _GNU_SOURCE 1

#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <dlfcn.h>

typedef ssize_t (*orig_read_ptr)(int fd, void *buf, size_t count);
static orig_read_ptr orig_read;

static int libtester_initialized = 0;


static void libtester_init()
{
  if (libtester_initialized) return;
  fprintf(stderr, "init(): in\n");
  orig_read  = (orig_read_ptr)dlsym(RTLD_NEXT, "read");
  libtester_initialized = 1;
  fprintf(stderr, "init(): out\n");
}

ssize_t read (int fd, void *buf, size_t count)
{
  int r;
  fprintf(stderr, "read(%d, %p, %d): in\n", fd, buf, count);
  libtester_init();
#if 1
  r = orig_read(fd, buf, count);
#else
  memset(buf, 0, count);
  r = count;
#endif
  fprintf(stderr, "read(): out\n");
  return r;
}