/* Test 11 -> Checks whether the write function in the library
/* works properly in APPEND mode
**/

#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <string.h>
#include <dlfcn.h>
#include <stdlib.h>


int fill_random(char *buf)
{
    int i;
    for(i=0; i<4096; i++) {
         buf[i] = 'a' + random() % 26;
    }
}

int main()
{
   int fd1 = -1, fd2 = -1;
   int err;
   void * handle = NULL;
   char buf[4096];
   char new_buf[4096];
   int i=0;
   int data_read = 0;
   off_t cur=0;

    handle = dlopen("/lib/libc.so.6",  RTLD_LAZY);
    if (handle == NULL) {
	fprintf(stderr, "%s", dlerror());
	return -1;
    }
    int (*o_open)(const char *, int) = (int (*)(const char *, int)) dlsym(handle, "open");
    ssize_t (*o_read)(int, void *, size_t) = (ssize_t (*)(int, void *, size_t)) dlsym(handle, "read");
    ssize_t (*o_write)(int, void *, size_t) = (ssize_t (*)(int, void *, size_t)) dlsym(handle, "write");
    off_t (*o_lseek)(int, off_t, int) = (off_t (*)(int, off_t, int)) dlsym(handle, "lseek");
    int (*o_close)(int) = (int (*)(int)) dlsym(handle, "close");


/* Bootstrap the file with libfsprotect.c */
   fd1 = open("file5", O_RDWR | O_APPEND);
   if(fd1 == -1) {
         return -1;
   }

   fill_random(new_buf);
   data_read = write(fd1, new_buf, 4096);
   if(data_read != 4096) {
        close(fd1);
        return -1;
   }

   err = close(fd1);
   if(err == -1)
        return -1;

/* Read through libc and see if the data was written */ 
   fd1 = (*o_open)("file5", O_RDONLY);  
   if(fd1 == -1) {
         return -1;
   }
   cur = (*o_lseek)(fd1, 0, SEEK_END);
   (*o_lseek)(fd1, cur-4096, 0);

   data_read = (*o_read)(fd1, buf, 4096);
   if(data_read != 4096)
        goto fail;

/* Mismatch between data written and read */
   if(memcmp(buf, new_buf, 4096) != 0)
        goto fail;

pass:
   (*o_close)(fd1);
   return 0;

fail:
   (*o_close)(fd1);
   return -1;

}