#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <stdlib.h>
#include <sys/fcntl.h>

/* Preload the OS's cache with all files of one branch for recursive diffs */

#define __NR_readahead 225

asm(
"__readahead:\n\t"
        "pushl %ebx\n\t"
        "pushl %esi\n\t"
	"movl 12(%esp),%ebx\n\t"
	"movl 16(%esp),%ecx\n\t"
	"movl 20(%esp),%edx\n\t"
	"movl 24(%esp),%esi\n\t"
	"movl $225,%eax\n\t"
	"int $0x80\n\t"
	"popl %esi\n\t"
	"popl %ebx\n\t"
	"ret"
);

extern ssize_t __readahead(int fd, loff_t offset, size_t size);

void
preread (dir)
	const char *dir;
{

  DIR *d;
  struct dirent *dent;

  d = opendir(dir);
  if (d == NULL) return;

  while ((dent = readdir(d)) != NULL)
    {
      int fd;
      struct stat st;
      char *name, *path;

      name = dent->d_name;
      if (name[0] == '.' && (name[1] == 0 || (name[1] == '.' && name[2] == 0)))
            continue;

      path = malloc(strlen(dir)+strlen(name)+2);
      strcpy(path, dir);
      strcat(path, "/");
      strcat(path, name);

      fd = open(path, O_RDONLY);
      if (fd >= 0) {
      	if (fstat(fd, &st) == 0) {
	      if (S_ISDIR(st.st_mode))
	           preread(path);
	      else if (S_ISREG(st.st_mode))
	        {
          	__readahead(fd, 0, ~0UL);
	        }
	}
	close(fd);
      }
      free(path);
  }
  closedir(d);
}

int main(int argc, char **argv)
{
	preread(argv[1]);
	return 0;
}