#include "stdio_impl.h"
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

FILE* __fdopen(int fd, const char* mode) {
  FILE* f;

  /* Check for valid initial mode character */
  if (!strchr("rwa", *mode)) {
    errno = EINVAL;
    return 0;
  }

  /* Allocate FILE+buffer or fail */
  if (!(f = malloc(sizeof *f + UNGET + BUFSIZ)))
    return 0;

  /* Zero-fill only the struct, not the buffer */
  memset(f, 0, sizeof *f);

  /* Impose mode restrictions */
  if (!strchr(mode, '+'))
    f->flags = (*mode == 'r') ? F_NOWR : F_NORD;

  /* Apply close-on-exec flag */
  if (strchr(mode, 'e'))
    __syscall(SYS_fcntl, fd, F_SETFD, FD_CLOEXEC);

  /* Set append mode on fd if opened for append */
  if (*mode == 'a') {
    int flags = __syscall(SYS_fcntl, fd, F_GETFL);
    if (!(flags & O_APPEND))
      __syscall(SYS_fcntl, fd, F_SETFL, flags | O_APPEND);
    f->flags |= F_APP;
  }

  f->fd = fd;
  f->buf = (unsigned char*)f + sizeof *f + UNGET;
  f->buf_size = BUFSIZ;

  /* Activate line buffered mode for terminals */
  f->lbf = EOF;
  if (!(f->flags & F_NOWR) && isatty(fd))
    f->lbf = '\n';

  /* Initialize op ptrs. No problem if some are unneeded. */
  f->read = __stdio_read;
  f->write = __stdio_write;
  f->seek = __stdio_seek;
  f->close = __stdio_close;

  if (!libc.threaded)
    f->lock = -1;

  /* Add new FILE to open file list */
  return __ofl_add(f);
}

weak_alias(__fdopen, fdopen);