zircon/system/utest/stdio/util.c

// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "util.h"

#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>

// readable: is the pipe readable on the child side?
// returns [our_fd, child_fd]
int stdio_pipe(int pipe_fds[2], bool readable) {
  int r;
  if ((r = pipe(pipe_fds)) != 0) {  // Initially gives [reader, writer]
    return r;
  }

  if (readable) {
    // If child is to be readable, we want
    // [our_fd: writer, child_fd: reader], so we must swap
    int tmp = pipe_fds[0];
    pipe_fds[0] = pipe_fds[1];
    pipe_fds[1] = tmp;
  }

  return 0;
}

int read_to_end(int fd, uint8_t** buf, size_t* buf_size) {
  size_t start_len = *buf_size;
  size_t unused = 16;

  *buf_size += unused;
  *buf = realloc(*buf, *buf_size);

  while (1) {
    if (unused == 0) {
      // Double the buffer size
      unused = *buf_size;
      *buf_size += unused;
      *buf = realloc(*buf, *buf_size);
    }

    uint8_t* buf_slice = &(*buf)[*buf_size - unused];
    ssize_t result = read(fd, buf_slice, unused);
    if (result == 0) {
      *buf_size -= unused;
      return (int)(*buf_size - start_len);
    } else if (result > 0) {
      unused -= result;
    } else if (result == EINTR) {
    } else {
      *buf_size -= unused;
      return (int)result;
    }
  }
}