/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

/* @UNSAFE: whole file */

#include "lib.h"
#include "ioloop.h"
#include "istream-file-private.h"
#include "net.h"

#include <time.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>

void i_stream_file_close(struct iostream_private *stream,
			 bool close_parent ATTR_UNUSED)
{
	struct istream_private *_stream =
		container_of(stream, struct istream_private, iostream);
	struct file_istream *fstream =
		container_of(_stream, struct file_istream, istream);

	if (fstream->autoclose_fd && _stream->fd != -1) {
		/* Ignore ECONNRESET because we don't really care about it here,
		   as we are closing the socket down in any case. There might be
		   unsent data but nothing we can do about that. */
		if (unlikely(close(_stream->fd) < 0 && errno != ECONNRESET)) {
			i_error("file_istream.close(%s) failed: %m",
				i_stream_get_name(&_stream->istream));
		}
	}
	_stream->fd = -1;
}

static int i_stream_file_open(struct istream_private *stream)
{
	const char *path = i_stream_get_name(&stream->istream);

	stream->fd = open(path, O_RDONLY);
	if (stream->fd == -1) {
		io_stream_set_error(&stream->iostream,
				    "open(%s) failed: %m", path);
		stream->istream.stream_errno = errno;
		return -1;
	}
	return 0;
}

ssize_t i_stream_file_read(struct istream_private *stream)
{
	struct file_istream *fstream =
		container_of(stream, struct file_istream, istream);
	uoff_t offset;
	size_t size;
	ssize_t ret;

	if (!i_stream_try_alloc(stream, 1, &size))
		return -2;

	if (stream->fd == -1) {
		if (i_stream_file_open(stream) < 0)
			return -1;
		i_assert(stream->fd != -1);
	}

	offset = stream->istream.v_offset + (stream->pos - stream->skip);

	if (fstream->file) {
		ret = pread(stream->fd, stream->w_buffer + stream->pos,
			    size, offset);
	} else if (fstream->seen_eof) {
		/* don't try to read() again. EOF from keyboard (^D)
		   requires this to work right. */
		ret = 0;
	} else {
		ret = read(stream->fd, stream->w_buffer + stream->pos,
			   size);
	}

	if (ret == 0) {
		/* EOF */
		stream->istream.eof = TRUE;
		fstream->seen_eof = TRUE;
		return -1;
	}

	if (unlikely(ret < 0)) {
		if ((errno == EINTR || errno == EAGAIN) &&
		    !stream->istream.blocking) {
			ret = 0;
		} else {
			i_assert(errno != 0);
			/* if we get EBADF for a valid fd, it means something's
			   really wrong and we'd better just crash. */
			i_assert(errno != EBADF);
			if (fstream->file) {
				io_stream_set_error(&stream->iostream,
					"pread(size=%zu offset=%"PRIuUOFF_T") failed: %m",
					size, offset);
			} else {
				io_stream_set_error(&stream->iostream,
					"read(size=%zu) failed: %m",
					size);
			}
			stream->istream.stream_errno = errno;
			return -1;
		}
	}

	if (ret > 0 && fstream->skip_left > 0) {
		i_assert(!fstream->file);
		i_assert(stream->skip == stream->pos);

		if (fstream->skip_left >= (size_t)ret) {
			fstream->skip_left -= ret;
			ret = 0;
		} else {
			ret -= fstream->skip_left;
			stream->pos += fstream->skip_left;
			stream->skip += fstream->skip_left;
			fstream->skip_left = 0;
		}
	}

	stream->pos += ret;
	i_assert(ret != 0 || !fstream->file);
	i_assert(ret != -1);
	return ret;
}

static void i_stream_file_seek(struct istream_private *stream, uoff_t v_offset,
			       bool mark ATTR_UNUSED)
{
	struct file_istream *fstream =
		container_of(stream, struct file_istream, istream);

	if (!stream->istream.seekable) {
		if (v_offset < stream->istream.v_offset)
			i_panic("stream doesn't support seeking backwards");
		fstream->skip_left += v_offset - stream->istream.v_offset;
	}

	stream->istream.v_offset = v_offset;
	stream->skip = stream->pos = 0;
	fstream->seen_eof = FALSE;
}

static void i_stream_file_sync(struct istream_private *stream)
{
	if (!stream->istream.seekable) {
		/* can't do anything or data would be lost */
		return;
	}

	stream->skip = stream->pos = 0;
	stream->istream.eof = FALSE;
}

static int
i_stream_file_stat(struct istream_private *stream, bool exact ATTR_UNUSED)
{
	struct file_istream *fstream =
		container_of(stream, struct file_istream, istream);
	const char *name = i_stream_get_name(&stream->istream);

	if (!fstream->file) {
		/* return defaults */
	} else if (stream->fd != -1) {
		if (fstat(stream->fd, &stream->statbuf) < 0) {
			stream->istream.stream_errno = errno;
			io_stream_set_error(&stream->iostream,
				"file_istream.fstat(%s) failed: %m", name);
			i_error("%s", i_stream_get_error(&stream->istream));
			return -1;
		}
	} else {
		if (stat(name, &stream->statbuf) < 0) {
			stream->istream.stream_errno = errno;
			io_stream_set_error(&stream->iostream,
				"file_istream.stat(%s) failed: %m", name);
			i_error("%s", i_stream_get_error(&stream->istream));
			return -1;
		}
	}
	return 0;
}

struct istream *
i_stream_create_file_common(struct file_istream *fstream,
			    int fd, const char *path,
			    size_t max_buffer_size, bool autoclose_fd)
{
	struct istream *input;
	struct stat st;
	bool is_file;
	int flags;

	fstream->autoclose_fd = autoclose_fd;

	fstream->istream.iostream.close = i_stream_file_close;
	fstream->istream.max_buffer_size = max_buffer_size;
	fstream->istream.read = i_stream_file_read;
	fstream->istream.seek = i_stream_file_seek;
	fstream->istream.sync = i_stream_file_sync;
	fstream->istream.stat = i_stream_file_stat;

	/* if it's a file, set the flags properly */
	if (fd == -1) {
		/* only the path is known for now - the fd is opened later */
		is_file = TRUE;
	} else if (fstat(fd, &st) < 0)
		is_file = FALSE;
	else if (S_ISREG(st.st_mode))
		is_file = TRUE;
	else if (!S_ISDIR(st.st_mode))
		is_file = FALSE;
	else {
		/* we're trying to open a directory.
		   we're not designed for it. */
		io_stream_set_error(&fstream->istream.iostream,
			"%s is a directory, can't read it as file",
			path != NULL ? path : t_strdup_printf("<fd %d>", fd));
		fstream->istream.istream.stream_errno = EISDIR;
		is_file = FALSE;
	}
	if (is_file) {
		fstream->file = TRUE;
		fstream->istream.istream.blocking = TRUE;
		fstream->istream.istream.seekable = TRUE;
	} else if ((flags = fcntl(fd, F_GETFL, 0)) < 0) {
		i_assert(fd > -1);
		/* shouldn't happen */
		fstream->istream.istream.stream_errno = errno;
		io_stream_set_error(&fstream->istream.iostream,
			"fcntl(%d, F_GETFL) failed: %m", fd);
	} else if ((flags & O_NONBLOCK) == 0) {
		/* blocking socket/fifo */
		fstream->istream.istream.blocking = TRUE;
	}
	fstream->istream.istream.readable_fd = TRUE;

	input = i_stream_create(&fstream->istream, NULL, fd, 0);
	i_stream_set_name(input, is_file ? "(file)" : "(fd)");
	return input;
}

struct istream *i_stream_create_fd(int fd, size_t max_buffer_size)
{
	struct file_istream *fstream;

	i_assert(fd != -1);

	fstream = i_new(struct file_istream, 1);
	return i_stream_create_file_common(fstream, fd, NULL,
					   max_buffer_size, FALSE);
}

struct istream *i_stream_create_fd_autoclose(int *fd, size_t max_buffer_size)
{
	struct istream *input;
	struct file_istream *fstream;

	i_assert(*fd != -1);

	fstream = i_new(struct file_istream, 1);
	input = i_stream_create_file_common(fstream, *fd, NULL,
					   max_buffer_size, TRUE);
	*fd = -1;
	return input;
}

struct istream *i_stream_create_file(const char *path, size_t max_buffer_size)
{
	struct file_istream *fstream;
	struct istream *input;

	fstream = i_new(struct file_istream, 1);
	input = i_stream_create_file_common(fstream, -1, path,
					    max_buffer_size, TRUE);
	i_stream_set_name(input, path);
	return input;
}