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istream-seekable.c
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istream-seekable.c
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/* Copyright (c) 2005-2016 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "buffer.h"
#include "str.h"
#include "read-full.h"
#include "write-full.h"
#include "safe-mkstemp.h"
#include "istream-private.h"
#include "istream-concat.h"
#include "istream-seekable.h"
#include <unistd.h>
#define BUF_INITIAL_SIZE (1024*32)
struct seekable_istream {
struct istream_private istream;
char *temp_path;
uoff_t write_peak;
uoff_t size;
int (*fd_callback)(const char **path_r, void *context);
void *context;
buffer_t *membuf;
struct istream **input, *cur_input;
struct istream *fd_input;
unsigned int cur_idx;
int fd;
bool free_context;
};
static void i_stream_seekable_close(struct iostream_private *stream,
bool close_parent ATTR_UNUSED)
{
struct seekable_istream *sstream = (struct seekable_istream *)stream;
sstream->fd = -1;
if (sstream->fd_input != NULL)
i_stream_close(sstream->fd_input);
}
static void unref_streams(struct seekable_istream *sstream)
{
unsigned int i;
for (i = 0; sstream->input[i] != NULL; i++)
i_stream_unref(&sstream->input[i]);
}
static void i_stream_seekable_destroy(struct iostream_private *stream)
{
struct seekable_istream *sstream = (struct seekable_istream *)stream;
if (sstream->membuf != NULL)
buffer_free(&sstream->membuf);
if (sstream->fd_input != NULL)
i_stream_unref(&sstream->fd_input);
unref_streams(sstream);
if (sstream->free_context)
i_free(sstream->context);
i_free(sstream->temp_path);
i_free(sstream->input);
}
static void
i_stream_seekable_set_max_buffer_size(struct iostream_private *stream,
size_t max_size)
{
struct seekable_istream *sstream = (struct seekable_istream *)stream;
unsigned int i;
sstream->istream.max_buffer_size = max_size;
if (sstream->fd_input != NULL)
i_stream_set_max_buffer_size(sstream->fd_input, max_size);
for (i = 0; sstream->input[i] != NULL; i++)
i_stream_set_max_buffer_size(sstream->input[i], max_size);
}
static int copy_to_temp_file(struct seekable_istream *sstream)
{
struct istream_private *stream = &sstream->istream;
const char *path;
const unsigned char *buffer;
size_t size;
int fd;
fd = sstream->fd_callback(&path, sstream->context);
if (fd == -1)
return -1;
/* copy our currently read buffer to it */
if (write_full(fd, sstream->membuf->data, sstream->membuf->used) < 0) {
if (!ENOSPACE(errno))
i_error("istream-seekable: write_full(%s) failed: %m", path);
i_close_fd(&fd);
return -1;
}
sstream->temp_path = i_strdup(path);
sstream->write_peak = sstream->membuf->used;
sstream->fd = fd;
sstream->fd_input =
i_stream_create_fd_autoclose(&fd, sstream->istream.max_buffer_size);
i_stream_set_name(sstream->fd_input, t_strdup_printf(
"(seekable temp-istream for: %s)", i_stream_get_name(&stream->istream)));
/* read back the data we just had in our buffer */
i_stream_seek(sstream->fd_input, stream->istream.v_offset);
for (;;) {
buffer = i_stream_get_data(sstream->fd_input, &size);
if (size >= stream->pos)
break;
if (i_stream_read(sstream->fd_input) <= 0) {
i_error("istream-seekable: Couldn't read back "
"in-memory input %s",
i_stream_get_name(&stream->istream));
i_stream_destroy(&sstream->fd_input);
return -1;
}
}
stream->buffer = buffer;
stream->pos = size;
buffer_free(&sstream->membuf);
return 0;
}
static ssize_t read_more(struct seekable_istream *sstream)
{
size_t size;
ssize_t ret;
if (sstream->cur_input == NULL) {
sstream->istream.istream.eof = TRUE;
return -1;
}
while ((ret = i_stream_read(sstream->cur_input)) == -1) {
if (sstream->cur_input->stream_errno != 0) {
io_stream_set_error(&sstream->istream.iostream,
"read(%s) failed: %s",
i_stream_get_name(sstream->cur_input),
i_stream_get_error(sstream->cur_input));
sstream->istream.istream.eof = TRUE;
sstream->istream.istream.stream_errno =
sstream->cur_input->stream_errno;
return -1;
}
/* go to next stream */
sstream->cur_input = sstream->input[sstream->cur_idx++];
if (sstream->cur_input == NULL) {
/* last one, EOF */
sstream->size = sstream->istream.istream.v_offset;
sstream->istream.istream.eof = TRUE;
unref_streams(sstream);
return -1;
}
/* see if stream has pending data */
size = i_stream_get_data_size(sstream->cur_input);
if (size != 0)
return size;
}
return ret;
}
static bool read_from_buffer(struct seekable_istream *sstream, ssize_t *ret_r)
{
struct istream_private *stream = &sstream->istream;
const unsigned char *data;
size_t size, pos, offset;
i_assert(stream->skip == 0);
if (stream->istream.v_offset + stream->pos >= sstream->membuf->used) {
/* need to read more */
if (sstream->membuf->used >= stream->max_buffer_size)
return FALSE;
size = sstream->cur_input == NULL ? 0 :
i_stream_get_data_size(sstream->cur_input);
if (size == 0) {
/* read more to buffer */
*ret_r = read_more(sstream);
if (*ret_r == 0 || *ret_r == -1)
return TRUE;
}
/* we should have more now. */
data = i_stream_get_data(sstream->cur_input, &size);
i_assert(size > 0);
buffer_append(sstream->membuf, data, size);
i_stream_skip(sstream->cur_input, size);
}
offset = stream->istream.v_offset;
stream->buffer = CONST_PTR_OFFSET(sstream->membuf->data, offset);
pos = sstream->membuf->used - offset;
*ret_r = pos - stream->pos;
i_assert(*ret_r > 0);
stream->pos = pos;
return TRUE;
}
static int i_stream_seekable_write_failed(struct seekable_istream *sstream)
{
struct istream_private *stream = &sstream->istream;
void *data;
i_assert(sstream->membuf == NULL);
sstream->membuf =
buffer_create_dynamic(default_pool, sstream->write_peak);
data = buffer_append_space_unsafe(sstream->membuf, sstream->write_peak);
if (pread_full(sstream->fd, data, sstream->write_peak, 0) < 0) {
i_error("istream-seekable: read(%s) failed: %m", sstream->temp_path);
buffer_free(&sstream->membuf);
return -1;
}
i_stream_destroy(&sstream->fd_input);
i_close_fd(&sstream->fd);
stream->max_buffer_size = (size_t)-1;
i_free_and_null(sstream->temp_path);
return 0;
}
static ssize_t i_stream_seekable_read(struct istream_private *stream)
{
struct seekable_istream *sstream = (struct seekable_istream *)stream;
const unsigned char *data;
size_t size, pos;
ssize_t ret;
stream->buffer = CONST_PTR_OFFSET(stream->buffer, stream->skip);
stream->pos -= stream->skip;
stream->skip = 0;
if (sstream->membuf != NULL) {
if (read_from_buffer(sstream, &ret))
return ret;
/* copy everything to temp file and use it as the stream */
if (copy_to_temp_file(sstream) < 0) {
stream->max_buffer_size = (size_t)-1;
if (!read_from_buffer(sstream, &ret))
i_unreached();
return ret;
}
i_assert(sstream->membuf == NULL);
}
i_assert(stream->istream.v_offset + stream->pos <= sstream->write_peak);
if (stream->istream.v_offset + stream->pos == sstream->write_peak) {
/* need to read more */
ret = read_more(sstream);
if (ret == -1 || ret == 0)
return ret;
/* save to our file */
data = i_stream_get_data(sstream->cur_input, &size);
ret = write(sstream->fd, data, size);
if (ret <= 0) {
if (ret < 0 && !ENOSPACE(errno)) {
i_error("istream-seekable: write_full(%s) failed: %m",
sstream->temp_path);
}
if (i_stream_seekable_write_failed(sstream) < 0)
return -1;
if (!read_from_buffer(sstream, &ret))
i_unreached();
return ret;
}
i_stream_sync(sstream->fd_input);
i_stream_skip(sstream->cur_input, ret);
sstream->write_peak += ret;
}
i_stream_seek(sstream->fd_input, stream->istream.v_offset);
ret = i_stream_read(sstream->fd_input);
if (ret <= 0) {
stream->istream.eof = sstream->fd_input->eof;
stream->istream.stream_errno =
sstream->fd_input->stream_errno;
} else {
ret = -2;
}
stream->buffer = i_stream_get_data(sstream->fd_input, &pos);
stream->pos -= stream->skip;
stream->skip = 0;
ret = pos > stream->pos ? (ssize_t)(pos - stream->pos) : ret;
stream->pos = pos;
return ret;
}
static int
i_stream_seekable_stat(struct istream_private *stream, bool exact)
{
struct seekable_istream *sstream = (struct seekable_istream *)stream;
const struct stat *st;
uoff_t old_offset;
ssize_t ret;
if (sstream->size != (uoff_t)-1) {
/* we've already reached EOF and know the size */
stream->statbuf.st_size = sstream->size;
return 0;
}
/* we want to know the full size of the file, so read until
we're finished */
old_offset = stream->istream.v_offset;
do {
i_stream_skip(&stream->istream,
stream->pos - stream->skip);
} while ((ret = i_stream_seekable_read(stream)) > 0);
if (ret == 0) {
i_panic("i_stream_stat() used for non-blocking "
"seekable stream %s offset %"PRIuUOFF_T,
i_stream_get_name(sstream->cur_input),
sstream->cur_input->v_offset);
}
i_stream_skip(&stream->istream, stream->pos - stream->skip);
i_stream_seek(&stream->istream, old_offset);
unref_streams(sstream);
if (stream->istream.stream_errno != 0)
return -1;
if (sstream->fd_input != NULL) {
/* using a file backed buffer, we can use real fstat() */
if (i_stream_stat(sstream->fd_input, exact, &st) < 0)
return -1;
stream->statbuf = *st;
} else {
/* buffer is completely in memory */
i_assert(sstream->membuf != NULL);
stream->statbuf.st_size = sstream->membuf->used;
}
return 0;
}
static void i_stream_seekable_seek(struct istream_private *stream,
uoff_t v_offset, bool mark)
{
if (v_offset <= stream->istream.v_offset) {
/* seeking backwards */
stream->istream.v_offset = v_offset;
stream->skip = stream->pos = 0;
} else {
/* we can't skip over data we haven't yet read and written to
our buffer/temp file */
i_stream_default_seek_nonseekable(stream, v_offset, mark);
}
}
struct istream *
i_streams_merge(struct istream *input[], size_t max_buffer_size,
int (*fd_callback)(const char **path_r, void *context),
void *context) ATTR_NULL(4)
{
struct seekable_istream *sstream;
const unsigned char *data;
unsigned int count;
size_t size;
bool blocking = TRUE;
i_assert(max_buffer_size > 0);
/* if any of the streams isn't blocking, set ourself also nonblocking */
for (count = 0; input[count] != NULL; count++) {
if (!input[count]->blocking)
blocking = FALSE;
i_stream_ref(input[count]);
}
i_assert(count != 0);
sstream = i_new(struct seekable_istream, 1);
sstream->fd_callback = fd_callback;
sstream->context = context;
sstream->membuf = buffer_create_dynamic(default_pool, BUF_INITIAL_SIZE);
sstream->istream.max_buffer_size = max_buffer_size;
sstream->fd = -1;
sstream->size = (uoff_t)-1;
sstream->input = i_new(struct istream *, count + 1);
memcpy(sstream->input, input, sizeof(*input) * count);
sstream->cur_input = sstream->input[0];
/* initialize our buffer from first stream's pending data */
data = i_stream_get_data(sstream->cur_input, &size);
buffer_append(sstream->membuf, data, size);
i_stream_skip(sstream->cur_input, size);
sstream->istream.iostream.close = i_stream_seekable_close;
sstream->istream.iostream.destroy = i_stream_seekable_destroy;
sstream->istream.iostream.set_max_buffer_size =
i_stream_seekable_set_max_buffer_size;
sstream->istream.read = i_stream_seekable_read;
sstream->istream.stat = i_stream_seekable_stat;
sstream->istream.seek = i_stream_seekable_seek;
sstream->istream.istream.readable_fd = FALSE;
sstream->istream.istream.blocking = blocking;
sstream->istream.istream.seekable = TRUE;
return i_stream_create(&sstream->istream, NULL, -1);
}
static bool inputs_are_seekable(struct istream *input[])
{
unsigned int count;
for (count = 0; input[count] != NULL; count++) {
if (!input[count]->seekable)
return FALSE;
}
return TRUE;
}
struct istream *
i_stream_create_seekable(struct istream *input[],
size_t max_buffer_size,
int (*fd_callback)(const char **path_r, void *context),
void *context)
{
i_assert(max_buffer_size > 0);
/* If all input streams are seekable, use concat istream instead */
if (inputs_are_seekable(input))
return i_stream_create_concat(input);
return i_streams_merge(input, max_buffer_size, fd_callback, context);
}
static int seekable_fd_callback(const char **path_r, void *context)
{
char *temp_path_prefix = context;
string_t *path;
int fd;
path = t_str_new(128);
str_append(path, temp_path_prefix);
fd = safe_mkstemp(path, 0600, (uid_t)-1, (gid_t)-1);
if (fd == -1) {
i_error("istream-seekable: safe_mkstemp(%s) failed: %m", str_c(path));
return -1;
}
/* we just want the fd, unlink it */
if (i_unlink(str_c(path)) < 0) {
/* shouldn't happen.. */
i_close_fd(&fd);
return -1;
}
*path_r = str_c(path);
return fd;
}
struct istream *
i_stream_create_seekable_path(struct istream *input[],
size_t max_buffer_size,
const char *temp_path_prefix)
{
struct seekable_istream *sstream;
struct istream *stream;
i_assert(temp_path_prefix != NULL);
i_assert(max_buffer_size > 0);
if (inputs_are_seekable(input))
return i_stream_create_concat(input);
stream = i_stream_create_seekable(input, max_buffer_size,
seekable_fd_callback,
i_strdup(temp_path_prefix));
sstream = (struct seekable_istream *)stream->real_stream;
sstream->free_context = TRUE;
return stream;
}