Mercurial > dovecot > core-2.2
view src/lib/istream-seekable.c @ 23007:36e01285b5b8
lib: buffer - Improve header comment for buffer_insert() and buffer_delete().
author | Stephan Bosch <stephan.bosch@dovecot.fi> |
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date | Mon, 18 Mar 2019 00:52:37 +0100 |
parents | cb108f786fb4 |
children |
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/* Copyright (c) 2005-2018 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, I_MAX(stream->pos, 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; ssize_t ret; if ((ret = i_stream_read(sstream->fd_input)) <= 0) { i_assert(ret != 0); i_assert(ret != -2); i_error("istream-seekable: Couldn't read back " "in-memory input %s: %s", i_stream_get_name(&stream->istream), i_stream_get_error(sstream->fd_input)); i_stream_destroy(&sstream->fd_input); return -1; } } /* Set the max buffer size only after we've already read everything into memory. For example with istream-data it's possible that more data exists in buffer than max_buffer_size. */ i_stream_set_max_buffer_size(sstream->fd_input, sstream->istream.max_buffer_size); 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; }