{
struct mbox_sync_mail *mails;
uoff_t offset, end_offset, dest_offset, space_diff;
- uint32_t idx, extra_per_mail;
+ uint32_t idx, padding_per_mail;
size_t size;
int ret = 0;
complexity, we just leave all the rest of the extra space to first
mail */
idx = last_seq - first_seq;
- extra_per_mail = extra_space / (idx + 1);
+ padding_per_mail = extra_space / (idx + 1);
/* after expunge the next mail must have been missing space, or we
would have moved it backwards already */
do {
/* this message's body is always moved space_diff bytes
forward along with next message's headers, so current
- message gets temporarily space_diff amount of extra
- whitespace.
+ message gets temporarily space_diff amount of padding.
- the moving stops at next message's beginning of extra
- space. each message gets left extra_per_mail bytes of
- space. what gets left over is given to first message */
+ the moving stops at next message's beginning of padding.
+ each message gets left padding_per_mail bytes of space.
+ what gets left over is given to first message */
i_assert(mails[idx].space > 0);
space_diff = mails[idx].space;
end_offset = mails[idx].offset + mails[idx].space;
if ((mails[idx].flags & MBOX_EXPUNGED) == 0) {
- space_diff -= extra_per_mail;
- end_offset -= extra_per_mail;
- mails[idx].space = extra_per_mail;
+ space_diff -= padding_per_mail;
+ end_offset -= padding_per_mail;
+ mails[idx].space = padding_per_mail;
}
idx--;
Here's how we do it:
- - Start reading the mails mail headers from the beginning
- - X-Keywords and X-UID headers may contain extra spaces at the end of them,
- remember how much extra each message has and offset to beginning of the
- spaces
- - If message flags are dirty and there's enough space to write them, do it
- - If we didn't have enough space, remember how much was missing and keep
- the total amount of them
- - When we encounter expunged message, check if the amount of empty space in
- previous messages plus size of expunged message is enough to cover the
- missing space. If yes,
- - execute the rewrite plan
- - forget all the messages before the expunged message. only remember
- how much data we still have to move to cover the expunged message
- - If we encounter end of file, grow the file and execute the rewrite plan
-
- Rewrite plan goes:
-
- - Start from the first message that needs more space
- - If there's expunged messages before us, we have to write over them.
- - Move all messages after it backwards to fill it
- - Each moved message's X-Keywords header should have n bytes extra
- space, unless there's not enough space to do it.
- - If there's no expunged messages, we can move data either forward or
- backward to get it. Calculate which requires less moving. Forward
- counting may encounter more messages which require extra space, count
- that too.
- - If we decide to move forwards and we had to go through dirty
- messages, do the moving from last to first dirty message
- - If we encounter end of file, grow the file enough to get the required
- amount of space plus enough space to fill X-Keywords headers full of
- spaces.
+ - Start reading the mails from the beginning
+ - X-Keywords, X-UID and X-IMAPbase headers may contain padding at the end
+ of them, remember how much each message has and offset to beginning of the
+ padding
+ - If header needs to be rewritten and there's enough space, do it
+ - If we didn't have enough space, remember how much was missing
+ - Continue reading and counting the padding in each message. If available
+ padding is enough to rewrite all the previous messages needing it, do it
+ - When we encounter expunged message, treat all of it as padding and
+ rewrite previous messages if needed (and there's enough space).
+ Afterwards keep moving messages backwards to fill the expunged space.
+ Moving is done by rewriting each message's headers, with possibly adding
+ missing Content-Length header and padding. Message bodies are moved
+ without modifications.
+ - If we encounter end of file, grow the file and rewrite needed messages
+ - Rewriting is done by moving message body forward, rewriting message's
+ header and doing the same for previous message, until all of them are
+ rewritten.
*/
#include "lib.h"
i_assert(grow_size > 0);
- /* put the extra space between last message's header and body */
+ /* put the padding between last message's header and body */
file_size = i_stream_get_size(sync_ctx->file_input) + grow_size;
if (file_set_size(sync_ctx->fd, file_size) < 0) {
mbox_set_syscall_error(sync_ctx->ibox, "file_set_size()");
mbox_sync_handle_missing_space(struct mbox_sync_mail_context *mail_ctx)
{
struct mbox_sync_context *sync_ctx = mail_ctx->sync_ctx;
- uoff_t extra_space;
+ uoff_t padding;
buffer_append(sync_ctx->mails, &mail_ctx->mail, sizeof(mail_ctx->mail));
return 0;
/* we have enough space now */
- extra_space = MBOX_HEADER_EXTRA_SPACE *
+ padding = MBOX_HEADER_PADDING *
(sync_ctx->seq - sync_ctx->need_space_seq + 1);
if (mail_ctx->mail.uid == 0 &&
- (uoff_t)sync_ctx->space_diff > extra_space) {
- /* don't waste too much on extra spacing */
- sync_ctx->expunged_space = sync_ctx->space_diff - extra_space;
- sync_ctx->space_diff = extra_space;
+ (uoff_t)sync_ctx->space_diff > padding) {
+ /* don't waste too much on padding */
+ sync_ctx->expunged_space = sync_ctx->space_diff - padding;
+ sync_ctx->space_diff = padding;
} else {
sync_ctx->expunged_space = 0;
}
static int mbox_sync_handle_eof_updates(struct mbox_sync_context *sync_ctx,
struct mbox_sync_mail_context *mail_ctx)
{
- uoff_t offset, extra_space, trailer_size;
+ uoff_t offset, padding, trailer_size;
int need_rewrite;
if (!istream_raw_mbox_is_eof(sync_ctx->input)) {
if (sync_ctx->need_space_seq != 0) {
i_assert(sync_ctx->space_diff < 0);
- extra_space = MBOX_HEADER_EXTRA_SPACE *
+ padding = MBOX_HEADER_PADDING *
(sync_ctx->seq - sync_ctx->need_space_seq + 1);
- sync_ctx->space_diff -= extra_space;
+ sync_ctx->space_diff -= padding;
sync_ctx->space_diff += sync_ctx->expunged_space;
if (sync_ctx->expunged_space <= -sync_ctx->space_diff)
buffer_append(sync_ctx->mails, &mail_ctx->mail,
sizeof(mail_ctx->mail));
- if (mbox_sync_rewrite(sync_ctx, extra_space,
+ if (mbox_sync_rewrite(sync_ctx, padding,
sync_ctx->need_space_seq,
sync_ctx->seq) < 0)
return -1;
projects / thirdparty / dovecot / core.git / commitdiff
