index/maildir/maildir-copy.c

	maildir-copy.c revision d22301419109ed4a38351715e6760011421dadec
/* Copyright (c) 2002-2010 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "ioloop.h"
#include "str.h"
#include "nfs-workarounds.h"
#include "maildir-storage.h"
#include "maildir-uidlist.h"
#include "maildir-filename.h"
#include "maildir-keywords.h"
#include "maildir-sync.h"
#include "index-mail.h"
#include "mail-copy.h"

#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>

struct hardlink_ctx {
    string_t *dest_path;
    const char *dest_fname;
    unsigned int base_end_pos;

    unsigned int size_set:1;
    unsigned int vsize_set:1;
    unsigned int success:1;
    unsigned int preserve_filename:1;
};

static int do_save_mail_size(struct maildir_mailbox *mbox, const char *path,
                 struct hardlink_ctx *ctx)
{
    const char *fname, *str;
    struct stat st;
    uoff_t size;

    fname = strrchr(path, '/');
    fname = fname != NULL ? fname + 1 : path;

    if (!maildir_filename_get_size(fname, MAILDIR_EXTRA_FILE_SIZE,
                       &size)) {
        if (stat(path, &st) < 0) {
            if (errno == ENOENT)
                return 0;
            mail_storage_set_critical(&mbox->storage->storage,
                          "stat(%s) failed: %m", path);
            return -1;
        }
        size = st.st_size;
    }

    str = t_strdup_printf(",%c=%"PRIuUOFF_T, MAILDIR_EXTRA_FILE_SIZE, size);
    str_insert(ctx->dest_path, ctx->base_end_pos, str);

    ctx->dest_fname = strrchr(str_c(ctx->dest_path), '/') + 1;
    ctx->size_set = TRUE;
    return 1;
}

static void do_save_mail_vsize(const char *path, struct hardlink_ctx *ctx)
{
    const char *fname, *str;
    uoff_t size;

    fname = strrchr(path, '/');
    fname = fname != NULL ? fname + 1 : path;

    if (!maildir_filename_get_size(fname, MAILDIR_EXTRA_VIRTUAL_SIZE,
                       &size))
        return;

    str = t_strdup_printf(",%c=%"PRIuUOFF_T,
                  MAILDIR_EXTRA_VIRTUAL_SIZE, size);
    str_insert(ctx->dest_path, ctx->base_end_pos, str);

    ctx->dest_fname = strrchr(str_c(ctx->dest_path), '/') + 1;
    ctx->vsize_set = TRUE;
}

static int do_hardlink(struct maildir_mailbox *mbox, const char *path,
               struct hardlink_ctx *ctx)
{
    int ret;

    if (!ctx->preserve_filename) {
        if (!ctx->size_set) {
            if ((ret = do_save_mail_size(mbox, path, ctx)) <= 0)
                return ret;
        }
        /* set virtual size if it's in the original file name */
        if (!ctx->vsize_set)
            do_save_mail_vsize(path, ctx);
    }

    if (mbox->storage->storage.set->mail_nfs_storage)
        ret = nfs_safe_link(path, str_c(ctx->dest_path), FALSE);
    else
        ret = link(path, str_c(ctx->dest_path));
    if (ret < 0) {
        if (errno == ENOENT)
            return 0;

        if (ENOSPACE(errno)) {
            mail_storage_set_error(&mbox->storage->storage,
                MAIL_ERROR_NOSPACE, MAIL_ERRSTR_NO_SPACE);
            return -1;
        }

        /* we could handle the EEXIST condition by changing the
           filename, but it practically never happens so just fallback
           to standard copying for the rare cases when it does. */
        if (errno == EACCES || ECANTLINK(errno) || errno == EEXIST)
            return 1;

        mail_storage_set_critical(&mbox->storage->storage,
                      "link(%s, %s) failed: %m",
                      path, str_c(ctx->dest_path));
        return -1;
    }

    ctx->success = TRUE;
    return 1;
}

static const char *
maildir_copy_get_preserved_fname(struct maildir_mailbox *src_mbox,
                 struct maildir_mailbox *dest_mbox,
                 uint32_t uid)
{
    enum maildir_uidlist_rec_flag flags;
    const char *fname;

    /* see if the filename exists in destination maildir's
       uidlist. if it doesn't, we can use it. otherwise generate
       a new filename. FIXME: There's a race condition here if
       another process is just doing the same copy. */
    if (maildir_uidlist_lookup(src_mbox->uidlist, uid, &flags,
                   &fname) <= 0)
        return NULL;

    if (maildir_uidlist_refresh(dest_mbox->uidlist) <= 0)
        return NULL;
    if (maildir_uidlist_get_full_filename(dest_mbox->uidlist,
                          fname) != NULL) {
        /* already exists in destination */
        return NULL;
    }
    /* fname may be freed by a later uidlist sync. make sure it gets
       strduped. */
    return t_strcut(t_strdup(fname), ':');
}

static int
maildir_copy_hardlink(struct mail_save_context *ctx, struct mail *mail)
{
    struct maildir_mailbox *dest_mbox =
        (struct maildir_mailbox *)ctx->transaction->box;
    struct maildir_mailbox *src_mbox;
    struct hardlink_ctx do_ctx;
    const char *path, *filename = NULL;

    if (strcmp(mail->box->storage->name, MAILDIR_STORAGE_NAME) == 0)
        src_mbox = (struct maildir_mailbox *)mail->box;
    else if (strcmp(mail->box->storage->name, "raw") == 0) {
        /* lda uses raw format */
        src_mbox = NULL;
    } else {
        /* Can't hard link files from the source storage */
        return 0;
    }

    if (mail_index_is_deleted(dest_mbox->box.index)) {
        mailbox_set_deleted(&dest_mbox->box);
        return -1;
    }

    memset(&do_ctx, 0, sizeof(do_ctx));
    do_ctx.dest_path = str_new(default_pool, 512);

    if (dest_mbox->storage->set->maildir_copy_preserve_filename &&
        src_mbox != NULL) {
        filename = maildir_copy_get_preserved_fname(src_mbox, dest_mbox,
                                mail->uid);
    }
    if (filename == NULL) {
        /* the generated filename is _always_ unique, so we don't
           bother trying to check if it already exists */
        do_ctx.dest_fname = maildir_filename_generate();
    } else {
        do_ctx.dest_fname = filename;
        do_ctx.preserve_filename = TRUE;
    }

    /* hard link to tmp/ with basename and later when we
       have uidlist locked, move it to new/cur. */
    str_printfa(do_ctx.dest_path, "%s/tmp/%s",
            dest_mbox->box.path, do_ctx.dest_fname);
    do_ctx.base_end_pos = str_len(do_ctx.dest_path);
    if (src_mbox != NULL) {
        /* maildir */
        if (maildir_file_do(src_mbox, mail->uid,
                    do_hardlink, &do_ctx) < 0)
            return -1;
    } else {
        /* raw / lda */
        if (mail_get_special(mail, MAIL_FETCH_UIDL_FILE_NAME,
                     &path) < 0 || *path == '\0')
            return 0;
        if (do_hardlink(dest_mbox, path, &do_ctx) < 0)
            return -1;
    }

    if (!do_ctx.success) {
        /* couldn't copy with hardlinking, fallback to copying */
        return 0;
    }

    /* hardlinked to tmp/, treat as normal copied mail */
    maildir_save_add(ctx, do_ctx.dest_fname);
    return 1;
}

static bool
maildir_compatible_file_modes(struct mailbox *box1, struct mailbox *box2)
{
    return box1->file_create_mode == box2->file_create_mode &&
        box1->file_create_gid == box2->file_create_gid;
}

int maildir_copy(struct mail_save_context *ctx, struct mail *mail)
{
    struct mailbox_transaction_context *_t = ctx->transaction;
    struct maildir_mailbox *mbox = (struct maildir_mailbox *)_t->box;
    int ret;

    i_assert((_t->flags & MAILBOX_TRANSACTION_FLAG_EXTERNAL) != 0);

    if (mbox->storage->set->maildir_copy_with_hardlinks &&
        maildir_compatible_file_modes(&mbox->box, mail->box)) {
        T_BEGIN {
            ret = maildir_copy_hardlink(ctx, mail);
        } T_END;

        if (ret != 0) {
            index_save_context_free(ctx);
            return ret > 0 ? 0 : -1;
        }

        /* non-fatal hardlinking failure, try the slow way */
    }

    return mail_storage_copy(ctx, mail);
}