memfile.c

VIM文本编辑器

/*
 * release as many blocks as possible
 * Used in case of out of memory
 *
 * return TRUE if any memory was released
 */
    int
mf_release_all()
{
    BUF		*buf;
    MEMFILE	*mfp;
    BHDR	*hp;
    int		retval = FALSE;

    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
    {
	mfp = buf->b_ml.ml_mfp;
	/* only if there is a memfile with a file */
	if (mfp != NULL && mfp->mf_fd >= 0)
	    for (hp = mfp->mf_used_last; hp != NULL; )
	    {
		if (!(hp->bh_flags & BH_LOCKED) && (!(hp->bh_flags & BH_DIRTY)
						|| mf_write(mfp, hp) != FAIL))
		{
		    mf_rem_used(mfp, hp);
		    mf_rem_hash(mfp, hp);
		    mf_free_bhdr(hp);
		    hp = mfp->mf_used_last;	/* re-start, list was changed */
		    retval = TRUE;
		}
		else
		    hp = hp->bh_prev;
	    }
    }
    return retval;
}

/*
 * Allocate a block header and a block of memory for it
 */
    static BHDR *
mf_alloc_bhdr(mfp, page_count)
    MEMFILE	*mfp;
    int		page_count;
{
    BHDR    *hp;

    if ((hp = (BHDR *)alloc((unsigned)sizeof(BHDR))) != NULL)
    {
	if ((hp->bh_data = (char_u *)alloc(mfp->mf_page_size * page_count))
								      == NULL)
	{
	    vim_free(hp);	    /* not enough memory */
	    return NULL;
	}
	hp->bh_page_count = page_count;
    }
    return hp;
}

/*
 * Free a block header and the block of memory for it
 */
    static void
mf_free_bhdr(hp)
    BHDR	*hp;
{
    vim_free(hp->bh_data);
    vim_free(hp);
}

/*
 * insert entry *hp in the free list
 */
    static void
mf_ins_free(mfp, hp)
    MEMFILE *mfp;
    BHDR    *hp;
{
    hp->bh_next = mfp->mf_free_first;
    mfp->mf_free_first = hp;
}

/*
 * remove the first entry from the free list and return a pointer to it
 * Note: caller must check that mfp->mf_free_first is not NULL!
 */
    static BHDR *
mf_rem_free(mfp)
    MEMFILE *mfp;
{
    BHDR    *hp;

    hp = mfp->mf_free_first;
    mfp->mf_free_first = hp->bh_next;
    return hp;
}

/*
 * read a block from disk
 *
 * Return FAIL for failure, OK otherwise
 */
    static int
mf_read(mfp, hp)
    MEMFILE	*mfp;
    BHDR	*hp;
{
    off_t	offset;
    unsigned	page_size;
    unsigned	size;

    if (mfp->mf_fd < 0)	    /* there is no file, can't read */
	return FAIL;

    page_size = mfp->mf_page_size;
    offset = page_size * hp->bh_bnum;
    size = page_size * hp->bh_page_count;
    if (lseek(mfp->mf_fd, offset, SEEK_SET) != offset)
    {
	EMSG("Seek error in swap file read");
	return FAIL;
    }
    if ((unsigned)read(mfp->mf_fd, (char *)hp->bh_data, (size_t)size) != size)
    {
	EMSG("Read error in swap file");
	return FAIL;
    }
    return OK;
}

/*
 * write a block to disk
 *
 * Return FAIL for failure, OK otherwise
 */
    static int
mf_write(mfp, hp)
    MEMFILE	*mfp;
    BHDR	*hp;
{
    off_t	offset;	    /* offset in the file */
    blocknr_t	nr;	    /* block nr which is being written */
    BHDR	*hp2;
    unsigned	page_size;  /* number of bytes in a page */
    unsigned	page_count; /* number of pages written */
    unsigned	size;	    /* number of bytes written */

    if (mfp->mf_fd < 0)	    /* there is no file, can't write */
	return FAIL;

    if (hp->bh_bnum < 0)	/* must assign file block number */
	if (mf_trans_add(mfp, hp) == FAIL)
	    return FAIL;

    page_size = mfp->mf_page_size;

    /*
     * We don't want gaps in the file. Write the blocks in front of *hp
     * to extend the file.
     * If block 'mf_infile_count' is not in the hash list, it has been
     * freed. Fill the space in the file with data from the current block.
     */
    for (;;)
    {
	nr = hp->bh_bnum;
	if (nr > mfp->mf_infile_count)		/* beyond end of file */
	{
	    nr = mfp->mf_infile_count;
	    hp2 = mf_find_hash(mfp, nr);	/* NULL catched below */
	}
	else
	    hp2 = hp;

	offset = page_size * nr;
	if (lseek(mfp->mf_fd, offset, SEEK_SET) != offset)
	{
	    EMSG("Seek error in swap file write");
	    return FAIL;
	}
	if (hp2 == NULL)	    /* freed block, fill with dummy data */
	    page_count = 1;
	else
	    page_count = hp2->bh_page_count;
	size = page_size * page_count;
	if ((unsigned)write(mfp->mf_fd,
	     (char *)(hp2 == NULL ? hp : hp2)->bh_data, (size_t)size) != size)
	{
	    /*
	     * Avoid repeating the error message, this mostly happens when the
	     * disk is full. We give the message again only after a succesful
	     * write or when hitting a key. We keep on trying, in case some
	     * space becomes available.
	     */
	    if (!did_swapwrite_msg)
		EMSG("Write error in swap file");
	    did_swapwrite_msg = TRUE;
	    return FAIL;
	}
	did_swapwrite_msg = FALSE;
	if (hp2 != NULL)		    /* written a non-dummy block */
	    hp2->bh_flags &= ~BH_DIRTY;
					    /* appended to the file */
	if (nr + (blocknr_t)page_count > mfp->mf_infile_count)
	    mfp->mf_infile_count = nr + page_count;
	if (nr == hp->bh_bnum)		    /* written the desired block */
	    break;
    }
    return OK;
}

/*
 * Make block number for *hp positive and add it to the translation list
 *
 * Return FAIL for failure, OK otherwise
 */
    static int
mf_trans_add(mfp, hp)
    MEMFILE *mfp;
    BHDR    *hp;
{
    BHDR	*freep;
    blocknr_t	new_bnum;
    int		hash;
    NR_TRANS	*np;
    int		page_count;

    if (hp->bh_bnum >= 0)		    /* it's already positive */
	return OK;

    if ((np = (NR_TRANS *)alloc((unsigned)sizeof(NR_TRANS))) == NULL)
	return FAIL;

/*
 * get a new number for the block.
 * If the first item in the free list has sufficient pages, use its number
 * Otherwise use mf_blocknr_max.
 */
    freep = mfp->mf_free_first;
    page_count = hp->bh_page_count;
    if (freep != NULL && freep->bh_page_count >= page_count)
    {
	new_bnum = freep->bh_bnum;
	/*
	 * If the page count of the free block was larger, recude it.
	 * If the page count matches, remove the block from the free list
	 */
	if (freep->bh_page_count > page_count)
	{
	    freep->bh_bnum += page_count;
	    freep->bh_page_count -= page_count;
	}
	else
	{
	    freep = mf_rem_free(mfp);
	    vim_free(freep);
	}
    }
    else
    {
	new_bnum = mfp->mf_blocknr_max;
	mfp->mf_blocknr_max += page_count;
    }

    np->nt_old_bnum = hp->bh_bnum;	    /* adjust number */
    np->nt_new_bnum = new_bnum;

    mf_rem_hash(mfp, hp);		    /* remove from old hash list */
    hp->bh_bnum = new_bnum;
    mf_ins_hash(mfp, hp);		    /* insert in new hash list */

    hash = MEMHASH(np->nt_old_bnum);	    /* insert in trans list */
    np->nt_next = mfp->mf_trans[hash];
    mfp->mf_trans[hash] = np;
    if (np->nt_next != NULL)
	np->nt_next->nt_prev = np;
    np->nt_prev = NULL;

    return OK;
}

/*
 * Lookup a tranlation from the trans lists and delete the entry
 *
 * Return the positive new number when found, the old number when not found
 */
    blocknr_t
mf_trans_del(mfp, old_nr)
    MEMFILE	*mfp;
    blocknr_t	old_nr;
{
    int		hash;
    NR_TRANS	*np;
    blocknr_t	new_bnum;

    hash = MEMHASH(old_nr);
    for (np = mfp->mf_trans[hash]; np != NULL; np = np->nt_next)
	if (np->nt_old_bnum == old_nr)
	    break;
    if (np == NULL)		/* not found */
	return old_nr;

    mfp->mf_neg_count--;
    new_bnum = np->nt_new_bnum;
    if (np->nt_prev != NULL)		/* remove entry from the trans list */
	np->nt_prev->nt_next = np->nt_next;
    else
	mfp->mf_trans[hash] = np->nt_next;
    if (np->nt_next != NULL)
	np->nt_next->nt_prev = np->nt_prev;
    vim_free(np);

    return new_bnum;
}

/*
 * Set mfp->mf_ffname according to mfp->mf_fname and some other things.
 * Only called when creating or renaming the swapfile.	Either way it's a new
 * name so we must work out the full path name.
 */
    void
mf_set_ffname(mfp)
    MEMFILE	*mfp;
{
    mfp->mf_ffname = FullName_save(mfp->mf_fname, FALSE);
}

/*
 * Make the name of the file used for the memfile a full path.
 * Used before doing a :cd
 */
    void
mf_fullname(mfp)
    MEMFILE	*mfp;
{
    if (mfp != NULL && mfp->mf_fname != NULL && mfp->mf_ffname != NULL)
    {
	vim_free(mfp->mf_fname);
	mfp->mf_fname = mfp->mf_ffname;
	mfp->mf_ffname = NULL;
    }
}

/*
 * return TRUE if there are any translations pending for 'mfp'
 */
    int
mf_need_trans(mfp)
    MEMFILE	*mfp;
{
    return (mfp->mf_fname != NULL && mfp->mf_neg_count > 0);
}

/*
 * Open a swap file for a memfile.
 * The "fname" must be in allocated memory, and is consumed (also when an
 * error occurs).
 */
    static void
mf_do_open(mfp, fname, trunc_file)
    MEMFILE	*mfp;
    char_u	*fname;
    int		trunc_file;
{
    mfp->mf_fname = fname;
    /*
     * Get the full path name before the open, because this is
     * not possible after the open on the Amiga.
     * fname cannot be NameBuff, because it must have been allocated.
     */
    mf_set_ffname(mfp);
#if defined(MSDOS) || defined(WIN32) || defined(RISCOS)
    /*
     * A ":!cd e:xxx" may change the directory without us knowning, use the
     * full pathname always.  Careful: This frees fname!
     */
    mf_fullname(mfp);
#endif

    /*
     * try to open the file
     */
    mfp->mf_fd = open((char *)mfp->mf_fname,
	    (trunc_file ? (O_CREAT | O_RDWR | O_TRUNC) : (O_RDONLY)) | O_EXTRA
#if defined(UNIX) || defined(RISCOS)		 /* open in rw------- mode */
		    , (mode_t)0600
#endif
#if defined(MSDOS) || defined(WIN32) || defined(__EMX__)
		    , S_IREAD | S_IWRITE	 /* open read/write */
#endif
#ifdef VMS		    /* open in rw------- mode */
		    , 0600
#endif
		    );

    /*
     * If the file cannot be opened, use memory only
     */
    if (mfp->mf_fd < 0)
    {
	vim_free(mfp->mf_fname);
	vim_free(mfp->mf_ffname);
	mfp->mf_fname = NULL;
	mfp->mf_ffname = NULL;
    }
    else
	mch_hide(mfp->mf_fname);    /* try setting the 'hidden' flag */
}