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| -rw-r--r-- | libstore/mvol.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/libstore/mvol.c b/libstore/mvol.c new file mode 100644 index 00000000..b0753dac --- /dev/null +++ b/libstore/mvol.c @@ -0,0 +1,151 @@ +/* Multiple-volume store backend + + Copyright (C) 1996, 1997 Free Software Foundation, Inc. + Written by Miles Bader <miles@gnu.ai.mit.edu> + This file is part of the GNU Hurd. + + The GNU Hurd is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2, or (at + your option) any later version. + + The GNU Hurd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */ + +#include <stdlib.h> +#include <string.h> +#include <stdio.h> + +#include "store.h" + +struct mvol_state +{ + /* The current `volume'. */ + ssize_t cur_vol; + + /* A function to change volumes, making NEW_VOL readable on the store + instead of OLD_VOL. OLD_VOL is initially -1, */ + error_t (*swap_vols) (struct store *store, size_t new_vol, ssize_t old_vol); +}; + +static error_t +ensure_vol (struct store *store, size_t vol) +{ + error_t err = 0; + struct mvol_state *mv = store->hook; + if (vol != mv->cur_vol) + { + err = (*mv->swap_vols) (store, vol, mv->cur_vol); + if (! err) + mv->cur_vol = vol; + } + return err; +} + +static error_t +mvol_read (struct store *store, + off_t addr, size_t index, size_t amount, + void **buf, size_t *len) +{ + error_t err = ensure_vol (store, index); + if (! err) + err = store_read (store->children[0], addr, amount, buf, len); + return err; +} + +static error_t +mvol_write (struct store *store, + off_t addr, size_t index, void *buf, size_t len, + size_t *amount) +{ + error_t err = ensure_vol (store, index); + if (! err) + err = store_write (store->children[0], addr, buf, len, amount); + return err; +} + +error_t +mvol_remap (struct store *source, + const struct store_run *runs, size_t num_runs, + struct store **store) +{ + return store_remap_create (source, runs, num_runs, 0, store); +} + +struct store_class +store_mvol_class = +{ + -1, "mvol", mvol_read, mvol_write, + 0, 0, 0, + store_set_child_flags, store_clear_child_flags, 0, 0, mvol_remap +}; + +/* Return a new store in STORE that multiplexes multiple physical volumes + from PHYS as one larger virtual volume. SWAP_VOLS is a function that will + be called whenever the volume currently active isn't correct. PHYS is + consumed. */ +error_t +store_mvol_create (struct store *phys, + error_t (*swap_vols) (struct store *store, size_t new_vol, + ssize_t old_vol), + int flags, + struct store **store) +{ + error_t err; + struct store_run run; + + run.start = 0; + run.length = phys->end; + + err = _store_create (&store_mvol_class, MACH_PORT_NULL, + flags | phys->flags, phys->block_size, + &run, 1, 0, store); + if (! err) + { + struct mvol_state *mv = malloc (sizeof (struct mvol_state)); + if (mv) + { + mv->swap_vols = swap_vols; + mv->cur_vol = -1; + (*store)->hook = mv; + } + else + err = ENOMEM; + + if (! err) + err = store_set_children (*store, &phys, 1); + + if (! err) + { + if (phys->name) + { + size_t nlen = + strlen (phys->class->name) + 1 + strlen (phys->name) + 1; + char *name = malloc (nlen); + + if (name) + { + snprintf (name, nlen, "%s:%s", phys->class->name, phys->name); + (*store)->name = name; + } + else + err = ENOMEM; + } + } + + if (err) + { + if (mv) + free (mv); + store_free (*store); + } + } + + return err; +} |