diff options
Diffstat (limited to 'libstore/null.c')
-rw-r--r-- | libstore/null.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/libstore/null.c b/libstore/null.c new file mode 100644 index 00000000..dd30ded1 --- /dev/null +++ b/libstore/null.c @@ -0,0 +1,109 @@ +/* Null store backend + + Copyright (C) 1995, 1996 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., 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#include <assert.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "store.h" + +static error_t +null_read (struct store *store, + off_t addr, size_t index, mach_msg_type_number_t amount, + char **buf, mach_msg_type_number_t *len) +{ + if (*len < amount) + { + error_t err = + vm_allocate (mach_task_self (), (vm_address_t *)buf, amount, 1); + if (! err) + *len = amount; + return err; + } + else + { + bzero (*buf, amount); + *len = amount; + return 0; + } +} + +static error_t +null_write (struct store *store, + off_t addr, size_t index, char *buf, mach_msg_type_number_t len, + mach_msg_type_number_t *amount) +{ + return 0; +} + +error_t +null_allocate_encoding (const struct store *store, struct store_enc *enc) +{ + enc->num_ints += 2; + enc->num_offsets += 1; + return 0; +} + +error_t +null_encode (const struct store *store, struct store_enc *enc) +{ + enc->ints[enc->cur_int++] = store->class->id; + enc->ints[enc->cur_int++] = store->flags; + enc->offsets[enc->cur_offset++] = store->size; + return 0; +} + +error_t +null_decode (struct store_enc *enc, struct store_class *classes, + struct store **store) +{ + off_t size; + int type, flags; + + if (enc->cur_int + 2 > enc->num_ints + || enc->cur_offset + 1 > enc->num_offsets) + return EINVAL; + + type = enc->ints[enc->cur_int++]; + flags = enc->ints[enc->cur_int++]; + size = enc->offsets[enc->cur_offset++]; + + return store_null_create (size, flags, store); +} + +static struct store_class +null_class = +{ + STORAGE_NULL, "null", null_read, null_write, + null_allocate_encoding, null_encode, null_decode +}; +_STORE_STD_CLASS (null_class); + +/* Return a new null store SIZE bytes long in STORE. */ +error_t +store_null_create (size_t size, int flags, struct store **store) +{ + struct store_run run = { 0, size }; + *store = _make_store (&null_class, MACH_PORT_NULL, flags, 1, &run, 1, 0); + return *store ? 0 : ENOMEM; +} |