From 10fe387708ddfba6449b9abd74cfbdf67d495465 Mon Sep 17 00:00:00 2001 From: Jason Downs Date: Fri, 21 Nov 2008 21:33:39 +0000 Subject: Initial revision --- src/gdbmstore.c | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 src/gdbmstore.c (limited to 'src/gdbmstore.c') diff --git a/src/gdbmstore.c b/src/gdbmstore.c new file mode 100644 index 0000000..cc2bee7 --- /dev/null +++ b/src/gdbmstore.c @@ -0,0 +1,156 @@ +/* gdbmstore.c - Add a new key/data pair to the database. */ + +/* This file is part of GDBM, the GNU data base manager. + Copyright (C) 1990, 1991, 1993, 2007 Free Software Foundation, Inc. + + This program 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 3, or (at your option) + any later version. + + This program 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ + +/* Include system configuration before all else. */ +#include "autoconf.h" + +#include "gdbmdefs.h" +#include "gdbmerrno.h" + + +/* Add a new element to the database. CONTENT is keyed by KEY. The + file on disk is updated to reflect the structure of the new database + before returning from this procedure. The FLAGS define the action to + take when the KEY is already in the database. The value GDBM_REPLACE + asks that the old data be replaced by the new CONTENT. The value + GDBM_INSERT asks that an error be returned and no action taken. A + return value of 0 means no errors. A return value of -1 means that + the item was not stored in the data base because the caller was not an + official writer. A return value of 0 means that the item was not stored + because the argument FLAGS was GDBM_INSERT and the KEY was already in + the database. */ + +int +gdbm_store (gdbm_file_info *dbf, datum key, datum content, int flags) +{ + int new_hash_val; /* The new hash value. */ + int elem_loc; /* The location in hash bucket. */ + off_t file_adr; /* The address of new space in the file. */ + off_t file_pos; /* The position after a lseek. */ + int num_bytes; /* Used for error detection. */ + off_t free_adr; /* For keeping track of a freed section. */ + int free_size; + int new_size; /* Used in allocating space. */ + char *temp; /* Used in _gdbm_findkey call. */ + + + /* First check to make sure this guy is a writer. */ + if (dbf->read_write == GDBM_READER) + { + gdbm_errno = GDBM_READER_CANT_STORE; + return -1; + } + + /* Check for illegal data values. A NULL dptr field is illegal because + NULL dptr returned by a lookup procedure indicates an error. */ + if ((key.dptr == NULL) || (content.dptr == NULL)) + { + gdbm_errno = GDBM_ILLEGAL_DATA; + return -1; + } + + /* Initialize the gdbm_errno variable. */ + gdbm_errno = GDBM_NO_ERROR; + + /* Look for the key in the file. + A side effect loads the correct bucket and calculates the hash value. */ + elem_loc = _gdbm_findkey (dbf, key, &temp, &new_hash_val); + + /* Initialize these. */ + file_adr = 0; + new_size = key.dsize + content.dsize; + + /* Did we find the item? */ + if (elem_loc != -1) + { + if (flags == GDBM_REPLACE) + { + /* Just replace the data. */ + free_adr = dbf->bucket->h_table[elem_loc].data_pointer; + free_size = dbf->bucket->h_table[elem_loc].key_size + + dbf->bucket->h_table[elem_loc].data_size; + if (free_size != new_size) + { + _gdbm_free (dbf, free_adr, free_size); + } + else + { + /* Just reuse the same address! */ + file_adr = free_adr; + } + } + else + { + gdbm_errno = GDBM_CANNOT_REPLACE; + return 1; + } + } + + + /* Get the file address for the new space. + (Current bucket's free space is first place to look.) */ + if (file_adr == 0) + { + file_adr = _gdbm_alloc (dbf, new_size); + } + + /* If this is a new entry in the bucket, we need to do special things. */ + if (elem_loc == -1) + { + if (dbf->bucket->count == dbf->header->bucket_elems) + { + /* Split the current bucket. */ + _gdbm_split_bucket (dbf, new_hash_val); + } + + /* Find space to insert into bucket and set elem_loc to that place. */ + elem_loc = new_hash_val % dbf->header->bucket_elems; + while (dbf->bucket->h_table[elem_loc].hash_value != -1) + { elem_loc = (elem_loc + 1) % dbf->header->bucket_elems; } + + /* We now have another element in the bucket. Add the new information.*/ + dbf->bucket->count += 1; + dbf->bucket->h_table[elem_loc].hash_value = new_hash_val; + memcpy (dbf->bucket->h_table[elem_loc].key_start, key.dptr, + (SMALL < key.dsize ? SMALL : key.dsize)); + } + + + /* Update current bucket data pointer and sizes. */ + dbf->bucket->h_table[elem_loc].data_pointer = file_adr; + dbf->bucket->h_table[elem_loc].key_size = key.dsize; + dbf->bucket->h_table[elem_loc].data_size = content.dsize; + + /* Write the data to the file. */ + file_pos = __lseek (dbf, file_adr, L_SET); + if (file_pos != file_adr) _gdbm_fatal (dbf, "lseek error"); + num_bytes = __write (dbf, key.dptr, key.dsize); + if (num_bytes != key.dsize) _gdbm_fatal (dbf, "write error"); + num_bytes = __write (dbf, content.dptr, content.dsize); + if (num_bytes != content.dsize) _gdbm_fatal (dbf, "write error"); + + /* Current bucket has changed. */ + dbf->cache_entry->ca_changed = TRUE; + dbf->bucket_changed = TRUE; + + /* Write everything that is needed to the disk. */ + _gdbm_end_update (dbf); + return 0; + +} -- cgit v1.2.1