diff options
Diffstat (limited to 'src/gdbmdelete.c')
| -rw-r--r-- | src/gdbmdelete.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/src/gdbmdelete.c b/src/gdbmdelete.c new file mode 100644 index 0000000..1970422 --- /dev/null +++ b/src/gdbmdelete.c @@ -0,0 +1,106 @@ +/* gdbmdelete.c - Remove the key and its associated data from the database. */ + +/* This file is part of GDBM, the GNU data base manager. + Copyright (C) 1990, 1991, 1993, 2007, 2011, 2013 Free Software Foundation, + Inc. + + GDBM 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. + + GDBM 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 GDBM. If not, see <http://www.gnu.org/licenses/>. */ + +/* Include system configuration before all else. */ +#include "autoconf.h" + +#include "gdbmdefs.h" + +/* Remove the KEYed item and the KEY from the database DBF. The file on disk + is updated to reflect the structure of the new database before returning + from this procedure. */ + +int +gdbm_delete (GDBM_FILE dbf, datum key) +{ + int elem_loc; /* The location in the current hash bucket. */ + int last_loc; /* Last location emptied by the delete. */ + int home; /* Home position of an item. */ + bucket_element elem; /* The element to be deleted. */ + char *find_data; /* Return pointer from findkey. */ + int hash_val; /* Returned by findkey. */ + off_t free_adr; /* Temporary stroage for address and size. */ + int free_size; + + /* First check to make sure this guy is a writer. */ + if (dbf->read_write == GDBM_READER) + { + gdbm_errno = GDBM_READER_CANT_DELETE; + return -1; + } + + /* Initialize the gdbm_errno variable. */ + gdbm_errno = GDBM_NO_ERROR; + + /* Find the item. */ + elem_loc = _gdbm_findkey (dbf, key, &find_data, &hash_val); + if (elem_loc == -1) + { + gdbm_errno = GDBM_ITEM_NOT_FOUND; + return -1; + } + + /* Save the element. */ + elem = dbf->bucket->h_table[elem_loc]; + + /* Delete the element. */ + dbf->bucket->h_table[elem_loc].hash_value = -1; + dbf->bucket->count--; + + /* Move other elements to guarantee that they can be found. */ + last_loc = elem_loc; + elem_loc = (elem_loc + 1) % dbf->header->bucket_elems; + while (elem_loc != last_loc + && dbf->bucket->h_table[elem_loc].hash_value != -1) + { + home = dbf->bucket->h_table[elem_loc].hash_value + % dbf->header->bucket_elems; + if ( (last_loc < elem_loc && (home <= last_loc || home > elem_loc)) + || (last_loc > elem_loc && home <= last_loc && home > elem_loc)) + + { + dbf->bucket->h_table[last_loc] = dbf->bucket->h_table[elem_loc]; + dbf->bucket->h_table[elem_loc].hash_value = -1; + last_loc = elem_loc; + } + elem_loc = (elem_loc + 1) % dbf->header->bucket_elems; + } + + /* Free the file space. */ + free_adr = elem.data_pointer; + free_size = elem.key_size + elem.data_size; + _gdbm_free (dbf, free_adr, free_size); + + /* Set the flags. */ + dbf->bucket_changed = TRUE; + + /* Clear out the data cache for the current bucket. */ + if (dbf->cache_entry->ca_data.dptr != NULL) + { + free (dbf->cache_entry->ca_data.dptr); + dbf->cache_entry->ca_data.dptr = NULL; + } + dbf->cache_entry->ca_data.hash_val = -1; + dbf->cache_entry->ca_data.key_size = 0; + dbf->cache_entry->ca_data.elem_loc = -1; + + /* Do the writes. */ + _gdbm_end_update (dbf); + return 0; +} |