scsh-0.5/scsh/db.scm

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;;; Very vanilla DBM processing code
;;; Copyright (c) 1995 by David Albertz (dalbertz@clark.lcs.mit.edu).
;;; See file COPYING.
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;;; This code is freely available for use by anyone for any purpose,
;;; so long as you don't charge money for it, remove this notice, or
;;; hold us liable for any results of its use. --enjoy.
;;; This is just a straight translation of the UNIX freebie NDBM code.
;;; Usage: (db-open name flags mode type info)
;;; name := name of database file (no extension)
;;; flags := file access flags (open/create etc.)
;;; mode := file access modes (privileges)
;;; type := DBTYPE as defined in db.h (btree, hash, recno)
;;; info := access method specific structure
;;; (NULL gives defaults)
;;; Return: Alien value pointer to the open DBM structure
;;; Usage: (dbm-close db)
;;; db := The pointer returned by dbm-open
;;; Return: Always returns 0
;;; Usage: (dbm-fetch db key)
;;; db := The pointer returned by dbm-open
;;; key := The key value of data to be retrieved
;;; Return: String containing data associated with key
;;; Usage: (dbm-store db key data flag)
;;; db := The pointer returned by dbm-open
;;; key := The key value to be associated with data
;;; data := The data to be stored with the key
;;; flag := 0 for insert, 1 for replace
;;; Return: Integer returned by UNIX dbm_store routine
;;; Usage: (dbm-delete db key)
;;; db := The pointer returned by dbm-open
;;; key := The key value of data to be deleted
;;; Return: Integer returned by UNIX dbm_delete routine
;;; Usage: (dbm-firstkey db)
;;; db := The pointer returned by dbm-open
;;; Return: First key value stored in database hash table.
;;; Usage: (dbm-nextkey db)
;;; db := The pointer returned by dbm-open
;;; Return: Next key value stored in database hash table.
;;; Usage: (dbm-error db)
;;; db := The pointer returned by dbm-open
;;; Return: Error number returned by UNIX dbm_error routine
;;; Usage: (dbm-clearerr db)
;;; db := The pointer returned by dbm-open
;;; Return: Clears any database error condition and returns the
;;; integer from the UNIX dbm_clearerr routine
;;; ***NOTE: All key and data elements must be strings
;;; Scheme48 implementation.
(foreign-source
"#include <sys/types.h>"
"#include <errno.h>"
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"#include <limits.h>"
"#include \"/usr/local/include/db.h\""
""
"#define errno_or_false(x) (((x) == -1) ? ENTER_FIXNUM(errno) : SCHFALSE)"
"" "")
(define-foreign %db-open (db_open (string file)
(integer flags)
(integer mode)
(integer type))
(to-scheme integer errno_or_false) ; error flag
(C DB**)) ; DBM structure
(define (db-open file flags mode type)
(receive (err dbm) (%db-open file flags mode type)
(if err
(errno-error err db-open)
dbm)))