db_ret.c
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上传日期:2022-05-23
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文件大小:3k
- /*-
- * See the file LICENSE for redistribution information.
- *
- * Copyright (c) 1996-2002
- * Sleepycat Software. All rights reserved.
- */
- #include "db_config.h"
- #ifndef lint
- static const char revid[] = "$Id: db_ret.c,v 11.21 2002/03/28 19:21:47 bostic Exp $";
- #endif /* not lint */
- #ifndef NO_SYSTEM_INCLUDES
- #include <sys/types.h>
- #include <string.h>
- #endif
- #include "db_int.h"
- #include "dbinc/db_page.h"
- #include "dbinc/db_am.h"
- /*
- * __db_ret --
- * Build return DBT.
- *
- * PUBLIC: int __db_ret __P((DB *,
- * PUBLIC: PAGE *, u_int32_t, DBT *, void **, u_int32_t *));
- */
- int
- __db_ret(dbp, h, indx, dbt, memp, memsize)
- DB *dbp;
- PAGE *h;
- u_int32_t indx;
- DBT *dbt;
- void **memp;
- u_int32_t *memsize;
- {
- BKEYDATA *bk;
- HOFFPAGE ho;
- BOVERFLOW *bo;
- u_int32_t len;
- u_int8_t *hk;
- void *data;
- switch (TYPE(h)) {
- case P_HASH:
- hk = P_ENTRY(dbp, h, indx);
- if (HPAGE_PTYPE(hk) == H_OFFPAGE) {
- memcpy(&ho, hk, sizeof(HOFFPAGE));
- return (__db_goff(dbp, dbt,
- ho.tlen, ho.pgno, memp, memsize));
- }
- len = LEN_HKEYDATA(dbp, h, dbp->pgsize, indx);
- data = HKEYDATA_DATA(hk);
- break;
- case P_LBTREE:
- case P_LDUP:
- case P_LRECNO:
- bk = GET_BKEYDATA(dbp, h, indx);
- if (B_TYPE(bk->type) == B_OVERFLOW) {
- bo = (BOVERFLOW *)bk;
- return (__db_goff(dbp, dbt,
- bo->tlen, bo->pgno, memp, memsize));
- }
- len = bk->len;
- data = bk->data;
- break;
- default:
- return (__db_pgfmt(dbp->dbenv, h->pgno));
- }
- return (__db_retcopy(dbp->dbenv, dbt, data, len, memp, memsize));
- }
- /*
- * __db_retcopy --
- * Copy the returned data into the user's DBT, handling special flags.
- *
- * PUBLIC: int __db_retcopy __P((DB_ENV *, DBT *,
- * PUBLIC: void *, u_int32_t, void **, u_int32_t *));
- */
- int
- __db_retcopy(dbenv, dbt, data, len, memp, memsize)
- DB_ENV *dbenv;
- DBT *dbt;
- void *data;
- u_int32_t len;
- void **memp;
- u_int32_t *memsize;
- {
- int ret;
- /* If returning a partial record, reset the length. */
- if (F_ISSET(dbt, DB_DBT_PARTIAL)) {
- data = (u_int8_t *)data + dbt->doff;
- if (len > dbt->doff) {
- len -= dbt->doff;
- if (len > dbt->dlen)
- len = dbt->dlen;
- } else
- len = 0;
- }
- /*
- * Return the length of the returned record in the DBT size field.
- * This satisfies the requirement that if we're using user memory
- * and insufficient memory was provided, return the amount necessary
- * in the size field.
- */
- dbt->size = len;
- /*
- * Allocate memory to be owned by the application: DB_DBT_MALLOC,
- * DB_DBT_REALLOC.
- *
- * !!!
- * We always allocate memory, even if we're copying out 0 bytes. This
- * guarantees consistency, i.e., the application can always free memory
- * without concern as to how many bytes of the record were requested.
- *
- * Use the memory specified by the application: DB_DBT_USERMEM.
- *
- * !!!
- * If the length we're going to copy is 0, the application-supplied
- * memory pointer is allowed to be NULL.
- */
- if (F_ISSET(dbt, DB_DBT_MALLOC)) {
- if ((ret = __os_umalloc(dbenv, len, &dbt->data)) != 0)
- return (ret);
- } else if (F_ISSET(dbt, DB_DBT_REALLOC)) {
- if ((ret = __os_urealloc(dbenv, len, &dbt->data)) != 0)
- return (ret);
- } else if (F_ISSET(dbt, DB_DBT_USERMEM)) {
- if (len != 0 && (dbt->data == NULL || dbt->ulen < len))
- return (ENOMEM);
- } else if (memp == NULL || memsize == NULL) {
- return (EINVAL);
- } else {
- if (len != 0 && (*memsize == 0 || *memsize < len)) {
- if ((ret = __os_realloc(dbenv, len, memp)) != 0) {
- *memsize = 0;
- return (ret);
- }
- *memsize = len;
- }
- dbt->data = *memp;
- }
- if (len != 0)
- memcpy(dbt->data, data, len);
- return (0);
- }