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BFLPUSH.C
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1989-08-30
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/* Copyright (c) 1989 Citadel */
/* All Rights Reserved */
/* #ident "bflpush.c 1.1 - 89/07/03" */
#include <errno.h>
/* #include <string.h> */
#include "blkio_.h"
/*man---------------------------------------------------------------------------
NAME
bflpush - push block onto free list
SYNOPSIS
#include <blkio.h>
int bflpush(bp, bn_p)
BLKFILE *bp;
bpos_t *bn_p;
DESCRIPTION
The bflpush function puts the block number pointed to by bn_p into
the free list of the block file associated with BLKFILE pointer bp.
If the value pointed to by bn_p is one block past the end of the
file, it is accepted but not actually added to the list.
bflpush will fail if one or more of the following is true:
[EINVAL] bp is not a valid BLKFILE pointer.
[EINVAL] bn_p is the NULL pointer.
[EINVAL] bn_p points to a value less than 1.
[BEEOF] bp is empty.
[BEEOF] bn_p points to a value farther than one
block past the end of file.
[BENFL] bp does not have a free list.
[BENOPEN] bp is not open for writing.
SEE ALSO
bflpop.
DIAGNOSTICS
Upon successful completion, a value of 0 is returned. Otherwise, a
value of -1 is returned, and errno set to indicate the error.
NOTES
To use the free list functions in the blkio library, the first element
of the file header must be the free list head with type size_t. This
must be initialized to 0 immediately after the file is created and not
accessed afterward except using bflpush and bflpush. Also, the block
size must be at least sizeof(size_t).
------------------------------------------------------------------------------*/
int bflpush(bp, bn_p)
BLKFILE * bp;
bpos_t * bn_p;
{
int rs = 0;
bpos_t oldflhno = 0;
bpos_t newflhno = 0;
void * buf = NULL;
errno = 0;
/* validate arguments */
if ((!b_valid(bp)) || (bn_p == NULL)) {
errno = EINVAL;
return -1;
}
if (*bn_p < 1) {
errno = EINVAL;
return -1;
}
/* check if not open */
if (!(bp->flags & BIOWRITE)) {
errno = BENOPEN;
return -1;
}
/* check if no free list */
if ((bp->hdrsize < sizeof(oldflhno)) || (bp->blksize < sizeof(oldflhno))) {
errno = BENFL;
return -1;
}
/* check if header not yet written */
if (bp->endblk < 1) {
errno = BEEOF;
return -1;
}
/* check if block past endblk */
if (*bn_p > bp->endblk) {
errno = BEEOF;
return -1;
}
/* check if block is endblk */
if (*bn_p == bp->endblk) {
errno = 0;
return 0;
}
/* get block number of current free list head */
rs = bgethf(bp, (size_t)0, (void *)&oldflhno, sizeof(oldflhno));
if (rs == -1) {
BEPRINT;
return -1;
}
/* link to rest of free list */
newflhno = *bn_p;
buf = calloc(1, bp->blksize);
if (buf == NULL) {
BEPRINT;
errno = ENOMEM;
return -1;
}
memcpy(buf, (void *)&oldflhno, sizeof(oldflhno));
rs = bputb(bp, newflhno, buf);
if (rs == -1) {
BEPRINT;
free(buf);
buf = NULL;
return -1;
}
free(buf);
buf = NULL;
/* write new free list head number to header */
rs = bputhf(bp, (size_t)0, (void *)&newflhno, sizeof(newflhno));
if (rs == -1) {
BEPRINT;
return -1;
}
errno = 0;
return 0;
}