91 lines
2.1 KiB
C
91 lines
2.1 KiB
C
/* Copyright 2021 Alain Knaff.
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* This file is part of mtools.
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*
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* Mtools is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Mtools is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Mtools. If not, see <http://www.gnu.org/licenses/>.
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*
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* filter to support filesystems stored at an offset into their image
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*/
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#include "sysincludes.h"
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#include "msdos.h"
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#include "mtools.h"
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#include "offset.h"
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typedef struct Offset_t {
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struct Stream_t head;
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mt_off_t offset;
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} Offset_t;
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static ssize_t offset_pread(Stream_t *Stream, char *buf,
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mt_off_t start, size_t len)
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{
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DeclareThis(Offset_t);
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return PREADS(This->head.Next, buf, start+This->offset, len);
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}
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static ssize_t offset_pwrite(Stream_t *Stream, char *buf,
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mt_off_t start, size_t len)
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{
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DeclareThis(Offset_t);
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return PWRITES(This->head.Next, buf, start+This->offset, len);
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}
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static Class_t OffsetClass = {
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0,
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0,
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offset_pread,
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offset_pwrite,
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0, /* flush */
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0, /* free */
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set_geom_pass_through, /* set_geom */
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0, /* get_data */
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0, /* pre-allocate */
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get_dosConvert_pass_through, /* dos convert */
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0, /* discard */
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};
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Stream_t *OpenOffset(Stream_t *Next, struct device *dev, off_t offset,
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char *errmsg, mt_off_t *maxSize) {
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Offset_t *This;
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This = New(Offset_t);
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if (!This){
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printOom();
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return 0;
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}
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memset((void*)This, 0, sizeof(Offset_t));
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init_head(&This->head, &OffsetClass, Next);
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This->offset = offset;
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if(maxSize) {
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if(This->offset > *maxSize) {
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if(errmsg)
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sprintf(errmsg,"init: Big disks not supported");
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goto exit_0;
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}
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*maxSize -= This->offset;
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}
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if(adjust_tot_sectors(dev, This->offset, errmsg) < 0)
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goto exit_0;
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return &This->head;
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exit_0:
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Free(This);
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return NULL;
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}
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