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934 lines
18 KiB
C
934 lines
18 KiB
C
/*
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* Copyright (C) 1984-2011 Mark Nudelman
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*
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* You may distribute under the terms of either the GNU General Public
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* License or the Less License, as specified in the README file.
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*
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* For more information about less, or for information on how to
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* contact the author, see the README file.
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*/
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/*
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* Low level character input from the input file.
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* We use these special purpose routines which optimize moving
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* both forward and backward from the current read pointer.
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*/
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#include "less.h"
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#if MSDOS_COMPILER==WIN32C
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#include <errno.h>
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#include <windows.h>
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#endif
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#if HAVE_STAT_INO
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#include <sys/stat.h>
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extern dev_t curr_dev;
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extern ino_t curr_ino;
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#endif
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typedef POSITION BLOCKNUM;
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public int ignore_eoi;
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/*
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* Pool of buffers holding the most recently used blocks of the input file.
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* The buffer pool is kept as a doubly-linked circular list,
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* in order from most- to least-recently used.
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* The circular list is anchored by the file state "thisfile".
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*/
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struct bufnode {
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struct bufnode *next, *prev;
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struct bufnode *hnext, *hprev;
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};
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#define LBUFSIZE 8192
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struct buf {
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struct bufnode node;
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BLOCKNUM block;
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unsigned int datasize;
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unsigned char data[LBUFSIZE];
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};
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#define bufnode_buf(bn) ((struct buf *) bn)
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/*
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* The file state is maintained in a filestate structure.
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* A pointer to the filestate is kept in the ifile structure.
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*/
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#define BUFHASH_SIZE 64
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struct filestate {
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struct bufnode buflist;
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struct bufnode hashtbl[BUFHASH_SIZE];
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int file;
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int flags;
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POSITION fpos;
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int nbufs;
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BLOCKNUM block;
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unsigned int offset;
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POSITION fsize;
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};
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#define ch_bufhead thisfile->buflist.next
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#define ch_buftail thisfile->buflist.prev
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#define ch_nbufs thisfile->nbufs
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#define ch_block thisfile->block
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#define ch_offset thisfile->offset
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#define ch_fpos thisfile->fpos
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#define ch_fsize thisfile->fsize
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#define ch_flags thisfile->flags
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#define ch_file thisfile->file
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#define END_OF_CHAIN (&thisfile->buflist)
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#define END_OF_HCHAIN(h) (&thisfile->hashtbl[h])
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#define BUFHASH(blk) ((blk) & (BUFHASH_SIZE-1))
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/*
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* Macros to manipulate the list of buffers in thisfile->buflist.
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*/
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#define FOR_BUFS(bn) \
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for (bn = ch_bufhead; bn != END_OF_CHAIN; bn = bn->next)
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#define BUF_RM(bn) \
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(bn)->next->prev = (bn)->prev; \
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(bn)->prev->next = (bn)->next;
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#define BUF_INS_HEAD(bn) \
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(bn)->next = ch_bufhead; \
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(bn)->prev = END_OF_CHAIN; \
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ch_bufhead->prev = (bn); \
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ch_bufhead = (bn);
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#define BUF_INS_TAIL(bn) \
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(bn)->next = END_OF_CHAIN; \
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(bn)->prev = ch_buftail; \
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ch_buftail->next = (bn); \
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ch_buftail = (bn);
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/*
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* Macros to manipulate the list of buffers in thisfile->hashtbl[n].
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*/
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#define FOR_BUFS_IN_CHAIN(h,bn) \
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for (bn = thisfile->hashtbl[h].hnext; \
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bn != END_OF_HCHAIN(h); bn = bn->hnext)
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#define BUF_HASH_RM(bn) \
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(bn)->hnext->hprev = (bn)->hprev; \
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(bn)->hprev->hnext = (bn)->hnext;
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#define BUF_HASH_INS(bn,h) \
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(bn)->hnext = thisfile->hashtbl[h].hnext; \
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(bn)->hprev = END_OF_HCHAIN(h); \
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thisfile->hashtbl[h].hnext->hprev = (bn); \
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thisfile->hashtbl[h].hnext = (bn);
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static struct filestate *thisfile;
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static int ch_ungotchar = -1;
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static int maxbufs = -1;
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extern int autobuf;
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extern int sigs;
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extern int secure;
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extern int screen_trashed;
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extern int follow_mode;
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extern constant char helpdata[];
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extern constant int size_helpdata;
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extern IFILE curr_ifile;
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#if LOGFILE
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extern int logfile;
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extern char *namelogfile;
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#endif
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static int ch_addbuf();
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/*
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* Get the character pointed to by the read pointer.
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*/
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int
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ch_get()
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{
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register struct buf *bp;
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register struct bufnode *bn;
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register int n;
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register int slept;
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register int h;
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POSITION pos;
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POSITION len;
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if (thisfile == NULL)
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return (EOI);
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/*
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* Quick check for the common case where
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* the desired char is in the head buffer.
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*/
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if (ch_bufhead != END_OF_CHAIN)
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{
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bp = bufnode_buf(ch_bufhead);
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if (ch_block == bp->block && ch_offset < bp->datasize)
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return bp->data[ch_offset];
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}
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slept = FALSE;
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/*
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* Look for a buffer holding the desired block.
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*/
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h = BUFHASH(ch_block);
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FOR_BUFS_IN_CHAIN(h, bn)
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{
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bp = bufnode_buf(bn);
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if (bp->block == ch_block)
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{
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if (ch_offset >= bp->datasize)
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/*
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* Need more data in this buffer.
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*/
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break;
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goto found;
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}
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}
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if (bn == END_OF_HCHAIN(h))
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{
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/*
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* Block is not in a buffer.
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* Take the least recently used buffer
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* and read the desired block into it.
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* If the LRU buffer has data in it,
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* then maybe allocate a new buffer.
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*/
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if (ch_buftail == END_OF_CHAIN ||
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bufnode_buf(ch_buftail)->block != -1)
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{
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/*
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* There is no empty buffer to use.
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* Allocate a new buffer if:
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* 1. We can't seek on this file and -b is not in effect; or
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* 2. We haven't allocated the max buffers for this file yet.
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*/
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if ((autobuf && !(ch_flags & CH_CANSEEK)) ||
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(maxbufs < 0 || ch_nbufs < maxbufs))
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if (ch_addbuf())
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/*
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* Allocation failed: turn off autobuf.
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*/
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autobuf = OPT_OFF;
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}
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bn = ch_buftail;
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bp = bufnode_buf(bn);
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BUF_HASH_RM(bn); /* Remove from old hash chain. */
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bp->block = ch_block;
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bp->datasize = 0;
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BUF_HASH_INS(bn, h); /* Insert into new hash chain. */
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}
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read_more:
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pos = (ch_block * LBUFSIZE) + bp->datasize;
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if ((len = ch_length()) != NULL_POSITION && pos >= len)
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/*
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* At end of file.
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*/
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return (EOI);
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if (pos != ch_fpos)
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{
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/*
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* Not at the correct position: must seek.
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* If input is a pipe, we're in trouble (can't seek on a pipe).
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* Some data has been lost: just return "?".
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*/
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if (!(ch_flags & CH_CANSEEK))
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return ('?');
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if (lseek(ch_file, (off_t)pos, SEEK_SET) == BAD_LSEEK)
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{
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error("seek error", NULL_PARG);
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clear_eol();
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return (EOI);
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}
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ch_fpos = pos;
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}
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/*
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* Read the block.
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* If we read less than a full block, that's ok.
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* We use partial block and pick up the rest next time.
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*/
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if (ch_ungotchar != -1)
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{
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bp->data[bp->datasize] = ch_ungotchar;
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n = 1;
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ch_ungotchar = -1;
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} else if (ch_flags & CH_HELPFILE)
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{
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bp->data[bp->datasize] = helpdata[ch_fpos];
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n = 1;
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} else
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{
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n = iread(ch_file, &bp->data[bp->datasize],
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(unsigned int)(LBUFSIZE - bp->datasize));
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}
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if (n == READ_INTR)
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return (EOI);
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if (n < 0)
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{
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#if MSDOS_COMPILER==WIN32C
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if (errno != EPIPE)
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#endif
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{
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error("read error", NULL_PARG);
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clear_eol();
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}
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n = 0;
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}
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#if LOGFILE
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/*
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* If we have a log file, write the new data to it.
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*/
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if (!secure && logfile >= 0 && n > 0)
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write(logfile, (char *) &bp->data[bp->datasize], n);
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#endif
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ch_fpos += n;
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bp->datasize += n;
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/*
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* If we have read to end of file, set ch_fsize to indicate
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* the position of the end of file.
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*/
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if (n == 0)
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{
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ch_fsize = pos;
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if (ignore_eoi)
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{
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/*
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* We are ignoring EOF.
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* Wait a while, then try again.
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*/
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if (!slept)
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{
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PARG parg;
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parg.p_string = wait_message();
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ierror("%s", &parg);
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}
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#if !MSDOS_COMPILER
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sleep(1);
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#else
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#if MSDOS_COMPILER==WIN32C
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Sleep(1000);
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#endif
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#endif
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slept = TRUE;
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#if HAVE_STAT_INO
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if (follow_mode == FOLLOW_NAME)
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{
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/* See whether the file's i-number has changed.
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* If so, force the file to be closed and
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* reopened. */
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struct stat st;
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int r = stat(get_filename(curr_ifile), &st);
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if (r == 0 && (st.st_ino != curr_ino ||
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st.st_dev != curr_dev))
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{
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/* screen_trashed=2 causes
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* make_display to reopen the file. */
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screen_trashed = 2;
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return (EOI);
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}
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}
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#endif
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}
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if (sigs)
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return (EOI);
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}
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found:
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if (ch_bufhead != bn)
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{
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/*
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* Move the buffer to the head of the buffer chain.
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* This orders the buffer chain, most- to least-recently used.
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*/
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BUF_RM(bn);
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BUF_INS_HEAD(bn);
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/*
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* Move to head of hash chain too.
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*/
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BUF_HASH_RM(bn);
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BUF_HASH_INS(bn, h);
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}
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if (ch_offset >= bp->datasize)
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/*
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* After all that, we still don't have enough data.
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* Go back and try again.
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*/
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goto read_more;
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return (bp->data[ch_offset]);
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}
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/*
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* ch_ungetchar is a rather kludgy and limited way to push
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* a single char onto an input file descriptor.
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*/
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public void
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ch_ungetchar(c)
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int c;
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{
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if (c != -1 && ch_ungotchar != -1)
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error("ch_ungetchar overrun", NULL_PARG);
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ch_ungotchar = c;
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}
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#if LOGFILE
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/*
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* Close the logfile.
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* If we haven't read all of standard input into it, do that now.
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*/
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public void
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end_logfile()
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{
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static int tried = FALSE;
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if (logfile < 0)
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return;
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if (!tried && ch_fsize == NULL_POSITION)
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{
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tried = TRUE;
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ierror("Finishing logfile", NULL_PARG);
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while (ch_forw_get() != EOI)
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if (ABORT_SIGS())
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break;
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}
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close(logfile);
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logfile = -1;
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namelogfile = NULL;
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}
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/*
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* Start a log file AFTER less has already been running.
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* Invoked from the - command; see toggle_option().
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* Write all the existing buffered data to the log file.
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*/
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public void
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sync_logfile()
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{
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register struct buf *bp;
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register struct bufnode *bn;
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int warned = FALSE;
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BLOCKNUM block;
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BLOCKNUM nblocks;
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nblocks = (ch_fpos + LBUFSIZE - 1) / LBUFSIZE;
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for (block = 0; block < nblocks; block++)
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{
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int wrote = FALSE;
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FOR_BUFS(bn)
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{
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bp = bufnode_buf(bn);
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if (bp->block == block)
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{
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write(logfile, (char *) bp->data, bp->datasize);
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wrote = TRUE;
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break;
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}
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}
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if (!wrote && !warned)
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{
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error("Warning: log file is incomplete",
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NULL_PARG);
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warned = TRUE;
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}
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}
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}
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#endif
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/*
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* Determine if a specific block is currently in one of the buffers.
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*/
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static int
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buffered(block)
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BLOCKNUM block;
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{
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register struct buf *bp;
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register struct bufnode *bn;
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register int h;
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h = BUFHASH(block);
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FOR_BUFS_IN_CHAIN(h, bn)
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{
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bp = bufnode_buf(bn);
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if (bp->block == block)
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return (TRUE);
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}
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return (FALSE);
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}
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/*
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* Seek to a specified position in the file.
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* Return 0 if successful, non-zero if can't seek there.
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*/
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public int
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ch_seek(pos)
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register POSITION pos;
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{
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BLOCKNUM new_block;
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POSITION len;
|
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if (thisfile == NULL)
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return (0);
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len = ch_length();
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if (pos < ch_zero() || (len != NULL_POSITION && pos > len))
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return (1);
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new_block = pos / LBUFSIZE;
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if (!(ch_flags & CH_CANSEEK) && pos != ch_fpos && !buffered(new_block))
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{
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if (ch_fpos > pos)
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return (1);
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while (ch_fpos < pos)
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|
{
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if (ch_forw_get() == EOI)
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return (1);
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if (ABORT_SIGS())
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return (1);
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}
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return (0);
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}
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/*
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* Set read pointer.
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*/
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ch_block = new_block;
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ch_offset = pos % LBUFSIZE;
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return (0);
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}
|
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|
|
/*
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* Seek to the end of the file.
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*/
|
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public int
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ch_end_seek()
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{
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POSITION len;
|
|
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if (thisfile == NULL)
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return (0);
|
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|
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if (ch_flags & CH_CANSEEK)
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ch_fsize = filesize(ch_file);
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len = ch_length();
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if (len != NULL_POSITION)
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return (ch_seek(len));
|
|
|
|
/*
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* Do it the slow way: read till end of data.
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|
*/
|
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while (ch_forw_get() != EOI)
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|
if (ABORT_SIGS())
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return (1);
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return (0);
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}
|
|
|
|
/*
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* Seek to the beginning of the file, or as close to it as we can get.
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* We may not be able to seek there if input is a pipe and the
|
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* beginning of the pipe is no longer buffered.
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*/
|
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public int
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ch_beg_seek()
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|
{
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register struct bufnode *bn;
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register struct bufnode *firstbn;
|
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|
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/*
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* Try a plain ch_seek first.
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|
*/
|
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if (ch_seek(ch_zero()) == 0)
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return (0);
|
|
|
|
/*
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* Can't get to position 0.
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|
* Look thru the buffers for the one closest to position 0.
|
|
*/
|
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firstbn = ch_bufhead;
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if (firstbn == END_OF_CHAIN)
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return (1);
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FOR_BUFS(bn)
|
|
{
|
|
if (bufnode_buf(bn)->block < bufnode_buf(firstbn)->block)
|
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firstbn = bn;
|
|
}
|
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ch_block = bufnode_buf(firstbn)->block;
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ch_offset = 0;
|
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return (0);
|
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}
|
|
|
|
/*
|
|
* Return the length of the file, if known.
|
|
*/
|
|
public POSITION
|
|
ch_length()
|
|
{
|
|
if (thisfile == NULL)
|
|
return (NULL_POSITION);
|
|
if (ignore_eoi)
|
|
return (NULL_POSITION);
|
|
if (ch_flags & CH_HELPFILE)
|
|
return (size_helpdata);
|
|
return (ch_fsize);
|
|
}
|
|
|
|
/*
|
|
* Return the current position in the file.
|
|
*/
|
|
public POSITION
|
|
ch_tell()
|
|
{
|
|
if (thisfile == NULL)
|
|
return (NULL_POSITION);
|
|
return (ch_block * LBUFSIZE) + ch_offset;
|
|
}
|
|
|
|
/*
|
|
* Get the current char and post-increment the read pointer.
|
|
*/
|
|
public int
|
|
ch_forw_get()
|
|
{
|
|
register int c;
|
|
|
|
if (thisfile == NULL)
|
|
return (EOI);
|
|
c = ch_get();
|
|
if (c == EOI)
|
|
return (EOI);
|
|
if (ch_offset < LBUFSIZE-1)
|
|
ch_offset++;
|
|
else
|
|
{
|
|
ch_block ++;
|
|
ch_offset = 0;
|
|
}
|
|
return (c);
|
|
}
|
|
|
|
/*
|
|
* Pre-decrement the read pointer and get the new current char.
|
|
*/
|
|
public int
|
|
ch_back_get()
|
|
{
|
|
if (thisfile == NULL)
|
|
return (EOI);
|
|
if (ch_offset > 0)
|
|
ch_offset --;
|
|
else
|
|
{
|
|
if (ch_block <= 0)
|
|
return (EOI);
|
|
if (!(ch_flags & CH_CANSEEK) && !buffered(ch_block-1))
|
|
return (EOI);
|
|
ch_block--;
|
|
ch_offset = LBUFSIZE-1;
|
|
}
|
|
return (ch_get());
|
|
}
|
|
|
|
/*
|
|
* Set max amount of buffer space.
|
|
* bufspace is in units of 1024 bytes. -1 mean no limit.
|
|
*/
|
|
public void
|
|
ch_setbufspace(bufspace)
|
|
int bufspace;
|
|
{
|
|
if (bufspace < 0)
|
|
maxbufs = -1;
|
|
else
|
|
{
|
|
maxbufs = ((bufspace * 1024) + LBUFSIZE-1) / LBUFSIZE;
|
|
if (maxbufs < 1)
|
|
maxbufs = 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Flush (discard) any saved file state, including buffer contents.
|
|
*/
|
|
public void
|
|
ch_flush()
|
|
{
|
|
register struct bufnode *bn;
|
|
|
|
if (thisfile == NULL)
|
|
return;
|
|
|
|
if (!(ch_flags & CH_CANSEEK))
|
|
{
|
|
/*
|
|
* If input is a pipe, we don't flush buffer contents,
|
|
* since the contents can't be recovered.
|
|
*/
|
|
ch_fsize = NULL_POSITION;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Initialize all the buffers.
|
|
*/
|
|
FOR_BUFS(bn)
|
|
{
|
|
bufnode_buf(bn)->block = -1;
|
|
}
|
|
|
|
/*
|
|
* Figure out the size of the file, if we can.
|
|
*/
|
|
ch_fsize = filesize(ch_file);
|
|
|
|
/*
|
|
* Seek to a known position: the beginning of the file.
|
|
*/
|
|
ch_fpos = 0;
|
|
ch_block = 0; /* ch_fpos / LBUFSIZE; */
|
|
ch_offset = 0; /* ch_fpos % LBUFSIZE; */
|
|
|
|
#if 1
|
|
/*
|
|
* This is a kludge to workaround a Linux kernel bug: files in
|
|
* /proc have a size of 0 according to fstat() but have readable
|
|
* data. They are sometimes, but not always, seekable.
|
|
* Force them to be non-seekable here.
|
|
*/
|
|
if (ch_fsize == 0)
|
|
{
|
|
ch_fsize = NULL_POSITION;
|
|
ch_flags &= ~CH_CANSEEK;
|
|
}
|
|
#endif
|
|
|
|
if (lseek(ch_file, (off_t)0, SEEK_SET) == BAD_LSEEK)
|
|
{
|
|
/*
|
|
* Warning only; even if the seek fails for some reason,
|
|
* there's a good chance we're at the beginning anyway.
|
|
* {{ I think this is bogus reasoning. }}
|
|
*/
|
|
error("seek error to 0", NULL_PARG);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate a new buffer.
|
|
* The buffer is added to the tail of the buffer chain.
|
|
*/
|
|
static int
|
|
ch_addbuf()
|
|
{
|
|
register struct buf *bp;
|
|
register struct bufnode *bn;
|
|
|
|
/*
|
|
* Allocate and initialize a new buffer and link it
|
|
* onto the tail of the buffer list.
|
|
*/
|
|
bp = (struct buf *) calloc(1, sizeof(struct buf));
|
|
if (bp == NULL)
|
|
return (1);
|
|
ch_nbufs++;
|
|
bp->block = -1;
|
|
bn = &bp->node;
|
|
|
|
BUF_INS_TAIL(bn);
|
|
BUF_HASH_INS(bn, 0);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
*
|
|
*/
|
|
static void
|
|
init_hashtbl()
|
|
{
|
|
register int h;
|
|
|
|
for (h = 0; h < BUFHASH_SIZE; h++)
|
|
{
|
|
thisfile->hashtbl[h].hnext = END_OF_HCHAIN(h);
|
|
thisfile->hashtbl[h].hprev = END_OF_HCHAIN(h);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Delete all buffers for this file.
|
|
*/
|
|
static void
|
|
ch_delbufs()
|
|
{
|
|
register struct bufnode *bn;
|
|
|
|
while (ch_bufhead != END_OF_CHAIN)
|
|
{
|
|
bn = ch_bufhead;
|
|
BUF_RM(bn);
|
|
free(bufnode_buf(bn));
|
|
}
|
|
ch_nbufs = 0;
|
|
init_hashtbl();
|
|
}
|
|
|
|
/*
|
|
* Is it possible to seek on a file descriptor?
|
|
*/
|
|
public int
|
|
seekable(f)
|
|
int f;
|
|
{
|
|
#if MSDOS_COMPILER
|
|
extern int fd0;
|
|
if (f == fd0 && !isatty(fd0))
|
|
{
|
|
/*
|
|
* In MS-DOS, pipes are seekable. Check for
|
|
* standard input, and pretend it is not seekable.
|
|
*/
|
|
return (0);
|
|
}
|
|
#endif
|
|
return (lseek(f, (off_t)1, SEEK_SET) != BAD_LSEEK);
|
|
}
|
|
|
|
/*
|
|
* Initialize file state for a new file.
|
|
*/
|
|
public void
|
|
ch_init(f, flags)
|
|
int f;
|
|
int flags;
|
|
{
|
|
/*
|
|
* See if we already have a filestate for this file.
|
|
*/
|
|
thisfile = (struct filestate *) get_filestate(curr_ifile);
|
|
if (thisfile == NULL)
|
|
{
|
|
/*
|
|
* Allocate and initialize a new filestate.
|
|
*/
|
|
thisfile = (struct filestate *)
|
|
calloc(1, sizeof(struct filestate));
|
|
thisfile->buflist.next = thisfile->buflist.prev = END_OF_CHAIN;
|
|
thisfile->nbufs = 0;
|
|
thisfile->flags = 0;
|
|
thisfile->fpos = 0;
|
|
thisfile->block = 0;
|
|
thisfile->offset = 0;
|
|
thisfile->file = -1;
|
|
thisfile->fsize = NULL_POSITION;
|
|
ch_flags = flags;
|
|
init_hashtbl();
|
|
/*
|
|
* Try to seek; set CH_CANSEEK if it works.
|
|
*/
|
|
if ((flags & CH_CANSEEK) && !seekable(f))
|
|
ch_flags &= ~CH_CANSEEK;
|
|
set_filestate(curr_ifile, (void *) thisfile);
|
|
}
|
|
if (thisfile->file == -1)
|
|
thisfile->file = f;
|
|
ch_flush();
|
|
}
|
|
|
|
/*
|
|
* Close a filestate.
|
|
*/
|
|
public void
|
|
ch_close()
|
|
{
|
|
int keepstate = FALSE;
|
|
|
|
if (thisfile == NULL)
|
|
return;
|
|
|
|
if (ch_flags & (CH_CANSEEK|CH_POPENED|CH_HELPFILE))
|
|
{
|
|
/*
|
|
* We can seek or re-open, so we don't need to keep buffers.
|
|
*/
|
|
ch_delbufs();
|
|
} else
|
|
keepstate = TRUE;
|
|
if (!(ch_flags & CH_KEEPOPEN))
|
|
{
|
|
/*
|
|
* We don't need to keep the file descriptor open
|
|
* (because we can re-open it.)
|
|
* But don't really close it if it was opened via popen(),
|
|
* because pclose() wants to close it.
|
|
*/
|
|
if (!(ch_flags & (CH_POPENED|CH_HELPFILE)))
|
|
close(ch_file);
|
|
ch_file = -1;
|
|
} else
|
|
keepstate = TRUE;
|
|
if (!keepstate)
|
|
{
|
|
/*
|
|
* We don't even need to keep the filestate structure.
|
|
*/
|
|
free(thisfile);
|
|
thisfile = NULL;
|
|
set_filestate(curr_ifile, (void *) NULL);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Return ch_flags for the current file.
|
|
*/
|
|
public int
|
|
ch_getflags()
|
|
{
|
|
if (thisfile == NULL)
|
|
return (0);
|
|
return (ch_flags);
|
|
}
|
|
|
|
#if 0
|
|
public void
|
|
ch_dump(struct filestate *fs)
|
|
{
|
|
struct buf *bp;
|
|
struct bufnode *bn;
|
|
unsigned char *s;
|
|
|
|
if (fs == NULL)
|
|
{
|
|
printf(" --no filestate\n");
|
|
return;
|
|
}
|
|
printf(" file %d, flags %x, fpos %x, fsize %x, blk/off %x/%x\n",
|
|
fs->file, fs->flags, fs->fpos,
|
|
fs->fsize, fs->block, fs->offset);
|
|
printf(" %d bufs:\n", fs->nbufs);
|
|
for (bn = fs->next; bn != &fs->buflist; bn = bn->next)
|
|
{
|
|
bp = bufnode_buf(bn);
|
|
printf("%x: blk %x, size %x \"",
|
|
bp, bp->block, bp->datasize);
|
|
for (s = bp->data; s < bp->data + 30; s++)
|
|
if (*s >= ' ' && *s < 0x7F)
|
|
printf("%c", *s);
|
|
else
|
|
printf(".");
|
|
printf("\"\n");
|
|
}
|
|
}
|
|
#endif
|