/* * Copyright (C) 1984-2012 Mark Nudelman * Modified for use with illumos by Garrett D'Amore. * Copyright 2014 Garrett D'Amore * * You may distribute under the terms of either the GNU General Public * License or the Less License, as specified in the README file. * * For more information, see the README file. */ /* * Low level character input from the input file. * We use these special purpose routines which optimize moving * both forward and backward from the current read pointer. */ #include "less.h" #include extern dev_t curr_dev; extern ino_t curr_ino; extern int less_is_more; typedef off_t BLOCKNUM; int ignore_eoi; /* * Pool of buffers holding the most recently used blocks of the input file. * The buffer pool is kept as a doubly-linked circular list, * in order from most- to least-recently used. * The circular list is anchored by the file state "thisfile". */ struct bufnode { struct bufnode *next, *prev; struct bufnode *hnext, *hprev; }; #define LBUFSIZE 8192 struct buf { struct bufnode node; BLOCKNUM block; unsigned int datasize; unsigned char data[LBUFSIZE]; }; #define bufnode_buf(bn) ((struct buf *)bn) /* * The file state is maintained in a filestate structure. * A pointer to the filestate is kept in the ifile structure. */ #define BUFHASH_SIZE 64 struct filestate { struct bufnode buflist; struct bufnode hashtbl[BUFHASH_SIZE]; int file; int flags; off_t fpos; int nbufs; BLOCKNUM block; unsigned int offset; off_t fsize; }; #define ch_bufhead thisfile->buflist.next #define ch_buftail thisfile->buflist.prev #define ch_nbufs thisfile->nbufs #define ch_block thisfile->block #define ch_offset thisfile->offset #define ch_fpos thisfile->fpos #define ch_fsize thisfile->fsize #define ch_flags thisfile->flags #define ch_file thisfile->file #define END_OF_CHAIN (&thisfile->buflist) #define END_OF_HCHAIN(h) (&thisfile->hashtbl[h]) #define BUFHASH(blk) ((blk) & (BUFHASH_SIZE-1)) /* * Macros to manipulate the list of buffers in thisfile->buflist. */ #define FOR_BUFS(bn) \ for ((bn) = ch_bufhead; (bn) != END_OF_CHAIN; (bn) = (bn)->next) #define BUF_RM(bn) \ (bn)->next->prev = (bn)->prev; \ (bn)->prev->next = (bn)->next; #define BUF_INS_HEAD(bn) \ (bn)->next = ch_bufhead; \ (bn)->prev = END_OF_CHAIN; \ ch_bufhead->prev = (bn); \ ch_bufhead = (bn); #define BUF_INS_TAIL(bn) \ (bn)->next = END_OF_CHAIN; \ (bn)->prev = ch_buftail; \ ch_buftail->next = (bn); \ ch_buftail = (bn); /* * Macros to manipulate the list of buffers in thisfile->hashtbl[n]. */ #define FOR_BUFS_IN_CHAIN(h, bn) \ for (bn = thisfile->hashtbl[h].hnext; \ bn != END_OF_HCHAIN(h); bn = bn->hnext) #define BUF_HASH_RM(bn) \ (bn)->hnext->hprev = (bn)->hprev; \ (bn)->hprev->hnext = (bn)->hnext; #define BUF_HASH_INS(bn, h) \ (bn)->hnext = thisfile->hashtbl[h].hnext; \ (bn)->hprev = END_OF_HCHAIN(h); \ thisfile->hashtbl[h].hnext->hprev = (bn); \ thisfile->hashtbl[h].hnext = (bn); static struct filestate *thisfile; static int ch_ungotchar = -1; static int maxbufs = -1; extern int autobuf; extern volatile sig_atomic_t sigs; extern int secure; extern int screen_trashed; extern int follow_mode; extern IFILE curr_ifile; extern int logfile; extern char *namelogfile; static int ch_addbuf(void); /* * Get the character pointed to by the read pointer. */ int ch_get(void) { struct buf *bp; struct bufnode *bn; int n; int slept; int h; off_t pos; off_t len; if (thisfile == NULL) return (EOI); /* * Quick check for the common case where * the desired char is in the head buffer. */ if (ch_bufhead != END_OF_CHAIN) { bp = bufnode_buf(ch_bufhead); if (ch_block == bp->block && ch_offset < bp->datasize) return (bp->data[ch_offset]); } slept = FALSE; /* * Look for a buffer holding the desired block. */ h = BUFHASH(ch_block); FOR_BUFS_IN_CHAIN(h, bn) { bp = bufnode_buf(bn); if (bp->block == ch_block) { if (ch_offset >= bp->datasize) /* * Need more data in this buffer. */ break; goto found; } } if (bn == END_OF_HCHAIN(h)) { /* * Block is not in a buffer. * Take the least recently used buffer * and read the desired block into it. * If the LRU buffer has data in it, * then maybe allocate a new buffer. */ if (ch_buftail == END_OF_CHAIN || bufnode_buf(ch_buftail)->block != -1) { /* * There is no empty buffer to use. * Allocate a new buffer if: * 1. We can't seek on this file and -b is not in * effect; or * 2. We haven't allocated the max buffers for this * file yet. */ if ((autobuf && !(ch_flags & CH_CANSEEK)) || (maxbufs < 0 || ch_nbufs < maxbufs)) if (ch_addbuf()) /* * Allocation failed: turn off autobuf. */ autobuf = OPT_OFF; } bn = ch_buftail; bp = bufnode_buf(bn); BUF_HASH_RM(bn); /* Remove from old hash chain. */ bp->block = ch_block; bp->datasize = 0; BUF_HASH_INS(bn, h); /* Insert into new hash chain. */ } read_more: pos = (ch_block * LBUFSIZE) + bp->datasize; if ((len = ch_length()) != -1 && pos >= len) /* * At end of file. */ return (EOI); if (pos != ch_fpos) { /* * Not at the correct position: must seek. * If input is a pipe, we're in trouble (can't seek on a pipe). * Some data has been lost: just return "?". */ if (!(ch_flags & CH_CANSEEK)) return ('?'); if (lseek(ch_file, (off_t)pos, SEEK_SET) == (off_t)-1) { error("seek error", NULL); clear_eol(); return (EOI); } ch_fpos = pos; } /* * Read the block. * If we read less than a full block, that's ok. * We use partial block and pick up the rest next time. */ if (ch_ungotchar != -1) { bp->data[bp->datasize] = (unsigned char)ch_ungotchar; n = 1; ch_ungotchar = -1; } else { n = iread(ch_file, &bp->data[bp->datasize], (unsigned int)(LBUFSIZE - bp->datasize)); } if (n == READ_INTR) return (EOI); if (n < 0) { error("read error", NULL); clear_eol(); n = 0; } /* * If we have a log file, write the new data to it. */ if (!secure && logfile >= 0 && n > 0) (void) write(logfile, (char *)&bp->data[bp->datasize], n); ch_fpos += n; bp->datasize += n; /* * If we have read to end of file, set ch_fsize to indicate * the position of the end of file. */ if (n == 0) { ch_fsize = pos; if (ignore_eoi) { /* * We are ignoring EOF. * Wait a while, then try again. */ if (!slept) { PARG parg; parg.p_string = wait_message(); ierror("%s", &parg); } sleep(1); slept = TRUE; if (follow_mode == FOLLOW_NAME) { /* * See whether the file's i-number has changed. * If so, force the file to be closed and * reopened. */ struct stat st; int r = stat(get_filename(curr_ifile), &st); if (r == 0 && (st.st_ino != curr_ino || st.st_dev != curr_dev)) { /* * screen_trashed=2 causes * make_display to reopen the file. */ screen_trashed = 2; return (EOI); } } } if (sigs) return (EOI); } found: if (ch_bufhead != bn) { /* * Move the buffer to the head of the buffer chain. * This orders the buffer chain, most- to least-recently used. */ BUF_RM(bn); BUF_INS_HEAD(bn); /* * Move to head of hash chain too. */ BUF_HASH_RM(bn); BUF_HASH_INS(bn, h); } if (ch_offset >= bp->datasize) /* * After all that, we still don't have enough data. * Go back and try again. */ goto read_more; return (bp->data[ch_offset]); } /* * ch_ungetchar is a rather kludgy and limited way to push * a single char onto an input file descriptor. */ void ch_ungetchar(int c) { if (c != -1 && ch_ungotchar != -1) error("ch_ungetchar overrun", NULL); ch_ungotchar = c; } /* * Close the logfile. * If we haven't read all of standard input into it, do that now. */ void end_logfile(void) { static int tried = FALSE; if (logfile < 0) return; if (!tried && ch_fsize == -1) { tried = TRUE; ierror("Finishing logfile", NULL); while (ch_forw_get() != EOI) if (ABORT_SIGS()) break; } close(logfile); logfile = -1; namelogfile = NULL; } /* * Start a log file AFTER less has already been running. * Invoked from the - command; see toggle_option(). * Write all the existing buffered data to the log file. */ void sync_logfile(void) { struct buf *bp; struct bufnode *bn; int warned = FALSE; BLOCKNUM block; BLOCKNUM nblocks; nblocks = (ch_fpos + LBUFSIZE - 1) / LBUFSIZE; for (block = 0; block < nblocks; block++) { int wrote = FALSE; FOR_BUFS(bn) { bp = bufnode_buf(bn); if (bp->block == block) { (void) write(logfile, (char *)bp->data, bp->datasize); wrote = TRUE; break; } } if (!wrote && !warned) { error("Warning: log file is incomplete", NULL); warned = TRUE; } } } /* * Determine if a specific block is currently in one of the buffers. */ static int buffered(BLOCKNUM block) { struct buf *bp; struct bufnode *bn; int h; h = BUFHASH(block); FOR_BUFS_IN_CHAIN(h, bn) { bp = bufnode_buf(bn); if (bp->block == block) return (TRUE); } return (FALSE); } /* * Seek to a specified position in the file. * Return 0 if successful, non-zero if can't seek there. */ int ch_seek(off_t pos) { BLOCKNUM new_block; off_t len; if (thisfile == NULL) return (0); len = ch_length(); if (pos < ch_zero() || (len != -1 && pos > len)) return (1); new_block = pos / LBUFSIZE; if (!(ch_flags & CH_CANSEEK) && pos != ch_fpos && !buffered(new_block)) { if (ch_fpos > pos) return (1); while (ch_fpos < pos) { if (ch_forw_get() == EOI) return (1); if (ABORT_SIGS()) return (1); } return (0); } /* * Set read pointer. */ ch_block = new_block; ch_offset = pos % LBUFSIZE; return (0); } /* * Seek to the end of the file. */ int ch_end_seek(void) { off_t len; if (thisfile == NULL) return (0); if (ch_flags & CH_CANSEEK) ch_fsize = filesize(ch_file); len = ch_length(); if (len != -1) return (ch_seek(len)); /* * Do it the slow way: read till end of data. */ while (ch_forw_get() != EOI) if (ABORT_SIGS()) return (1); return (0); } /* * Seek to the beginning of the file, or as close to it as we can get. * We may not be able to seek there if input is a pipe and the * beginning of the pipe is no longer buffered. */ int ch_beg_seek(void) { struct bufnode *bn; struct bufnode *firstbn; /* * Try a plain ch_seek first. */ if (ch_seek(ch_zero()) == 0) return (0); /* * Can't get to position 0. * Look thru the buffers for the one closest to position 0. */ firstbn = ch_bufhead; if (firstbn == END_OF_CHAIN) return (1); FOR_BUFS(bn) { if (bufnode_buf(bn)->block < bufnode_buf(firstbn)->block) firstbn = bn; } ch_block = bufnode_buf(firstbn)->block; ch_offset = 0; return (0); } /* * Return the length of the file, if known. */ off_t ch_length(void) { if (thisfile == NULL) return (-1); if (ignore_eoi) return (-1); if (ch_flags & CH_NODATA) return (0); return (ch_fsize); } /* * Return the current position in the file. */ off_t ch_tell(void) { if (thisfile == NULL) return (-1); return ((ch_block * LBUFSIZE) + ch_offset); } /* * Get the current char and post-increment the read pointer. */ int ch_forw_get(void) { 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. */ int ch_back_get(void) { 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. */ void ch_setbufspace(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. */ void ch_flush(void) { 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 = -1; 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 = -1; ch_flags &= ~CH_CANSEEK; } #endif if (lseek(ch_file, (off_t)0, SEEK_SET) == (off_t)-1) { /* * 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); } } /* * Allocate a new buffer. * The buffer is added to the tail of the buffer chain. */ static int ch_addbuf(void) { struct buf *bp; struct bufnode *bn; /* * Allocate and initialize a new buffer and link it * onto the tail of the buffer list. */ bp = 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(void) { 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(void) { 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? */ int seekable(int f) { return (lseek(f, (off_t)1, SEEK_SET) != (off_t)-1); } /* * Force EOF to be at the current read position. * This is used after an ignore_eof read, during which the EOF may change. */ void ch_set_eof(void) { ch_fsize = ch_fpos; } /* * Initialize file state for a new file. */ void ch_init(int f, int flags) { /* * See if we already have a filestate for this file. */ thisfile = get_filestate(curr_ifile); if (thisfile == NULL) { /* * Allocate and initialize a new filestate. */ thisfile = 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 = -1; 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. */ void ch_close(void) { 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)) 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, NULL); } } /* * Return ch_flags for the current file. */ int ch_getflags(void) { if (thisfile == NULL) return (0); return (ch_flags); }