diff options
author | Lorry Tar Creator <lorry-tar-importer@baserock.org> | 2012-07-21 20:40:00 +0000 |
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committer | Lorry <lorry@roadtrain.codethink.co.uk> | 2012-09-24 16:52:48 +0000 |
commit | 09a405d8f652b56944c93ebf5c673cdfe5319b04 (patch) | |
tree | 9cc4518b0a21096735b20ac3204a6fa032f1c566 /ch.c | |
download | less-master.tar.gz |
Imported from /srv/lorry/lorry-area/less/less-451.tar.gz.HEADless-451masterbaserock/morph
Diffstat (limited to 'ch.c')
-rwxr-xr-x | ch.c | 945 |
1 files changed, 945 insertions, 0 deletions
@@ -0,0 +1,945 @@ +/* + * Copyright (C) 1984-2012 Mark Nudelman + * + * 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" +#if MSDOS_COMPILER==WIN32C +#include <errno.h> +#include <windows.h> +#endif + +#if HAVE_STAT_INO +#include <sys/stat.h> +extern dev_t curr_dev; +extern ino_t curr_ino; +#endif + +typedef POSITION BLOCKNUM; + +public 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; + POSITION fpos; + int nbufs; + BLOCKNUM block; + unsigned int offset; + POSITION 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 int sigs; +extern int secure; +extern int screen_trashed; +extern int follow_mode; +extern constant char helpdata[]; +extern constant int size_helpdata; +extern IFILE curr_ifile; +#if LOGFILE +extern int logfile; +extern char *namelogfile; +#endif + +static int ch_addbuf(); + + +/* + * Get the character pointed to by the read pointer. + */ + int +ch_get() +{ + register struct buf *bp; + register struct bufnode *bn; + register int n; + register int slept; + register int h; + POSITION pos; + POSITION 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()) != NULL_POSITION && 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) == BAD_LSEEK) + { + error("seek error", NULL_PARG); + 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] = ch_ungotchar; + n = 1; + ch_ungotchar = -1; + } else if (ch_flags & CH_HELPFILE) + { + bp->data[bp->datasize] = helpdata[ch_fpos]; + n = 1; + } else + { + n = iread(ch_file, &bp->data[bp->datasize], + (unsigned int)(LBUFSIZE - bp->datasize)); + } + + if (n == READ_INTR) + return (EOI); + if (n < 0) + { +#if MSDOS_COMPILER==WIN32C + if (errno != EPIPE) +#endif + { + error("read error", NULL_PARG); + clear_eol(); + } + n = 0; + } + +#if LOGFILE + /* + * If we have a log file, write the new data to it. + */ + if (!secure && logfile >= 0 && n > 0) + write(logfile, (char *) &bp->data[bp->datasize], n); +#endif + + 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); + } +#if !MSDOS_COMPILER + sleep(1); +#else +#if MSDOS_COMPILER==WIN32C + Sleep(1000); +#endif +#endif + slept = TRUE; + +#if HAVE_STAT_INO + 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); + } + } +#endif + } + 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. + */ + public void +ch_ungetchar(c) + int c; +{ + if (c != -1 && ch_ungotchar != -1) + error("ch_ungetchar overrun", NULL_PARG); + ch_ungotchar = c; +} + +#if LOGFILE +/* + * Close the logfile. + * If we haven't read all of standard input into it, do that now. + */ + public void +end_logfile() +{ + static int tried = FALSE; + + if (logfile < 0) + return; + if (!tried && ch_fsize == NULL_POSITION) + { + tried = TRUE; + ierror("Finishing logfile", NULL_PARG); + 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. + */ + public void +sync_logfile() +{ + register struct buf *bp; + register 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) + { + write(logfile, (char *) bp->data, bp->datasize); + wrote = TRUE; + break; + } + } + if (!wrote && !warned) + { + error("Warning: log file is incomplete", + NULL_PARG); + warned = TRUE; + } + } +} + +#endif + +/* + * Determine if a specific block is currently in one of the buffers. + */ + static int +buffered(block) + BLOCKNUM block; +{ + register struct buf *bp; + register struct bufnode *bn; + register 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. + */ + public int +ch_seek(pos) + register POSITION pos; +{ + BLOCKNUM new_block; + POSITION len; + + if (thisfile == NULL) + return (0); + + len = ch_length(); + if (pos < ch_zero() || (len != NULL_POSITION && 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. + */ + public int +ch_end_seek() +{ + POSITION len; + + if (thisfile == NULL) + return (0); + + if (ch_flags & CH_CANSEEK) + ch_fsize = filesize(ch_file); + + len = ch_length(); + if (len != NULL_POSITION) + 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. + */ + public int +ch_beg_seek() +{ + register struct bufnode *bn; + register 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. + */ + public POSITION +ch_length() +{ + if (thisfile == NULL) + return (NULL_POSITION); + if (ignore_eoi) + return (NULL_POSITION); + if (ch_flags & CH_HELPFILE) + return (size_helpdata); + if (ch_flags & CH_NODATA) + return (0); + 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); +} + +/* + * Force EOF to be at the current read position. + * This is used after an ignore_eof read, during which the EOF may change. + */ + public void +ch_set_eof() +{ + ch_fsize = ch_fpos; +} + + +/* + * 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 |