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Diffstat (limited to 'usr.bin/more/input.c')
| -rw-r--r-- | usr.bin/more/input.c | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/usr.bin/more/input.c b/usr.bin/more/input.c new file mode 100644 index 0000000..521bc53 --- /dev/null +++ b/usr.bin/more/input.c @@ -0,0 +1,241 @@ +/* + * Copyright (c) 1988 Mark Nudleman + * Copyright (c) 1988, 1993 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#ifndef lint +static char sccsid[] = "@(#)input.c 8.1 (Berkeley) 6/6/93"; +#endif /* not lint */ + +/* + * High level routines dealing with getting lines of input + * from the file being viewed. + * + * When we speak of "lines" here, we mean PRINTABLE lines; + * lines processed with respect to the screen width. + * We use the term "raw line" to refer to lines simply + * delimited by newlines; not processed with respect to screen width. + */ + +#include <sys/types.h> +#include <less.h> + +extern int squeeze; +extern int sigs; +extern char *line; + +off_t ch_tell(); + +/* + * Get the next line. + * A "current" position is passed and a "new" position is returned. + * The current position is the position of the first character of + * a line. The new position is the position of the first character + * of the NEXT line. The line obtained is the line starting at curr_pos. + */ +off_t +forw_line(curr_pos) + off_t curr_pos; +{ + off_t new_pos; + register int c; + + if (curr_pos == NULL_POSITION || ch_seek(curr_pos)) + return (NULL_POSITION); + + c = ch_forw_get(); + if (c == EOI) + return (NULL_POSITION); + + prewind(); + for (;;) + { + if (sigs) + return (NULL_POSITION); + if (c == '\n' || c == EOI) + { + /* + * End of the line. + */ + new_pos = ch_tell(); + break; + } + + /* + * Append the char to the line and get the next char. + */ + if (pappend(c)) + { + /* + * The char won't fit in the line; the line + * is too long to print in the screen width. + * End the line here. + */ + new_pos = ch_tell() - 1; + break; + } + c = ch_forw_get(); + } + (void) pappend('\0'); + + if (squeeze && *line == '\0') + { + /* + * This line is blank. + * Skip down to the last contiguous blank line + * and pretend it is the one which we are returning. + */ + while ((c = ch_forw_get()) == '\n') + if (sigs) + return (NULL_POSITION); + if (c != EOI) + (void) ch_back_get(); + new_pos = ch_tell(); + } + + return (new_pos); +} + +/* + * Get the previous line. + * A "current" position is passed and a "new" position is returned. + * The current position is the position of the first character of + * a line. The new position is the position of the first character + * of the PREVIOUS line. The line obtained is the one starting at new_pos. + */ +off_t +back_line(curr_pos) + off_t curr_pos; +{ + off_t new_pos, begin_new_pos; + int c; + + if (curr_pos == NULL_POSITION || curr_pos <= (off_t)0 || + ch_seek(curr_pos-1)) + return (NULL_POSITION); + + if (squeeze) + { + /* + * Find out if the "current" line was blank. + */ + (void) ch_forw_get(); /* Skip the newline */ + c = ch_forw_get(); /* First char of "current" line */ + (void) ch_back_get(); /* Restore our position */ + (void) ch_back_get(); + + if (c == '\n') + { + /* + * The "current" line was blank. + * Skip over any preceeding blank lines, + * since we skipped them in forw_line(). + */ + while ((c = ch_back_get()) == '\n') + if (sigs) + return (NULL_POSITION); + if (c == EOI) + return (NULL_POSITION); + (void) ch_forw_get(); + } + } + + /* + * Scan backwards until we hit the beginning of the line. + */ + for (;;) + { + if (sigs) + return (NULL_POSITION); + c = ch_back_get(); + if (c == '\n') + { + /* + * This is the newline ending the previous line. + * We have hit the beginning of the line. + */ + new_pos = ch_tell() + 1; + break; + } + if (c == EOI) + { + /* + * We have hit the beginning of the file. + * This must be the first line in the file. + * This must, of course, be the beginning of the line. + */ + new_pos = ch_tell(); + break; + } + } + + /* + * Now scan forwards from the beginning of this line. + * We keep discarding "printable lines" (based on screen width) + * until we reach the curr_pos. + * + * {{ This algorithm is pretty inefficient if the lines + * are much longer than the screen width, + * but I don't know of any better way. }} + */ + if (ch_seek(new_pos)) + return (NULL_POSITION); + loop: + begin_new_pos = new_pos; + prewind(); + + do + { + c = ch_forw_get(); + if (c == EOI || sigs) + return (NULL_POSITION); + new_pos++; + if (c == '\n') + break; + if (pappend(c)) + { + /* + * Got a full printable line, but we haven't + * reached our curr_pos yet. Discard the line + * and start a new one. + */ + (void) pappend('\0'); + (void) ch_back_get(); + new_pos--; + goto loop; + } + } while (new_pos < curr_pos); + + (void) pappend('\0'); + + return (begin_new_pos); +} |
