WIP: pager #127
8
Makefile
8
Makefile
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@ -102,11 +102,15 @@ mm: build/bin/mm
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build/bin/mm: src/mm.c build
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$(CC) $(CFLAGS) -o $@ src/mm.c
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.PHONY: npc
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npc: build/bin/npc
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build/bin/npc: src/npc.c build
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$(CC) $(CFLAGAS) -o $@ src/npc.c
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$(CC) $(CFLAGS) -o $@ src/npc.c
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.PHONY: pg
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pg: build/bin/pg
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build/bin/pg: src/pg.c build
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$(CC) $(CFLAGS) -o $@ src/pg.c
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.PHONY: rpn
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rpn: build/bin/rpn
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52
docs/pg.1
Normal file
52
docs/pg.1
Normal file
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@ -0,0 +1,52 @@
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.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
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.\" Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
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.\"
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.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
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.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
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.\"
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.TH PG 1 2024-06-26 "Harakit X.X.X"
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.SH NAME
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pg \(en paginate
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.\"
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.SH SYNOPSIS
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pg
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.RB ( -p
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.RB [ prompt ])
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.\"
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.SH DESCRIPTION
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Print standard input to standard output, accepting commands between pages.
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|
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.\"
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.SH OPTIONS
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.IP -p
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Replace the default prompt (\(lq: \(rq) with the option argument.
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.\"
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.SH DIAGNOSTICS
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In the event of an error, a debug message will be printed and the program will
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exit with the appropriate
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.BR sysexits.h (3)
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error code.
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.\"
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.SH RATIONALE
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Plan 9 from Bell Labs had
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.BR p (1),
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a similar \(lqcooked\(rq-mode paginator (as opposed to \(lqraw\(rq mode, which a
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vast majority of paginators use).
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.\"
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.SH AUTHOR
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Written by DTB
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.MT trinity@trinity.moe
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.ME .
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.\"
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.SH COPYRIGHT
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Copyright \(co 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
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<https://gnu.org/licenses/agpl.html>.
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.\"
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.SH SEE ALSO
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.BR more (1p)
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260
src/pg.c
Normal file
260
src/pg.c
Normal file
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@ -0,0 +1,260 @@
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/*
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* Copyright (c) 2024 DTB <trinity@trinity.moe>
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU Affero General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
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* details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see https://www.gnu.org/licenses/.
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*/
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#include <errno.h> /* errno */
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#include <stdio.h> /* fclose(3), feof(3), fgetc(3), fgets(3), fopen(3),
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* fprintf(3), fputc(3), stderr, stdin, stdout, EOF, FILE,
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* NULL */
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#include <stdlib.h> /* size_t */
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#include <string.h> /* strchr(3), strcmp(3), strerror(3), strtok(3) */
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#include <unistd.h> /* getopt(3) */
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/* Commands start with cmd_. They take an argc and NULL-terminated argv, like
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* main, and return a status from <sysexits.h>. Return values other than EX_OK
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* and EX_USAGE cause pg(1) to exit with that value, except EX_UNAVAILABLE,
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* which causes pg(1) to exit with the status EX_OK. */
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#include <sysexits.h>
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#define CMDLINE_MAX 99+1 /* Maximum length of command line. */
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static char *whitespace = " \n\r\t\v";
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static struct {
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size_t quantity;
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enum { LINES = 0, BYTES = 1 } type;
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} default_page_unit = { 22, LINES } /* Plan 9 default */;
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static FILE *input;
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static char *prompt = ": ";
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static char *program_name = "pg";
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static char *permute_out(char *str, size_t index){
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size_t j;
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for(j = index; str[j - 1] != '\0'; ++j)
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str[j - 1] = str[j];
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return str;
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}
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/* strtok(3p), but supports double-quotes and escapes (but only for escaping
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* quotes). UTF-8 is safe only in str. Unmatched quotes in str are considered
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* literal. The behavior of strtok_quoted when '"' or '\\' are in sep is
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* undefined. */
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/* TODO: Seems to only ever return NULL. */
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static char *strtok_quoted(char *str, char *sep){
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static char *s;
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size_t i;
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size_t j;
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if(str != NULL)
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s = str;
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while(strchr(sep, *s) == NULL)
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if(*++s == '\0')
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return NULL; /* no remaining characters except seperators */
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{
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char in_escape;
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int in_quotes;
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in_escape = 0;
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in_quotes = -1;
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for(i = 0; s[i] != '\0'; ++i)
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switch(s[i]){
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case '\\':
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if(in_escape)
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permute_out(s, i--);
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in_escape = !in_escape;
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break;
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case '"':
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if(in_escape){
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s[i] = s[i - 1];
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permute_out(s, i--);
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}else if(in_quotes != -1){
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permute_out(s, in_quotes);
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--i;
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permute_out(s, i--);
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in_quotes = -1;
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}else
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in_quotes = i;
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break;
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case '\0':
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return s;
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default:
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if(!in_escape && strchr(sep, s[i]) != NULL){
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s[i] = '\0';
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return s;
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}
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}
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}
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return s;
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}
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/* Page at most l bytes from f without consideration of a buffer (print them to
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* stdout). */
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static int pg_b_u(FILE *f, size_t l){
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int c;
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while((c = fgetc(f)) != EOF)
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if((c = fputc(c, stdout)) == EOF || --l == 0)
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break;
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return c;
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}
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/* Page at most l lines, which are lengths of characters terminated by nl, from
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* f without consideration of a buffer (print them to stdout). */
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static int pg_l_u(FILE *f, size_t l, char nl){
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int c;
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while((c = fgetc(f)) != EOF)
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if((c = fputc(c, stdout)) == EOF || (l -= (c == nl)) == 0)
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break;
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return c;
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}
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static int cmd_quit(int argc, char **argv, char **envp){return EX_UNAVAILABLE;}
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static int cmd_default_page(int argc, char **argv, char **envp){
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if(argc > 1) /* This shouldn't be possible. */
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return EX_USAGE;
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if(default_page_unit.type == BYTES)
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return pg_b_u(input, default_page_unit.quantity) == EOF
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? EX_UNAVAILABLE
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: EX_OK;
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else if(default_page_unit.type == LINES)
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return pg_l_u(input, default_page_unit.quantity, '\n') == EOF
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? EX_UNAVAILABLE
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: EX_OK;
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else
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return EX_SOFTWARE;
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}
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static int cmd_page_down_lines(int argc, char **argv, char **envp){
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switch(argc){
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case 1:
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return cmd_default_page(argc, argv, envp);
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case 2: /* not implemented */
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default:
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fprintf(stderr, "Usage: %s" /*" (lines)"*/ "\n", argv[0]);
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return EX_USAGE;
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}
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}
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/* A CmdMap must be NULL-terminated. */
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static struct CmdMap{ char *name; int (*fn)(int, char **, char **); }
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builtins[] = {
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{ "", cmd_default_page },
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{ "+", cmd_page_down_lines },
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/* don't make the user feel trapped */
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{ ":q", cmd_quit }, { ":q!", cmd_quit },
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{ "exit", cmd_quit }, { "q", cmd_quit }, { "Q", cmd_quit },
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{ "quit", cmd_quit }, { "ZZ", cmd_quit },
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{ NULL, NULL }
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};
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#define ARGV_MAX 10
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/* Find and execute the command in the command map, given a corresponding
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* command line. */
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static int cmdline_exec(struct CmdMap *map, char *cmdline, char **envp){
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/* Command line word splitting is naive and based on whitespace ONLY; no
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* fancy quoting or escaping here. Adding that would (ideally) entail
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* replacing strtok(3) with something specific to this task. */
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static int argc;
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static char *argv[ARGV_MAX];
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if((argv[(argc = 0)] = strtok(cmdline, whitespace)) == NULL){
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while(cmdline[0] != '\0')
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cmdline = &cmdline[1];
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argv[argc] = cmdline;
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argv[++argc] = NULL;
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}else{
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while((argv[++argc] = strtok(NULL, whitespace)) != NULL
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&& argc < ARGV_MAX);
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}
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for(; map->name != NULL; map = &map[1])
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if(strcmp(map->name, argv[0]) == 0)
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return map->fn(argc, argv, envp);
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fprintf(stderr, "%s: %s: not found\n", program_name, argv[0]);
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return EX_USAGE;
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}
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int usage(char *s){
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fprintf(stderr, "Usage: %s (-p [prompt])\n", s);
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return EX_USAGE;
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}
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int main(int argc, char *argv[]){
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unsigned char cmd[CMDLINE_MAX];
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FILE *t;
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input = stdin;
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if(argc < 1)
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program_name = argv[0];
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else{
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int c;
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while((c = getopt(argc, argv, "p:")) != -1)
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switch(c){
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case 'p': prompt = optarg; break;
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default:
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return usage(program_name);
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}
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}
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if(argc > optind)
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return usage(program_name);
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if((t = fopen("/dev/tty", "rb")) == NULL){
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fprintf(stderr, "%s: /dev/tty: %s\n", program_name, strerror(errno));
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return EX_OSERR;
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}
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for(;;){
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fputs(prompt, stderr);
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fgets((char *)cmd, (sizeof cmd) / (sizeof *cmd), t);
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if(strchr((char *)cmd, '\n') == NULL){ /* fast-forward stream */
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int c;
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while((c = fgetc(t)) != '\n')
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if(c == EOF)
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break;
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}
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if(feof(t))
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return EX_OK;
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{ int r;
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switch((r = cmdline_exec(builtins, (char *)cmd, NULL))){
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case EX_OK: case EX_USAGE: break;
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case EX_UNAVAILABLE: return EX_OK;
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default: return r;
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} }
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}
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/* UNREACHABLE */
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return EX_SOFTWARE;
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}
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Loading…
Reference in New Issue
Block a user
Elaborate on pages here.