coreutils/src/cat.c

105 lines
2.6 KiB
C

/*
* Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
* SPDX-License-Identifier: AGPL-3.0-or-later
*
* This file is part of YAC coreutils.
*
* YAC coreutils is free software: you can redistribute it and/or modify it
* under the terms of the GNU Affero General Public License as published by the
* Free Software Foundation, either version 3 of the License, or (at your
* option) any later version.
*
* YAC coreutils is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
* details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
#include <errno.h>
#include <sysexits.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include "yac.h"
void cat(FILE *file, bool u) {
int byte = 0; /* variable for storing bytes as they are read */
int p = 0; /* index counter for bytes in buffered reading */
char buf[4096]; /* buffer for buffered reading */
if (u) {
while ((byte = fgetc(file)) != EOF) { putchar(byte); }
} else {
while ((byte = fgetc(file)) != EOF) {
if (p > sizeof(buf) - 1) {
fputs(buf, stdout);
p = 0;
} else {
buf[p] = byte;
p++;
}
}
fwrite(buf, 1, p, stdout);
fflush(stdout);
}
}
int main(int argc, char *argv[]) {
bool u = false;
int opt;
int i;
extern int optind;
while ((opt = getopt(argc, argv, "u")) != -1) {
switch (opt) {
/*
* From cat(1p):
*
* -u Write bytes from the input file to the standard output
* without delay as each is read.
*/
case 'u':
u = true;
break;
default:
fprintf(stderr, "Usage: %s (-u) file...\n", argv[0]);
return EX_USAGE;
}
}
/*
* From cat(1p):
*
* file A pathname of an input file. If no file operands are
* specified, the standard input shall be used. If a file is
* '-', the cat utility shall read from the standard input at
* that point in the sequence. The cat utility shall not close
* and reopen standard input when it is referenced in this way,
* but shall accept multiple occurrences of '-' as a file
* operand.
*/
if (optind == argc) {
cat(stdin, u);
return 0;
}
FILE *file;
for (i = optind; i < argc; i++) {
file = rpath(argv[0], argv[i]);
if (file != NULL) {
cat(file, u);
if (file != stdin) { fclose(file); }
} else { continue; }
}
return EX_OK;
}