73 lines
1.3 KiB
C
73 lines
1.3 KiB
C
/* vim: tabstop=4 shiftwidth=4 noexpandtab
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* This file is part of ToaruOS and is released under the terms
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* of the NCSA / University of Illinois License - see LICENSE.md
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* Copyright (C) 2018 K. Lange
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*
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* head - Print the first `n` lines of a file.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <getopt.h>
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#include <errno.h>
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int main(int argc, char * argv[]) {
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int n = 10;
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int opt;
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int print_names = 0;
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int retval = 0;
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while ((opt = getopt(argc, argv, "n:")) != -1) {
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switch (opt) {
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case 'n':
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n = atoi(optarg);
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break;
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}
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}
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if (argc > optind + 1) {
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/* Multiple files */
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print_names = 1;
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}
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if (argc == optind) {
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/* This is silly, but should work due to reasons. */
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argv[optind] = "-";
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argc++;
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}
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for (int i = optind; i < argc; ++i) {
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FILE * f = (!strcmp(argv[i],"-")) ? stdin : fopen(argv[i],"r");
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if (!f) {
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fprintf(stderr, "%s: %s: %s\n", argv[0], argv[i], strerror(errno));
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retval = 1;
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continue;
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}
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if (print_names) {
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fprintf(stdout, "==> %s <==\n", (f == stdin) ? "standard input" : argv[i]);
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}
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int line = 1;
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while (!feof(f)) {
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int c = fgetc(f);
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if (c >= 0) {
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fputc(c, stdout);
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if (c == '\n') {
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line++;
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if (line > n) break;
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}
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}
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}
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if (f != stdin) {
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fclose(f);
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}
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}
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return retval;
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}
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