94 lines
1.5 KiB
C
94 lines
1.5 KiB
C
#include <fcntl.h>
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include "config.h"
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char v_flag;
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char c_flag;
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long parse_long(const char *str) {
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char *ptr;
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long ret = strtol(str, &ptr, 0);
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if (*ptr) {
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fprintf(stderr, "head: %s invalid number\n", ptr);
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exit(1);
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}
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return ret;
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}
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void print(const char *file, FILE *fp, long lines, long bytes) {
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if (v_flag)
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printf(HEAD_FMT, file);
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long lcount = 0;
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long bcount = 0;
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while (1) {
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int c = getc(fp);
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bcount++;
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if (c == '\n')
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lcount++;
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if (c == EOF || lcount == lines || (c_flag && bcount == bytes))
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break;
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putchar(c);
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}
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}
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int main(int argc, char **argv) {
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long lines = 10;
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long bytes = 0;
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int opt;
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while ((opt = getopt(argc, argv, "n:c:v")) != -1) {
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switch (opt) {
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case 'n':
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lines = parse_long(optarg);
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break;
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case 'c':
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c_flag = 1;
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bytes = parse_long(optarg);
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break;
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case 'v':
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v_flag = 1;
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break;
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default:
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printf("head [ncv] [file1 file2...]\n\t-n Print N lines\n\t-c Print N bytes\n\t-v Print headers\n");
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return 0;
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}
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}
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argv += optind;
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argc -= optind;
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if (argc == 0)
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print("-", stdin, lines, bytes);
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for (int i = 0; i < argc; i++) {
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FILE *fp = NULL;
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if (argv[i][0] == '-')
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fp = stdin;
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else
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fp = fopen(argv[i], "r");
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if (fp == NULL) {
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fprintf(stderr, "head: %s: %s\n", argv[i], strerror(errno));
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return 1;
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}
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print(argv[i], fp, lines, bytes);
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fclose(fp);
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}
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return 0;
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}
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