141 lines
3 KiB
C
141 lines
3 KiB
C
#include "command.h"
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#include "lslib.h"
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#include <stdlib.h>
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static struct {
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int count;
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bool lines;
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bool print_headers;
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bool dont_print_headers;
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} flags;
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static void head_file_lines(FILE* file) {
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size_t len = 0;
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char* line = NULL;
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int count = flags.count;
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while(count > 0 && getline(&line, &len, file) != -1) {
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printf("%s", line);
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count--;
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}
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free(line);
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fclose(file);
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}
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static void head_file_chars(FILE* file) {
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char c;
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int count = flags.count;
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while(count > 0 && (c = getc(file)) != EOF) {
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putchar(c);
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count--;
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}
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fclose(file);
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}
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static void help(void) {
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printf("Usage: head [OPTIONS] [FILE]...\n\n");
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printf("Print first 10 lines of FILEs (or stdin)\n");
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printf("With more than one FILE, precede each with a filename header.\n\n");
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printf("\t-c [+]N[bkm]\tPrint first N bytes\n");
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printf("\t-n N[bkm]\tPrint first N lines\n");
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printf("\t\t\t(b:*512 k:*1024 m:*1024^2)\n");
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printf("\t-q\t\tNever print headers\n");
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printf("\t-v\t\tAlways print headers\n");
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}
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static void print_header(char* path, bool many) {
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if (flags.dont_print_headers) return;
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if (!many && !flags.print_headers) return;
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if (streql("-", path)) {
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printf("\n==> standard input <==\n");
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} else {
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printf("\n=>> %s <==\n", path);
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}
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}
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static void head_file(char* path, bool many) {
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FILE* file = get_file(path, "r");
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print_header(path, many);
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if (flags.lines) {
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head_file_lines(file);
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} else {
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head_file_chars(file);
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}
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}
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static int short_arg(char c, char* next) {
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switch(c) {
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case 'c': {
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long int bkm;
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flags.lines = false;
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check_arg(next);
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bkm = get_blkm(next);
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if (bkm < 1) {
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error("bkm cannot be less than 1");
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}
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flags.count = bkm;
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return ARG_USED;
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}
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case 'n': {
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long int bkm;
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flags.lines = true;
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check_arg(next);
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bkm = get_blkm(next);
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if (bkm < 1) {
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error("bkm cannot be less than 1");
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}
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flags.count = bkm;
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return ARG_USED;
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}
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case 'q':
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flags.dont_print_headers = true;
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break;
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case 'v':
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flags.print_headers = true;
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break;
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default:
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return ARG_INVALID;
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}
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return ARG_UNUSED;
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}
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COMMAND(head_main) {
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int start, count, i;
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flags.count = 10;
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flags.lines = true;
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flags.print_headers = false;
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flags.dont_print_headers = false;
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start = parse_args(argc, argv, help, short_arg, NULL);
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count = argc - start;
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if (count < 1) {
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head_file_lines(stdin);
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return EXIT_SUCCESS;
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}
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if (count == 1) {
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head_file(argv[start], false);
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return EXIT_SUCCESS;
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}
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for (i = 0; i < count; i++) {
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head_file(argv[start + i], true);
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}
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return EXIT_SUCCESS;
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}
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