106 lines
2 KiB
C
106 lines
2 KiB
C
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#include "../command.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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static void help(void) {
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printf("Usage: tac [FILE]...\n\n");
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printf("Concatenate FILEs and print them in reverse\n");
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}
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static void print_range(FILE* file, int start, int end) {
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int len = end - start;
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fseek(file, start, SEEK_SET);
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for (int i = 0; i < len; i++) {
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putchar(getc(file));
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}
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fflush(stdout);
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}
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static char stdin_path[PATH_MAX];
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static FILE* read_stdin() {
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static bool read;
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static FILE* file;
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if (read) goto finished;
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read = true;
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srand(time(NULL));
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int r = rand() % 1000000;
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sprintf(stdin_path, "/tmp/%d.tac", r);
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file = get_file(stdin_path, "w");
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char c;
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while((c = getchar()) != EOF) putc(c, file);
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fclose(file);
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file = get_file(stdin_path, "r");
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finished:
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return file;
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}
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static void parse_file(FILE* file, struct Stack* stack) {
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char buf[1024];
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int read;
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int total = 1;
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stack_push_int(stack, 0);
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rewind(file);
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while ((read = fread(buf, 1, 1024, file)) > 0) {
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for (int i = 0; i < read; i++) {
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char c = buf[i];
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if (c != '\n') continue;
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stack_push_int(stack, total + i);
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}
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total += read;
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}
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}
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static void tac_file(FILE* file) {
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struct Stack stack;
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stack_init(&stack, 80);
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parse_file(file, &stack);
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rewind(file);
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int last, current;
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if (!stack_pop_int(&stack, &last)) goto cleanup;
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while(stack_pop_int(&stack, ¤t)) {
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print_range(file, current, last);
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last = current;
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}
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cleanup:
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stack_free(&stack);
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}
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COMMAND(tac) {
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parse_help(argc, argv, help);
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FILE* in = read_stdin();
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if (argc < 1) {
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tac_file(in);
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return EXIT_SUCCESS;
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}
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for (int i = 0; i < argc; i++) {
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FILE* file = get_file(argv[i], "r");
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if (file == stdin) {
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tac_file(in);
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} else {
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tac_file(file);
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fclose(file);
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}
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}
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fclose(in);
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remove(stdin_path);
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return EXIT_SUCCESS;
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}
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