139 lines
3.2 KiB
C
139 lines
3.2 KiB
C
/**
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* file: echo.c
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* command: echo
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* author: Tyler Murphy
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*/
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#include "command.h"
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#include "lslib.h"
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#include <stdlib.h>
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/**
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* Flags that are to be used with echo
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*/
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static struct {
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bool escape_codes;
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bool newline;
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} flags;
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/**
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* Prints a null terminated string to standard out and changes each char based on input flags
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* @param str the string to print
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*/
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static void print_with_escape_codes(const char* str) {
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size_t index = 0; /* current index in the string */
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char c; /* current char being read */
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char n; /* next char being read */
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while (true) {
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c = str[index]; /* read current char */
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index++;
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if (c == '\0') break; /* if we hit the NUL, break */
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if (c != '\\') { /* if its not a escaped code, print and continue */
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putchar(c);
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continue;
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}
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/* read next character */
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n = str[index];
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index++;
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/* check each char against the valid escape codes */
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switch (n) {
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case '\\':
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putchar('\\');
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break;
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case 'b':
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putchar('\b');
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break;
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case 'c':
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exit(EXIT_SUCCESS);
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case 'n':
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putchar('\n');
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break;
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case 'r':
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putchar('\r');
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break;
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case 't':
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putchar('\t');
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break;
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case 'v':
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putchar('\v');
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break;
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default: /* if none found print both chars as is */
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putchar(c);
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putchar(n);
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}
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}
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}
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/**
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* Takes in each argument that has a single - and parses it
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* @param c the character after the -
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* @param next the next argument in argv that hasnt been parsed
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* @reutrn if the next arg was used or if the arg was invalid
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*/
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static int short_arg(char c, char* next) {
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UNUSED(next);
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switch (c) {
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case 'e':
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flags.escape_codes = true;
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break;
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case 'E':
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flags.escape_codes = false;
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break;
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case 'n':
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flags.newline = false;
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break;
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default:
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flags.newline = true;
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flags.escape_codes = false;
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return ARG_IGNORE;
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};
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return ARG_UNUSED;
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}
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/**
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* Prints data in each argument to stdout
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*/
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COMMAND(echo_main) {
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int start, i;
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/* if no arguments supplied exit */
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if (argc < 1) {
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return EXIT_FAILURE;
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}
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/* set default flags */
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flags.escape_codes = false;
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flags.newline = true;
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/* parse arguments, no help message */
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start = parse_args(argc, argv, NULL, short_arg, NULL);
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/* for each argument either print as is or parse each character for escape codes */
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for (i = start; i < argc; i++) {
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if (flags.escape_codes) {
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print_with_escape_codes(argv[i]);
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} else {
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printf("%s", argv[i]);
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}
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/* put a space seperator between arguments */
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if (i + 1 != argc) {
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putchar(' ');
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}
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}
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/* if set to put a new line at the end (default), do so */
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if (flags.newline) {
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putchar('\n');
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}
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/* done */
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return EXIT_SUCCESS;
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}
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