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