split strings into exec-able args list

main.c

#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

typedef struct func_args {
  char **data;
  int count;
} func_args;


void run_command(char **program) {
    if (fork()) return;
    execvp((char*)program[0], (char**)program);
}


int cmd_count_args(const char *line) {
  int count = 0;
  int i;

  bool in_quotes = false;
  bool in_dquotes = false;

  for (i = 0; i < strlen(line); i++) {
    switch (line[i]) {
      case ' ':
        if (!in_quotes && !in_dquotes){
          count++;
        }
        break;
      case '\'':
        if (in_dquotes)
          break;

        in_quotes = !in_quotes;
        break;
      case '"':
        if (in_quotes)
          break;

        in_dquotes = !in_dquotes;
        break;
    }
  }
  return ++count; // extra for NULL terminator
}

func_args *cmd_split_line(const char *line) {
  func_args *fa;
  fa = (func_args*)malloc(sizeof(func_args));
  fa->count = cmd_count_args(line);
  fa->data = malloc((fa->count + 1) * sizeof(char *));
  int data_i = 0;

  char tmp[strlen(line)];
  int tmp_i = 0;

  int i;
  bool in_quotes = false;
  bool in_dquotes = false;

  for (i = 0; i < strlen(line); i++) {
    switch (line[i]) {
      case ' ':
        if (!in_quotes && !in_dquotes) {
          tmp[tmp_i] = '\0';
          fa->data[data_i++] = strndup(tmp, tmp_i);
          tmp_i = 0;
        } else{
          tmp[tmp_i++] = line[i];
        }
        break;
      case '\'':
        if (in_dquotes){
          tmp[tmp_i++] = line[i];
          break;
        }
        in_quotes = !in_quotes;
        break;
      case '"':
        if (in_quotes){
          tmp[tmp_i++] = line[i];
          break;
        }
        in_dquotes = !in_dquotes;
        break;
      case '\0':
        break;
      default:
        tmp[tmp_i++] = line[i];
        break;
    }
  }
  if (tmp_i > 0) {
    fa->data[data_i++] = strndup(tmp, tmp_i);
  }

  fa->data[data_i] = NULL;
  return fa;
}

void free_func_args(func_args *fa) {
  int i;
  for (i = 0; i < fa->count; i++) {
    free(fa->data[i]);
  }
  free(fa->data);
  free(fa);
}


int main(int argc, char *argv[]) {
  func_args *fa;
  int i;

  const char *cmd = "echo -e \"$PWD\" 'things and stuff' 'me\"ow' hmmmmm";

  fa = cmd_split_line(cmd);

  for (i = 0; i < fa->count; i++) {
    printf("> %s\n", fa->data[i]);
  }

  run_command(fa->data);

  free_func_args(fa);

  return EXIT_SUCCESS;
}