C-Shell/src/tokenizer/tokenizer.c at main · JeetMajumdar2003/C-Shell · GitHub

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#include "shell/tokenizer/tokenizer.h"

#include <ctype.h>
#include <stddef.h>
#include <stdlib.h>

int shell_parse_args_inplace(char *cmd, char *argv[], int maxargs) {
  int argc = 0;
  char *p = cmd;
  char *dst = cmd; /* write pointer */

  while (*p != '\0' && argc < maxargs - 1) {
    /* skip leading whitespace */
    while (*p == ' ' || *p == '\t')
      p++;
    if (*p == '\0')
      break;

    /* start a new arg */
    argv[argc++] = dst;

    while (*p != '\0') {
      /* Backslash escaping (only outside quotes): copy next char literally */
      if (*p == '\\') {
        p++; /* skip backslash */
        if (*p != '\0') {
          *dst++ = *p++;
        }
        continue;
      }
      if (*p == '\'') {
        /* single-quoted sequence: copy literally until next single quote */
        p++; /* skip opening quote */
        while (*p != '\0' && *p != '\'') {
          *dst++ = *p++;
        }
        if (*p == '\'')
          p++; /* skip closing quote if present */
        continue;
      }
      if (*p == '"') {
        /* double-quoted sequence: copy literally until next double quote,
           but allow \" and \\ escapes inside double quotes (they become " and \) */
        p++; /* skip opening quote */
        while (*p != '\0' && *p != '"') {
          if (*p == '\\') {
            /* If next char is " or \\, treat it as escaped and copy the char without the backslash
             */
            if (p[1] == '"' || p[1] == '\\') {
              p++;           /* skip backslash */
              *dst++ = *p++; /* copy escaped char */
            } else {
              /* Backslash followed by other char: backslash is literal */
              *dst++ = *p++;
            }
            continue;
          }
          *dst++ = *p++;
        }
        if (*p == '"')
          p++; /* skip closing quote if present */
        continue;
      }
      if (*p == ' ' || *p == '\t') {
        /* end of this arg */
        p++;
        break;
      }
      /* normal character */
      *dst++ = *p++;
    }
    *dst++ = '\0';
  }
  argv[argc] = NULL;
  return argc;
}