shell - Parser generating segfaults in C -

i've been trying work past 2 weeks no avail. have project create shell implements parsing , built-in commands. issue i'm having when pass char* parse function , returns, when try access part of it, segfault. i've tried different methods including struct holding char** same problems, i'm guessing it's issue parser. appreciate help. code parser.c:

#define bufsize 1024 #define tok_bufsize 64 #define tok_delim " \t\r\n\a"  char*** parse(char *line0){ char* null_ptr = 0; char*** cmd = malloc(max_size * sizeof(char**)); /* char arg[] = argument char* argv[] = argument array char** cmd[] = array of argument arrays */ int bufsize = max_size, cmdp = 0, argp = 0, com = false, redir = false; char *token; char* line = malloc(100*sizeof(char)); strcpy(line,line0);  token = strtok(line, tok_delim); while (token){     if (*token == ';'){ // new command string         char* tmp1 = malloc(bufsize * sizeof(char));         char** tmpa = malloc(bufsize * sizeof(char*));         strcpy(tmp1, token);         tmp1[sizeof(token)] = null_ptr;         tmpa[0]=tmp1;         cmd[cmdp] = tmpa;         argp = 0;         cmdp++;         com = false;         redir = false;     }     else if (*token == '>' || *token == '<' || token == ">>"){  // redirects         argp = 0;         char* tmp1 = malloc(bufsize * sizeof(char));         char** tmpa = malloc(bufsize * sizeof(char*));         strcpy(tmp1, token);         tmp1[sizeof(token)] = null_ptr;         tmpa[argp]=tmp1;         argp++;         printf("redirect: %s\n",tmp1);         com = false;         redir = true;     }     else if (*token == '|'){        // pipe         printf("pipe\n");         cmdp++;         argp = 0;         com = false;     }     else if (redir){        // redirect file name         // redirect token stored in arg[]         char* tmp1 = malloc(bufsize * sizeof(char));         char** tmpa = malloc(bufsize * sizeof(char*));         strcpy(tmp1, token);         tmp1[sizeof(token)] = null_ptr;         tmpa[argp]=tmp1;         cmd[cmdp]=tmpa;         argp = 0;         cmdp++;         redir = false;         com = false;         printf("file: %s\n", token);     }     else if (token == "&")      // background     {         cmdp++;         argp = 0;         char* tmp1 = malloc(bufsize * sizeof(char));         char** tmpa = malloc(bufsize * sizeof(char*));         strcpy(tmp1, token);         tmp1[sizeof(token)] = null_ptr;         tmpa[0]=tmp1;         cmd[cmdp]=tmpa;          printf("background");     }     else if (!com && !redir){   // command entered         argp = 0;         char* tmp1 = malloc(bufsize * sizeof(char));         char** tmpa = malloc(bufsize * sizeof(char*));         strcpy(tmp1, token);         tmp1[sizeof(token)] = null_ptr;         tmpa[argp] = tmp1;          argp++;         printf("command %s\n", token);         com = true;     }     else if (com){      // argument command, other redirects , pipes taken care of         char* tmp1 = malloc(bufsize * sizeof(char));         char** tmpa = malloc(bufsize * sizeof(char*));         strcpy(tmp1, token);         tmp1[sizeof(token)] = null_ptr;         tmpa[argp] = tmp1;         argp++;             printf("argument: %s\n", token);             //cmd[cmdp] = argv;     // save current working argument array             //cmdp++;         }         // end of if else statements          token = strtok(null, tok_delim);        }   // end of while     cmdp++;     cmd[cmdp] = null;  return &cmd; } 

when compiled code on command-line typing in:

gcc /path/to/yourcodefilename.c -wall -wextra 

but replacing /path/to/yourcodefilename.c actual filename of code containing main function calls function (my file test2.c), received warnings. first being:

./test2.c:21: error: 'aaa' undeclared (first use in function) ./test2.c:21: error: (each undeclared identifier reported once ./test2.c:21: error: each function appears in.) 

and received few of those. "aaa" replaced named of used inside function has not been defined. includes word true , false. correct this, can use @ top of program:

#define false n #define true y 

where n , y numbers representing false , true respectively. way correct include header files containing definitions "true" , "false".

the second thing noticed on few lines is:

warning: assignment makes integer pointer without cast 

make sure don't convert data on 1 type another. example, don't set character variable pointer value.

for example, change:

  tmp1[sizeof(token)] = null_ptr; 

to:

  tmp1[sizeof(token)] = '\0'; 

because specifying index char* means specifying char, , null_ptr of type char* , char* , char not same. did assigned null value char.

i hope helps troubleshooting