Segmentation Fault when I use popen()

Question

I have a function to encrypt some string. It's fabulous but ... it's bug :(

I can use the function one time, but the second time, crash.

Thank you ! :)

I working with bash ubuntu (W10), no warning (and error) when i compile my project.

char * encryptPassword(char * string){
    printf("DEBUT\n");
    FILE *fp=NULL;
    char path[1035];
    char password[32];
    //char * password = NULL; //for the encrypt password
    printf("MALLOC\n");
    //password = (char *)malloc(33*sizeof(char));
    char * result = NULL;
    char chaine[128] = "echo "; 
    char end_chaine[128] = " | openssl md5 | cut -d ' ' -f2"; 
    //Create the command
    printf("STRCAT\n");
    strcat(chaine,string); 
    strcat(chaine,end_chaine); 
    //Execute
    printf("POPEN %s\n",chaine);
    fp = popen(chaine, "r");
    //Reclaim the encrypted password
    printf("GETS\n");
    fgets(path, sizeof(path)-1, fp);
    pclose(fp);
    //To remove the character '\n'
    printf("SPRINTF\n");
    sprintf(password,"%32s",path);
    result = strtok(password,"\n");
    printf("%s\n",result);
    //OK IT'S FINISH !
    return (result);
}

Answer 1

Segmentation Fault when I use popen()

your problem is probably here :

 strcat(chaine,string); 

if the input parameter string more the other fields are too large for chaine and in that case you write out of it with an undefined behavior (it seems a crah in your case)

Compute the needed length then allocate the string before to fill it.

Note you can do that in a lazy way with two calls to snprintf, a first to compute the needed size and the second to fill the command. Is a lazy way because here you just concatenate strings, you don't write numbers etc needing a non constant size.

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However is can be also here after the popen :

sprintf(password,"%32s",path);

because password is sized 32 and sprintf will writes 33 character to also place the final null character

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And if miraculously you return from the function you will probably not survive of the use of the result because it is NULL or a pointer to the stack not anymore valid : password is a local variable so strtok returns NULL or the address of password becoming the result of the function