CERT C: Rule STR30-C

The issue Modifying string literal occurs when you attempt to modify a string literal. For instance, Polyspace^® reports a violation if you:

Polyspace considers these as string literals:

Attempting to modify string literal results in undefined behavior. Because string literals are typically stored in read-only memory, attempting to modify a string literal can result in an access violation

Avoid modifying string literal. For instance, assign string literals to const-qualified pointers or const-qualified objects.

See examples of fixes below.

If you do not want to fix the issue, add comments to your result or code to avoid another review. See:

#include <string.h>

char* buffer = "abcdeXXXXXXX";

void func(char* string) {
    char *ptr = (char*)strchr(buffer,'X');
    if(ptr)
        strcpy(ptr,string); //Noncompliant
}

In this example, because buffer is a string literal, strchr(buffer,'X') returns a string literal. When string literal is used as the destination argument of strcpy, Polyspace reports a violation of this rule.

To resolve this violation, use the string literal as an initializer for the array buffer. This way, a copy of the string literal is stored in buffer, which can be modified safely.

#include <string.h>

char buffer[] = "abcdeXXXXXXX";

void func(char* string) { 
    char *ptr = (char*)strchr(buffer,'X');
    if(ptr)
        strcpy(ptr,string);
}