Synopsis

Do not rely on an environment pointer following an operation that may invalidate it

Enabled by default

Yes

Severity/Certainty

Low/Medium

Full description

Modifying the environment by any means may cause the environment memory to be reallocated, invalidating the `envp' pointer

Coding standards

Code examples

The following code example fails the check and will give a warning:

#include <stdio.h>
#include <stdlib.h>

int main(int argc, const char *argv[], const char *envp[]) {
  if (setenv("MY_NEW_VAR", "new_value", 1) != 0) {
    /* Handle error */
  }
  if (envp != NULL) {
    for (size_t i = 0; envp[i] != NULL; ++i) {
      puts(envp[i]);
    }
  }
  return 0;
}

The following code example passes the check and will not give a warning about this issue:

#include <stdio.h>
#include <stdlib.h>

extern char **environ;

int main(void) {
  if (setenv("MY_NEW_VAR", "new_value", 1) != 0) {
    /* Handle error */
  }
  if (environ != NULL) {
    for (size_t i = 0; environ[i] != NULL; ++i) {
      puts(environ[i]);
    }
  }
  return 0;
}