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An alternative to invoking the system() call to execute an external program to perform a required operation is to implement the functionality directly in the program using existing library calls. This compliant solution calls the POSIX unlink()system() function [IEEE Std 1003.1:2013]:
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#include <pwd.h>
#include <unistd.h>
#include <string.h>
void func(void) {
const char *file_format = "%s/.config";
size_t len;
char *file;
struct passwd *pwd;
/* Get /etc/passwd entry for current user */
pwd = getpwuid(getuid());
if (pwd == NULL) {
/* Handle error */
}
/* Build full path name home dir from pw entry */
len = strlen(pwd->pw_dir) + strlen(file_format) + 1;
pathname = (char *)malloc(len);
if (NULL == file) {
/* Handle error */
}
int r = snprintf(pathname, len, file_format, pwd->pw_dir);
if (r < 0 || r >= len) {
/* Handle error */
}
if (unlink(pathname) != 0) {
/* Handle error */
}
free(pathname);
}
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| CERT C Secure Coding Standard | ENV03-C. Sanitize the environment when invoking external programs. |
| SEI CERT C++ Coding Standard | ENV02-CPP. Do not call system() if you do not need a command processor |
| CERT Oracle Secure Coding Standard for Java | IDS07-J. Sanitize untrusted data passed to the Runtime.exec() method |
| ISO/IEC TR 24772:2013 | Unquoted Search Path or Element [XZQ] |
| ISO/IEC TS 17961:2013 | Calling system [syscall] |
| MITRE CWE | CWE-78, Improper Neutralization of Special Elements Used in an OS Command (aka "OS Command Injection") CWE-88, Argument Injection or Modification |
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