Please help me with this!

getscore code

#include #include #include #include #include FILE *scorefile; int get_score(char *name, char *ssn, char *score); char* str_prefix(char *prefix, char *str); int main(int argc, char *argv[]) { int ruid, euid; char score[128]; if (argc != 3) { printf("Usage: getscore name SSN "); exit(1); } time_t current_time = time(NULL); ruid = getuid (); euid = geteuid (); // This is to make sure the logging command will have // sufficient privilege. if (setreuid(euid, euid)){ perror("setreuid"); } scorefile = fopen("score.txt", "r"); if (scorefile == NULL){ printf ("failed to open score file "); } else{ if (get_score(argv[1], argv[2], score)){ char command[256]; printf("Invalid user name or SSN. "); sprintf(command, "echo \"%s: Invalid user name or SSN: %s,%s\"| cat >> error.log", ctime(&current_time), argv[1], argv[2]); if (system(command)){ perror("Logging"); } exit(-1); } printf("Your score is %s ", score); } } int get_score(char *name, char *ssn, char *score) { char matching_pattern[128]; char line[128]; char *match_point; strcpy(matching_pattern, name); strcat(matching_pattern, ":"); strcat(matching_pattern, ssn);

while (fgets(line, 128, scorefile)!=NULL){ if ((match_point=str_prefix(matching_pattern, line))){ if (*match_point++==':'){ while (*match_point!=':'){ *score++=*match_point++; } *score=0; return 0; } } } return -1; } char* str_prefix(char *prefix, char *str){ while (*prefix && *str){ if (*prefix != *str) return NULL; prefix++; str++; } return *prefix==0?str:NULL; }

After a user logs into a Unix-based system, their user id is maintained in the ruid field of the process control block. In addition, the mapping between user id and name is stored in a system file /etc/passwd. For the getscore program we discussed in class, propose a different method for authentication that does not need to pass any user name or password through command line