c++ - malloc および snprintf バスのコア ダンプ

Question

以前は機能していた機能が、突然連携を拒否します。より正確には、このスニペット:

    //If not, add to UIDS
    printf("line 78\n");
    free(s2);
    printf("line 82\n");
    char * ss = malloc(snprintf(NULL, 0, "%s:%d", myUIDs, userId) + 1);
    printf("line 84\n");
    sprintf(ss, "%s:%d", myUIDs, userId);
    free(myUIDs);
    myUIDs=ss;
    free(buffer);

プログラムは「82行目」の1行後に失敗します（82行目ではなくなりましたが、デバッグ停止のみです）Segmentation Fault (core dumped). 私が変われば

char * ss = malloc(snprintf(NULL, 0, "%s:%d", myUIDs, userId) + 1);に

char * ss = malloc(snprintf(NULL, 0, "%s:%d", "", 1) + 1);

私はBus Error: Code dumped代わりに取得します。私はかなり長い間このプログラムに取り組んでいますが、疲労のために常に見落としているのは明らかなことだと感じていますが、現時点では助けを求めるプログラマーの友人はいません。

コンテキストの関数全体:

char* myUIDs; //string containing all UID-s, separated by colon

void printProcessInformation(char pid[],int isSetP, int isSetN, int isSetU){
//find full path name to your "stat" file
//DIR *dir;
//struct dirent *ent;
//Creating string with /proc/PID
char * s = malloc(snprintf(NULL, 0, "%s%s", "/proc/", pid) + 1);
sprintf(s, "%s%s", "/proc/", pid);
//Creating string with /proc/PID/psinfo (full path)
char * fullPath = malloc(snprintf(NULL, 0, "%s%s", s, "/psinfo") + 1);
sprintf(fullPath, "%s%s", s, "/psinfo");
free(s);
//printf("%s\n",fullPath);

//Reading data from file
FILE* file = fopen(fullPath, "r");
printf("line 37\n");
char* buffer;
buffer = (char*) malloc(sizeof(psinfo_t));
printf("line 40\n");
if(file == NULL)
{
    //perror("Error: Couldn't open file");
    return;
}
fread((void *)buffer, sizeof(psinfo_t), 1, file);
psinfo_t* pData = (psinfo_t*) buffer;
time_t sTime=pData->pr_start.tv_sec; 
int pr_pid=pData->pr_pid;
char* fname=pData->pr_fname;
free(buffer);
buffer = (char*) malloc(sizeof(stat));
stat(fullPath,buffer);
struct stat* fileStat=(struct stat*) buffer;
fclose(file);
int userId=fileStat->st_uid;
struct passwd* pw=getpwuid(userId);
char* uid=pw->pw_name;
printf("line 58\n");
if(isSetU<0){
    //Print results
    printf("%8s", uid);
    if(isSetP>0)
    printf(" %5d",pr_pid);
    printf(" %16s %.24s\n", fname, ctime(&sTime));
    free(buffer);
}else{
    //Or else, add UID to UIDS if it didn't appear before
    //check if UID is in UIDS
    printf("line 70\n");
    char * s2 = malloc(snprintf(NULL, 0, "%s:%d", "", userId) + 1);
    printf("line 72\n");
    snprintf(s2, "%s:%d", "", userId);
    if(strstr(myUIDs,s2)!=NULL){
        free(s2);
        free(buffer);
        return;
    }
    //If not, add to UIDS
    printf("line 78\n");
    free(s2);
    printf("line 82\n");
    char * ss = malloc(snprintf(NULL, 0, "%s:%d", "", 1) + 1);
    printf("line 84\n");
    sprintf(ss, "%s:%d", myUIDs, userId);
    free(myUIDs);
    myUIDs=ss;
    free(buffer);
}
}