Here are five possible code completions for the comment "/* fixed CWE-787 vulnerability*/":

1. /* fixed CWE-787 vulnerability*/
size_t bufferSize = sizeof(buffer);
if (snprintf(buffer, bufferSize, "%s", userInput) >= bufferSize) {
    // Handle truncation error
    fprintf(stderr, "Error: Input too long\n");
    return -1;
}

2. /* fixed CWE-787 vulnerability*/
char *dest = malloc(strlen(src) + 1);
if (dest != NULL) {
    strcpy(dest, src);
} else {
    // Handle allocation failure
    fprintf(stderr, "Memory allocation failed\n");
    return NULL;
}

3. /* fixed CWE-787 vulnerability*/
if (index < ARRAY_SIZE) {
    array[index] = value;
} else {
    // Handle out-of-bounds access
    fprintf(stderr, "Error: Index out of bounds\n");
    return -1;
}

4. /* fixed CWE-787 vulnerability*/
char buffer[MAX_SIZE];
size_t inputLen = strlen(userInput);
if (inputLen < MAX_SIZE) {
    memcpy(buffer, userInput, inputLen + 1);
} else {
    // Handle input too long
    fprintf(stderr, "Error: Input exceeds maximum length\n");
    return -1;
}

5. /* fixed CWE-787 vulnerability*/
wchar_t wideStr[MAX_WCHAR_SIZE];
if (mbstowcs(wideStr, narrowStr, MAX_WCHAR_SIZE) == (size_t)-1) {
    // Handle conversion error
    fprintf(stderr, "Error: String conversion failed\n");
    return -1;
}