Disable stdout printing

1. Performance:
○ Avoid calling srand() multiple times in a program. Instead, call it once at the startup. Re-seeding with GetSystemTimePreciseAsFileTime should be done outside of repetitive scenarios unless necessary for specific randomness properties.

2. Readable and well-structured code:
○ Avoid using magic numbers. Use OUTPUT_LENGTH directly.
○ The initialization syntax { [OUTPUT_LENGTH] = '\1' } is non-standard and could cause confusion. Simplify it to char random_string[OUTPUT_LENGTH + 1]; memset(random_string, '\0', OUTPUT_LENGTH + 1);.
○ Consider separating concerns better by implementing a dedicated function for clipboard operations.
3. Security:
○ Use a stronger random generator for any cryptographic or highly sensitive random generation needs. The rand() function is not cryptographically secure.
4. Potential Bugs:
○ NULL check after GlobalLock() without handling memPtr being NULL before memcpy.
○ Ensure to clear and free any global memory objects properly to avoid memory leaks in case of partial failures.
5. Pattern Usage:
○ Usage of modern C libraries or wrappers for clipboard and random number generation might improve maintainability.
By implementing these suggestions, the code will be more efficient, readable, reliable, and secure.

random_clipboard.c

@@ -7,20 +7,20 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
+#define OUTPUT_LENGTH 16
 
-void rand_str(char*, size_t);
 
 
 void rand_str(char* dest, size_t length) {
     char charset[] = "0123456789"
         "abcdefghijklmnopqrstuvwxyz"
-        "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
-    srand((unsigned int)time(NULL));
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+        "-_";
+
     while (length-- > 0) {
 
 
-        //size_t index = (double)rand() / RAND_MAX * (sizeof charset - 1);
-        size_t index = (size_t)((double)rand() / RAND_MAX * sizeof(charset));
+        size_t index = rand() %  (sizeof(charset) -1);
         *dest++ = charset[index];
     }
     *dest = '\0';
@@ -29,21 +29,50 @@ void rand_str(char* dest, size_t length) {
 
 int main()
 {
-    char str[17] = { [16] = '\1' }; // make the last character non-zero so we can test based on it later
-    rand_str(str, sizeof str - 1);
-    assert(str[16] == '\0');      // test the correct insertion of string terminator
-    puts(str);
+
+    FILETIME ft;
+    ULARGE_INTEGER ui;
+    GetSystemTimePreciseAsFileTime(&ft);
+    ui.LowPart = ft.dwLowDateTime;
+    ui.HighPart = ft.dwHighDateTime;
+    unsigned long long micros = ui.QuadPart / 10;
+    srand((unsigned int) (micros & 0xFFFFFFFF));
 
+    char random_string[OUTPUT_LENGTH +1] = { [OUTPUT_LENGTH] = '\1' }; // make the last character non-zero so we can test based on it later
+    rand_str(random_string, sizeof random_string - 1);
+    assert(random_string[OUTPUT_LENGTH] == '\0');      // test the correct insertion of string terminator
 
-   // const char* output = "Test";
-    const size_t len = strlen(str) + 1;
-    HGLOBAL hMem = GlobalAlloc(GMEM_MOVEABLE, len);
-    memcpy(GlobalLock(hMem), str, len);
+
+    const size_t random_string_len = strlen(random_string) + 1;
+    HGLOBAL hMem = GlobalAlloc(GMEM_MOVEABLE, random_string_len);
+
+    if (hMem == NULL)
+    {
+        fprintf(stderr, "GlobalAlloc failed \n");
+        return 1;
+    }
+
+
+    char* memPtr = (char*)GlobalLock(hMem);
+
+    if (memPtr != NULL) {
+        memcpy(memPtr, random_string, random_string_len);
+    }
+    else {
+        fprintf(stderr, "GlobalLock failed\n");
+        GlobalFree(hMem); // Free allocated memory on failure 
+        return 1;
+
+    }
+
+
+
     GlobalUnlock(hMem);
     OpenClipboard(0);
     EmptyClipboard();
     SetClipboardData(CF_TEXT, hMem);
     CloseClipboard();
+
 }
 
 // Exécuter le programme : Ctrl+F5 ou menu Déboguer > Exécuter sans débogage

random_clipboard.vcxproj

@@ -106,7 +106,7 @@
       <ConformanceMode>true</ConformanceMode>
     </ClCompile>
     <Link>
-      <SubSystem>Windows</SubSystem>
+      <SubSystem>Console</SubSystem>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <EntryPointSymbol>mainCRTStartup</EntryPointSymbol>
     </Link>