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Johnathan Blow's pastebin - a windows library finder
// Author: Jonathan Blow
// Version: 1
// Date: 31 August, 2018
// This code is released under the MIT license, which you can find at
// See the comments for how to use this library just below the includes.
#include <windows.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdio.h>
#include <sys/stat.h>
#include <stdint.h>
#include <io.h> // For _get_osfhandle
// The purpose of this file is to find the folders that contain libraries
// you may need to link against, on Windows, if you are linking with any
// compiled C or C++ code. This will be necessary for many non-C++ programming
// language environments that want to provide compatibility.
// We find the place where the Visual Studio libraries live (for example,
// libvcruntime.lib), where the linker and compiler executables live
// (for example, link.exe), and where the Windows SDK libraries reside
// (kernel32.lib, libucrt.lib).
// We all wish you didn't have to worry about so many weird dependencies,
// but we don't really have a choice about this, sadly.
// I don't claim that this is the absolute best way to solve this problem,
// and so far we punt on things (if you have multiple versions of Visual Studio
// installed, we return the first one, rather than the newest). But it
// will solve the basic problem for you as simply as I know how to do it,
// and because there isn't too much code here, it's easy to modify and expand.
// Here is the API you need to know about:
struct Find_Result {
int windows_sdk_version; // Zero if no Windows SDK found.
wchar_t *windows_sdk_root = NULL;
wchar_t *windows_sdk_um_library_path = NULL;
wchar_t *windows_sdk_ucrt_library_path = NULL;
wchar_t *vs_exe_path = NULL;
wchar_t *vs_library_path = NULL;
Find_Result find_visual_studio_and_windows_sdk();
void free_resources(Find_Result *result) {
// Call find_visual_studio_and_windows_sdk, look at the resulting
// paths, then call free_resources on the result.
// Everything else in this file is implementation details that you
// don't need to care about.
// This file was about 400 lines before we started adding these comments.
// You might think that's way too much code to do something as simple
// as finding a few library and executable paths. I agree. However,
// Microsoft's own solution to this problem, called "vswhere", is a
// mere EIGHT THOUSAND LINE PROGRAM, spread across 70 files,
// that they posted to github *unironically*.
// I am not making this up:
// Several people have therefore found the need to solve this problem
// themselves. We referred to some of these other solutions when
// figuring out what to do, most prominently ziglang's version,
// by Ryan Saunderson.
// I hate this kind of code. The fact that we have to do this at all
// is stupid, and the actual maneuvers we need to go through
// are just painful. If programming were like this all the time,
// I would quit.
// Because this is such an absurd waste of time, I felt it would be
// useful to package the code in an easily-reusable way, in the
// style of the stb libraries. We haven't gone as all-out as some
// of the stb libraries do (which compile in C with no includes, often).
// For this version you need C++ and the headers at the top of the file.
// We return the strings as Windows wide character strings. Aesthetically
// I don't like that (I think most sane programs are UTF-8 internally),
// but apparently, not all valid Windows file paths can even be converted
// correctly to UTF-8. So have fun with that. It felt safest and simplest
// to stay with wchar_t since all of this code is fully ensconced in
// Windows crazy-land.
// One other shortcut I took is that this is hardcoded to return the
// folders for x64 libraries. If you want x86 or arm, you can make
// slight edits to the code below, or, if enough people want this,
// I can work it in here.
// Defer macro/thing.
#define CONCAT_INTERNAL(x,y) x##y
#define CONCAT(x,y) CONCAT_INTERNAL(x,y)
template<typename T>
struct ExitScope {
T lambda;
ExitScope(T lambda):lambda(lambda){}
ExitScope(const ExitScope&);
ExitScope& operator =(const ExitScope&);
class ExitScopeHelp {
template<typename T>
ExitScope<T> operator+(T t){ return t;}
#define defer const auto& CONCAT(defer__, __LINE__) = ExitScopeHelp() + [&]()
// COM objects for the ridiculous Microsoft craziness.
struct DECLSPEC_UUID("B41463C3-8866-43B5-BC33-2B0676F7F42E") DECLSPEC_NOVTABLE ISetupInstance : public IUnknown
STDMETHOD(GetInstanceId)(_Out_ BSTR* pbstrInstanceId) = 0;
STDMETHOD(GetInstallDate)(_Out_ LPFILETIME pInstallDate) = 0;
STDMETHOD(GetInstallationName)(_Out_ BSTR* pbstrInstallationName) = 0;
STDMETHOD(GetInstallationPath)(_Out_ BSTR* pbstrInstallationPath) = 0;
STDMETHOD(GetInstallationVersion)(_Out_ BSTR* pbstrInstallationVersion) = 0;
STDMETHOD(GetDisplayName)(_In_ LCID lcid, _Out_ BSTR* pbstrDisplayName) = 0;
STDMETHOD(GetDescription)(_In_ LCID lcid, _Out_ BSTR* pbstrDescription) = 0;
STDMETHOD(ResolvePath)(_In_opt_z_ LPCOLESTR pwszRelativePath, _Out_ BSTR* pbstrAbsolutePath) = 0;
struct DECLSPEC_UUID("6380BCFF-41D3-4B2E-8B2E-BF8A6810C848") DECLSPEC_NOVTABLE IEnumSetupInstances : public IUnknown
STDMETHOD(Next)(_In_ ULONG celt, _Out_writes_to_(celt, *pceltFetched) ISetupInstance** rgelt, _Out_opt_ _Deref_out_range_(0, celt) ULONG* pceltFetched) = 0;
STDMETHOD(Skip)(_In_ ULONG celt) = 0;
STDMETHOD(Reset)(void) = 0;
STDMETHOD(Clone)(_Deref_out_opt_ IEnumSetupInstances** ppenum) = 0;
struct DECLSPEC_UUID("42843719-DB4C-46C2-8E7C-64F1816EFD5B") DECLSPEC_NOVTABLE ISetupConfiguration : public IUnknown
STDMETHOD(EnumInstances)(_Out_ IEnumSetupInstances** ppEnumInstances) = 0;
STDMETHOD(GetInstanceForCurrentProcess)(_Out_ ISetupInstance** ppInstance) = 0;
STDMETHOD(GetInstanceForPath)(_In_z_ LPCWSTR wzPath, _Out_ ISetupInstance** ppInstance) = 0;
// The beginning of the actual code that does things.
struct Version_Data {
int32_t best_version[4]; // For Windows 8 versions, only two of these numbers are used.
wchar_t *best_name;
bool os_file_exists(wchar_t *name) {
// @Robustness: What flags do we really want to check here?
auto attrib = GetFileAttributesW(name);
if (attrib == INVALID_FILE_ATTRIBUTES) return false;
if (attrib & FILE_ATTRIBUTE_DIRECTORY) return false;
return true;
wchar_t *concat(wchar_t *a, wchar_t *b, wchar_t *c = nullptr, wchar_t *d = nullptr) {
// Concatenate up to 4 wide strings together. Allocated with malloc.
// If you don't like that, use a programming language that actually
// helps you with using custom allocators. Or just edit the code.
auto len_a = wcslen(a);
auto len_b = wcslen(b);
auto len_c = 0;
if (c) len_c = wcslen(c);
auto len_d = 0;
if (d) len_d = wcslen(d);
wchar_t *result = (wchar_t *)malloc((len_a + len_b + len_c + len_d + 1) * 2);
memcpy(result, a, len_a*2);
memcpy(result + len_a, b, len_b*2);
if (c) memcpy(result + len_a + len_b, c, len_c * 2);
if (d) memcpy(result + len_a + len_b + len_c, d, len_d * 2);
result[len_a + len_b + len_c + len_d] = 0;
return result;
typedef void (*Visit_Proc_W)(wchar_t *short_name, wchar_t *full_name, Version_Data *data);
bool visit_files_w(wchar_t *dir_name, Version_Data *data, Visit_Proc_W proc) {
// Visit everything in one folder (non-recursively). If it's a directory
// that doesn't start with ".", call the visit proc on it. The visit proc
// will see if the filename conforms to the expected versioning pattern.
auto wildcard_name = concat(dir_name, L"\\*");
defer { free(wildcard_name); };
WIN32_FIND_DATAW find_data;
auto handle = FindFirstFileW(wildcard_name, &find_data);
if (handle == INVALID_HANDLE_VALUE) return false;
while (true) {
if ((find_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) && (find_data.cFileName[0] != '.')) {
auto full_name = concat(dir_name, L"\\", find_data.cFileName);
defer { free(full_name); };
proc(find_data.cFileName, full_name, data);
auto success = FindNextFileW(handle, &find_data);
if (!success) break;
return true;
wchar_t *find_windows_kit_root(HKEY key, wchar_t *version) {
// Given a key to an already opened registry entry,
// get the value stored under the 'version' subkey.
// If that's not the right terminology, hey, I never do registry stuff.
DWORD required_length;
auto rc = RegQueryValueExW(key, version, NULL, NULL, NULL, &required_length);
if (rc != 0) return NULL;
DWORD length = required_length + 2; // The +2 is for the maybe optional zero later on. Probably we are over-allocating.
wchar_t *value = (wchar_t *)malloc(length);
if (!value) return NULL;
rc = RegQueryValueExW(key, version, NULL, NULL, (LPBYTE)value, &length); // We know that version is zero-terminated...
if (rc != 0) return NULL;
// The documentation says that if the string for some reason was not stored
// with zero-termination, we need to manually terminate it. Sigh!!
if (value[length]) {
value[length+1] = 0;
return value;
void win10_best(wchar_t *short_name, wchar_t *full_name, Version_Data *data) {
// Find the Windows 10 subdirectory with the highest version number.
int i0, i1, i2, i3;
auto success = swscanf_s(short_name, L"%d.%d.%d.%d", &i0, &i1, &i2, &i3);
if (success < 4) return;
if (i0 < data->best_version[0]) return;
else if (i0 == data->best_version[0]) {
if (i1 < data->best_version[1]) return;
else if (i1 == data->best_version[1]) {
if (i2 < data->best_version[2]) return;
else if (i2 == data->best_version[2]) {
if (i3 < data->best_version[3]) return;
// we have to copy_string and free here because visit_files free's the full_name string
// after we execute this function, so Win*_Data would contain an invalid pointer.
if (data->best_name) free(data->best_name);
data->best_name = _wcsdup(full_name);
if (data->best_name) {
data->best_version[0] = i0;
data->best_version[1] = i1;
data->best_version[2] = i2;
data->best_version[3] = i3;
void win8_best(wchar_t *short_name, wchar_t *full_name, Version_Data *data) {
// Find the Windows 8 subdirectory with the highest version number.
int i0, i1;
auto success = swscanf_s(short_name, L"winv%d.%d", &i0, &i1);
if (success < 2) return;
if (i0 < data->best_version[0]) return;
else if (i0 == data->best_version[0]) {
if (i1 < data->best_version[1]) return;
// we have to copy_string and free here because visit_files free's the full_name string
// after we execute this function, so Win*_Data would contain an invalid pointer.
if (data->best_name) free(data->best_name);
data->best_name = _wcsdup(full_name);
if (data->best_name) {
data->best_version[0] = i0;
data->best_version[1] = i1;
void find_windows_kit_root(Find_Result *result) {
// Information about the Windows 10 and Windows 8 development kits
// is stored in the same place in the registry. We open a key
// to that place, first checking preferntially for a Windows 10 kit,
// then, if that's not found, a Windows 8 kit.
HKEY main_key;
auto rc = RegOpenKeyExA(HKEY_LOCAL_MACHINE, "SOFTWARE\\Microsoft\\Windows Kits\\Installed Roots",
if (rc != S_OK) return;
defer { RegCloseKey(main_key); };
// Look for a Windows 10 entry.
auto windows10_root = find_windows_kit_root(main_key, L"KitsRoot10");
if (windows10_root) {
defer { free(windows10_root); };
Version_Data data = {0};
auto windows10_lib = concat(windows10_root, L"Lib");
defer { free(windows10_lib); };
visit_files_w(windows10_lib, &data, win10_best);
if (data.best_name) {
result->windows_sdk_version = 10;
result->windows_sdk_root = data.best_name;
// Look for a Windows 8 entry.
auto windows8_root = find_windows_kit_root(main_key, L"KitsRoot81");
if (windows8_root) {
defer { free(windows8_root); };
auto windows8_lib = concat(windows8_root, L"Lib");
defer { free(windows8_lib); };
Version_Data data = {0};
visit_files_w(windows8_lib, &data, win8_best);
if (data.best_name) {
result->windows_sdk_version = 8;
result->windows_sdk_root = data.best_name;
// If we get here, we failed to find anything.
void find_visual_studio_by_fighting_through_microsoft_craziness(Find_Result *result) {
// The name of this procedure is kind of cryptic. Its purpose is
// to fight through Microsoft craziness. The things that the fine
// Visual Studio team want you to do, JUST TO FIND A SINGLE FOLDER
// THAT EVERYONE NEEDS TO FIND, are ridiculous garbage.
// For earlier versions of Visual Studio, you'd find this information in the registry,
// similarly to the Windows Kits above. But no, now it's the future, so to ask the
// question "Where is the Visual Studio folder?" you have to do a bunch of COM object
// instantiation, enumeration, and querying. (For extra bonus points, try doing this in
// a new, underdeveloped programming language where you don't have COM routines up
// and running yet. So fun.)
// If all this COM object instantiation, enumeration, and querying doesn't give us
// a useful result, we drop back to the registry-checking method.
auto rc = CoInitialize(NULL);
// "Subsequent valid calls return false." So ignore false.
// if rc != S_OK return false;
GUID my_uid = {0x42843719, 0xDB4C, 0x46C2, {0x8E, 0x7C, 0x64, 0xF1, 0x81, 0x6E, 0xFD, 0x5B}};
GUID CLSID_SetupConfiguration = {0x177F0C4A, 0x1CD3, 0x4DE7, {0xA3, 0x2C, 0x71, 0xDB, 0xBB, 0x9F, 0xA3, 0x6D}};
ISetupConfiguration *config = NULL;
auto hr = CoCreateInstance(CLSID_SetupConfiguration, NULL, CLSCTX_INPROC_SERVER, my_uid, (void **)&config);
if (hr != 0) return;
defer { config->Release(); };
IEnumSetupInstances *instances = NULL;
hr = config->EnumInstances(&instances);
if (hr != 0) return;
if (!instances) return;
defer { instances->Release(); };
while (1) {
ULONG found = 0;
ISetupInstance *instance = NULL;
auto hr = instances->Next(1, &instance, &found);
if (hr != S_OK) break;
defer { instance->Release(); };
BSTR bstr_inst_path;
hr = instance->GetInstallationPath(&bstr_inst_path);
if (hr != S_OK) continue;
defer { SysFreeString(bstr_inst_path); };
auto tools_filename = concat(bstr_inst_path, L"\\VC\\Auxiliary\\Build\\Microsoft.VCToolsVersion.default.txt");
defer { free(tools_filename); };
FILE *f = nullptr;
auto open_result = _wfopen_s(&f, tools_filename, L"rt");
if (open_result != 0) continue;
if (!f) continue;
defer { fclose(f); };
LARGE_INTEGER tools_file_size;
auto file_handle = (HANDLE)_get_osfhandle(_fileno(f));
BOOL success = GetFileSizeEx(file_handle, &tools_file_size);
if (!success) continue;
auto version_bytes = (tools_file_size.QuadPart + 1) * 2; // Warning: This multiplication by 2 presumes there is no variable-length encoding in the wchars (wacky characters in the file could betray this expectation).
wchar_t *version = (wchar_t *)malloc(version_bytes);
defer { free(version); };
auto read_result = fgetws(version, version_bytes, f);
if (!read_result) continue;
auto version_tail = wcschr(version, '\n');
if (version_tail) *version_tail = 0; // Stomp the data, because nobody cares about it.
auto library_path = concat(bstr_inst_path, L"\\VC\\Tools\\MSVC\\", version, L"\\lib\\x64");
auto library_file = concat(library_path, L"\\vcruntime.lib"); // @Speed: Could have library_path point to this string, with a smaller count, to save on memory flailing!
if (os_file_exists(library_file)) {
auto link_exe_path = concat(bstr_inst_path, L"\\VC\\Tools\\MSVC\\", version, L"\\bin\\Hostx64\\x64");
result->vs_exe_path = link_exe_path;
result->vs_library_path = library_path;
Ryan Saunderson said:
"Clang uses the 'SetupInstance->GetInstallationVersion' / ISetupHelper->ParseVersion to find the newest version
and then reads the tools file to define the tools path - which is definitely better than what i did."
So... @Incomplete: Should probably pick the newest version...
// If we get here, we didn't find Visual Studio 2017. Try earlier versions.
HKEY vs7_key;
rc = RegOpenKeyExA(HKEY_LOCAL_MACHINE, "SOFTWARE\\Microsoft\\VisualStudio\\SxS\\VS7", 0, KEY_QUERY_VALUE | KEY_WOW64_32KEY, &vs7_key);
if (rc != S_OK) return;
defer { RegCloseKey(vs7_key); };
// Hardcoded search for 4 prior Visual Studio versions. Is there something better to do here?
wchar_t *versions[] = { L"14.0", L"12.0", L"11.0", L"10.0" };
const int NUM_VERSIONS = sizeof(versions) / sizeof(versions[0]);
for (int i = 0; i < NUM_VERSIONS; i++) {
auto v = versions[i];
DWORD dw_type;
DWORD cb_data;
auto rc = RegQueryValueExW(vs7_key, v, NULL, &dw_type, NULL, &cb_data);
if ((rc == ERROR_FILE_NOT_FOUND) || (dw_type != REG_SZ)) {
auto buffer = (wchar_t *)malloc(cb_data);
if (!buffer) return;
defer { free(buffer); };
rc = RegQueryValueExW(vs7_key, v, NULL, NULL, (LPBYTE)buffer, &cb_data);
if (rc != 0) continue;
// @Robustness: Do the zero-termination thing suggested in the RegQueryValue docs?
auto lib_path = concat(buffer, L"VC\\Lib\\amd64");
// Check to see whether a vcruntime.lib actually exists here.
auto vcruntime_filename = concat(lib_path, L"\\vcruntime.lib");
defer { free(vcruntime_filename); };
if (os_file_exists(vcruntime_filename)) {
result->vs_exe_path = concat(buffer, L"VC\\bin");
result->vs_library_path = lib_path;
// If we get here, we failed to find anything.
Find_Result find_visual_studio_and_windows_sdk() {
Find_Result result;
if (result.windows_sdk_root) {
result.windows_sdk_um_library_path = concat(result.windows_sdk_root, L"\\um\\x64");
result.windows_sdk_ucrt_library_path = concat(result.windows_sdk_root, L"\\ucrt\\x64");
return result;
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