Import deputil from old v4 repo.

4 files changed, 838 insertions, 0 deletions

diff --git a/src/dutil/deputil.cpp b/src/dutil/deputil.cpp
new file mode 100644
index 00000000..b2db0dd6
--- /dev/null
+++ b/src/dutil/deputil.cpp
@@ -0,0 +1,688 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+#include "precomp.h"
+
+#define ARRAY_GROWTH_SIZE 5
+
+static LPCWSTR vcszVersionValue = L"Version";
+static LPCWSTR vcszDisplayNameValue = L"DisplayName";
+static LPCWSTR vcszMinVersionValue = L"MinVersion";
+static LPCWSTR vcszMaxVersionValue = L"MaxVersion";
+static LPCWSTR vcszAttributesValue = L"Attributes";
+
+enum eRequiresAttributes { RequiresAttributesMinVersionInclusive = 256, RequiresAttributesMaxVersionInclusive = 512 };
+
+// We write to Software\Classes explicitly based on the current security context instead of HKCR.
+// See http://msdn.microsoft.com/en-us/library/ms724475(VS.85).aspx for more information.
+static LPCWSTR vsczRegistryRoot = L"Software\\Classes\\Installer\\Dependencies\\";
+static LPCWSTR vsczRegistryDependents = L"Dependents";
+
+static HRESULT AllocDependencyKeyName(
+    __in_z LPCWSTR wzName,
+    __deref_out_z LPWSTR* psczKeyName
+    );
+
+static HRESULT GetDependencyNameFromKey(
+    __in HKEY hkHive,
+    __in LPCWSTR wzKey,
+    __deref_out_z LPWSTR* psczName
+    );
+
+DAPI_(HRESULT) DepGetProviderInformation(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey,
+    __deref_out_z_opt LPWSTR* psczId,
+    __deref_out_z_opt LPWSTR* psczName,
+    __out_opt DWORD64* pqwVersion
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczKey = NULL;
+    HKEY hkKey = NULL;
+
+    // Format the provider dependency registry key.
+    hr = AllocDependencyKeyName(wzProviderKey, &sczKey);
+    ExitOnFailure(hr, "Failed to allocate the registry key for dependency \"%ls\".", wzProviderKey);
+
+    // Try to open the dependency key.
+    hr = RegOpen(hkHive, sczKey, KEY_READ, &hkKey);
+    if (E_FILENOTFOUND == hr)
+    {
+        ExitFunction1(hr = E_NOTFOUND);
+    }
+    ExitOnFailure(hr, "Failed to open the registry key for the dependency \"%ls\".", wzProviderKey);
+
+    // Get the Id if requested and available.
+    if (psczId)
+    {
+        hr = RegReadString(hkKey, NULL, psczId);
+        if (E_FILENOTFOUND == hr)
+        {
+            hr = S_OK;
+        }
+        ExitOnFailure(hr, "Failed to get the id for the dependency \"%ls\".", wzProviderKey);
+    }
+
+    // Get the DisplayName if requested and available.
+    if (psczName)
+    {
+        hr = RegReadString(hkKey, vcszDisplayNameValue, psczName);
+        if (E_FILENOTFOUND == hr)
+        {
+            hr = S_OK;
+        }
+        ExitOnFailure(hr, "Failed to get the name for the dependency \"%ls\".", wzProviderKey);
+    }
+
+    // Get the Version if requested and available.
+    if (pqwVersion)
+    {
+        hr = RegReadVersion(hkKey, vcszVersionValue, pqwVersion);
+        if (E_FILENOTFOUND == hr)
+        {
+            hr = S_OK;
+        }
+        ExitOnFailure(hr, "Failed to get the version for the dependency \"%ls\".", wzProviderKey);
+    }
+
+LExit:
+    ReleaseRegKey(hkKey);
+    ReleaseStr(sczKey);
+
+    return hr;
+}
+
+DAPI_(HRESULT) DepCheckDependency(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey,
+    __in_z_opt LPCWSTR wzMinVersion,
+    __in_z_opt LPCWSTR wzMaxVersion,
+    __in int iAttributes,
+    __in STRINGDICT_HANDLE sdDependencies,
+    __deref_inout_ecount_opt(*pcDependencies) DEPENDENCY** prgDependencies,
+    __inout LPUINT pcDependencies
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczKey = NULL;
+    HKEY hkKey = NULL;
+    DWORD64 dw64Version = 0;
+    int cchMinVersion = 0;
+    DWORD64 dw64MinVersion = 0;
+    int cchMaxVersion = 0;
+    DWORD64 dw64MaxVersion = 0;
+    BOOL fAllowEqual = FALSE;
+    LPWSTR sczName = NULL;
+
+    // Format the provider dependency registry key.
+    hr = AllocDependencyKeyName(wzProviderKey, &sczKey);
+    ExitOnFailure(hr, "Failed to allocate the registry key for dependency \"%ls\".", wzProviderKey);
+
+    // Try to open the key. If that fails, add the missing dependency key to the dependency array if it doesn't already exist.
+    hr = RegOpen(hkHive, sczKey, KEY_READ, &hkKey);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to open the registry key for dependency \"%ls\".", wzProviderKey);
+
+        // If there are no registry values, consider the key orphaned and treat it as missing.
+        hr = RegReadVersion(hkKey, vcszVersionValue, &dw64Version);
+        if (E_FILENOTFOUND != hr)
+        {
+            ExitOnFailure(hr, "Failed to read the %ls registry value for dependency \"%ls\".", vcszVersionValue, wzProviderKey);
+        }
+    }
+
+    // If the key was not found or the Version value was not found, add the missing dependency key to the dependency array.
+    if (E_FILENOTFOUND == hr)
+    {
+        hr = DictKeyExists(sdDependencies, wzProviderKey);
+        if (E_NOTFOUND != hr)
+        {
+            ExitOnFailure(hr, "Failed to check the dictionary for missing dependency \"%ls\".", wzProviderKey);
+        }
+        else
+        {
+            hr = DepDependencyArrayAlloc(prgDependencies, pcDependencies, wzProviderKey, NULL);
+            ExitOnFailure(hr, "Failed to add the missing dependency \"%ls\" to the array.", wzProviderKey);
+
+            hr = DictAddKey(sdDependencies, wzProviderKey);
+            ExitOnFailure(hr, "Failed to add the missing dependency \"%ls\" to the dictionary.", wzProviderKey);
+        }
+
+        // Exit since the check already failed.
+        ExitFunction1(hr = E_NOTFOUND);
+    }
+
+    // Check MinVersion if provided.
+    if (wzMinVersion)
+    {
+        cchMinVersion = lstrlenW(wzMinVersion);
+        if (0 < cchMinVersion)
+        {
+            hr = FileVersionFromStringEx(wzMinVersion, cchMinVersion, &dw64MinVersion);
+            ExitOnFailure(hr, "Failed to get the 64-bit version number from \"%ls\".", wzMinVersion);
+
+            fAllowEqual = iAttributes & RequiresAttributesMinVersionInclusive;
+            if (!(fAllowEqual && dw64MinVersion <= dw64Version || dw64MinVersion < dw64Version))
+            {
+                hr = DictKeyExists(sdDependencies, wzProviderKey);
+                if (E_NOTFOUND != hr)
+                {
+                    ExitOnFailure(hr, "Failed to check the dictionary for the older dependency \"%ls\".", wzProviderKey);
+                }
+                else
+                {
+                    hr = RegReadString(hkKey, vcszDisplayNameValue, &sczName);
+                    ExitOnFailure(hr, "Failed to get the display name of the older dependency \"%ls\".", wzProviderKey);
+
+                    hr = DepDependencyArrayAlloc(prgDependencies, pcDependencies, wzProviderKey, sczName);
+                    ExitOnFailure(hr, "Failed to add the older dependency \"%ls\" to the dependencies array.", wzProviderKey);
+
+                    hr = DictAddKey(sdDependencies, wzProviderKey);
+                    ExitOnFailure(hr, "Failed to add the older dependency \"%ls\" to the unique dependency string list.", wzProviderKey);
+                }
+
+                // Exit since the check already failed.
+                ExitFunction1(hr = E_NOTFOUND);
+            }
+        }
+    }
+
+    // Check MaxVersion if provided.
+    if (wzMaxVersion)
+    {
+        cchMaxVersion = lstrlenW(wzMaxVersion);
+        if (0 < cchMaxVersion)
+        {
+            hr = FileVersionFromStringEx(wzMaxVersion, cchMaxVersion, &dw64MaxVersion);
+            ExitOnFailure(hr, "Failed to get the 64-bit version number from \"%ls\".", wzMaxVersion);
+
+            fAllowEqual = iAttributes & RequiresAttributesMaxVersionInclusive;
+            if (!(fAllowEqual && dw64Version <= dw64MaxVersion || dw64Version < dw64MaxVersion))
+            {
+                hr = DictKeyExists(sdDependencies, wzProviderKey);
+                if (E_NOTFOUND != hr)
+                {
+                    ExitOnFailure(hr, "Failed to check the dictionary for the newer dependency \"%ls\".", wzProviderKey);
+                }
+                else
+                {
+                    hr = RegReadString(hkKey, vcszDisplayNameValue, &sczName);
+                    ExitOnFailure(hr, "Failed to get the display name of the newer dependency \"%ls\".", wzProviderKey);
+
+                    hr = DepDependencyArrayAlloc(prgDependencies, pcDependencies, wzProviderKey, sczName);
+                    ExitOnFailure(hr, "Failed to add the newer dependency \"%ls\" to the dependencies array.", wzProviderKey);
+
+                    hr = DictAddKey(sdDependencies, wzProviderKey);
+                    ExitOnFailure(hr, "Failed to add the newer dependency \"%ls\" to the unique dependency string list.", wzProviderKey);
+                }
+
+                // Exit since the check already failed.
+                ExitFunction1(hr = E_NOTFOUND);
+            }
+        }
+    }
+
+LExit:
+    ReleaseStr(sczName);
+    ReleaseRegKey(hkKey);
+    ReleaseStr(sczKey);
+
+    return hr;
+}
+
+DAPI_(HRESULT) DepCheckDependents(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey,
+    __reserved int /*iAttributes*/,
+    __in C_STRINGDICT_HANDLE sdIgnoredDependents,
+    __deref_inout_ecount_opt(*pcDependents) DEPENDENCY** prgDependents,
+    __inout LPUINT pcDependents
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczKey = NULL;
+    HKEY hkProviderKey = NULL;
+    HKEY hkDependentsKey = NULL;
+    LPWSTR sczDependentKey = NULL;
+    LPWSTR sczDependentName = NULL;
+
+    // Format the provider dependency registry key.
+    hr = AllocDependencyKeyName(wzProviderKey, &sczKey);
+    ExitOnFailure(hr, "Failed to allocate the registry key for dependency \"%ls\".", wzProviderKey);
+
+    // Try to open the key. If that fails, the dependency information is corrupt.
+    hr = RegOpen(hkHive, sczKey, KEY_READ, &hkProviderKey);
+    ExitOnFailure(hr, "Failed to open the registry key \"%ls\". The dependency store is corrupt.", sczKey);
+
+    // Try to open the dependencies key. If that does not exist, there are no dependents.
+    hr = RegOpen(hkProviderKey, vsczRegistryDependents, KEY_READ, &hkDependentsKey);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to open the registry key for dependents of \"%ls\".", wzProviderKey);
+    }
+    else
+    {
+        ExitFunction1(hr = S_OK);
+    }
+
+    // Now enumerate the dependent keys. If they are not defined in the ignored list, add them to the array.
+    for (DWORD dwIndex = 0; ; ++dwIndex)
+    {
+        hr = RegKeyEnum(hkDependentsKey, dwIndex, &sczDependentKey);
+        if (E_NOMOREITEMS != hr)
+        {
+            ExitOnFailure(hr, "Failed to enumerate the dependents key of \"%ls\".", wzProviderKey);
+        }
+        else
+        {
+            hr = S_OK;
+            break;
+        }
+
+        // If the key isn't ignored, add it to the dependent array.
+        hr = DictKeyExists(sdIgnoredDependents, sczDependentKey);
+        if (E_NOTFOUND != hr)
+        {
+            ExitOnFailure(hr, "Failed to check the dictionary of ignored dependents.");
+        }
+        else
+        {
+            // Get the name of the dependent from the key.
+            hr = GetDependencyNameFromKey(hkHive, sczDependentKey, &sczDependentName);
+            ExitOnFailure(hr, "Failed to get the name of the dependent from the key \"%ls\".", sczDependentKey);
+
+            hr = DepDependencyArrayAlloc(prgDependents, pcDependents, sczDependentKey, sczDependentName);
+            ExitOnFailure(hr, "Failed to add the dependent key \"%ls\" to the string array.", sczDependentKey);
+        }
+    }
+
+LExit:
+    ReleaseStr(sczDependentName);
+    ReleaseStr(sczDependentKey);
+    ReleaseRegKey(hkDependentsKey);
+    ReleaseRegKey(hkProviderKey);
+    ReleaseStr(sczKey);
+
+    return hr;
+}
+
+DAPI_(HRESULT) DepRegisterDependency(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey,
+    __in_z LPCWSTR wzVersion,
+    __in_z LPCWSTR wzDisplayName,
+    __in_z_opt LPCWSTR wzId,
+    __in int iAttributes
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczKey = NULL;
+    HKEY hkKey = NULL;
+    BOOL fCreated = FALSE;
+
+    // Format the provider dependency registry key.
+    hr = AllocDependencyKeyName(wzProviderKey, &sczKey);
+    ExitOnFailure(hr, "Failed to allocate the registry key for dependency \"%ls\".", wzProviderKey);
+
+    // Create the dependency key (or open it if it already exists).
+    hr = RegCreateEx(hkHive, sczKey, KEY_WRITE, FALSE, NULL, &hkKey, &fCreated);
+    ExitOnFailure(hr, "Failed to create the dependency registry key \"%ls\".", sczKey);
+
+    // Set the id if it was provided.
+    if (wzId)
+    {
+        hr = RegWriteString(hkKey, NULL, wzId);
+        ExitOnFailure(hr, "Failed to set the %ls registry value to \"%ls\".", L"default", wzId);
+    }
+
+    // Set the version.
+    hr = RegWriteString(hkKey, vcszVersionValue, wzVersion);
+    ExitOnFailure(hr, "Failed to set the %ls registry value to \"%ls\".", vcszVersionValue, wzVersion);
+
+    // Set the display name.
+    hr = RegWriteString(hkKey, vcszDisplayNameValue, wzDisplayName);
+    ExitOnFailure(hr, "Failed to set the %ls registry value to \"%ls\".", vcszDisplayNameValue, wzDisplayName);
+
+    // Set the attributes if non-zero.
+    if (0 != iAttributes)
+    {
+        hr = RegWriteNumber(hkKey, vcszAttributesValue, static_cast<DWORD>(iAttributes));
+        ExitOnFailure(hr, "Failed to set the %ls registry value to %d.", vcszAttributesValue, iAttributes);
+    }
+
+LExit:
+    ReleaseRegKey(hkKey);
+    ReleaseStr(sczKey);
+
+    return hr;
+}
+
+DAPI_(HRESULT) DepDependentExists(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzDependencyProviderKey,
+    __in_z LPCWSTR wzProviderKey
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczDependentKey = NULL;
+    HKEY hkDependentKey = NULL;
+
+    // Format the provider dependents registry key.
+    hr = StrAllocFormatted(&sczDependentKey, L"%ls%ls\\%ls\\%ls", vsczRegistryRoot, wzDependencyProviderKey, vsczRegistryDependents, wzProviderKey);
+    ExitOnFailure(hr, "Failed to format registry key to dependent.");
+
+    hr = RegOpen(hkHive, sczDependentKey, KEY_READ, &hkDependentKey);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to open the dependent registry key at: \"%ls\".", sczDependentKey);
+    }
+
+LExit:
+    ReleaseRegKey(hkDependentKey);
+    ReleaseStr(sczDependentKey);
+
+    return hr;
+}
+
+DAPI_(HRESULT) DepRegisterDependent(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzDependencyProviderKey,
+    __in_z LPCWSTR wzProviderKey,
+    __in_z_opt LPCWSTR wzMinVersion,
+    __in_z_opt LPCWSTR wzMaxVersion,
+    __in int iAttributes
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczDependencyKey = NULL;
+    HKEY hkDependencyKey = NULL;
+    LPWSTR sczKey = NULL;
+    HKEY hkKey = NULL;
+    BOOL fCreated = FALSE;
+
+    // Format the provider dependency registry key.
+    hr = AllocDependencyKeyName(wzDependencyProviderKey, &sczDependencyKey);
+    ExitOnFailure(hr, "Failed to allocate the registry key for dependency \"%ls\".", wzDependencyProviderKey);
+
+    // Create the dependency key (or open it if it already exists).
+    hr = RegCreateEx(hkHive, sczDependencyKey, KEY_WRITE, FALSE, NULL, &hkDependencyKey, &fCreated);
+    ExitOnFailure(hr, "Failed to create the dependency registry key \"%ls\".", sczDependencyKey);
+
+    // Create the subkey to register the dependent.
+    hr = StrAllocFormatted(&sczKey, L"%ls\\%ls", vsczRegistryDependents, wzProviderKey);
+    ExitOnFailure(hr, "Failed to allocate dependent subkey \"%ls\" under dependency \"%ls\".", wzProviderKey, wzDependencyProviderKey);
+
+    hr = RegCreateEx(hkDependencyKey, sczKey, KEY_WRITE, FALSE, NULL, &hkKey, &fCreated);
+    ExitOnFailure(hr, "Failed to create the dependency subkey \"%ls\".", sczKey);
+
+    // Set the minimum version if not NULL.
+    hr = RegWriteString(hkKey, vcszMinVersionValue, wzMinVersion);
+    ExitOnFailure(hr, "Failed to set the %ls registry value to \"%ls\".", vcszMinVersionValue, wzMinVersion);
+
+    // Set the maximum version if not NULL.
+    hr = RegWriteString(hkKey, vcszMaxVersionValue, wzMaxVersion);
+    ExitOnFailure(hr, "Failed to set the %ls registry value to \"%ls\".", vcszMaxVersionValue, wzMaxVersion);
+
+    // Set the attributes if non-zero.
+    if (0 != iAttributes)
+    {
+        hr = RegWriteNumber(hkKey, vcszAttributesValue, static_cast<DWORD>(iAttributes));
+        ExitOnFailure(hr, "Failed to set the %ls registry value to %d.", vcszAttributesValue, iAttributes);
+    }
+
+LExit:
+    ReleaseRegKey(hkKey);
+    ReleaseStr(sczKey);
+    ReleaseRegKey(hkDependencyKey);
+    ReleaseStr(sczDependencyKey);
+
+    return hr;
+}
+
+DAPI_(HRESULT) DepUnregisterDependency(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczKey = NULL;
+    HKEY hkKey = NULL;
+
+    // Format the provider dependency registry key.
+    hr = AllocDependencyKeyName(wzProviderKey, &sczKey);
+    ExitOnFailure(hr, "Failed to allocate the registry key for dependency \"%ls\".", wzProviderKey);
+
+    // Delete the entire key including all sub-keys.
+    hr = RegDelete(hkHive, sczKey, REG_KEY_DEFAULT, TRUE);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to delete the key \"%ls\".", sczKey);
+    }
+
+LExit:
+    ReleaseRegKey(hkKey);
+    ReleaseStr(sczKey);
+
+    return hr;
+}
+
+DAPI_(HRESULT) DepUnregisterDependent(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzDependencyProviderKey,
+    __in_z LPCWSTR wzProviderKey
+    )
+{
+    HRESULT hr = S_OK;
+    HKEY hkRegistryRoot = NULL;
+    HKEY hkDependencyProviderKey = NULL;
+    HKEY hkRegistryDependents = NULL;
+    DWORD cSubKeys = 0;
+    DWORD cValues = 0;
+
+    // Open the root key. We may delete the wzDependencyProviderKey during clean up.
+    hr = RegOpen(hkHive, vsczRegistryRoot, KEY_READ, &hkRegistryRoot);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to open root registry key \"%ls\".", vsczRegistryRoot);
+    }
+    else
+    {
+        ExitFunction();
+    }
+
+    // Try to open the dependency key. If that does not exist, simply return.
+    hr = RegOpen(hkRegistryRoot, wzDependencyProviderKey, KEY_READ, &hkDependencyProviderKey);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to open the registry key for the dependency \"%ls\".", wzDependencyProviderKey);
+    }
+    else
+    {
+        ExitFunction();
+    }
+
+    // Try to open the dependents subkey to enumerate.
+    hr = RegOpen(hkDependencyProviderKey, vsczRegistryDependents, KEY_READ, &hkRegistryDependents);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to open the dependents subkey under the dependency \"%ls\".", wzDependencyProviderKey);
+    }
+    else
+    {
+        ExitFunction();
+    }
+
+    // Delete the wzProviderKey dependent sub-key.
+    hr = RegDelete(hkRegistryDependents, wzProviderKey, REG_KEY_DEFAULT, TRUE);
+    ExitOnFailure(hr, "Failed to delete the dependent \"%ls\" under the dependency \"%ls\".", wzProviderKey, wzDependencyProviderKey);
+
+    // If there are no remaining dependents, delete the Dependents subkey.
+    hr = RegQueryKey(hkRegistryDependents, &cSubKeys, NULL);
+    ExitOnFailure(hr, "Failed to get the number of dependent subkeys under the dependency \"%ls\".", wzDependencyProviderKey);
+    
+    if (0 < cSubKeys)
+    {
+        ExitFunction();
+    }
+
+    // Release the handle to make sure it's deleted immediately.
+    ReleaseRegKey(hkRegistryDependents);
+
+    // Fail if there are any subkeys since we just checked.
+    hr = RegDelete(hkDependencyProviderKey, vsczRegistryDependents, REG_KEY_DEFAULT, FALSE);
+    ExitOnFailure(hr, "Failed to delete the dependents subkey under the dependency \"%ls\".", wzDependencyProviderKey);
+
+    // If there are no values, delete the provider dependency key.
+    hr = RegQueryKey(hkDependencyProviderKey, NULL, &cValues);
+    ExitOnFailure(hr, "Failed to get the number of values under the dependency \"%ls\".", wzDependencyProviderKey);
+
+    if (0 == cValues)
+    {
+        // Release the handle to make sure it's deleted immediately.
+        ReleaseRegKey(hkDependencyProviderKey);
+
+        // Fail if there are any subkeys since we just checked.
+        hr = RegDelete(hkRegistryRoot, wzDependencyProviderKey, REG_KEY_DEFAULT, FALSE);
+        ExitOnFailure(hr, "Failed to delete the dependency \"%ls\".", wzDependencyProviderKey);
+    }
+
+LExit:
+    ReleaseRegKey(hkRegistryDependents);
+    ReleaseRegKey(hkDependencyProviderKey);
+    ReleaseRegKey(hkRegistryRoot);
+
+    return hr;
+}
+
+DAPI_(HRESULT) DepDependencyArrayAlloc(
+    __deref_inout_ecount_opt(*pcDependencies) DEPENDENCY** prgDependencies,
+    __inout LPUINT pcDependencies,
+    __in_z LPCWSTR wzKey,
+    __in_z_opt LPCWSTR wzName
+    )
+{
+    HRESULT hr = S_OK;
+    UINT cRequired = 0;
+    DEPENDENCY* pDependency = NULL;
+
+    hr = ::UIntAdd(*pcDependencies, 1, &cRequired);
+    ExitOnFailure(hr, "Failed to increment the number of elements required in the dependency array.");
+
+    hr = MemEnsureArraySize(reinterpret_cast<LPVOID*>(prgDependencies), cRequired, sizeof(DEPENDENCY), ARRAY_GROWTH_SIZE);
+    ExitOnFailure(hr, "Failed to allocate memory for the dependency array.");
+
+    pDependency = static_cast<DEPENDENCY*>(&(*prgDependencies)[*pcDependencies]);
+    ExitOnNull(pDependency, hr, E_POINTER, "The dependency element in the array is invalid.");
+
+    hr = StrAllocString(&(pDependency->sczKey), wzKey, 0);
+    ExitOnFailure(hr, "Failed to allocate the string key in the dependency array.");
+
+    if (wzName)
+    {
+        hr = StrAllocString(&(pDependency->sczName), wzName, 0);
+        ExitOnFailure(hr, "Failed to allocate the string name in the dependency array.");
+    }
+
+    // Update the number of current elements in the dependency array.
+    *pcDependencies = cRequired;
+
+LExit:
+    return hr;
+}
+
+DAPI_(void) DepDependencyArrayFree(
+    __in_ecount(cDependencies) DEPENDENCY* rgDependencies,
+    __in UINT cDependencies
+    )
+{
+    for (UINT i = 0; i < cDependencies; ++i)
+    {
+        ReleaseStr(rgDependencies[i].sczKey);
+        ReleaseStr(rgDependencies[i].sczName);
+    }
+
+    ReleaseMem(rgDependencies);
+}
+
+/***************************************************************************
+ AllocDependencyKeyName - Allocates and formats the root registry key name.
+
+***************************************************************************/
+static HRESULT AllocDependencyKeyName(
+    __in_z LPCWSTR wzName,
+    __deref_out_z LPWSTR* psczKeyName
+    )
+{
+    HRESULT hr = S_OK;
+    size_t cchName = 0;
+    size_t cchKeyName = 0;
+
+    // Get the length of the static registry root once.
+    static size_t cchRegistryRoot = ::lstrlenW(vsczRegistryRoot);
+
+    // Get the length of the dependency, and add to the length of the root.
+    hr = ::StringCchLengthW(wzName, STRSAFE_MAX_CCH, &cchName);
+    ExitOnFailure(hr, "Failed to get string length of dependency name.");
+
+    // Add the sizes together to allocate memory once (callee will add space for nul).
+    hr = ::SizeTAdd(cchRegistryRoot, cchName, &cchKeyName);
+    ExitOnFailure(hr, "Failed to add the string lengths together.");
+
+    // Allocate and concat the strings together.
+    hr = StrAllocString(psczKeyName, vsczRegistryRoot, cchKeyName);
+    ExitOnFailure(hr, "Failed to allocate string for dependency registry root.");
+
+    hr = StrAllocConcat(psczKeyName, wzName, cchName);
+    ExitOnFailure(hr, "Failed to concatenate the dependency key name.");
+
+LExit:
+    return hr;
+}
+
+/***************************************************************************
+ GetDependencyNameFromKey - Attempts to name of the dependency from the key.
+
+***************************************************************************/
+static HRESULT GetDependencyNameFromKey(
+    __in HKEY hkHive,
+    __in LPCWSTR wzProviderKey,
+    __deref_out_z LPWSTR* psczName
+    )
+{
+    HRESULT hr = S_OK;
+    LPWSTR sczKey = NULL;
+    HKEY hkKey = NULL;
+
+    // Format the provider dependency registry key.
+    hr = AllocDependencyKeyName(wzProviderKey, &sczKey);
+    ExitOnFailure(hr, "Failed to allocate the registry key for dependency \"%ls\".", wzProviderKey);
+
+    // Try to open the dependency key.
+    hr = RegOpen(hkHive, sczKey, KEY_READ, &hkKey);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to open the registry key for the dependency \"%ls\".", wzProviderKey);
+    }
+    else
+    {
+        ExitFunction1(hr = S_OK);
+    }
+
+    // Get the DisplayName if available.
+    hr = RegReadString(hkKey, vcszDisplayNameValue, psczName);
+    if (E_FILENOTFOUND != hr)
+    {
+        ExitOnFailure(hr, "Failed to get the dependency name for the dependency \"%ls\".", wzProviderKey);
+    }
+    else
+    {
+        ExitFunction1(hr = S_OK);
+    }
+
+LExit:
+    ReleaseRegKey(hkKey);
+    ReleaseStr(sczKey);
+
+    return hr;
+}
diff --git a/src/dutil/dutil.vcxproj b/src/dutil/dutil.vcxproj
index 95b90665..606eb87b 100644
--- a/src/dutil/dutil.vcxproj
+++ b/src/dutil/dutil.vcxproj
@@ -171,6 +171,7 @@
     <ClCompile Include="condutil.cpp" />
     <ClCompile Include="conutil.cpp" />
     <ClCompile Include="cryputil.cpp" />
+    <ClCompile Include="deputil.cpp" />
     <ClCompile Include="dictutil.cpp" />
     <ClCompile Include="dirutil.cpp" />
     <ClCompile Include="dlutil.cpp" />
@@ -238,6 +239,7 @@
     <ClInclude Include="inc\condutil.h" />
     <ClInclude Include="inc\conutil.h" />
     <ClInclude Include="inc\cryputil.h" />
+    <ClInclude Include="inc\deputil.h" />
     <ClInclude Include="inc\dictutil.h" />
     <ClInclude Include="inc\dirutil.h" />
     <ClInclude Include="inc\dlutil.h" />
diff --git a/src/dutil/inc/deputil.h b/src/dutil/inc/deputil.h
new file mode 100644
index 00000000..a08d2eb5
--- /dev/null
+++ b/src/dutil/inc/deputil.h
@@ -0,0 +1,147 @@
+#pragma once
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define ReleaseDependencyArray(rg, c) if (rg) { DepDependencyArrayFree(rg, c); }
+#define ReleaseNullDependencyArray(rg, c) if (rg) { DepDependencyArrayFree(rg, c); rg = NULL; }
+
+typedef struct _DEPENDENCY
+{
+    LPWSTR sczKey;
+    LPWSTR sczName;
+} DEPENDENCY;
+
+
+/***************************************************************************
+ DepGetProviderInformation - gets the various pieces of data registered
+  with a dependency.
+
+ Note: Returns E_NOTFOUND if the dependency was not found.
+***************************************************************************/
+DAPI_(HRESULT) DepGetProviderInformation(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey,
+    __deref_out_z_opt LPWSTR* psczId,
+    __deref_out_z_opt LPWSTR* psczName,
+    __out_opt DWORD64* pqwVersion
+    );
+
+/***************************************************************************
+ DepCheckDependency - Checks that the dependency is registered and within
+                      the proper version range.
+
+ Note: Returns E_NOTFOUND if the dependency was not found.
+***************************************************************************/
+DAPI_(HRESULT) DepCheckDependency(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey,
+    __in_z_opt LPCWSTR wzMinVersion,
+    __in_z_opt LPCWSTR wzMaxVersion,
+    __in int iAttributes,
+    __in STRINGDICT_HANDLE sdDependencies,
+    __deref_inout_ecount_opt(*pcDependencies) DEPENDENCY** prgDependencies,
+    __inout LPUINT pcDependencies
+    );
+
+/***************************************************************************
+ DepCheckDependents - Checks if any dependents are still installed for the
+                      given provider key.
+
+***************************************************************************/
+DAPI_(HRESULT) DepCheckDependents(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey,
+    __in int iAttributes,
+    __in C_STRINGDICT_HANDLE sdIgnoredDependents,
+    __deref_inout_ecount_opt(*pcDependents) DEPENDENCY** prgDependents,
+    __inout LPUINT pcDependents
+    );
+
+/***************************************************************************
+ DepRegisterDependency - Registers the dependency provider.
+
+***************************************************************************/
+DAPI_(HRESULT) DepRegisterDependency(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey,
+    __in_z LPCWSTR wzVersion,
+    __in_z LPCWSTR wzDisplayName,
+    __in_z_opt LPCWSTR wzId,
+    __in int iAttributes
+    );
+
+/***************************************************************************
+ DepDependentExists - Determines if a dependent is registered.
+
+ Note: Returns S_OK if dependent is registered.
+       Returns E_FILENOTFOUND if dependent is not registered
+***************************************************************************/
+DAPI_(HRESULT) DepDependentExists(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzDependencyProviderKey,
+    __in_z LPCWSTR wzProviderKey
+    );
+
+/***************************************************************************
+ DepRegisterDependent - Registers a dependent under the dependency provider.
+
+***************************************************************************/
+DAPI_(HRESULT) DepRegisterDependent(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzDependencyProviderKey,
+    __in_z LPCWSTR wzProviderKey,
+    __in_z_opt LPCWSTR wzMinVersion,
+    __in_z_opt LPCWSTR wzMaxVersion,
+    __in int iAttributes
+    );
+
+/***************************************************************************
+ DepUnregisterDependency - Removes the dependency provider.
+
+ Note: Caller should call CheckDependents prior to remove a dependency.
+       Returns E_FILENOTFOUND if the dependency is not registered.
+***************************************************************************/
+DAPI_(HRESULT) DepUnregisterDependency(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzProviderKey
+    );
+
+/***************************************************************************
+ DepUnregisterDependent - Removes a dependent under the dependency provider.
+
+ Note: Returns E_FILENOTFOUND if neither the dependency or dependent are
+       registered.
+ ***************************************************************************/
+DAPI_(HRESULT) DepUnregisterDependent(
+    __in HKEY hkHive,
+    __in_z LPCWSTR wzDependencyProviderKey,
+    __in_z LPCWSTR wzProviderKey
+    );
+
+/***************************************************************************
+ DependencyArrayAlloc - Allocates or expands an array of DEPENDENCY structs.
+
+***************************************************************************/
+DAPI_(HRESULT) DepDependencyArrayAlloc(
+    __deref_inout_ecount_opt(*pcDependencies) DEPENDENCY** prgDependencies,
+    __inout LPUINT pcDependencies,
+    __in_z LPCWSTR wzKey,
+    __in_z_opt LPCWSTR wzName
+    );
+
+/***************************************************************************
+ DepDependencyArrayFree - Frees an array of DEPENDENCY structs.
+
+***************************************************************************/
+DAPI_(void) DepDependencyArrayFree(
+    __in_ecount(cDependencies) DEPENDENCY* rgDependencies,
+    __in UINT cDependencies
+    );
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/src/dutil/precomp.h b/src/dutil/precomp.h
index 3acbca43..c305573d 100644
--- a/src/dutil/precomp.h
+++ b/src/dutil/precomp.h
@@ -56,6 +56,7 @@
 #include "guidutil.h"
 #include "gdiputil.h"
 #include "dictutil.h"
+#include "deputil.h" // NOTE: This must come after dictutil.h since it uses it.
 #include "inetutil.h"
 #include "iniutil.h"
 #include "jsonutil.h"