[PATCH] ntdll/env: RtlCreateProcessParametersEx: Don't add unnecessary padding

[Keno Fischer]

RtlCreateProcessParametersEx tries to align all strings to either 8 or 4 byte
boundaries (it seems wine and various windows versions disagree about which).
However, using the previous algorithm, we would adding padding bytes for the
alignment of the Environment, even if no Environment was specified. Windows
does not add these padding bytes and in fact we were testing that they are
not present. Prior to this patch, I am seeing the following test failure locally:

env.c:461: Test failed: wrong end ptr 00000000002427D6/00000000002427D8

This patch fixes the issue by not allocating the superfluous padding bytes,
matching the Windows behavior and fixing the test.

Signed-off-by: Keno Fischer <keno(a)juliacomputing.com>
---
 dlls/ntdll/env.c | 42 ++++++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/dlls/ntdll/env.c b/dlls/ntdll/env.c
index bb8931a556b..454ca4c234d 100644
--- a/dlls/ntdll/env.c
+++ b/dlls/ntdll/env.c
@@ -499,6 +499,11 @@ PRTL_USER_PROCESS_PARAMETERS WINAPI RtlDeNormalizeProcessParams( RTL_USER_PROCES
 
 #define ROUND_SIZE(size) (((size) + sizeof(void *) - 1) & ~(sizeof(void *) - 1))
 
+static void *align_ptr(void *ptr)
+{
+    return (void*)(((UINT_PTR)ptr + sizeof(void *) - 1) & ~(sizeof(void *) - 1));
+}
+
 /* append a unicode string to the process params data; helper for RtlCreateProcessParameters */
 static void append_unicode_string( void **data, const UNICODE_STRING *src,
                                    UNICODE_STRING *dst )
@@ -507,13 +512,19 @@ static void append_unicode_string( void **data, const UNICODE_STRING *src,
     dst->MaximumLength = src->MaximumLength;
     if (dst->MaximumLength)
     {
-        dst->Buffer = *data;
+        dst->Buffer = align_ptr( *data );
         memcpy( dst->Buffer, src->Buffer, dst->Length );
-        *data = (char *)dst->Buffer + ROUND_SIZE( dst->MaximumLength );
+        *data = (char *)dst->Buffer + dst->MaximumLength;
     }
     else dst->Buffer = NULL;
 }
 
+static void add_rounded_size(SIZE_T *size, SIZE_T new_size)
+{
+    if (new_size) {
+        *size = ROUND_SIZE(*size) + new_size;
+    }
+}
 
 /******************************************************************************
  *  RtlCreateProcessParametersEx  [NTDLL.@]
@@ -556,17 +567,20 @@ NTSTATUS WINAPI RtlCreateProcessParametersEx( RTL_USER_PROCESS_PARAMETERS **resu
     if (!ShellInfo) ShellInfo = &empty_str;
     if (!RuntimeInfo) RuntimeInfo = &null_str;
 
-    if (Environment) env_size = get_env_length( Environment ) * sizeof(WCHAR);
-
-    size = (sizeof(RTL_USER_PROCESS_PARAMETERS)
-            + ROUND_SIZE( ImagePathName->MaximumLength )
-            + ROUND_SIZE( DllPath->MaximumLength )
-            + ROUND_SIZE( curdir.MaximumLength )
-            + ROUND_SIZE( CommandLine->MaximumLength )
-            + ROUND_SIZE( WindowTitle->MaximumLength )
-            + ROUND_SIZE( Desktop->MaximumLength )
-            + ROUND_SIZE( ShellInfo->MaximumLength )
-            + ROUND_SIZE( RuntimeInfo->MaximumLength ));
+    size = sizeof(RTL_USER_PROCESS_PARAMETERS);
+    add_rounded_size(&size, ImagePathName->MaximumLength);
+    add_rounded_size(&size, DllPath->MaximumLength);
+    add_rounded_size(&size, curdir.MaximumLength);
+    add_rounded_size(&size, CommandLine->MaximumLength);
+    add_rounded_size(&size, WindowTitle->MaximumLength);
+    add_rounded_size(&size, Desktop->MaximumLength);
+    add_rounded_size(&size, ShellInfo->MaximumLength);
+    add_rounded_size(&size, RuntimeInfo->MaximumLength);
+
+    if (Environment) {
+        env_size = get_env_length( Environment ) * sizeof(WCHAR);
+        size = ROUND_SIZE(size);
+    }
 
     if ((ptr = RtlAllocateHeap( GetProcessHeap(), HEAP_ZERO_MEMORY, size + ROUND_SIZE( env_size ) )))
     {
@@ -587,7 +601,7 @@ NTSTATUS WINAPI RtlCreateProcessParametersEx( RTL_USER_PROCESS_PARAMETERS **resu
         append_unicode_string( &ptr, Desktop, ¶ms->Desktop );
         append_unicode_string( &ptr, ShellInfo, ¶ms->ShellInfo );
         append_unicode_string( &ptr, RuntimeInfo, ¶ms->RuntimeInfo );
-        if (Environment) params->Environment = memcpy( ptr, Environment, env_size );
+        if (Environment) params->Environment = memcpy( align_ptr(ptr), Environment, env_size );
         *result = params;
         if (!(flags & PROCESS_PARAMS_FLAG_NORMALIZED)) RtlDeNormalizeProcessParams( params );
     }
-- 
2.25.1