- Realize DoEnvironmentSubstA via ExpandEnvironmentStringsA.
- Fix types and return values.
- Add prototype into shellapi.h.

dlls/shell32/shellord.c

diff --git a/dlls/shell32/shellord.c b/dlls/shell32/shellord.c
index 3f36fd0..a8e36b4 100644
--- a/dlls/shell32/shellord.c
+++ b/dlls/shell32/shellord.c
@@ -1354,32 +1354,57 @@
 /************************************************************************
  *	DoEnvironmentSubstA			[SHELL32.@]
  *
+ * Replace %KEYWORD% in the str with the value of variable KEYWORD
+ * from environment. If it is not found the %KEYWORD% is left
+ * intact. If the buffer is too small, str is not modified.
+ *
+ * pszString   [I] '\0' terminated string with %keyword%.
+ *             [O] '\0' terminated string with %keyword% substituted.
+ * cchString   [I] size of str.
+ *
+ * Return
+ *     cchString length in the HIWORD;
+ *     TRUE in LOWORD if subst was successful and FALSE in other case
  */
-HRESULT WINAPI DoEnvironmentSubstA(LPSTR x, LPSTR y)
+DWORD WINAPI DoEnvironmentSubstA(LPSTR pszString, UINT cchString)
 {
-	FIXME("(%s, %s) stub\n", debugstr_a(x), debugstr_a(y));
-	return 0;
+    LPSTR dst;
+    BOOL res = FALSE;
+    FIXME("(%s, %d) stub\n", debugstr_a(pszString), cchString);
+    if (pszString == NULL) /* Really return 0? */
+        return 0;
+    if ((dst = HeapAlloc(GetProcessHeap(), 0, cchString * sizeof(CHAR))))
+    {
+        DWORD num = ExpandEnvironmentStringsA(pszString, dst, cchString);
+        if (num && num < cchString) /* dest buffer is too small */
+        {
+            res = TRUE;
+            memcpy(pszString, dst, num);
+        }
+        HeapFree(GetProcessHeap(), 0, dst);
+    }
+    return MAKELONG(res,cchString); /* Always cchString? */
 }
 
 /************************************************************************
  *	DoEnvironmentSubstW			[SHELL32.@]
  *
  */
-HRESULT WINAPI DoEnvironmentSubstW(LPWSTR x, LPWSTR y)
+DWORD WINAPI DoEnvironmentSubstW(LPWSTR pszString, UINT cchString)
 {
-	FIXME("(%s, %s): stub\n", debugstr_w(x), debugstr_w(y));
-	return 0;
+	FIXME("(%s, %d): stub\n", debugstr_w(pszString), cchString);
+	return MAKELONG(FALSE,cchString);
 }
 
 /************************************************************************
  *	DoEnvironmentSubst			[SHELL32.53]
  *
  */
-HRESULT WINAPI DoEnvironmentSubstAW(LPVOID x, LPVOID y)
+DWORD WINAPI DoEnvironmentSubstAW(LPVOID x, UINT y)
 {
-	if (SHELL_OsIsUnicode())
-	  return DoEnvironmentSubstW(x, y);
-	return DoEnvironmentSubstA(x, y);
+    if (SHELL_OsIsUnicode())
+        return DoEnvironmentSubstW(x, y);
+    return DoEnvironmentSubstA(x, y);
 }
 
 /*************************************************************************

include/shellapi.h

diff --git a/include/shellapi.h b/include/shellapi.h
index 4bb283d..74bbefd 100644
--- a/include/shellapi.h
+++ b/include/shellapi.h
@@ -442,6 +442,10 @@
 int         WINAPIV ShellMessageBoxA(HINSTANCE,HWND,LPCSTR,LPCSTR,UINT,...);
 int         WINAPIV ShellMessageBoxW(HINSTANCE,HWND,LPCWSTR,LPCWSTR,UINT,...);
 #define     ShellMessageBox WINELIB_NAME_AW(ShellMessageBox)
+DWORD       WINAPI DoEnvironmentSubstA(LPSTR, UINT);
+DWORD       WINAPI DoEnvironmentSubstW(LPWSTR, UINT);
+#define     DoEnvironmentSubst WINELIB_NAME_AW(DoEnvironmentSubst)
+
 
 #ifdef __cplusplus
 } /* extern "C" */