Obey the bufSize and write to the length parameter in glGetSynciv.

src/libANGLE/Context.cpp

@@ -4013,7 +4013,7 @@ void Context::renderbufferStorageMultisample(GLenum target,
 void Context::getSynciv(GLsync sync, GLenum pname, GLsizei bufSize, GLsizei *length, GLint *values)
 {
     const FenceSync *syncObject = getFenceSync(sync);
-    handleError(QuerySynciv(syncObject, pname, values));
+    handleError(QuerySynciv(syncObject, pname, bufSize, length, values));
 }
 
 void Context::getFramebufferParameteriv(GLenum target, GLenum pname, GLint *params)

src/libANGLE/queryutils.cpp

@@ -888,10 +888,24 @@ void QueryFramebufferParameteriv(const Framebuffer *framebuffer, GLenum pname, G
     }
 }
 
-Error QuerySynciv(const FenceSync *sync, GLenum pname, GLint *values)
+Error QuerySynciv(const FenceSync *sync,
+                  GLenum pname,
+                  GLsizei bufSize,
+                  GLsizei *length,
+                  GLint *values)
 {
     ASSERT(sync);
 
+    // All queries return one value, exit early if the buffer can't fit anything.
+    if (bufSize < 1)
+    {
+        if (length != nullptr)
+        {
+            *length = 0;
+        }
+        return NoError();
+    }
+
     switch (pname)
     {
         case GL_OBJECT_TYPE:
@@ -912,6 +926,11 @@ Error QuerySynciv(const FenceSync *sync, GLenum pname, GLint *values)
             break;
     }
 
+    if (length != nullptr)
+    {
+        *length = 1;
+    }
+
     return NoError();
 }
 

src/libANGLE/queryutils.h

@@ -97,7 +97,11 @@ void QueryInternalFormativ(const TextureCaps &format, GLenum pname, GLsizei bufS
 
 void QueryFramebufferParameteriv(const Framebuffer *framebuffer, GLenum pname, GLint *params);
 
-Error QuerySynciv(const FenceSync *sync, GLenum pname, GLint *values);
+Error QuerySynciv(const FenceSync *sync,
+                  GLenum pname,
+                  GLsizei bufSize,
+                  GLsizei *length,
+                  GLint *values);
 
 void SetTexParameterf(Texture *texture, GLenum pname, GLfloat param);
 void SetTexParameterfv(Texture *texture, GLenum pname, const GLfloat *params);