Add checks for some invalid values to public API

There were no checks for invalid values or asserts for all invalid NULL
pointers to glfwSetWindowIcon or glfwCreateCursor.

Fixes #1862

CONTRIBUTORS.md

@@ -84,6 +84,7 @@ video tutorials.
  - Paul Holden
  - Warren Hu
  - Charles Huber
+ - Brent Huisman
  - illustris
  - InKryption
  - IntellectualKitty

include/GLFW/glfw3.h

@@ -3258,7 +3258,8 @@ GLFWAPI void glfwSetWindowTitle(GLFWwindow* window, const char* title);
  *  count is zero.
  *
  *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED, @ref
- *  GLFW_PLATFORM_ERROR and @ref GLFW_FEATURE_UNAVAILABLE (see remarks).
+ *  GLFW_INVALID_VALUE, @ref GLFW_PLATFORM_ERROR and @ref
+ *  GLFW_FEATURE_UNAVAILABLE (see remarks).
  *
  *  @pointer_lifetime The specified image data is copied before this function
  *  returns.
@@ -4892,8 +4893,8 @@ GLFWAPI void glfwSetCursorPos(GLFWwindow* window, double xpos, double ypos);
  *  @return The handle of the created cursor, or `NULL` if an
  *  [error](@ref error_handling) occurred.
  *
- *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED and @ref
+ *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED, @ref
- *  GLFW_PLATFORM_ERROR.
+ *  GLFW_INVALID_VALUE and @ref GLFW_PLATFORM_ERROR.
  *
  *  @pointer_lifetime The specified image data is copied before this function
  *  returns.

src/input.c

@@ -764,9 +764,16 @@ GLFWAPI GLFWcursor* glfwCreateCursor(const GLFWimage* image, int xhot, int yhot)
     _GLFWcursor* cursor;
 
     assert(image != NULL);
+    assert(image->pixels != NULL);
 
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
 
+    if (image->width <= 0 || image->height <= 0)
+    {
+        _glfwInputError(GLFW_INVALID_VALUE, "Invalid image dimensions for cursor");
+        return NULL;
+    }
+
     cursor = _glfw_calloc(1, sizeof(_GLFWcursor));
     cursor->next = _glfw.cursorListHead;
     _glfw.cursorListHead = cursor;

src/window.c

@@ -514,12 +514,33 @@ GLFWAPI void glfwSetWindowTitle(GLFWwindow* handle, const char* title)
 GLFWAPI void glfwSetWindowIcon(GLFWwindow* handle,
                                int count, const GLFWimage* images)
 {
+    int i;
     _GLFWwindow* window = (_GLFWwindow*) handle;
+
     assert(window != NULL);
     assert(count >= 0);
     assert(count == 0 || images != NULL);
 
     _GLFW_REQUIRE_INIT();
+
+    if (count < 0)
+    {
+        _glfwInputError(GLFW_INVALID_VALUE, "Invalid image count for window icon");
+        return;
+    }
+
+    for (i = 0; i < count; i++)
+    {
+        assert(images[i].pixels != NULL);
+
+        if (images[i].width <= 0 || images[i].height <= 0)
+        {
+            _glfwInputError(GLFW_INVALID_VALUE,
+                            "Invalid image dimensions for window icon");
+            return;
+        }
+    }
+
     _glfw.platform.setWindowIcon(window, count, images);
 }