From 46511652726afdaf3d92173f8f14d900f1f75994 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Camilla=20L=C3=B6wy?= <elmindreda@elmindreda.org>
Date: Thu, 24 Mar 2022 18:02:48 +0100
Subject: [PATCH] Wayland: Simplify clipboard string allocation

---
 src/wl_init.c     | 10 --------
 src/wl_platform.h |  1 -
 src/wl_window.c   | 59 ++++++++++++++++++++---------------------------
 3 files changed, 25 insertions(+), 45 deletions(-)

diff --git a/src/wl_init.c b/src/wl_init.c
index 4368f3fa..972c38f6 100644
--- a/src/wl_init.c
+++ b/src/wl_init.c
@@ -1413,15 +1413,6 @@ int _glfwInitWayland(void)
             wl_data_device_manager_get_data_device(_glfw.wl.dataDeviceManager,
                                                    _glfw.wl.seat);
         wl_data_device_add_listener(_glfw.wl.dataDevice, &dataDeviceListener, NULL);
-
-        _glfw.wl.clipboardSize = 4096;
-        _glfw.wl.clipboardString = _glfw_calloc(_glfw.wl.clipboardSize, 1);
-        if (!_glfw.wl.clipboardString)
-        {
-            _glfwInputError(GLFW_OUT_OF_MEMORY,
-                            "Wayland: Failed to allocate clipboard memory");
-            return GLFW_FALSE;
-        }
     }
 
     return GLFW_TRUE;
@@ -1513,6 +1504,5 @@ void _glfwTerminateWayland(void)
         close(_glfw.wl.cursorTimerfd);
 
     _glfw_free(_glfw.wl.clipboardString);
-    _glfw_free(_glfw.wl.clipboardSendString);
 }
 
diff --git a/src/wl_platform.h b/src/wl_platform.h
index 7bec2919..861f7cfe 100644
--- a/src/wl_platform.h
+++ b/src/wl_platform.h
@@ -317,7 +317,6 @@ typedef struct _GLFWlibraryWayland
     int                         keyboardLastScancode;
     char*                       clipboardString;
     size_t                      clipboardSize;
-    char*                       clipboardSendString;
     int                         timerfd;
     short int                   keycodes[256];
     short int                   scancodes[GLFW_KEY_LAST + 1];
diff --git a/src/wl_window.c b/src/wl_window.c
index e1c83fc2..f5ca406e 100644
--- a/src/wl_window.c
+++ b/src/wl_window.c
@@ -1591,7 +1591,7 @@ static void dataSourceHandleSend(void* userData,
                                  const char* mimeType,
                                  int fd)
 {
-    char* string = _glfw.wl.clipboardSendString;
+    char* string = _glfw.wl.clipboardString;
     size_t len = strlen(string);
     int ret;
 
@@ -1667,16 +1667,23 @@ void _glfwSetClipboardStringWayland(const char* string)
         _glfw.wl.selectionSource = NULL;
     }
 
-    char* copy = _glfw_strdup(string);
-    if (!copy)
+    const size_t requiredSize = strlen(string) + 1;
+    if (requiredSize > _glfw.wl.clipboardSize)
     {
-        _glfwInputError(GLFW_OUT_OF_MEMORY,
-                        "Wayland: Failed to allocate clipboard string");
-        return;
+        _glfw_free(_glfw.wl.clipboardString);
+        _glfw.wl.clipboardString = _glfw_calloc(requiredSize, 1);
+        if (!_glfw.wl.clipboardString)
+        {
+            _glfwInputError(GLFW_OUT_OF_MEMORY,
+                            "Wayland: Failed to allocate clipboard string");
+            return;
+        }
+
+        _glfw.wl.clipboardSize = requiredSize;
     }
 
-    _glfw_free(_glfw.wl.clipboardSendString);
-    _glfw.wl.clipboardSendString = copy;
+    // The argument may be a substring of the clipboard string
+    memmove(_glfw.wl.clipboardString, string, requiredSize);
 
     _glfw.wl.selectionSource =
         wl_data_device_manager_create_data_source(_glfw.wl.dataDeviceManager);
@@ -1684,8 +1691,6 @@ void _glfwSetClipboardStringWayland(const char* string)
     {
         _glfwInputError(GLFW_PLATFORM_ERROR,
                         "Wayland: Failed to create clipboard data source");
-        _glfw_free(_glfw.wl.clipboardSendString);
-        _glfw.wl.clipboardSendString = NULL;
         return;
     }
     wl_data_source_add_listener(_glfw.wl.selectionSource,
@@ -1697,22 +1702,6 @@ void _glfwSetClipboardStringWayland(const char* string)
                                  _glfw.wl.serial);
 }
 
-static GLFWbool growClipboardString(void)
-{
-    char* clipboard = _glfw.wl.clipboardString;
-
-    clipboard = _glfw_realloc(clipboard, _glfw.wl.clipboardSize * 2);
-    if (!clipboard)
-    {
-        _glfwInputError(GLFW_OUT_OF_MEMORY,
-                        "Wayland: Failed to grow clipboard string");
-        return GLFW_FALSE;
-    }
-    _glfw.wl.clipboardString = clipboard;
-    _glfw.wl.clipboardSize = _glfw.wl.clipboardSize * 2;
-    return GLFW_TRUE;
-}
-
 const char* _glfwGetClipboardStringWayland(void)
 {
     int fds[2];
@@ -1727,7 +1716,7 @@ const char* _glfwGetClipboardStringWayland(void)
     }
 
     if (_glfw.wl.selectionSource)
-        return _glfw.wl.clipboardSendString;
+        return _glfw.wl.clipboardString;
 
     ret = pipe2(fds, O_CLOEXEC);
     if (ret < 0)
@@ -1747,13 +1736,20 @@ const char* _glfwGetClipboardStringWayland(void)
     {
         // Grow the clipboard if we need to paste something bigger, there is no
         // shrink operation yet.
-        if (len + 4096 > _glfw.wl.clipboardSize)
+        const size_t requiredSize = len + 4096 + 1;
+        if (requiredSize > _glfw.wl.clipboardSize)
         {
-            if (!growClipboardString())
+            char* string = _glfw_realloc(_glfw.wl.clipboardString, requiredSize);
+            if (!string)
             {
+                _glfwInputError(GLFW_OUT_OF_MEMORY,
+                                "Wayland: Failed to grow clipboard string");
                 close(fds[0]);
                 return NULL;
             }
+
+            _glfw.wl.clipboardString = string;
+            _glfw.wl.clipboardSize = requiredSize;
         }
 
         // Then read from the fd to the clipboard, handling all known errors.
@@ -1773,11 +1769,6 @@ const char* _glfwGetClipboardStringWayland(void)
         len += ret;
     }
     close(fds[0]);
-    if (len + 1 > _glfw.wl.clipboardSize)
-    {
-        if (!growClipboardString())
-            return NULL;
-    }
     _glfw.wl.clipboardString[len] = '\0';
     return _glfw.wl.clipboardString;
 }