clipboard: tidy up bmp file header assembly

Sponsored by:   Krämer Pferdesport GmbH & Co KG

(cherry picked from commit e070902)

sesman/chansrv/clipboard.c

@@ -181,22 +181,8 @@ x-special/gnome-copied-files
 #include "ms-rdpeclip.h"
 #include "xrdp_constants.h"
 
-static char g_bmp_image_header[] =
-{
- /*
- * Bitmap file header
- * https://en.wikipedia.org/wiki/BMP_file_format#Bitmap_file_header
- *
- * NOTE: All of the integer values are stored in little-endian format
- */
- 0x42, 0x4d, /* signature */
- 0x00, 0x00, 0x00, 0x00, /* file size, to be filled later */
- 0x00, 0x00, /* reserved 1 */
- 0x00, 0x00, /* reserved 2 */
- 0x36, 0x00, 0x00, 0x00 /* offset to pixel array (14 + 40 bytes) */
-};
-
-#define BMPFILEHEADER_LEN sizeof(g_bmp_image_header)
+#define BMPFILEHEADER_LEN 14
+#define BMPINFOHEADER_LEN 40
 
 extern int g_cliprdr_chan_id; /* in chansrv.c */
 
@@ -1194,8 +1180,7 @@ clipboard_process_data_response_for_image(struct stream *s,
 {
  XSelectionRequestEvent *lxev;
  int len;
- char bmp_file_header[BMPFILEHEADER_LEN] = { 0 };
- uint32_t bmp_size; /* file size stored in bmp file header */
+ struct stream *bmp_hs;
 
  LOG_DEVEL(LOG_LEVEL_DEBUG, "clipboard_process_data_response_for_image: "
  "CLIPRDR_DATA_RESPONSE_FOR_IMAGE");
@@ -1220,20 +1205,30 @@ clipboard_process_data_response_for_image(struct stream *s,
  g_clip_c2s.total_bytes = len + BMPFILEHEADER_LEN;
  g_clip_c2s.read_bytes_done = g_clip_c2s.total_bytes;
 
- /* assemble bmp header */
- g_memcpy(bmp_file_header, g_bmp_image_header, BMPFILEHEADER_LEN);
- bmp_size = (uint32_t) g_clip_c2s.total_bytes;
-#if defined(L_ENDIAN)
- for (int i = 2, j = 0; i < 6; i++, j += 8)
-#else
- for (int i = 5, j = 0; i >= 2; i--, j += 8)
-#endif
+ /*
+ * Assemble bitmap file header
+ * https://en.wikipedia.org/wiki/BMP_file_format#Bitmap_file_header
+ */
+ make_stream(bmp_hs);
+ if (bmp_hs == 0)
  {
- bmp_file_header[i] = ((bmp_size >> j) & 0xff);
+ g_free(g_clip_c2s.data);
+ g_clip_c2s.total_bytes = 0;
+ return 0;
  }
+ init_stream(bmp_hs, BMPFILEHEADER_LEN);
+ out_uint8(bmp_hs, 'B');
+ out_uint8(bmp_hs, 'M');
+ out_uint32_le(bmp_hs, g_clip_c2s.total_bytes);
+ out_uint16_le(bmp_hs, 0);
+ out_uint16_le(bmp_hs, 0);
+ out_uint32_le(bmp_hs, BMPFILEHEADER_LEN + BMPINFOHEADER_LEN);
 
- g_memcpy(g_clip_c2s.data, bmp_file_header, BMPFILEHEADER_LEN);
+ /* Copy header and data to output stream */
+ g_memcpy(g_clip_c2s.data, bmp_hs->data, BMPFILEHEADER_LEN);
  in_uint8a(s, g_clip_c2s.data + BMPFILEHEADER_LEN, len);
+
+ free_stream(bmp_hs);
  LOG_DEVEL(LOG_LEVEL_DEBUG, "clipboard_process_data_response_for_image: calling "
  "clipboard_provide_selection_c2s");
  clipboard_provide_selection_c2s(lxev, lxev->target);