Merge branch 'shm-mmap-offset' into 'main'

Add extended shared memory attach support

Closes #217

See merge request wayland/wayland!161

protocol/generate-shm-formats.py

@@ -105,8 +105,10 @@ formats = {}
 for ident, val in idents.items():
     formats[drm_format_to_wl(ident)] = val.lower()
 # Special case for ARGB8888 and XRGB8888
-formats["argb8888"] = "0"
-formats["xrgb8888"] = "1"
+for (i, j) in enumerate(("argb8888", "xrgb8888")):
+    formats[j + "_new"] = formats[j]
+    descriptions[j + "_new"] = descriptions[j]
+    formats[j] = str(i)
 
 print("Loaded {} formats from drm_fourcc.h".format(len(formats)), file=sys.stderr)
 

protocol/wayland.xml

@@ -212,7 +212,7 @@
     </request>
   </interface>
 
-  <interface name="wl_shm_pool" version="2">
+  <interface name="wl_shm_pool" version="3">
     <description summary="a shared memory pool">
       The wl_shm_pool object encapsulates a piece of memory shared
       between the compositor and client.  Through the wl_shm_pool
@@ -233,9 +233,16 @@
 	of the next.  The format is the pixel format of the buffer and
 	must be one of those advertised through the wl_shm.format event.
 
-	A buffer will keep a reference to the pool it was created from
+	A buffer will keep a reference to the pool it was created from,
 	so it is valid to destroy the pool immediately after creating
 	a buffer from it.
+
+	The offset must not be negative.  If it is negative, an
+	invalid_stride error is raised.  This limits offsets to a
+	maximum of 2^31 - 1 bytes.
+
+	The version of the returned buffer is 1, regardless of the
+	version of the pool from which it was created.
       </description>
       <arg name="id" type="new_id" interface="wl_buffer" summary="buffer to create"/>
       <arg name="offset" type="int" summary="buffer byte offset within the pool"/>
@@ -267,6 +274,11 @@
 	file descriptor passed at creation time. It is the client's
 	responsibility to ensure that the file is at least as big as
 	the new pool size.
+
+	If the pool was created using version 3 or later of the wl_shm
+	interface, this request cannot be called once any buffers have
+	been created.  Attempting to do so will result in an
+	already_mapped error.
       </description>
       <arg name="size" type="int" summary="new size of the pool, in bytes"/>
     </request>
@@ -292,27 +304,35 @@
       <entry name="invalid_format" value="0" summary="buffer format is not known"/>
       <entry name="invalid_stride" value="1" summary="invalid size or stride during pool or buffer creation"/>
       <entry name="invalid_fd" value="2" summary="mmapping the file descriptor failed"/>
+      <entry name="already_mapped" value="3"
+	summary="a pool was created with version 3 or later of wl_shm, and an attempt was made to resize it after it had already been mapped"/>
     </enum>
 
     <enum name="format">
       <description summary="pixel formats">
 	This describes the memory layout of an individual pixel.
 
-	All renderers should support argb8888 and xrgb8888 but any other
+	All compositors must support argb8888 and xrgb8888. Compositors
+	supporting wl_shm v3 must support argb8888_new and xrgb8888_new
+	as well, even with version 1 wl_shm_pool objects. All other
 	formats are optional and may not be supported by the particular
 	renderer in use.
 
 	The drm format codes match the macros defined in drm_fourcc.h, except
 	argb8888 and xrgb8888. The formats actually supported by the compositor
-	will be reported by the format event.
+	will be reported by the format event, and are not limited to those in
+	this enum. Starting with version 2, argb8888_new and xrgb8888_new values
+	are provided, which match the corresponding values in drm_fourcc.h.
 
-	For all wl_shm formats and unless specified in another protocol
-	extension, pre-multiplied alpha is used for pixel values.
+	All wl_shm formats use pre-multiplied alpha for pixel values, unless
+	another protocol extension states otherwise.
       </description>
       <!-- Note to protocol writers: don't update this list manually, instead
 	   run the automated script that keeps it in sync with drm_fourcc.h. -->
       <entry name="argb8888" value="0" summary="32-bit ARGB format, [31:0] A:R:G:B 8:8:8:8 little endian"/>
       <entry name="xrgb8888" value="1" summary="32-bit RGB format, [31:0] x:R:G:B 8:8:8:8 little endian"/>
+      <entry name="argb8888_new" value="0x34325241" summary="[31:0] A:R:G:B 8:8:8:8 little endian"/>
+      <entry name="xrgb8888_new" value="0x34325258" summary="[31:0] x:R:G:B 8:8:8:8 little endian"/>
       <entry name="c8" value="0x20203843" summary="8-bit color index format, [7:0] C"/>
       <entry name="rgb332" value="0x38424752" summary="8-bit RGB format, [7:0] R:G:B 3:3:2"/>
       <entry name="bgr233" value="0x38524742" summary="8-bit BGR format, [7:0] B:G:R 2:3:3"/>
@@ -462,7 +482,12 @@
 
 	The pool can be used to create shared memory based buffer
 	objects.  The server will mmap size bytes of the passed file
-	descriptor, to use as backing memory for the pool.
+	descriptor, to use as backing memory for the pool.  If it is
+	unable to do so, an invalid_fd error is raised.
+
+	The size must be greater than zero.  Sizes less or equal to zero
+	raise an invalid_stride error.  This prevents the creation of
+	pools larger than 2^31 - 1 bytes.
       </description>
       <arg name="id" type="new_id" interface="wl_shm_pool" summary="pool to create"/>
       <arg name="fd" type="fd" summary="file descriptor for the pool"/>
@@ -488,6 +513,35 @@
 	Objects created via this interface remain unaffected.
       </description>
     </request>
+
+    <!-- Version 3 additions -->
+    <request name="create_pool2" since="3">
+      <description summary="create a shm pool">
+	Create a new wl_shm_pool object.
+
+	The pool can be used to create shared memory based buffer
+	objects.  The server will mmap size bytes of the passed file
+	descriptor at the provided offset to use as backing memory for
+	the pool.  If it is unable to do so, an invalid_fd error is
+	raised.
+
+	This request provides a strict superset of the functionality
+	provided by create_pool.  In particular, calling this request
+	with offset_lo and offset_hi set to 0 is equivalent to calling
+	create_pool.
+
+	If the size is zero or greater than 2^31 - 1, an invalid_stride
+	error is raised.  Compositors are not allowed to impose
+	arbitrary limits on the offset, beyond those imposed by the
+	operating system.  In particular, the offset may be negative
+	when cast to an off_t, and may be larger than 2^32 - 1.
+      </description>
+      <arg name="id" type="new_id" interface="wl_shm_pool" summary="pool to create"/>
+      <arg name="fd" type="fd" summary="file descriptor for the pool"/>
+      <arg name="size" type="uint" summary="pool size, in bytes"/>
+      <arg name="offset_lo" type="uint" summary="low-order 32 bits of offset for mmap, in bytes"/>
+      <arg name="offset_hi" type="uint" summary="high-order 32 bits of offset for mmap, in bytes"/>
+    </request>
   </interface>
 
   <interface name="wl_buffer" version="1">