binder: Add support for file-descriptor arrays

This patch introduces a new binder_fd_array object, that allows us to support one or more file descriptors embedded in a buffer that is scatter-gathered.

Martijn Coenen committed 9 years ago

Commit def95c71 parent 79802402 files · +165 −0Browse files

Showing the changes to include/uapi/linux (1 of 2 files). Show all

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include/uapi/linux/android/binder.h+28−0

@@ -33,6 +33,7 @@ enum { · 32 unmodified lines
33	33	BINDER_TYPE_HANDLE = B_PACK_CHARS('s', 'h', '*', B_TYPE_LARGE),
34	34	BINDER_TYPE_WEAK_HANDLE = B_PACK_CHARS('w', 'h', '*', B_TYPE_LARGE),
35	35	BINDER_TYPE_FD = B_PACK_CHARS('f', 'd', '*', B_TYPE_LARGE),
	36	+ BINDER_TYPE_FDA = B_PACK_CHARS('f', 'd', 'a', B_TYPE_LARGE),
36	37	BINDER_TYPE_PTR = B_PACK_CHARS('p', 't', '*', B_TYPE_LARGE),
37	38	};
38	39
@@ -129,6 +130,33 @@ enum { · 90 unmodified lines
129	130	BINDER_BUFFER_FLAG_HAS_PARENT = 0x01,
130	131	};
131	132
	133	+/* struct binder_fd_array_object - object describing an array of fds in a buffer
	134	+ * @hdr: common header structure
	135	+ * @num_fds: number of file descriptors in the buffer
	136	+ * @parent: index in offset array to buffer holding the fd array
	137	+ * @parent_offset: start offset of fd array in the buffer
	138	+ *
	139	+ * A binder_fd_array object represents an array of file
	140	+ * descriptors embedded in a binder_buffer_object. It is
	141	+ * different from a regular binder_buffer_object because it
	142	+ * describes a list of file descriptors to fix up, not an opaque
	143	+ * blob of memory, and hence the kernel needs to treat it differently.
	144	+ *
	145	+ * An example of how this would be used is with Android's
	146	+ * native_handle_t object, which is a struct with a list of integers
	147	+ * and a list of file descriptors. The native_handle_t struct itself
	148	+ * will be represented by a struct binder_buffer_objct, whereas the
	149	+ * embedded list of file descriptors is represented by a
	150	+ * struct binder_fd_array_object with that binder_buffer_object as
	151	+ * a parent.
	152	+ */
	153	+struct binder_fd_array_object {
	154	+ struct binder_object_header hdr;
	155	+ binder_size_t num_fds;
	156	+ binder_size_t parent;
	157	+ binder_size_t parent_offset;
	158	+};
	159	+
132	160	/*
133	161	* On 64-bit platforms where user code may run in 32-bits the driver must
134	162	* translate the buffer (and local binder) addresses appropriately.