move descriptor_table.h to headers/private

We're not yet ready to commit to making this API public, so we'll make it
private for now.

I've also expanded a comment in descriptor_table.c to explain the current ABI
for resource handles.

Signed-off-by: Joel Dice <[email protected]>

expected/wasm32-wasi-preview2/include-all.c

@@ -164,7 +164,6 @@
 #include <utime.h>
 #include <values.h>
 #include <wasi/api.h>
-#include <wasi/descriptor_table.h>
 #include <wasi/libc-environ.h>
 #include <wasi/libc-find-relpath.h>
 #include <wasi/libc-nocwd.h>

expected/wasm32-wasi-preview2/predefined-macros.txt

@@ -166,7 +166,6 @@
 #define DECIMAL_DIG 36
 #define DELAYTIMER_MAX 0x7fffffff
 #define DELETE ns_uop_delete
-#define DESCRIPTOR_TABLE_H 
 #define DEV_BSIZE 512
 #define DIRTYPE '5'
 #define DM 242

libc-bottom-half/sources/descriptor_table.c

@@ -3,11 +3,12 @@
  * descriptors.
  *
  * WASI Preview 2 has no notion of file descriptors and instead uses unforgeable
- * resource handles.  Moreover, there's not necessarily a one-to-one
- * correspondence between POSIX file descriptors and resource handles (e.g. a
- * TCP connection may require separate handles for reading, writing, and polling
- * the same connection).  We use this table to map each POSIX descriptor to a
- * set of one or more handles.
+ * resource handles (which are currently represented as integers at the ABI
+ * level, used as indices into per-component tables managed by the host).
+ * Moreover, there's not necessarily a one-to-one correspondence between POSIX
+ * file descriptors and resource handles (e.g. a TCP connection may require
+ * separate handles for reading, writing, and polling the same connection).  We
+ * use this table to map each POSIX descriptor to a set of one or more handles.
  *
  * As of this writing, we still rely on the WASI Preview 1 adapter
  * (https://github.com/bytecodealliance/wasmtime/tree/main/crates/wasi-preview1-component-adapter)