Noux: register inherited file descriptors

With this patch, a Noux process registers all inherited open file
descriptors in its local libc file descriptor registry at program start.

Fixes #882.

ports/include/noux_session/client.h

@@ -43,6 +43,11 @@ namespace Noux {
 
 				return result;
 			}
+
+			int next_open_fd(int start_fd)
+			{
+				return call<Rpc_next_open_fd>(start_fd);
+			}
 	};
 }
 

ports/include/noux_session/noux_session.h

@@ -137,6 +137,13 @@ namespace Noux {
 		 */
 		virtual bool syscall(Syscall syscall) = 0;
 
+		/*
+		 * Return the next open file descriptor, starting from (and including)
+		 * 'start_fd'.
+		 *
+		 * \return the next open file descriptor or -1
+		 */
+		virtual int next_open_fd(int start_fd) = 0;
 
 		/*********************
 		 ** RPC declaration **
@@ -144,8 +151,9 @@ namespace Noux {
 
 		GENODE_RPC(Rpc_sysio_dataspace, Dataspace_capability, sysio_dataspace);
 		GENODE_RPC(Rpc_syscall, bool, syscall, Syscall);
+		GENODE_RPC(Rpc_next_open_fd, int, next_open_fd, int);
 
-		GENODE_RPC_INTERFACE(Rpc_sysio_dataspace, Rpc_syscall);
+		GENODE_RPC_INTERFACE(Rpc_sysio_dataspace, Rpc_syscall, Rpc_next_open_fd);
 	};
 }
 

ports/src/lib/libc_noux/plugin.cc

@@ -647,22 +647,20 @@ namespace {
 
 	class Plugin : public Libc::Plugin
 	{
-		private:
-
-			Libc::File_descriptor *_stdin;
-			Libc::File_descriptor *_stdout;
-			Libc::File_descriptor *_stderr;
-
 		public:
 
 			/**
 			 * Constructor
 			 */
-			Plugin() :
-				_stdin (Libc::file_descriptor_allocator()->alloc(this, noux_context(0), 0)),
-				_stdout(Libc::file_descriptor_allocator()->alloc(this, noux_context(1), 1)),
-				_stderr(Libc::file_descriptor_allocator()->alloc(this, noux_context(2), 2))
-			{ }
+			Plugin()
+			{
+				/* register inherited open file descriptors */
+				int fd = 0;
+				while ((fd = noux()->next_open_fd(fd)) != -1) {
+					Libc::file_descriptor_allocator()->alloc(this, noux_context(fd), fd);
+					fd++;
+				}
+			}
 
 			bool supports_execve(char const *, char *const[],
 			                     char *const[])                  { return true; }

ports/src/noux/child.h

@@ -386,6 +386,15 @@ namespace Noux {
 			}
 
 			bool syscall(Syscall sc);
+
+			int next_open_fd(int start_fd)
+			{
+				if (start_fd >= 0)
+					for (int fd = start_fd; fd < MAX_FILE_DESCRIPTORS; fd++)
+						if (fd_in_use(fd))
+							return fd;
+				return -1;
+			}
 	};
 };