Implemented the traversal of the static translator stack.

trace_find can now traverse the translator stack, stop at the
necessary translator and return a port to it.

1 files changed, 162 insertions, 0 deletions

diff --git a/trace.c b/trace.c
index a9415322e..829cc7504 100644
--- a/trace.c
+++ b/trace.c
@@ -48,5 +48,167 @@ trace_find
 	mach_port_t * port
 	)
 	{
+	error_t err = 0;
+
+	/*Identity information about the current process*/
+	uid_t * uids;
+	size_t nuids;
+	
+	gid_t * gids;
+	size_t ngids;
+
+	/*The name and arguments of the translator being passed now*/
+	char * argz = NULL;
+	size_t argz_len = 0;
+
+	/*The current working directory*/
+	char * cwd = NULL;
+
+	/*The port to the directory containing the file pointed to by `underlying`*/
+	file_t dir;
+
+	/*The unauthenticated version of `dir`*/
+	file_t unauth_dir;
+	
+	/*The control port of the current translator*/
+	fsys_t fsys;
+	
+	/*The port to the translator we are currently looking at*/
+	mach_port_t node = underlying;
+	
+	/*The retry name and retry type returned by fsys_getroot*/
+	string_t retry_name;
+	retry_type retry;
+
+	/*Finalizes the execution of this function*/
+	void
+	finalize(void)
+		{
+		/*If there is a working directory, free it*/
+		if(cwd)
+			free(cwd);
+			
+		/*If the ports to the directory exist*/
+		if(dir)
+			PORT_DEALLOC(dir);
+		}/*finalize*/
+	
+	/*Obtain the current working directory*/
+	cwd = getcwd(NULL, 0);
+	if(!cwd)
+		{
+		LOG_MSG("trace_find: Could not obtain cwd.");
+		return EINVAL;
+		}
+	LOG_MSG("trace_find: cwd: '%s'", cwd);
+	
+	/*Open a port to this directory*/
+	dir = file_name_lookup(cwd, 0, 0);
+	if(!dir)
+		{
+		finalize();
+		return ENOENT;
+		}
+	
+	/*Try to get the number of effective UIDs*/
+	nuids = geteuids(0, 0);
+	if(nuids < 0)
+		{
+		finalize();
+		return EINVAL;
+		}
+	
+	/*Allocate some memory for the UIDs on the stack*/
+	uids = alloca(nuids * sizeof(uid_t));
+	
+	/*Fetch the UIDs themselves*/
+	nuids = geteuids(nuids, uids);
+	if(nuids < 0)
+		{
+		finalize();
+		return EINVAL;
+		}
+
+	/*Try to get the number of effective GIDs*/
+	ngids = getgroups(0, 0);
+	if(ngids < 0)
+		{
+		finalize();
+		return EINVAL;
+		}
+	
+	/*Allocate some memory for the GIDs on the stack*/
+	gids = alloca(ngids * sizeof(gid_t));
+	
+	/*Fetch the GIDs themselves*/
+	ngids = getgroups(ngids, gids);
+	if(ngids < 0)
+		{
+		finalize();
+		return EINVAL;
+		}
+
+	/*Obtain the unauthenticated version of `dir`*/
+	err = io_restrict_auth(dir, &unauth_dir, 0, 0, 0, 0);
+	if(err)
+		{
+		finalize();
+		return err;
+		}
+	
+	/*Go up the translator stack*/
+	for(; !err;)
+		{
+		/*retreive the name and options of the current translator*/
+		err = file_get_fs_options(node, &argz, &argz_len);
+		if(err)
+			break;
+		
+		LOG_MSG("trace_find: Obtained translator '%s'", argz);
+		
+		if(strcmp(argz, name) == 0)
+			{
+			LOG_MSG("trace_find: Match. Stopping here.");
+			break;
+			}
+		
+		/*try to fetch the control port for this translator*/
+		err = file_get_translator_cntl(node, &fsys);
+		LOG_MSG("trace_find: err = %d", (int)err);
+		if(err)
+			break;
+
+		LOG_MSG("trace_find: Translator control port: %lu", (unsigned long)fsys);
+
+		/*fetch the root of the translator*/
+		err = fsys_getroot
+			(
+			fsys, unauth_dir, MACH_MSG_TYPE_COPY_SEND,
+			uids, nuids, gids, ngids,
+			flags | O_NOTRANS, &retry, retry_name, &node
+			);
+			
+		LOG_MSG("trace_find: Translator root: %lu", (unsigned long)node);
+		
+		/*TODO: Remove this debug output.*/
+		/*char buf[256];
+		char * _buf = buf;
+		size_t len = 256;
+		io_read(node, &_buf, &len, 0, len);
+		LOG_MSG("trace_find: Read: '%s'", buf);*/
+		}
+		
+	/*If the error occurred (most probably) because of the fact that we
+		have reached the top of the translator stack*/
+	if((err == EMACH_SEND_INVALID_DEST) || (err == ENXIO))
+		/*this is OK*/
+		err = 0;
+	
+	/*Return the port to read from*/
+	*port = node;
+	
+	/*Return the result of operations*/
+	finalize();
+	return err;
 	}/*trace_find*/
 /*----------------------------------------------------------------------------*/