From: Tobias Ulmer <tu@emlix.com>
Date: Thu, 16 Jan 2014 17:23:26 +0000 (+0100)
Subject: Change and extend e2lib.poll() interface
X-Git-Tag: e2factory-2.3.15rc1~260
X-Git-Url: https://git.e2factory.org/?a=commitdiff_plain;h=ac4994e5943bbdb1adde6feb0f8d02ff48295550;p=e2factory.git

Change and extend e2lib.poll() interface

Instead of a single pos in the fdvec table, return a table of all
selected file descriptors. Allows handling more than one active file
descriptor in one go.

Signed-off-by: Tobias Ulmer <tu@emlix.com>
---

diff --git a/generic/e2lib.lua b/generic/e2lib.lua
index eb6e540..3f40738 100644
--- a/generic/e2lib.lua
+++ b/generic/e2lib.lua
@@ -213,16 +213,27 @@ function e2lib.wait(pid)
     return rc, childpid, sig
 end
 
---- Poll input output multiplexing.
--- Only indicates first selected file descriptor.
+--- Poll input output multiplexing. See poll(2) for details on flags etc.
 -- @param timeout Timeout in milliseconds (number).
--- @param fdvec Vector of file descriptors (table of numbers).
--- @return Returns 0 on timeout, < 0 on error and > 0 for the position in fdvec
--- that has an event waiting.
--- @return True if it's a POLLIN event.
--- @return True if it's a POLLOUT event.
+-- @param fdvec Vector of file descriptors. This wrapper listens for
+--              POLLIN and POLLOUT events on every fd.
+-- @return False on error, empty table on timeout, or a vector of tables for
+--         each selected file descriptor. The tables looks like this:
+--         { fd=(file descriptor number), fdvecpos=(index number),
+--         POLLIN=boolean, POLLOUT=boolean }.
+--         If a file descriptor is selected but neither POLLIN nor POLLOUT are
+--         set, the file descriptor was closed. fdvecpos is the position of the
+--         fd in the fdvec table.
+-- @return Error object on failure.
 function e2lib.poll(timeout, fdvec)
-    return le2lib.poll(timeout, fdvec)
+    local pollvec, errstring
+
+    pollvec, errstring = le2lib.poll(timeout, fdvec)
+    if not pollvec then
+        return false, err.new("poll() failed: %s", errstring)
+    end
+
+    return pollvec
 end
 
 --- Set file descriptor in non-blocking mode.
diff --git a/generic/le2lib.c b/generic/le2lib.c
index 981f054..d000708 100644
--- a/generic/le2lib.c
+++ b/generic/le2lib.c
@@ -315,7 +315,7 @@ static int
 poll_fd(lua_State *lua)
 {
 	int tmo = luaL_checkinteger(lua, 1);
-	int nfds = 0, f;
+	int nfds = 0, f, index = 0;
 	struct pollfd *fds = NULL;
 	luaL_checktype(lua, 2, LUA_TTABLE);
 
@@ -334,20 +334,49 @@ poll_fd(lua_State *lua)
 		nfds += 1;
 	}
 	f = poll(fds, nfds, tmo);
+	if (f < 0) {
+		lua_pushboolean(lua, 0);
+		lua_pushstring(lua, strerror(errno));
+		return 2;
+	}
 
-	if (f > 0) {
-		while (--nfds >= 0) {
-			if (fds[nfds].revents) {
-				lua_pushnumber(lua, nfds+1);
-				lua_pushboolean(lua, fds[nfds].revents & POLLIN);
-				lua_pushboolean(lua, fds[nfds].revents & POLLOUT);
-				free(fds);
-				return 3;
-			}
+	/* We want to return a table containing all selected fds looking like
+	 * this:
+	 * {
+	 *	{ fd = 3, fdvecpos=1, POLLIN = true, POLLOUT = false },
+	 *	{ fd = 5, fdvecpos=2, POLLIN = false, POLLOUT = false },
+	 *	...
+	 * }
+	 */
+
+	lua_newtable(lua);
+
+	while (index < f && --nfds >= 0) {
+		if (fds[nfds].revents) {
+			lua_createtable(lua, 0, 4); /* 4 elements */
+
+			lua_pushliteral(lua, "fd");
+			lua_pushnumber(lua, fds[nfds].fd);
+			lua_rawset(lua, -3);
+
+			lua_pushliteral(lua, "fdvecpos");
+			lua_pushnumber(lua, nfds+1);
+			lua_rawset(lua, -3);
+
+			lua_pushliteral(lua, "POLLIN");
+			lua_pushboolean(lua, fds[nfds].revents & POLLIN);
+			lua_rawset(lua, -3);
+
+			lua_pushliteral(lua, "POLLOUT");
+			lua_pushboolean(lua, fds[nfds].revents & POLLOUT);
+			lua_rawset(lua, -3);
+
+			/* commit table to newtable at index */
+			lua_rawseti(lua, -2, ++index);
 		}
 	}
+
 	free(fds);
-	lua_pushnumber(lua, f);
 	return 1;
 }