Package: glibc / 2.28-10

hurd-i386/tg-io_select_timeout.diff Patch series | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
From: Richard Braun <rbraun@sceen.net>
Subject: Fix timeout handling in _hurd_select
    
Rely on servers to implement timeouts, so that very short values (including
0) don't make mach_msg return before valid replies can be received. The
purpose of this scheme is to guarantee a full client-server round-trip,
whatever the timeout value.

This change depends on the new io_select_timeout RPC being implemented by
servers.

* hurd/Makefile (user-interfaces): Add io_reply and io_request.
* hurd/hurdselect.c: Include <sys/time.h>, <hurd/io_request.h> and <limits.h>.
(_hurd_select): Replace the call to __io_select with either __io_select_request
or __io_select_timeout_request, depending on the timeout. Count the number of
ready descriptors (replies for which at least one type bit is set). Implement
the timeout locally when there is no file descriptor.

TODO: see XXX

---
 hurd/Makefile     |    3 +-
 hurd/hurdselect.c |  116 +++++++++++++++++++++++++++++++++++------------------
 2 files changed, 79 insertions(+), 40 deletions(-)

--- a/hurd/Makefile
+++ b/hurd/Makefile
@@ -37,7 +37,8 @@ user-interfaces		:= $(addprefix hurd/,\
 				       process process_request \
 				       msg msg_reply msg_request \
 				       exec exec_startup crash interrupt \
-				       fs fsys io term tioctl socket ifsock \
+				       fs fsys io io_reply io_request \
+				       term tioctl socket ifsock \
 				       login password pfinet \
 				       )
 server-interfaces	:= hurd/msg faultexc
--- a/hurd/hurdselect.c
+++ b/hurd/hurdselect.c
@@ -16,14 +16,17 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <sys/time.h>
 #include <sys/types.h>
 #include <sys/poll.h>
 #include <hurd.h>
 #include <hurd/fd.h>
+#include <hurd/io_request.h>
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
 #include <stdint.h>
+#include <limits.h>
 
 /* All user select types.  */
 #define SELECT_ALL (SELECT_READ | SELECT_WRITE | SELECT_URG)
@@ -44,11 +47,13 @@ _hurd_select (int nfds,
 {
   int i;
   mach_port_t portset;
-  int got;
+  int got, ready;
   error_t err;
   fd_set rfds, wfds, xfds;
   int firstfd, lastfd;
-  mach_msg_timeout_t to = 0;
+  mach_msg_id_t reply_msgid;
+  mach_msg_timeout_t to;
+  struct timespec ts;
   struct
     {
       struct hurd_userlink ulink;
@@ -73,16 +78,39 @@ _hurd_select (int nfds,
       return -1;
     }
 
-  if (timeout != NULL)
+#define IO_SELECT_REPLY_MSGID (21012 + 100) /* XXX */
+#define IO_SELECT_TIMEOUT_REPLY_MSGID (21031 + 100) /* XXX */
+
+  if (timeout == NULL)
+    reply_msgid = IO_SELECT_REPLY_MSGID;
+  else
     {
-      if (timeout->tv_sec < 0 || timeout->tv_nsec < 0)
+      struct timeval now;
+
+      if (timeout->tv_sec < 0 || timeout->tv_nsec < 0 ||
+	  timeout->tv_nsec >= 1000000000)
 	{
 	  errno = EINVAL;
 	  return -1;
 	}
 
-      to = (timeout->tv_sec * 1000 +
-            (timeout->tv_nsec + 999999) / 1000000);
+      err = __gettimeofday(&now, NULL);
+      if (err)
+	return -1;
+
+      ts.tv_sec = now.tv_sec + timeout->tv_sec;
+      ts.tv_nsec = now.tv_usec * 1000 + timeout->tv_nsec;
+
+      if (ts.tv_nsec >= 1000000000)
+	{
+	  ts.tv_sec++;
+	  ts.tv_nsec -= 1000000000;
+	}
+
+      if (ts.tv_sec < 0)
+	ts.tv_sec = LONG_MAX; /* XXX */
+
+      reply_msgid = IO_SELECT_TIMEOUT_REPLY_MSGID;
     }
 
   if (sigmask && __sigprocmask (SIG_SETMASK, sigmask, &oset))
@@ -236,12 +264,13 @@ _hurd_select (int nfds,
 	  {
 	    int type = d[i].type;
 	    d[i].reply_port = __mach_reply_port ();
-	    err = __io_select (d[i].io_port, d[i].reply_port, 0, &type);
-	    switch (err)
+	    if (timeout == NULL)
+	      err = __io_select_request (d[i].io_port, d[i].reply_port, type);
+	    else
+	      err = __io_select_timeout_request (d[i].io_port, d[i].reply_port,
+						 ts, type);
+	    if (!err)
 	      {
-	      case MACH_RCV_TIMED_OUT:
-		/* No immediate response.  This is normal.  */
-		err = 0;
 		if (firstfd == lastfd)
 		  /* When there's a single descriptor, we don't need a
 		     portset, so just pretend we have one, but really
@@ -262,32 +291,24 @@ _hurd_select (int nfds,
 		      __mach_port_move_member (__mach_task_self (),
 					       d[i].reply_port, portset);
 		  }
-		break;
-
-	      default:
-		/* No other error should happen.  Callers of select
+	      }
+	    else
+	      {
+		/* No error should happen.  Callers of select
 		   don't expect to see errors, so we simulate
 		   readiness of the erring object and the next call
 		   hopefully will get the error again.  */
-		type = SELECT_ALL;
-		/* FALLTHROUGH */
-
-	      case 0:
-		/* We got an answer.  */
-		if ((type & SELECT_ALL) == 0)
-		  /* Bogus answer; treat like an error, as a fake positive.  */
-		  type = SELECT_ALL;
-
-		/* This port is already ready already.  */
-		d[i].type &= type;
 		d[i].type |= SELECT_RETURNED;
 		++got;
-		break;
 	      }
 	    _hurd_port_free (&d[i].cell->port, &d[i].ulink, d[i].io_port);
 	  }
     }
 
+  /* GOT is the number of replies (or errors), while READY is the number of
+     replies with at least one type bit set.  */
+  ready = 0;
+
   /* Now wait for reply messages.  */
   if (!err && got == 0)
     {
@@ -329,22 +350,35 @@ _hurd_select (int nfds,
 	    } success;
 #endif
 	} msg;
-      mach_msg_option_t options = (timeout == NULL ? 0 : MACH_RCV_TIMEOUT);
+      mach_msg_option_t options;
       error_t msgerr;
+
+      /* We rely on servers to implement the timeout, but when there are none,
+	 do it on the client side.  */
+      if (timeout != NULL && firstfd == -1)
+	{
+	  options = MACH_RCV_TIMEOUT;
+	  to = timeout->tv_sec * 1000 + (timeout->tv_nsec + 999999) / 1000000;
+	}
+      else
+	{
+	  options = 0;
+	  to = MACH_MSG_TIMEOUT_NONE;
+	}
+
       while ((msgerr = __mach_msg (&msg.head,
 				   MACH_RCV_MSG | MACH_RCV_INTERRUPT | options,
 				   0, sizeof msg, portset, to,
 				   MACH_PORT_NULL)) == MACH_MSG_SUCCESS)
 	{
 	  /* We got a message.  Decode it.  */
-#define IO_SELECT_REPLY_MSGID (21012 + 100) /* XXX */
 #ifdef MACH_MSG_TYPE_BIT
 	  const union typeword inttype =
 	  { type:
 	    { MACH_MSG_TYPE_INTEGER_T, sizeof (integer_t) * 8, 1, 1, 0, 0 }
 	  };
 #endif
-	  if (msg.head.msgh_id == IO_SELECT_REPLY_MSGID &&
+	  if (msg.head.msgh_id == reply_msgid &&
 	      msg.head.msgh_size >= sizeof msg.error &&
 	      !(msg.head.msgh_bits & MACH_MSGH_BITS_COMPLEX) &&
 #ifdef MACH_MSG_TYPE_BIT
@@ -362,12 +396,13 @@ _hurd_select (int nfds,
 		  err = EINTR;
 		  goto poll;
 		}
+	      /* Keep in mind msg.success.result can be 0 if a timeout
+		 occurred.  */
 	      if (msg.error.err ||
-		  msg.head.msgh_size != sizeof msg.success ||
 #ifdef MACH_MSG_TYPE_BIT
 		  msg.success.result_type.word != inttype.word ||
 #endif
-		  (msg.success.result & SELECT_ALL) == 0)
+		  msg.head.msgh_size != sizeof msg.success)
 		{
 		  /* Error or bogus reply.  Simulate readiness.  */
 		  __mach_msg_destroy (&msg.head);
@@ -384,6 +419,9 @@ _hurd_select (int nfds,
 			&& d[i].reply_port == msg.head.msgh_local_port)
 		      {
 			d[i].type &= msg.success.result;
+			if (d[i].type)
+			  ++ready;
+
 			d[i].type |= SELECT_RETURNED;
 			++got;
 		      }
@@ -415,7 +453,7 @@ _hurd_select (int nfds,
 	/* Interruption on our side (e.g. signal reception).  */
 	err = EINTR;
 
-      if (got)
+      if (ready)
 	/* At least one descriptor is known to be ready now, so we will
 	   return success.  */
 	err = 0;
@@ -459,9 +497,9 @@ _hurd_select (int nfds,
       }
   else
     {
-      /* Below we recalculate GOT to include an increment for each operation
+      /* Below we recalculate READY to include an increment for each operation
 	 allowed on each fd.  */
-      got = 0;
+      ready = 0;
 
       /* Set the user bitarrays.  We only ever have to clear bits, as all
 	 desired ones are initially set.  */
@@ -474,15 +512,15 @@ _hurd_select (int nfds,
 	      type = 0;
 
 	    if (type & SELECT_READ)
-	      got++;
+	      ready++;
 	    else if (readfds)
 	      FD_CLR (i, readfds);
 	    if (type & SELECT_WRITE)
-	      got++;
+	      ready++;
 	    else if (writefds)
 	      FD_CLR (i, writefds);
 	    if (type & SELECT_URG)
-	      got++;
+	      ready++;
 	    else if (exceptfds)
 	      FD_CLR (i, exceptfds);
 	  }
@@ -491,5 +529,5 @@ _hurd_select (int nfds,
   if (sigmask && __sigprocmask (SIG_SETMASK, &oset, NULL))
     return -1;
 
-  return got;
+  return ready;
 }