1 /* Notification to GDB. 2 Copyright (C) 1989-2020 Free Software Foundation, Inc. 3 4 This file is part of GDB. 5 6 This program is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3 of the License, or 9 (at your option) any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 18 19 /* Async notifications to GDB. When the state of remote target is 20 changed or something interesting to GDB happened, async 21 notifications are used to tell GDB. 22 23 Each type of notification is represented by an object 24 'struct notif_server', in which there is a queue for events to GDB 25 represented by 'struct notif_event'. GDBserver writes (by means of 26 'write' field) each event in the queue into the buffer and send the 27 contents in buffer to GDB. The contents in buffer is specified in 28 RSP. See more in the comments to field 'queue' of 29 'struct notif_server'. 30 31 Here is the workflow of sending events and managing queue: 32 1. At any time, when something interesting FOO happens, a object 33 of 'struct notif_event' or its sub-class EVENT is created for FOO. 34 35 2. Enque EVENT to the 'queue' field of 'struct notif_server' for 36 FOO and send corresponding notification packet to GDB if EVENT is 37 the first one. 38 #1 and #2 are done by function 'notif_push'. 39 40 3. EVENT is not deque'ed until the ack of FOO from GDB arrives. 41 Before ack of FOO arrives, FOO happens again, a new object of 42 EVENT is created and enque EVENT silently. 43 Once GDB has a chance to ack to FOO, it sends an ack to GDBserver, 44 and GDBserver repeatedly sends events to GDB and gets ack of FOO, 45 until queue is empty. Then, GDBserver sends 'OK' to GDB that all 46 queued notification events are done. 47 48 # 3 is done by function 'handle_notif_ack'. */ 49 50 #include "server.h" 51 #include "notif.h" 52 53 static struct notif_server *notifs[] = 54 { 55 ¬if_stop, 56 }; 57 58 /* Write another event or an OK, if there are no more left, to 59 OWN_BUF. */ 60 61 void 62 notif_write_event (struct notif_server *notif, char *own_buf) 63 { 64 if (!notif->queue.empty ()) 65 { 66 struct notif_event *event = notif->queue.front (); 67 68 notif->write (event, own_buf); 69 } 70 else 71 write_ok (own_buf); 72 } 73 74 /* Handle the ack in buffer OWN_BUF,and packet length is PACKET_LEN. 75 Return 1 if the ack is handled, and return 0 if the contents 76 in OWN_BUF is not a ack. */ 77 78 int 79 handle_notif_ack (char *own_buf, int packet_len) 80 { 81 size_t i; 82 struct notif_server *np; 83 84 for (i = 0; i < ARRAY_SIZE (notifs); i++) 85 { 86 const char *ack_name = notifs[i]->ack_name; 87 88 if (startswith (own_buf, ack_name) 89 && packet_len == strlen (ack_name)) 90 break; 91 } 92 93 if (i == ARRAY_SIZE (notifs)) 94 return 0; 95 96 np = notifs[i]; 97 98 /* If we're waiting for GDB to acknowledge a pending event, 99 consider that done. */ 100 if (!np->queue.empty ()) 101 { 102 struct notif_event *head = np->queue.front (); 103 np->queue.pop_front (); 104 105 if (remote_debug) 106 debug_printf ("%s: acking %d\n", np->ack_name, 107 (int) np->queue.size ()); 108 109 delete head; 110 } 111 112 notif_write_event (np, own_buf); 113 114 return 1; 115 } 116 117 /* Put EVENT to the queue of NOTIF. */ 118 119 void 120 notif_event_enque (struct notif_server *notif, 121 struct notif_event *event) 122 { 123 notif->queue.push_back (event); 124 125 if (remote_debug) 126 debug_printf ("pending events: %s %d\n", notif->notif_name, 127 (int) notif->queue.size ()); 128 129 } 130 131 /* Push one event NEW_EVENT of notification NP into NP->queue. */ 132 133 void 134 notif_push (struct notif_server *np, struct notif_event *new_event) 135 { 136 bool is_first_event = np->queue.empty (); 137 138 /* Something interesting. Tell GDB about it. */ 139 notif_event_enque (np, new_event); 140 141 /* If this is the first stop reply in the queue, then inform GDB 142 about it, by sending a corresponding notification. */ 143 if (is_first_event) 144 { 145 char buf[PBUFSIZ]; 146 char *p = buf; 147 148 xsnprintf (p, PBUFSIZ, "%s:", np->notif_name); 149 p += strlen (p); 150 151 np->write (new_event, p); 152 putpkt_notif (buf); 153 } 154 } 155