Example of cooperative rendering into one window by two processes
diff --git a/progs/xdemos/ipc.c b/progs/xdemos/ipc.c
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+/* Copyright (c) 2003 Tungsten Graphics, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files ("the
+ * Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions: The above copyright notice, the Tungsten
+ * Graphics splash screen, and this permission notice shall be included
+ * in all copies or substantial portions of the Software. THE SOFTWARE
+ * IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+ * SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
+ * THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * Simple IPC API
+ * Brian Paul
+ */
+
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include "ipc.h"
+
+#if defined(IRIX) || defined(irix)
+typedef int socklen_t;
+#endif
+
+#define NO_DELAY 1
+
+#define DEFAULT_MASTER_PORT 7011
+
+
+/*
+ * Return my hostname in <nameOut>.
+ * Return 1 for success, 0 for error.
+ */
+int
+MyHostName(char *nameOut, int maxNameLength)
+{
+ int k = gethostname(nameOut, maxNameLength);
+ return k==0;
+}
+
+
+/*
+ * Create a socket attached to a port. Later, we can call AcceptConnection
+ * on the socket returned from this function.
+ * Return the new socket number or -1 if error.
+ */
+int
+CreatePort(int *port)
+{
+ char hostname[1000];
+ struct sockaddr_in servaddr;
+ struct hostent *hp;
+ int so_reuseaddr = 1;
+ int tcp_nodelay = 1;
+ int sock, k;
+
+ /* create socket */
+ sock = socket(AF_INET, SOCK_STREAM, 0);
+ assert(sock > 2);
+
+ /* get my host name */
+ k = gethostname(hostname, 1000);
+ assert(k == 0);
+
+ /* get hostent info */
+ hp = gethostbyname(hostname);
+ assert(hp);
+
+ /* initialize the servaddr struct */
+ memset(&servaddr, 0, sizeof(servaddr) );
+ servaddr.sin_family = AF_INET;
+ servaddr.sin_port = htons((unsigned short) (*port));
+ memcpy((char *) &servaddr.sin_addr, hp->h_addr,
+ sizeof(servaddr.sin_addr));
+
+ /* deallocate when we exit */
+ k = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
+ (char *) &so_reuseaddr, sizeof(so_reuseaddr));
+ assert(k==0);
+
+ /* send packets immediately */
+#if NO_DELAY
+ k = setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
+ (char *) &tcp_nodelay, sizeof(tcp_nodelay));
+ assert(k==0);
+#endif
+
+ if (*port == 0)
+ *port = DEFAULT_MASTER_PORT;
+
+ k = 1;
+ while (k && (*port < 65534)) {
+ /* bind our address to the socket */
+ servaddr.sin_port = htons((unsigned short) (*port));
+ k = bind(sock, (struct sockaddr *) &servaddr, sizeof(servaddr));
+ if (k)
+ *port = *port + 1;
+ }
+
+#if 0
+ printf("###### Real Port: %d\n", *port);
+#endif
+
+ /* listen for connections */
+ k = listen(sock, 100);
+ assert(k == 0);
+
+ return sock;
+}
+
+
+/*
+ * Accept a connection on the named socket.
+ * Return a new socket for the new connection, or -1 if error.
+ */
+int
+AcceptConnection(int socket)
+{
+ struct sockaddr addr;
+ socklen_t addrLen;
+ int newSock;
+
+ addrLen = sizeof(addr);
+ newSock = accept(socket, &addr, &addrLen);
+ if (newSock == 1)
+ return -1;
+ else
+ return newSock;
+}
+
+
+/*
+ * Contact the server running on the given host on the named port.
+ * Return socket number or -1 if error.
+ */
+int
+Connect(const char *hostname, int port)
+{
+ struct sockaddr_in servaddr;
+ struct hostent *hp;
+ int sock, k;
+ int tcp_nodelay = 1;
+
+ assert(port);
+
+ sock = socket(AF_INET, SOCK_STREAM, 0);
+ assert(sock >= 0);
+
+ hp = gethostbyname(hostname);
+ assert(hp);
+
+ memset(&servaddr, 0, sizeof(servaddr));
+ servaddr.sin_family = AF_INET;
+ servaddr.sin_port = htons((unsigned short) port);
+ memcpy((char *) &servaddr.sin_addr, hp->h_addr, sizeof(servaddr.sin_addr));
+
+ k = connect(sock, (struct sockaddr *) &servaddr, sizeof(servaddr));
+ if (k != 0) {
+ perror("Connect:");
+ return -1;
+ }
+
+#if NO_DELAY
+ /* send packets immediately */
+ k = setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
+ (char *) &tcp_nodelay, sizeof(tcp_nodelay));
+ assert(k==0);
+#endif
+
+ return sock;
+}
+
+
+void
+CloseSocket(int socket)
+{
+ close(socket);
+}
+
+
+int
+SendData(int socket, const void *data, int bytes)
+{
+ int sent = 0;
+ int b;
+
+ while (sent < bytes) {
+ b = write(socket, (char *) data + sent, bytes - sent);
+ if (b <= 0)
+ return -1; /* something broke */
+ sent += b;
+ }
+ return sent;
+}
+
+
+int
+ReceiveData(int socket, void *data, int bytes)
+{
+ int received = 0, b;
+
+ while (received < bytes) {
+ b = read(socket, (char *) data + received, bytes - received);
+ if (b <= 0)
+ return -1;
+ received += b;
+ }
+ return received;
+}
+
+
+int
+SendString(int socket, const char *str)
+{
+ const int len = strlen(str);
+ int sent, b;
+
+ /* first, send a 4-byte length indicator */
+ b = write(socket, &len, sizeof(len));
+ if (b <= 0)
+ return -1;
+
+ sent = SendData(socket, str, len);
+ assert(sent == len);
+ return sent;
+}
+
+
+int
+ReceiveString(int socket, char *str, int maxLen)
+{
+ int len, received, b;
+
+ /* first, read 4 bytes to see how long of string to receive */
+ b = read(socket, &len, sizeof(len));
+ if (b <= 0)
+ return -1;
+
+ assert(len <= maxLen); /* XXX fix someday */
+ assert(len >= 0);
+ received = ReceiveData(socket, str, len);
+ assert(received != -1);
+ assert(received == len);
+ str[len] = 0;
+ return received;
+}