479 lines
15 KiB
C
479 lines
15 KiB
C
/*
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* vim:ts=4:sw=4:expandtab
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*
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* i3 - an improved dynamic tiling window manager
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* © 2009 Michael Stapelberg and contributors (see also: LICENSE)
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*
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* inject_randr1.5.c: An X11 proxy which interprets RandR 1.5 GetMonitors
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* requests and overwrites their reply with a custom reply.
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*
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* This tool can be refactored as necessary in order to perform the same
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* purpose for other request types. The RandR 1.5 specific portions of the code
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* have been marked as such to make such a refactoring easier.
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*
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*/
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#include "all.h"
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#include <ev.h>
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#include <fcntl.h>
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#include <libgen.h>
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#include <sys/mman.h>
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#include <sys/resource.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/un.h>
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#include <sys/wait.h>
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static void uds_connection_cb(EV_P_ ev_io *w, int revents);
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static void read_client_setup_request_cb(EV_P_ ev_io *w, int revents);
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static void read_server_setup_reply_cb(EV_P_ ev_io *w, int revents);
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static void read_client_x11_packet_cb(EV_P_ ev_io *w, int revents);
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static void read_server_x11_packet_cb(EV_P_ ev_io *w, int revents);
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static char *sun_path = NULL;
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static void cleanup_socket(void) {
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if (sun_path != NULL) {
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unlink(sun_path);
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free(sun_path);
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sun_path = NULL;
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}
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}
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struct injected_reply {
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void *buf;
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off_t len;
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};
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/* BEGIN RandR 1.5 specific */
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static struct injected_reply getmonitors_reply = {NULL, 0};
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static struct injected_reply getoutputinfo_reply = {NULL, 0};
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/* END RandR 1.5 specific */
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#define XCB_PAD(i) (-(i)&3)
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struct connstate {
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/* clientw is a libev watcher for the connection which we accept()ed. */
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ev_io *clientw;
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/* serverw is a libev watcher for the connection to X11 which we initiated
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* on behalf of the client. */
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ev_io *serverw;
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/* sequence is the client-side sequence number counter. In X11’s wire
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* encoding, sequence counters are not included in requests, only in
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* replies. */
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int sequence;
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/* BEGIN RandR 1.5 specific */
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/* sequence number of the most recent GetExtension request for RANDR */
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int getext_randr;
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/* sequence number of the most recent RRGetMonitors request */
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int getmonitors;
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/* sequence number of the most recent RRGetOutputInfo request */
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int getoutputinfo;
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int randr_major_opcode;
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/* END RandR 1.5 specific */
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};
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/*
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* Returns 0 on EOF
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* Returns -1 on error (with errno from read() untouched)
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*
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*/
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static size_t readall_into(void *buffer, const size_t len, int fd) {
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size_t read_bytes = 0;
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while (read_bytes < len) {
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ssize_t n = read(fd, buffer + read_bytes, len - read_bytes);
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if (n <= 0) {
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return n;
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}
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read_bytes += (size_t)n;
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}
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return read_bytes;
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}
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/*
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* Exits the program with an error if the read failed.
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*
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*/
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static void must_read(int n) {
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if (n == -1) {
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err(EXIT_FAILURE, "read()");
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}
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if (n == 0) {
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errx(EXIT_FAILURE, "EOF");
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}
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}
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/*
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* Exits the program with an error if the write failed.
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*
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*/
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static void must_write(int n) {
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if (n == -1) {
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err(EXIT_FAILURE, "write()");
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}
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}
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static void uds_connection_cb(EV_P_ ev_io *w, int revents) {
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struct sockaddr_un addr;
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socklen_t addrlen = sizeof(addr);
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const int clientfd = accept(w->fd, (struct sockaddr *)&addr, &addrlen);
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if (clientfd == -1) {
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if (errno == EINTR) {
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return;
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}
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err(EXIT_FAILURE, "accept()");
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}
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struct connstate *connstate = scalloc(1, sizeof(struct connstate));
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ev_io *clientw = scalloc(1, sizeof(ev_io));
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connstate->clientw = clientw;
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clientw->data = connstate;
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ev_io_init(clientw, read_client_setup_request_cb, clientfd, EV_READ);
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ev_io_start(EV_A_ clientw);
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}
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// https://www.x.org/releases/current/doc/xproto/x11protocol.html#Encoding::Connection_Setup
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static void read_client_setup_request_cb(EV_P_ ev_io *w, int revents) {
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ev_io_stop(EV_A_ w);
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struct connstate *connstate = (struct connstate *)w->data;
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/* Read X11 setup request in its entirety. */
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xcb_setup_request_t setup_request;
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must_read(readall_into(&setup_request, sizeof(setup_request), w->fd));
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/* Establish a connection to X11. */
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int fd = socket(AF_LOCAL, SOCK_STREAM, 0);
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if (fd == -1) {
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err(EXIT_FAILURE, "socket()");
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}
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char *host;
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int displayp;
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if (xcb_parse_display(getenv("DISPLAY"), &host, &displayp, NULL) == 0) {
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errx(EXIT_FAILURE, "Could not parse DISPLAY=%s", getenv("DISPLAY"));
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}
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free(host);
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struct sockaddr_un addr;
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memset(&addr, 0, sizeof(addr));
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addr.sun_family = AF_LOCAL;
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snprintf(addr.sun_path, sizeof(addr.sun_path), "/tmp/.X11-unix/X%d", displayp);
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if (connect(fd, (const struct sockaddr *)&addr, sizeof(struct sockaddr_un)) == -1) {
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err(EXIT_FAILURE, "connect(%s)", addr.sun_path);
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}
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/* Relay setup request. */
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must_write(writeall(fd, &setup_request, sizeof(setup_request)));
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if (setup_request.authorization_protocol_name_len > 0 ||
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setup_request.authorization_protocol_data_len > 0) {
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const size_t authlen = setup_request.authorization_protocol_name_len +
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XCB_PAD(setup_request.authorization_protocol_name_len) +
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setup_request.authorization_protocol_data_len +
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XCB_PAD(setup_request.authorization_protocol_data_len);
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void *buf = smalloc(authlen);
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must_read(readall_into(buf, authlen, w->fd));
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must_write(writeall(fd, buf, authlen));
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free(buf);
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}
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/* Wait for a response from the X11 server. */
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ev_io *serverw = scalloc(1, sizeof(ev_io));
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connstate->serverw = serverw;
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serverw->data = connstate;
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ev_io_init(serverw, read_server_setup_reply_cb, fd, EV_READ);
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ev_io_start(EV_A_ serverw);
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}
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static void read_server_setup_reply_cb(EV_P_ ev_io *w, int revents) {
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struct connstate *connstate = (struct connstate *)w->data;
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xcb_setup_failed_t setup_failed;
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must_read(readall_into(&setup_failed, sizeof(setup_failed), w->fd));
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switch (setup_failed.status) {
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case 0:
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errx(EXIT_FAILURE, "error authenticating at the X11 server");
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case 2:
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errx(EXIT_FAILURE, "two-factor auth not implemented");
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case 1:
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must_write(writeall(connstate->clientw->fd, &setup_failed, sizeof(xcb_setup_failed_t)));
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const size_t len = (setup_failed.length * 4);
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void *buf = smalloc(len);
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must_read(readall_into(buf, len, w->fd));
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must_write(writeall(connstate->clientw->fd, buf, len));
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free(buf);
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ev_set_cb(connstate->clientw, read_client_x11_packet_cb);
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ev_set_cb(connstate->serverw, read_server_x11_packet_cb);
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ev_io_start(EV_A_ connstate->clientw);
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break;
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default:
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errx(EXIT_FAILURE, "X11 protocol error: expected setup_failed.status in [0..2], got %d", setup_failed.status);
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}
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}
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// https://www.x.org/releases/current/doc/xproto/x11protocol.html#request_format
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typedef struct {
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uint8_t opcode;
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uint8_t pad0;
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uint16_t length;
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} generic_x11_request_t;
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// https://www.x.org/releases/current/doc/xproto/x11protocol.html#reply_format
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typedef struct {
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uint8_t code; /* if 1, this is a reply. if 0, this is an error. else, an event */
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uint8_t pad0;
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uint16_t sequence;
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uint32_t length;
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} generic_x11_reply_t;
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static void read_client_x11_packet_cb(EV_P_ ev_io *w, int revents) {
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struct connstate *connstate = (struct connstate *)w->data;
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void *request = smalloc(sizeof(generic_x11_request_t));
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must_read(readall_into(request, sizeof(generic_x11_request_t), connstate->clientw->fd));
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const size_t len = (((generic_x11_request_t *)request)->length * 4);
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if (len > sizeof(generic_x11_request_t)) {
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request = srealloc(request, len);
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must_read(readall_into(request + sizeof(generic_x11_request_t),
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len - sizeof(generic_x11_request_t),
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connstate->clientw->fd));
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}
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// XXX: sequence counter wrapping is not implemented, but should not be
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// necessary given that this tool is scoped for test cases.
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connstate->sequence++;
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/* BEGIN RandR 1.5 specific */
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const uint8_t opcode = ((generic_x11_request_t *)request)->opcode;
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if (opcode == XCB_QUERY_EXTENSION) {
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xcb_query_extension_request_t *req = request;
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const char *name = request + sizeof(xcb_query_extension_request_t);
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if (req->name_len == strlen("RANDR") &&
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strncmp(name, "RANDR", strlen("RANDR")) == 0) {
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connstate->getext_randr = connstate->sequence;
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}
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} else if (opcode == connstate->randr_major_opcode) {
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const uint8_t randr_opcode = ((generic_x11_request_t *)request)->pad0;
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if (randr_opcode == XCB_RANDR_GET_MONITORS) {
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connstate->getmonitors = connstate->sequence;
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} else if (randr_opcode == XCB_RANDR_GET_OUTPUT_INFO) {
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connstate->getoutputinfo = connstate->sequence;
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}
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}
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/* END RandR 1.5 specific */
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must_write(writeall(connstate->serverw->fd, request, len));
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free(request);
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}
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static bool handle_sequence(struct connstate *connstate, uint16_t sequence) {
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/* BEGIN RandR 1.5 specific */
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if (sequence == connstate->getmonitors) {
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printf("RRGetMonitors reply!\n");
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if (getmonitors_reply.buf != NULL) {
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printf("injecting reply\n");
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((generic_x11_reply_t *)getmonitors_reply.buf)->sequence = sequence;
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must_write(writeall(connstate->clientw->fd, getmonitors_reply.buf, getmonitors_reply.len));
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return true;
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}
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}
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if (sequence == connstate->getoutputinfo) {
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printf("RRGetOutputInfo reply!\n");
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if (getoutputinfo_reply.buf != NULL) {
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printf("injecting reply\n");
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((generic_x11_reply_t *)getoutputinfo_reply.buf)->sequence = sequence;
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must_write(writeall(connstate->clientw->fd, getoutputinfo_reply.buf, getoutputinfo_reply.len));
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return true;
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}
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}
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/* END RandR 1.5 specific */
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return false;
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}
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static void read_server_x11_packet_cb(EV_P_ ev_io *w, int revents) {
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struct connstate *connstate = (struct connstate *)w->data;
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// all packets from the server are at least 32 bytes in length
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size_t len = 32;
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void *packet = smalloc(len);
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must_read(readall_into(packet, len, connstate->serverw->fd));
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switch (((generic_x11_reply_t *)packet)->code) {
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case 0: { // error
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const uint16_t sequence = ((xcb_request_error_t *)packet)->sequence;
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if (handle_sequence(connstate, sequence)) {
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free(packet);
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return;
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}
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break;
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}
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case 1: // reply
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len += ((generic_x11_reply_t *)packet)->length * 4;
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if (len > 32) {
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packet = srealloc(packet, len);
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must_read(readall_into(packet + 32, len - 32, connstate->serverw->fd));
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}
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/* BEGIN RandR 1.5 specific */
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const uint16_t sequence = ((generic_x11_reply_t *)packet)->sequence;
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if (sequence == connstate->getext_randr) {
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xcb_query_extension_reply_t *reply = packet;
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connstate->randr_major_opcode = reply->major_opcode;
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}
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/* END RandR 1.5 specific */
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if (handle_sequence(connstate, sequence)) {
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free(packet);
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return;
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}
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break;
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default: // event
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break;
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}
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must_write(writeall(connstate->clientw->fd, packet, len));
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free(packet);
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}
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static void child_cb(EV_P_ ev_child *w, int revents) {
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ev_child_stop(EV_A_ w);
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if (WIFEXITED(w->rstatus)) {
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exit(WEXITSTATUS(w->rstatus));
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} else {
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exit(WTERMSIG(w->rstatus) + 128);
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}
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}
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static void must_read_reply(const char *filename, struct injected_reply *reply) {
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FILE *f;
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if ((f = fopen(filename, "r")) == NULL) {
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err(EXIT_FAILURE, "fopen(%s)", filename);
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}
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struct stat stbuf;
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if (fstat(fileno(f), &stbuf) != 0) {
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err(EXIT_FAILURE, "fstat(%s)", filename);
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}
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reply->len = stbuf.st_size;
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reply->buf = smalloc(stbuf.st_size);
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int n = fread(reply->buf, 1, stbuf.st_size, f);
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if (n != stbuf.st_size) {
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err(EXIT_FAILURE, "fread(%s)", filename);
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}
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fclose(f);
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}
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int main(int argc, char *argv[]) {
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static struct option long_options[] = {
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{"getmonitors_reply", required_argument, 0, 0},
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{"getoutputinfo_reply", required_argument, 0, 0},
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{0, 0, 0, 0},
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};
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char *options_string = "";
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int opt;
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int option_index = 0;
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while ((opt = getopt_long(argc, argv, options_string, long_options, &option_index)) != -1) {
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switch (opt) {
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case 0: {
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const char *option_name = long_options[option_index].name;
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if (strcmp(option_name, "getmonitors_reply") == 0) {
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must_read_reply(optarg, &getmonitors_reply);
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} else if (strcmp(option_name, "getoutputinfo_reply") == 0) {
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must_read_reply(optarg, &getoutputinfo_reply);
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}
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break;
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}
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default:
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exit(EXIT_FAILURE);
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}
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}
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if (optind >= argc) {
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errx(EXIT_FAILURE, "syntax: %s [options] <command>", argv[0]);
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}
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int fd = socket(AF_LOCAL, SOCK_STREAM, 0);
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if (fd == -1) {
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err(EXIT_FAILURE, "socket(AF_UNIX)");
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}
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if (fcntl(fd, F_SETFD, FD_CLOEXEC)) {
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warn("Could not set FD_CLOEXEC");
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}
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struct sockaddr_un addr;
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memset(&addr, 0, sizeof(struct sockaddr_un));
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addr.sun_family = AF_UNIX;
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int i;
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bool bound = false;
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for (i = 0; i < 100; i++) {
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/* XXX: The path to X11 sockets differs on some platforms (e.g. Trusted
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* Solaris, HPUX), but since libxcb doesn’t provide a function to
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* generate the path, we’ll just have to hard-code it for now. */
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snprintf(addr.sun_path, sizeof(addr.sun_path), "/tmp/.X11-unix/X%d", i);
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if (bind(fd, (struct sockaddr *)&addr, sizeof(struct sockaddr_un)) == -1) {
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warn("bind(%s)", addr.sun_path);
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} else {
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bound = true;
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/* Let the user know bind() was successful, so that they know the
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* error messages can be disregarded. */
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fprintf(stderr, "Successfuly bound to %s\n", addr.sun_path);
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sun_path = sstrdup(addr.sun_path);
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break;
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}
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}
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if (!bound) {
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err(EXIT_FAILURE, "bind()");
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}
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atexit(cleanup_socket);
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/* This program will be started for each testcase which requires it, so we
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* expect precisely one connection. */
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if (listen(fd, 1) == -1) {
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err(EXIT_FAILURE, "listen()");
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}
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pid_t child = fork();
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if (child == -1) {
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err(EXIT_FAILURE, "fork()");
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}
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if (child == 0) {
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char *display;
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sasprintf(&display, ":%d", i);
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setenv("DISPLAY", display, 1);
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free(display);
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char **child_args = argv + optind;
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execvp(child_args[0], child_args);
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err(EXIT_FAILURE, "exec()");
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}
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struct ev_loop *loop = ev_default_loop(0);
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ev_child cw;
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ev_child_init(&cw, child_cb, child, 0);
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ev_child_start(loop, &cw);
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ev_io watcher;
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ev_io_init(&watcher, uds_connection_cb, fd, EV_READ);
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ev_io_start(loop, &watcher);
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ev_run(loop, 0);
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}
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