test: Add a little xinit-like program for starting servers for testing

The normal xinit is racy because it doesn't use -displayfd.  This
implements the bare minimum for testing purposes, using -displayfd to
sequence starting the client, and avoids adding yet another dependency
to the server.

v2: Fix asprintf error checks.
v3: Add error checking for fork(), clarify calloc() arg.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

3 files changed, 239 insertions, 4 deletions

diff --git a/test/.gitignore b/test/.gitignore
index a62fc3d70..c44fc827a 100644
--- a/test/.gitignore
+++ b/test/.gitignore
@@ -11,5 +11,6 @@ xfree86
 xkb
 xtest
 signal-logging
+simple-xinit
 *.log
 *.trs
diff --git a/test/Makefile.am b/test/Makefile.am
index 4ccadf5b0..24bfc35bc 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,17 +1,22 @@
 if ENABLE_UNIT_TESTS
 SUBDIRS= .
-noinst_PROGRAMS = list string
+TEST_PROGS = list string
 if XORG
 # Tests that require at least some DDX functions in order to fully link
 # For now, requires xf86 ddx, could be adjusted to use another
 SUBDIRS += xi1 xi2
-noinst_PROGRAMS += xkb input xtest misc fixes xfree86 signal-logging touch
+TEST_PROGS += xkb input xtest misc fixes xfree86 signal-logging touch
 if RES
-noinst_PROGRAMS += hashtabletest
+TEST_PROGS += hashtabletest
 endif
 endif
 check_LTLIBRARIES = libxservertest.la
 
+noinst_PROGRAMS = \
+	simple-xinit \
+	$(TEST_PROGS) \
+	$(NULL)
+
 if XVFB
 XVFB_TESTS = scripts/xvfb-piglit.sh
 endif
@@ -21,7 +26,7 @@ SCRIPT_TESTS = \
 	$(NULL)
 
 TESTS = \
-	$(noinst_PROGRAMS) \
+	$(TEST_PROGS) \
 	$(SCRIPT_TESTS) \
 	$(NULL)
 
diff --git a/test/simple-xinit.c b/test/simple-xinit.c
new file mode 100644
index 000000000..89189a609
--- /dev/null
+++ b/test/simple-xinit.c
@@ -0,0 +1,229 @@
+/*
+ * Copyright © 2016 Broadcom
+ *
+ * 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 and this permission notice (including the next
+ * paragraph) 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.
+ */
+
+#ifdef HAVE_DIX_CONFIG_H
+#include <dix-config.h>
+#endif
+
+#include <errno.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+static void
+kill_server(int server_pid)
+{
+    int ret = kill(server_pid, SIGTERM);
+    int wstatus;
+
+    if (ret) {
+        fprintf(stderr, "Failed to send kill to the server: %s\n",
+                strerror(errno));
+        exit(1);
+    }
+
+    ret = waitpid(server_pid, &wstatus, 0);
+    if (ret < 0) {
+        fprintf(stderr, "Failed to wait for X to die: %s\n", strerror(errno));
+        exit(1);
+    }
+}
+
+static void
+usage(int argc, char **argv)
+{
+    fprintf(stderr, "%s <client command> -- <server command>\n", argv[0]);
+    exit(1);
+}
+
+/* Starts the X server, returning its pid. */
+static int
+start_server(char *const *server_args)
+{
+    int server_pid = fork();
+
+    if (server_pid == -1) {
+        fprintf(stderr, "Fork failed: %s\n", strerror(errno));
+        exit(1);
+    } else if (server_pid != 0) {
+        /* Continue along the main process that will exec the client. */
+        return server_pid;
+    }
+
+    /* Execute the server.  This only returns if an error occurred. */
+    execvp(server_args[0], server_args);
+    fprintf(stderr, "Error starting the server: %s\n", strerror(errno));
+    exit(1);
+}
+
+/* Reads the display number out of the started server's display socket. */
+static int
+get_display(int displayfd)
+{
+    char display_string[10];
+    ssize_t ret;
+
+    ret = read(displayfd, display_string, sizeof(display_string - 1));
+    if (ret <= 0) {
+        fprintf(stderr, "Failed reading displayfd: %s\n", strerror(errno));
+        exit(1);
+    }
+
+    /* We've read in the display number as a string terminated by
+     * '\n', but not '\0'.  Cap it and parse the number.
+     */
+    display_string[ret] = '\0';
+    return atoi(display_string);
+}
+
+static int
+start_client(char *const *client_args, int display)
+{
+    char *display_string;
+    int ret;
+    int client_pid;
+
+    ret = asprintf(&display_string, ":%d", display);
+    if (ret < 0) {
+        fprintf(stderr, "asprintf fail\n");
+        exit(1);
+    }
+
+    ret = setenv("DISPLAY", display_string, true);
+    if (ret) {
+        fprintf(stderr, "Failed to set DISPLAY\n");
+        exit(1);
+    }
+
+    client_pid = fork();
+    if (client_pid == -1) {
+        fprintf(stderr, "Fork failed: %s\n", strerror(errno));
+        exit(1);
+    } else if (client_pid) {
+        int wstatus;
+
+        ret = waitpid(client_pid, &wstatus, 0);
+        if (ret < 0) {
+            fprintf(stderr, "Error waiting for client to start: %s\n",
+                    strerror(errno));
+            return 1;
+        }
+
+        return WEXITSTATUS(wstatus);
+    } else {
+        execvp(client_args[0], client_args);
+        /* exec only returns if an error occurred. */
+        fprintf(stderr, "Error starting the client: %s\n", strerror(errno));
+        exit(1);
+    }
+}
+
+/* Splits the incoming argc/argv into a pair of NULL-terminated arrays
+ * of args.
+ */
+static void
+parse_args(int argc, char **argv,
+           char * const **out_client_args,
+           char * const **out_server_args,
+           int displayfd)
+{
+    /* We're stripping the -- and the program name, inserting two
+     * NULLs, and also the -displayfd and fd number.
+     */
+    char **args_storage = calloc(argc + 2, sizeof(char *));
+    char *const *client_args;
+    char *const *server_args = NULL;
+    char **next_arg = args_storage;
+    bool parsing_client = true;
+    int i, ret;
+    char *displayfd_string;
+
+    if (!args_storage)
+        exit(1);
+
+    client_args = args_storage;
+    for (i = 1; i < argc; i++) {
+        if (strcmp(argv[i], "--") == 0) {
+            if (!parsing_client)
+                usage(argc, argv);
+
+            /* Cap the client list */
+            *next_arg = NULL;
+            next_arg++;
+
+            /* Move to adding into server_args. */
+            server_args = next_arg;
+            parsing_client = false;
+            continue;
+        }
+
+        *next_arg = argv[i];
+        next_arg++;
+    }
+
+    if (client_args[0] == NULL || !server_args || server_args[0] == NULL)
+        usage(argc, argv);
+
+    /* Give the server -displayfd X */
+    *next_arg = (char *)"-displayfd";
+    next_arg++;
+
+    ret = asprintf(&displayfd_string, "%d", displayfd);
+    if (ret < 0) {
+        fprintf(stderr, "asprintf fail\n");
+        exit(1);
+    }
+    *next_arg = displayfd_string;
+    next_arg++;
+
+    *out_client_args = client_args;
+    *out_server_args = server_args;
+}
+
+int
+main(int argc, char **argv)
+{
+    char * const *client_args;
+    char * const *server_args;
+    int displayfd_pipe[2];
+    int display, server_pid;
+    int ret;
+
+    ret = pipe(displayfd_pipe);
+    if (ret) {
+        fprintf(stderr, "Pipe creation failure: %s", strerror(errno));
+        exit(1);
+    }
+
+    parse_args(argc, argv, &client_args, &server_args, displayfd_pipe[1]);
+    server_pid = start_server(server_args);
+    display = get_display(displayfd_pipe[0]);
+    ret = start_client(client_args, display);
+    kill_server(server_pid);
+
+    exit(ret);
+}