Merge pull request #290 from rcgordon/autoupdater

Initial shot at writing an ioquake3 autoupdater. Thank you icculus, and everyone who contributed to his patreon! https://www.patreon.com/icculus

code/sys/sys_autoupdater.c

@@ -0,0 +1,86 @@
+/*
+The code in this file is in the public domain. The rest of ioquake3
+is licensed under the GPLv2. Do not mingle code, please!
+*/
+
+#ifdef USE_AUTOUPDATER
+#  ifndef AUTOUPDATER_BIN
+#    error The build system should have defined AUTOUPDATER_BIN
+#  endif
+
+#  ifdef _WIN32
+#    define WIN32_LEAN_AND_MEAN 1
+#    include <windows.h>
+#  else
+#    include <unistd.h>
+#  endif
+
+#  include <stdio.h>
+#  include <string.h>
+#endif
+
+void Sys_LaunchAutoupdater(int argc, char **argv)
+{
+#ifdef USE_AUTOUPDATER
+	#ifdef _WIN32
+	{
+		/* We don't need the Unix pipe() tapdance here because Windows lets children wait on parent processes. */
+		PROCESS_INFORMATION procinfo;
+		STARTUPINFO startinfo;
+		char cmdline[128];
+		memset(&procinfo, '\0', sizeof (procinfo));
+		memset(&startinfo, '\0', sizeof (startinfo));
+		startinfo.cb = sizeof (startinfo);
+		sprintf(cmdline, "" AUTOUPDATER_BIN " --waitpid %u", (unsigned int) GetCurrentProcessId());
+
+		if (CreateProcessA(AUTOUPDATER_BIN, cmdline, NULL, NULL, FALSE, CREATE_NO_WINDOW, NULL, NULL, &startinfo, &procinfo))
+		{
+			/* close handles now so child cleans up immediately if nothing to do */
+			CloseHandle(procinfo.hProcess);
+			CloseHandle(procinfo.hThread);
+		}
+	}
+	#else
+	int updater_pipes[2];
+	if (pipe(updater_pipes) == 0)
+	{
+		pid_t pid = fork();
+		if (pid == -1)  /* failure, oh well. */
+		{
+			close(updater_pipes[0]);
+			close(updater_pipes[1]);
+		}
+		else if (pid == 0)  /* child process */
+		{
+			close(updater_pipes[1]);  /* don't need write end. */
+			if (dup2(updater_pipes[0], 3) != -1)
+			{
+				char pidstr[64];
+				char *ptr = strrchr(argv[0], '/');
+				if (ptr)
+					*ptr = '\0';
+				if (chdir(argv[0]) == -1) {
+					_exit(1);  /* oh well. */
+				}
+				#ifdef __APPLE__
+				if (chdir("../..") == -1) {  /* put this at base of app bundle so paths make sense later. */
+					_exit(1);  /* oh well. */
+				}
+				#endif
+				snprintf(pidstr, sizeof (pidstr), "%lld", (long long) getppid());
+				execl(AUTOUPDATER_BIN, AUTOUPDATER_BIN, "--waitpid", pidstr, NULL);
+			}
+			_exit(0);  /* oh well. */
+		}
+		else   /* parent process */
+		{
+			/* leave the write end open until we terminate so updater can block on it. */
+			close(updater_pipes[0]);
+		}
+	}
+	#endif
+#endif
+
+	(void) argc; (void) argv;  /* possibly unused. Pacify compilers. */
+}
+

code/sys/sys_main.c

@@ -683,6 +683,9 @@ int main( int argc, char **argv )
 	int   i;
 	char  commandLine[ MAX_STRING_CHARS ] = { 0 };
 
+	extern void Sys_LaunchAutoupdater(int argc, char **argv);
+	Sys_LaunchAutoupdater(argc, argv);
+
 #ifndef DEDICATED
 	// SDL version check