Enhanced the "pre-xfer exec" handling so that it gets the user's

request info and puts that into the environment as RSYNC_REQUEST.

clientserver.c

@@ -59,6 +59,8 @@ int module_id = -1;
 /* Length of lp_path() string when in daemon mode & not chrooted, else 0. */
 unsigned int module_dirlen = 0;
 
+#define MAX_REQ_LEN (MAXPATHLEN + 255)
+
 /**
  * Run a client connected to an rsyncd.  The alternative to this
  * function for remote-shell connections is do_cmd().
@@ -216,7 +218,27 @@ int start_inband_exchange(char *user, char *path, int f_in, int f_out,
 	return 0;
 }
 
+static char *finish_pre_exec(pid_t pid, int fd, char *request)
+{
+	int status = -1;
 
+	if (request) {
+		int len = strlen(request);
+		if (len > MAX_REQ_LEN)
+			len = MAX_REQ_LEN;
+		write(fd, request, len);
+	}
+	close(fd);
+
+	if (wait_process(pid, &status, 0) < 0
+	 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+		char *e;
+		if (asprintf(&e, "pre-xfer exec returned failure (%d)\n", status) < 0)
+			out_of_memory("finish_pre_exec");
+		return e;
+	}
+	return NULL;
+}
 
 static int rsync_module(int f_in, int f_out, int i)
 {
@@ -226,16 +248,14 @@ static int rsync_module(int f_in, int f_out, int i)
 	char line[BIGPATHBUFLEN];
 	uid_t uid = (uid_t)-2;  /* canonically "nobody" */
 	gid_t gid = (gid_t)-2;
-	char *p;
-#ifdef HAVE_PUTENV
-	char *s;
-#endif
+	char *p, *err_msg = NULL;
 	char *addr = client_addr(f_in);
 	char *host = client_name(f_in);
 	char *name = lp_name(i);
 	int use_chroot = lp_use_chroot(i);
 	int start_glob = 0;
-	int ret;
+	int ret, pre_exec_fd = -1;
+	pid_t pre_exec_pid = 0;
 	char *request = NULL;
 
 	if (!allow_access(addr, host, lp_hosts_allow(i), lp_hosts_deny(i))) {
@@ -351,9 +371,7 @@ static int rsync_module(int f_in, int f_out, int i)
 	log_init();
 
 #ifdef HAVE_PUTENV
-	s = lp_prexfer_exec(i);
-	p = lp_postxfer_exec(i);
-	if ((s && *s) || (p && *p)) {
+	if (*lp_prexfer_exec(i) || *lp_postxfer_exec(i)) {
 		char *modname, *modpath, *hostaddr, *hostname, *username;
 		int status;
 		if (asprintf(&modname, "RSYNC_MODULE_NAME=%s", name) < 0
@@ -368,15 +386,10 @@ static int rsync_module(int f_in, int f_out, int i)
 		putenv(hostname);
 		putenv(username);
 		umask(orig_umask);
-		if (s && *s) {
-			status = system(s);
-			if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
-				rprintf(FLOG, "prexfer-exec failed\n");
-				io_printf(f_out, "@ERROR: prexfer-exec failed\n");
-				return -1;
-			}
-		}
-		if (p && *p) {
+		/* For post-xfer exec, fork a new process to run the rsync
+		 * daemon while this process waits for the exit status and
+		 * runs the indicated command at that point. */
+		if (*lp_postxfer_exec(i)) {
 			pid_t pid = fork();
 			if (pid < 0) {
 				rsyserr(FLOG, errno, "fork failed");
@@ -385,7 +398,8 @@ static int rsync_module(int f_in, int f_out, int i)
 			}
 			if (pid) {
 				char *ret1, *ret2;
-				waitpid(pid, &status, 0);
+				if (wait_process(pid, &status, 0) < 0)
+					status = -1;
 				if (asprintf(&ret1, "RSYNC_RAW_STATUS=%d", status) > 0)
 					putenv(ret1);
 				if (WIFEXITED(status))
@@ -394,10 +408,44 @@ static int rsync_module(int f_in, int f_out, int i)
 					status = -1;
 				if (asprintf(&ret2, "RSYNC_EXIT_STATUS=%d", status) > 0)
 					putenv(ret2);
-				system(p);
+				system(lp_postxfer_exec(i));
 				_exit(status);
 			}
 		}
+		/* For pre-xfer exec, fork a child process to run the indicated
+		 * command, though it first waits for the parent process to
+		 * send us the user's request via a pipe. */
+		if (*lp_prexfer_exec(i)) {
+			int fds[2];
+			if (pipe(fds) < 0 || (pre_exec_pid = fork()) < 0) {
+				rsyserr(FLOG, errno, "pre-xfer exec preparation failed");
+				io_printf(f_out, "@ERROR: pre-xfer exec preparation failed\n");
+				return -1;
+			}
+			if (pre_exec_pid == 0) {
+				char buf[MAX_REQ_LEN+1];
+				int len;
+				close(fds[1]);
+				set_blocking(fds[0]);
+				len = read(fds[0], buf, MAX_REQ_LEN);
+				close(fds[0]);
+				if (len <= 0)
+					_exit(1);
+				buf[len] = '\0';
+				if (asprintf(&p, "RSYNC_REQUEST=%s", buf) < 0)
+					out_of_memory("rsync_module");
+				putenv(p);
+				close(STDIN_FILENO);
+				close(STDOUT_FILENO);
+				status = system(lp_prexfer_exec(i));
+				if (!WIFEXITED(status))
+					_exit(1);
+				_exit(WEXITSTATUS(status));
+			}
+			close(fds[0]);
+			set_blocking(fds[1]);
+			pre_exec_fd = fds[1];
+		}
 		umask(0);
 	}
 #endif
@@ -515,15 +563,24 @@ static int rsync_module(int f_in, int f_out, int i)
 				start_glob = 1;
 			break;
 		case 1:
+			if (pre_exec_pid) {
+				err_msg = finish_pre_exec(pre_exec_pid,
+							  pre_exec_fd, p);
+				pre_exec_pid = 0;
+			}
 			request = strdup(p);
 			start_glob = 2;
 			/* FALL THROUGH */
 		default:
-			glob_expand(name, &argv, &argc, &maxargs);
+			if (!err_msg)
+				glob_expand(name, &argv, &argc, &maxargs);
 			break;
 		}
 	}
 
+	if (pre_exec_pid)
+		err_msg = finish_pre_exec(pre_exec_pid, pre_exec_fd, request);
+
 	verbose = 0; /* future verbosity is controlled by client options */
 	ret = parse_arguments(&argc, (const char ***) &argv, 0);
 
@@ -552,7 +609,7 @@ static int rsync_module(int f_in, int f_out, int i)
 	if (protocol_version < 23
 	    && (protocol_version == 22 || am_sender))
 		io_start_multiplex_out();
-	else if (!ret) {
+	else if (!ret || err_msg) {
 		/* We have to get I/O multiplexing started so that we can
 		 * get the error back to the client.  This means getting
 		 * the protocol setup finished first in later versions. */
@@ -578,8 +635,11 @@ static int rsync_module(int f_in, int f_out, int i)
 		io_start_multiplex_out();
 	}
 
-	if (!ret) {
-		option_error();
+	if (!ret || err_msg) {
+		if (err_msg)
+			rprintf(FERROR, err_msg);
+		else
+			option_error();
 		msleep(400);
 		exit_cleanup(RERR_UNSUPPORTED);
 	}
@@ -684,7 +744,6 @@ int start_daemon(int f_in, int f_out)
 	return rsync_module(f_in, f_out, i);
 }
 
-
 int daemon_main(void)
 {
 	char *pid_file;