app: handle concatenated argv name-value correctly

The server used to crash when any option argument was passed with
a value concatenated to it, like this: '-lvalue', '-evalue'
instead of '-l value' and '-e value'.

However this is a valid way of writing values, and it should not
have crashed regardless of its validity.

The bug was in usage of 'optind' global variable from getopt()
function family. It is not supposed to be used for getting an
option's value. It points to a next argv to parse. Next argv !=
value of current argv, like it was with '-lvalue' and '-evalue'.

For getting a current value there is a variable 'optarg'.

Closes #4775

(cherry picked from commit 29cfd564)

src/lua/init.c

@@ -553,7 +553,7 @@ run_script_f(va_list ap)
 	const char *path = va_arg(ap, const char *);
 	bool interactive = va_arg(ap, int);
 	int optc = va_arg(ap, int);
-	char **optv = va_arg(ap, char **);
+	const char **optv = va_arg(ap, const char **);
 	int argc = va_arg(ap, int);
 	char **argv = va_arg(ap, char **);
 	/*
@@ -656,7 +656,7 @@ run_script_f(va_list ap)
 
 int
 tarantool_lua_run_script(char *path, bool interactive,
-			 int optc, char **optv, int argc, char **argv)
+			 int optc, const char **optv, int argc, char **argv)
 {
 	const char *title = path ? basename(path) : "interactive";
 	/*

src/lua/init.h

@@ -72,7 +72,7 @@ tarantool_lua_free();
  */
 int
 tarantool_lua_run_script(char *path, bool force_interactive,
-			 int optc, char **optv,
+			 int optc, const char **optv,
 			 int argc, char **argv);
 
 extern char *history;

src/main.cc

@@ -721,7 +721,7 @@ main(int argc, char **argv)
 	bool interactive = false;
 	/* Lua interpeter options, e.g. -e and -l */
 	int optc = 0;
-	char **optv = NULL;
+	const char **optv = NULL;
 	auto guard = make_scoped_guard([=]{ if (optc) free(optv); });
 
 	static struct option longopts[] = {
@@ -749,16 +749,13 @@ main(int argc, char **argv)
 		case 'e':
 			/* Save Lua interepter options to optv as is */
 			if (optc == 0) {
-				optv = (char **) calloc(argc, sizeof(char *));
+				optv = (const char **) calloc(argc,
+							      sizeof(optv[0]));
 				if (optv == NULL)
 					panic_syserror("No enough memory for arguments");
 			}
-			/*
-			 * The variable optind is the index of the next
-			 * element to be processed in argv.
-			 */
-			optv[optc++] = argv[optind - 2];
-			optv[optc++] = argv[optind - 1];
+			optv[optc++] = ch == 'l' ? "-l" : "-e";
+			optv[optc++] = optarg;
 			break;
 		default:
 			/* "invalid option" is printed by getopt */

test/app/gh-4775-crash-args-l-e.result

+-- test-run result file version 2
+--
+-- gh-4775: crash on option concatenated with value.
+--
+child = io.popen('tarantool -e"print(100) os.exit()"')
+ | ---
+ | ...
+child:read()
+ | ---
+ | - '100'
+ | ...
+-- :close() is omitted, because SIGCHILD may be handled by
+-- libev instead of Lua. In that case :close() with fail with
+-- ECHILD, but it does not matter for this test.

test/app/gh-4775-crash-args-l-e.test.lua

+--
+-- gh-4775: crash on option concatenated with value.
+--
+child = io.popen('tarantool -e"print(100) os.exit()"')
+child:read()
+-- :close() is omitted, because SIGCHILD may be handled by
+-- libev instead of Lua. In that case :close() with fail with
+-- ECHILD, but it does not matter for this test.