commit 126b027d222133ed53d6a70f2a12642b074e43fd
from: Omar Polo <op@omarpolo.com>
date: Wed Dec 01 08:48:04 2021 UTC

rewrite spawn to use varargs

it's seems neater than packing an array on the spot, we just do that
inside spawn before calling execvp.  If we get too many arguments, just
abort.

This also changes how the forking is handled: I set RVSEL only for the
child and call disable_handlers() and endwin() preemptively to avoid
possible races with our children.

commit - c71d4135f19f596d4b3a1160284e8a94f3cbc831
commit + 126b027d222133ed53d6a70f2a12642b074e43fd
blob - bae5608fa11859f9709db8b6ce80fe993f8db480
blob + a6f38957aa1cbf6053caa7c54d3e255e8ab1f28a
--- fm.c
+++ fm.c
@@ -129,6 +129,7 @@ static struct state {
 #define MAX(A, B)   ((A) > (B) ? (A) : (B))
 #define ISDIR(E)    (strchr((E), '/') != NULL)
 #define CTRL(x)     ((x) & 0x1f)
+#define nitems(a)   (sizeof(a)/sizeof(a[0]))
 
 /* Line Editing Macros. */
 #define EDIT_FULL(E)       ((E).left == (E).right)
@@ -393,23 +394,41 @@ get_user_programs()
 
 /* Do a fork-exec to external program (e.g. $EDITOR). */
 static void
-spawn(char **args)
+spawn(const char *argv0, ...)
 {
 	pid_t pid;
 	int status;
+	size_t i;
+	const char *argv[16], *last;
+	va_list ap;
 
-	setenv("RVSEL", fm.nfiles ? ENAME(ESEL) : "", 1);
-	pid = fork();
-	if (pid > 0) {
-		/* fork() succeeded. */
-		disable_handlers();
-		endwin();
+	va_start(ap, argv0);
+	argv[0] = argv0;
+	for (i = 1; i < nitems(argv); ++i) {
+		last = va_arg(ap, const char *);
+		if (last == NULL)
+			break;
+		argv[i] = last;
+	}
+	va_end(ap);
+
+	if (last != NULL)
+		abort();
+
+	disable_handlers();
+	endwin();
+
+	switch (pid = fork()) {
+	case -1:
+		quit("fork");
+	case 0: /* child */
+		setenv("RVSEL", fm.nfiles ? ENAME(ESEL) : "", 1);
+		execvp(argv[0], (char *const *)argv);
+		quit("execvp");
+	default:
 		waitpid(pid, &status, 0);
 		enable_handlers();
 		kill(getpid(), SIGWINCH);
-	} else if (pid == 0) {
-		/* Child process. */
-		execvp(args[0], args);
 	}
 }
 
@@ -446,9 +465,9 @@ open_with_env(char *program, char *path)
 		strncpy(BUF1, program, BUFLEN - 1);
 		strncat(BUF1, " ", BUFLEN - strlen(program) - 1);
 		shell_escaped_cat(BUF1, path, BUFLEN - strlen(program) - 2);
-		spawn((char *[]) { RV_SHELL, "-c", BUF1, NULL });
+		spawn(RV_SHELL, "-c", BUF1, NULL );
 #else
-		spawn((char *[]) { program, path, NULL });
+		spawn(program, path, NULL);
 #endif
 		return 1;
 	}