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97a781397

Denys Vlasenko

2026-01-27

SUCCESS Duration: 144s

Subject

ash: move applet handling out of tryexec() - making it similar to dash

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

gcc -Wp,-MD,applets/.usage.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer      -Iinclude -Iinclude -o applets/usage applets/usage.c

Build Log

(log yok)

Commit Diff GitHub →

shell/ash.c +61 -62

shell/ash.c+61 -62

@@ -8476,67 +8476,71 @@ static struct tblentry **cmdtable;
	static int builtinloc = -1; /* index in path of %builtin, or -1 */


-	static void
-	tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char cmd, char argv, char *envp)
-	{
	#if ENABLE_FEATURE_SH_STANDALONE
-	if (applet_no >= 0) {
-	if (!vforked && APPLET_IS_NOEXEC(applet_no)) {
-	dbg_show_dirtymem("dirtymem in NOEXEC tryexec");
-	clearenv();
-	while (*envp)
-	putenv(*envp++);
-	popredir(/drop:/ 1);
+	static void
+	tryexec_applet(int applet_no, const char cmd, char argv, char *envp)
+	{
+	if (!vforked && APPLET_IS_NOEXEC(applet_no)) {
+	dbg_show_dirtymem("dirtymem in NOEXEC tryexec");
+	clearenv();
+	while (*envp)
+	putenv(*envp++);
+	popredir(/drop:/ 1);
	//FIXME: exec resets all non-DFL, non-IGN signal handlers to DFL,
	//but we _don't_ exec, such signals will reach ash's handler instead!
	//Maybe add code there to set the handler to DFL, and signal itself?
	// This works for "CMD [\| CMD]..." pipes:
-	//vforkexec()
-	// vfork();
-	// forkchild(jp, n, FORK_FG); // this resets TSTP,TTOU,INT,TERM,QUIT to DFL
-	// shellexec(argv[0], argv, path, idx)
-	// tryexec()
-	// we are here
+	//vforkexec():
+	// vfork();
+	// forkchild(jp, n, FORK_FG); // this resets TSTP,TTOU,INT,TERM,QUIT to DFL
+	// shellexec(argv[0], argv, path, idx)
+	// tryexec_applet()
+	// we are here
	// And for "exec CMD":
-	//execcmd()
-	// iflag = 0;
-	// mflag = 0;
-	// optschanged(); // this resets TSTP,TTOU,INT,TERM to DFL
-	// shlvl++;
-	// setsignal(SIGQUIT); // this resets QUIT to DFL
-	// shellexec()
-	// tryexec()
-	// we are here
-	// But ash -c 'LAST_CMD_DOESNT_FORK' does not work!
-	//evalcommand()
-	// if (!(flags & EV_EXIT) \|\| may_have_traps)
-	// // we don't use this branch
-	// //else:
-	// shellexec()
-	// tryexec()
-	// we are here
+	//execcmd():
+	// iflag = 0;
+	// mflag = 0;
+	// optschanged(); // this resets TSTP,TTOU,INT,TERM to DFL
+	// shlvl++;
+	// setsignal(SIGQUIT); // this resets QUIT to DFL
+	// shellexec() ->
+	// tryexec_applet() ->
+	// we are here
+	// But ash -c 'LAST_CMD_WONT_FORK' does not work!
+	//evalcommand():
+	// if (!(flags & EV_EXIT) \|\| may_have_traps)
+	// // we don't use this branch
+	// //else:
+	// shellexec() ->
+	// tryexec_applet() ->
+	// we are here
	//SIGINT works 'by accident' (sets DFL+signals itself)
	//SIGQUIT is IGNORED!
-	//Fixed by adding in the evalcommand() before the shown shellexec():
-	// shlvl++;
-	// setsignal(SIGQUIT);
-	// //TODO: setsignal(TSTP,TTOU,INT,TERM) too?
+	//Fixed by adding in the evalcommand() before that shellexec():
+	// shlvl++;
+	// setsignal(SIGQUIT);
+	// //TODO: setsignal(TSTP,TTOU,INT,TERM) too?
	//
	// With traps set, this:
	// ash -c 'trap "echo HERE!" INT; exec xargs'
	// didn't work: ^C sets a "run trap later" flag and _returns_,
-	// which is not expected by the NOFORK'ed xargs!
+	// which is not expected by the NOEXEC'ed xargs applet! (It gets EINTR on read).
	// clear_traps() helps with this:
-	clear_traps();
-	run_noexec_applet_and_exit(applet_no, cmd, argv);
-	}
-	/* re-exec ourselves with the new arguments */
-	execve(bb_busybox_exec_path, argv, envp);
-	/* If they called chroot or otherwise made the binary no longer
-	* executable, fall through */
+	clear_traps();
+	run_noexec_applet_and_exit(applet_no, cmd, argv);
+	/* does not return */
	}
+	/* re-exec ourselves with the new arguments */
+	execve(bb_busybox_exec_path, argv, envp);
+	/* If they called chroot or otherwise made the binary
+	* no longer executable, return.
+	*/
+	}
	#endif

+	static void
+	tryexec(const char cmd, char argv, char *envp)
+	{
	repeat:
	#ifdef SYSV
	do {
@@ -8545,7 +8549,6 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char cmd, char *argv, c
	#else
	execve(cmd, argv, envp);
	#endif
-
	if (cmd != bb_busybox_exec_path && errno == ENOEXEC) {
	/* Run "cmd" as a shell script:
	* http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
@@ -8585,30 +8588,25 @@ static void shellexec(char prog, char argv, const char path, int idx)
	int e;
	char **envp;
	int exerrno;
-	int applet_no = -1; /* used only by FEATURE_SH_STANDALONE */

	envp = listvars(VEXPORT, VUNSET, /strlist:/ NULL, /end:/ NULL);
-	if (strchr(prog, '/') != NULL
-	#if ENABLE_FEATURE_SH_STANDALONE
-	\|\| (applet_no = find_applet_by_name(prog)) >= 0
-	#endif
-	) {
-	tryexec(IF_FEATURE_SH_STANDALONE(applet_no,) prog, argv, envp);
-	if (applet_no >= 0) {
-	/* We tried execing ourself, but it didn't work.
-	* Maybe /proc/self/exe doesn't exist?
-	* Try $PATH search.
-	*/
-	goto try_PATH;
-	}
+	if (strchr(prog, '/') != NULL) {
+	tryexec(prog, argv, envp);
	e = errno;
	} else {
-	try_PATH:
+	#if ENABLE_FEATURE_SH_STANDALONE
+	int applet_no = find_applet_by_name(prog);
+	if (applet_no >= 0)
+	tryexec_applet(applet_no, prog, argv, envp);
+	/* We tried execing ourself, but it didn't work.
+	* Maybe /proc/self/exe doesn't exist?
+	*/
+	#endif
	e = ENOENT;
	while (padvance(&path, argv[0]) >= 0) {
	cmdname = stackblock();
	if (--idx < 0 && pathopt == NULL) {
-	tryexec(IF_FEATURE_SH_STANDALONE(-1,) cmdname, argv, envp);
+	tryexec(cmdname, argv, envp);
	if (errno != ENOENT && errno != ENOTDIR)
	e = errno;
	}
@@ -10869,6 +10867,7 @@ evalcommand(union node *cmd, int flags)
	/* Testcase: ash -c 'ONE_CMD' will use EV_EXIT for ONE_CMD */
	shlvl++; /* dash does not need it because it doesn't ignore SIGQUIT */
	setsignal(SIGQUIT); /* we do (bash compat) */
+	//TODO: setsignal(TSTP,TTOU,INT,TERM) too?
	shellexec(argv[0], argv, path, cmdentry.u.index);
	/* NOTREACHED */
	} /* default */