05743d794

Denis Vlasenko

2008-02-10

FAILED Duration: 14s

Subject

hush: reinstate `cmd` handling for NOMMU (with fat big warning). hush: fix a case where none of pipe members could be started because of fork failure hush: rename functions: xxx_real -> xxx hush: try to add a bit more of vfork-friendliness hush: add rudimentary design docs hush: add TODO (newly di

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

—

Build Log

(log yok)

Commit Diff GitHub →

include/libbb.h +3 -0 shell/hush.c +101 -91 shell/hush_doc.txt +39 -0 shell/hush_test/run-all +4 -1 shell/hush_test/zbad2 +19 -0

include/libbb.h+3 -0

@@ -664,6 +664,9 @@ enum {
	void re_exec(char **argv) ATTRIBUTE_NORETURN;
	void forkexit_or_rexec(char **argv);
	extern bool re_execed;
+	int BUG_fork_is_unavailable_on_nommu(void);
+	int BUG_daemon_is_unavailable_on_nommu(void);
+	void BUG_bb_daemonize_is_unavailable_on_nommu(void);
	# define fork() BUG_fork_is_unavailable_on_nommu()
	# define daemon(a,b) BUG_daemon_is_unavailable_on_nommu()
	# define bb_daemonize(a) BUG_bb_daemonize_is_unavailable_on_nommu()

shell/hush.c+101 -91

@@ -84,12 +84,24 @@
	#include "busybox.h" /* for APPLET_IS_NOFORK/NOEXEC */


-	#if !BB_MMU
-	/* A bit drastic. Can allow some simpler commands
-	* by analysing command in generate_stream_from_list()
-	*/
-	#undef ENABLE_HUSH_TICK
-	#define ENABLE_HUSH_TICK 0
+	#if !BB_MMU && ENABLE_HUSH_TICK
+	//#undef ENABLE_HUSH_TICK
+	//#define ENABLE_HUSH_TICK 0
+	#warning On NOMMU, hush command substitution is dangerous.
+	#warning Dont use it for commands which produce lots of output.
+	#warning For more info see shell/hush.c, generate_stream_from_list().
+	#endif
+
+	#if !BB_MMU && ENABLE_HUSH_JOB
+	#undef ENABLE_HUSH_JOB
+	#define ENABLE_HUSH_JOB 0
+	#endif
+
+	#if !ENABLE_HUSH_INTERACTIVE
+	#undef ENABLE_FEATURE_EDITING
+	#define ENABLE_FEATURE_EDITING 0
+	#undef ENABLE_FEATURE_EDITING_FANCY_PROMPT
+	#define ENABLE_FEATURE_EDITING_FANCY_PROMPT 0
	#endif


@@ -176,13 +188,6 @@ void xxfree(void *ptr)
	#endif


-	#if !ENABLE_HUSH_INTERACTIVE
-	#undef ENABLE_FEATURE_EDITING
-	#define ENABLE_FEATURE_EDITING 0
-	#undef ENABLE_FEATURE_EDITING_FANCY_PROMPT
-	#define ENABLE_FEATURE_EDITING_FANCY_PROMPT 0
-	#endif
-
	#define SPECIAL_VAR_SYMBOL 3

	#define PARSEFLAG_EXIT_FROM_LOOP 1
@@ -508,10 +513,10 @@ static int free_pipe_list(struct pipe *head, int indent);
	static int free_pipe(struct pipe *pi, int indent);
	/* really run the final data structures: */
	static int setup_redirects(struct child_prog *prog, int squirrel[]);
-	static int run_list_real(struct pipe *pi);
+	static int run_list(struct pipe *pi);
	static void pseudo_exec_argv(char **argv) ATTRIBUTE_NORETURN;
	static void pseudo_exec(struct child_prog *child) ATTRIBUTE_NORETURN;
-	static int run_pipe_real(struct pipe *pi);
+	static int run_pipe(struct pipe *pi);
	/* extended glob support: */
	static char *globhack(const char src, char **strings);
	static int glob_needed(const char *s);
@@ -1416,7 +1421,7 @@ static void restore_redirects(int squirrel[])
	}
	}

-	/* Called after [v]fork() in run_pipe_real(), or from builtin_exec().
+	/* Called after [v]fork() in run_pipe(), or from builtin_exec().
	* Never returns.
	* XXX no exit() here. If you don't exec, use _exit instead.
	* The at_exit handlers apparently confuse the calling process,
@@ -1438,9 +1443,8 @@ static void pseudo_exec_argv(char **argv)
	/* If a variable is assigned in a forest, and nobody listens,
	* was it ever really set?
	*/
-	if (argv[0] == NULL) {
+	if (!argv[0])
	_exit(EXIT_SUCCESS);
-	}

	argv = expand_strvec_to_strvec(argv);

@@ -1484,15 +1488,15 @@ static void pseudo_exec_argv(char **argv)
	_exit(1);
	}

-	/* Called after [v]fork() in run_pipe_real()
+	/* Called after [v]fork() in run_pipe()
	*/
	static void pseudo_exec(struct child_prog *child)
	{
	// FIXME: buggy wrt NOMMU! Must not modify any global data
-	// until it does exec/_exit, but currently it does.
-	if (child->argv) {
+	// until it does exec/_exit, but currently it does
+	// (puts malloc'ed stuff into environment)
+	if (child->argv)
	pseudo_exec_argv(child->argv);
-	}

	if (child->group) {
	#if !BB_MMU
@@ -1501,11 +1505,12 @@ static void pseudo_exec(struct child_prog *child)
	int rcode;

	#if ENABLE_HUSH_INTERACTIVE
-	debug_printf_exec("pseudo_exec: setting interactive_fd=0\n");
-	interactive_fd = 0; /* crucial!!!! */
+	// run_list_level now takes care of it?
+	// debug_printf_exec("pseudo_exec: setting interactive_fd=0\n");
+	// interactive_fd = 0; /* crucial!!!! */
	#endif
-	debug_printf_exec("pseudo_exec: run_list_real\n");
-	rcode = run_list_real(child->group);
+	debug_printf_exec("pseudo_exec: run_list\n");
+	rcode = run_list(child->group);
	/* OK to leak memory by not calling free_pipe_list,
	* since this process is about to exit */
	_exit(rcode);
@@ -1672,7 +1677,7 @@ static int checkjobs(struct pipe* fg_pipe)
	if (dead) {
	fg_pipe->progs[i].pid = 0;
	fg_pipe->running_progs--;
-	if (i == fg_pipe->num_progs-1)
+	if (i == fg_pipe->num_progs - 1)
	/* last process gives overall exitstatus */
	rcode = WEXITSTATUS(status);
	} else {
@@ -1753,13 +1758,13 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
	}
	#endif

-	/* run_pipe_real() starts all the jobs, but doesn't wait for anything
+	/* run_pipe() starts all the jobs, but doesn't wait for anything
	* to finish. See checkjobs().
	*
	* return code is normally -1, when the caller has to wait for children
	* to finish to determine the exit status of the pipe. If the pipe
	* is a simple builtin command, however, the action is done by the
-	* time run_pipe_real returns, and the exit code is provided as the
+	* time run_pipe returns, and the exit code is provided as the
	* return value.
	*
	* The input of the pipe is always stdin, the output is always
@@ -1772,7 +1777,7 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
	* Returns -1 only if started some children. IOW: we have to
	* mask out retvals of builtins etc with 0xff!
	*/
-	static int run_pipe_real(struct pipe *pi)
+	static int run_pipe(struct pipe *pi)
	{
	int i;
	int nextin;
@@ -1785,7 +1790,7 @@ static int run_pipe_real(struct pipe *pi)
	int rcode;
	const int single_fg = (pi->num_progs == 1 && pi->followup != PIPE_BG);

-	debug_printf_exec("run_pipe_real start: single_fg=%d\n", single_fg);
+	debug_printf_exec("run_pipe start: single_fg=%d\n", single_fg);

	#if ENABLE_HUSH_JOB
	pi->pgrp = -1;
@@ -1801,11 +1806,11 @@ static int run_pipe_real(struct pipe *pi)
	if (single_fg && child->group && child->subshell == 0) {
	debug_printf("non-subshell grouping\n");
	setup_redirects(child, squirrel);
-	debug_printf_exec(": run_list_real\n");
-	rcode = run_list_real(child->group);
+	debug_printf_exec(": run_list\n");
+	rcode = run_list(child->group) & 0xff;
	restore_redirects(squirrel);
-	debug_printf_exec("run_pipe_real return %d\n", rcode);
-	return rcode; // do we need to add '... & 0xff' ?
+	debug_printf_exec("run_pipe return %d\n", rcode);
+	return rcode;
	}

	if (single_fg && child->argv != NULL) {
@@ -1847,7 +1852,7 @@ static int run_pipe_real(struct pipe *pi)
	rcode = x->function(argv_expanded) & 0xff;
	free(argv_expanded);
	restore_redirects(squirrel);
-	debug_printf_exec("run_pipe_real return %d\n", rcode);
+	debug_printf_exec("run_pipe return %d\n", rcode);
	return rcode;
	}
	}
@@ -1864,7 +1869,7 @@ static int run_pipe_real(struct pipe *pi)
	rcode = run_nofork_applet_prime(&nofork_save, a, argv_expanded) & 0xff;
	free(argv_expanded);
	restore_redirects(squirrel);
-	debug_printf_exec("run_pipe_real return %d\n", rcode);
+	debug_printf_exec("run_pipe return %d\n", rcode);
	return rcode;
	}
	}
@@ -1892,24 +1897,22 @@ static int run_pipe_real(struct pipe *pi)
	if ((i + 1) < pi->num_progs)
	xpipe(pipefds);

-	#if BB_MMU
-	child->pid = fork();
-	#else
-	child->pid = vfork();
-	#endif
+	child->pid = BB_MMU ? fork() : vfork();
	if (!child->pid) { /* child */
	#if ENABLE_HUSH_JOB
	/* Every child adds itself to new process group
-	* with pgid == pid of first child in pipe */
+	* with pgid == pid_of_first_child_in_pipe */
	if (run_list_level == 1 && interactive_fd) {
+	pid_t pgrp;
	/* Don't do pgrp restore anymore on fatal signals */
	set_fatal_sighandler(SIG_DFL);
-	if (pi->pgrp < 0) /* true for 1st process only */
-	pi->pgrp = getpid();
-	if (setpgid(0, pi->pgrp) == 0 && pi->followup != PIPE_BG) {
+	pgrp = pi->pgrp;
+	if (pgrp < 0) /* true for 1st process only */
+	pgrp = getpid();
+	if (setpgid(0, pgrp) == 0 && pi->followup != PIPE_BG) {
	/* We do it in every child, not just first,
	* to avoid races */
-	tcsetpgrp(interactive_fd, pi->pgrp);
+	tcsetpgrp(interactive_fd, pgrp);
	}
	}
	#endif
@@ -1930,7 +1933,7 @@ static int run_pipe_real(struct pipe *pi)

	if (child->pid < 0) { /* [v]fork failed */
	/* Clearly indicate, was it fork or vfork */
-	bb_perror_msg(BB_MMU ? "cannot fork" : "cannot vfork");
+	bb_perror_msg(BB_MMU ? "fork" : "vfork");
	} else {
	pi->running_progs++;
	#if ENABLE_HUSH_JOB
@@ -1948,7 +1951,12 @@ static int run_pipe_real(struct pipe *pi)
	nextin = pipefds[0];
	}

-	debug_printf_exec("run_pipe_real return -1\n");
+	if (!pi->running_progs) {
+	debug_printf_exec("run_pipe return 1 (all forks failed, no children)\n");
+	return 1;
+	}
+
+	debug_printf_exec("run_pipe return -1 (%u children started)\n", pi->running_progs);
	return -1;
	}

@@ -2017,7 +2025,7 @@ static void debug_print_tree(struct pipe *pi, int lvl)

	/* NB: called by pseudo_exec, and therefore must not modify any
	* global data until exec/_exit (we can be a child after vfork!) */
-	static int run_list_real(struct pipe *pi)
+	static int run_list(struct pipe *pi)
	{
	struct pipe *rpipe;
	#if ENABLE_HUSH_LOOPS
@@ -2026,7 +2034,6 @@ static int run_list_real(struct pipe *pi)
	char **for_list = NULL;
	int flag_rep = 0;
	#endif
-	int save_num_progs;
	int flag_skip = 1;
	int rcode = 0; /* probably for gcc only */
	int flag_restore = 0;
@@ -2038,7 +2045,7 @@ static int run_list_real(struct pipe *pi)
	reserved_style rword;
	reserved_style skip_more_for_this_rword = RES_XXXX;

-	debug_printf_exec("run_list_real start lvl %d\n", run_list_level + 1);
+	debug_printf_exec("run_list start lvl %d\n", run_list_level + 1);

	#if ENABLE_HUSH_LOOPS
	/* check syntax for "for" */
@@ -2047,7 +2054,7 @@ static int run_list_real(struct pipe *pi)
	&& (rpipe->next == NULL)
	) {
	syntax("malformed for"); /* no IN or no commands after IN */
-	debug_printf_exec("run_list_real lvl %d return 1\n", run_list_level);
+	debug_printf_exec("run_list lvl %d return 1\n", run_list_level);
	return 1;
	}
	if ((rpipe->res_word == RES_IN && rpipe->next->res_word == RES_IN && rpipe->next->progs[0].argv != NULL)
@@ -2055,7 +2062,7 @@ static int run_list_real(struct pipe *pi)
	) {
	/* TODO: what is tested in the first condition? */
	syntax("malformed for"); /* 2nd condition: not followed by IN */
-	debug_printf_exec("run_list_real lvl %d return 1\n", run_list_level);
+	debug_printf_exec("run_list lvl %d return 1\n", run_list_level);
	return 1;
	}
	}
@@ -2103,9 +2110,10 @@ static int run_list_real(struct pipe *pi)
	signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
	signal(SIGINT, handler_ctrl_c);
	}
-	#endif
+	#endif /* JOB */

	for (; pi; pi = flag_restore ? rpipe : pi->next) {
+	//why? int save_num_progs;
	rword = pi->res_word;
	#if ENABLE_HUSH_LOOPS
	if (rword == RES_WHILE \|\| rword == RES_UNTIL \|\| rword == RES_FOR) {
@@ -2178,12 +2186,12 @@ static int run_list_real(struct pipe *pi)
	#endif
	if (pi->num_progs == 0)
	continue;
-	save_num_progs = pi->num_progs; /* save number of programs */
-	debug_printf_exec(": run_pipe_real with %d members\n", pi->num_progs);
-	rcode = run_pipe_real(pi);
+	//why? save_num_progs = pi->num_progs;
+	debug_printf_exec(": run_pipe with %d members\n", pi->num_progs);
+	rcode = run_pipe(pi);
	if (rcode != -1) {
	/* We only ran a builtin: rcode was set by the return value
-	* of run_pipe_real(), and we don't need to wait for anything. */
+	* of run_pipe(), and we don't need to wait for anything. */
	} else if (pi->followup == PIPE_BG) {
	/* What does bash do with attempts to background builtins? */
	/* Even bash 3.2 doesn't do that well with nested bg:
@@ -2196,7 +2204,6 @@ static int run_list_real(struct pipe *pi)
	rcode = EXIT_SUCCESS;
	} else {
	#if ENABLE_HUSH_JOB
-	/* Paranoia, just "interactive_fd" should be enough? */
	if (run_list_level == 1 && interactive_fd) {
	/* waits for completion, then fg's main shell */
	rcode = checkjobs_and_fg_shell(pi);
@@ -2210,7 +2217,7 @@ static int run_list_real(struct pipe *pi)
	}
	debug_printf_exec(": setting last_return_code=%d\n", rcode);
	last_return_code = rcode;
-	pi->num_progs = save_num_progs; /* restore number of programs */
+	//why? pi->num_progs = save_num_progs;
	#if ENABLE_HUSH_IF
	if (rword == RES_IF \|\| rword == RES_ELIF)
	next_if_code = rcode; /* can be overwritten a number of times */
@@ -2241,7 +2248,7 @@ static int run_list_real(struct pipe *pi)
	signal(SIGINT, SIG_IGN);
	}
	#endif
-	debug_printf_exec("run_list_real lvl %d return %d\n", run_list_level + 1, rcode);
+	debug_printf_exec("run_list lvl %d return %d\n", run_list_level + 1, rcode);
	return rcode;
	}

@@ -2315,19 +2322,19 @@ static int free_pipe_list(struct pipe *head, int indent)
	}

	/* Select which version we will use */
-	static int run_list(struct pipe *pi)
+	static int run_and_free_list(struct pipe *pi)
	{
	int rcode = 0;
-	debug_printf_exec("run_list entered\n");
-	if (fake_mode == 0) {
-	debug_printf_exec(": run_list_real with %d members\n", pi->num_progs);
-	rcode = run_list_real(pi);
+	debug_printf_exec("run_and_free_list entered\n");
+	if (!fake_mode) {
+	debug_printf_exec(": run_list with %d members\n", pi->num_progs);
+	rcode = run_list(pi);
	}
	/* free_pipe_list has the side effect of clearing memory.
-	* In the long run that function can be merged with run_list_real,
+	* In the long run that function can be merged with run_list,
	* but doing that now would hobble the debugging effort. */
-	free_pipe_list(pi, 0);
-	debug_printf_exec("run_list return %d\n", rcode);
+	free_pipe_list(pi, /* indent: */ 0);
+	debug_printf_exec("run_nad_free_list return %d\n", rcode);
	return rcode;
	}

@@ -3221,15 +3228,17 @@ static FILE generate_stream_from_list(struct pipe head)
	int pid, channel[2];

	xpipe(channel);
-	pid = fork();
-	if (pid < 0) {
-	bb_perror_msg_and_die("fork");
-	} else if (pid == 0) {
+	/* * NOMMU WARNING * */
+	/* By using vfork here, we suspend parent till child exits or execs.
+	* If child will not do it before it fills the pipe, it can block forever
+	* in write(STDOUT_FILENO), and parent (shell) will be also stuck.
+	*/
+	pid = BB_MMU ? fork() : vfork();
+	if (pid < 0)
+	bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
+	if (pid == 0) { /* child */
	close(channel[0]);
-	if (channel[1] != 1) {
-	dup2(channel[1], 1);
-	close(channel[1]);
-	}
+	xmove_fd(channel[1], 1);
	/* Prevent it from trying to handle ctrl-z etc */
	#if ENABLE_HUSH_JOB
	run_list_level = 1;
@@ -3241,11 +3250,12 @@ static FILE generate_stream_from_list(struct pipe head)
	* everywhere outside actual command execution. */
	/set_jobctrl_sighandler(SIG_IGN);/
	set_misc_sighandler(SIG_DFL);
-	_exit(run_list_real(head)); /* leaks memory */
+	_exit(run_list(head)); /* leaks memory */
	}
	close(channel[1]);
	pf = fdopen(channel[0], "r");
	return pf;
+	/* head is freed by the caller */
	}

	/* Return code is exit status of the process that is run. */
@@ -3269,7 +3279,8 @@ static int process_command_subs(o_string dest, struct p_context ctx,
	b_free(&result);

	p = generate_stream_from_list(inner.list_head);
-	if (p == NULL) return 1;
+	if (p == NULL)
+	return 1;
	close_on_exec_on(fileno(p));
	setup_file_in_str(&pipe_str, p);

@@ -3294,7 +3305,7 @@ static int process_command_subs(o_string dest, struct p_context ctx,
	* at the same time. That would be a lot of work, and contrary
	* to the KISS philosophy of this program. */
	retcode = fclose(p);
-	free_pipe_list(inner.list_head, 0);
+	free_pipe_list(inner.list_head, /* indent: */ 0);
	debug_printf("closed FILE from child, retcode=%d\n", retcode);
	return retcode;
	}
@@ -3674,8 +3685,8 @@ static int parse_and_run_stream(struct in_str *inp, int parse_flag)
	done_word(&temp, &ctx);
	done_pipe(&ctx, PIPE_SEQ);
	debug_print_tree(ctx.list_head, 0);
-	debug_printf_exec("parse_stream_outer: run_list\n");
-	run_list(ctx.list_head);
+	debug_printf_exec("parse_stream_outer: run_and_free_list\n");
+	run_and_free_list(ctx.list_head);
	} else {
	if (ctx.old_flag != 0) {
	free(ctx.stack);
@@ -3684,7 +3695,7 @@ static int parse_and_run_stream(struct in_str *inp, int parse_flag)
	temp.nonnull = 0;
	temp.o_quote = 0;
	inp->p = NULL;
-	free_pipe_list(ctx.list_head, 0);
+	free_pipe_list(ctx.list_head, /* indent: */ 0);
	}
	b_free(&temp);
	} while (rcode != -1 && !(parse_flag & PARSEFLAG_EXIT_FROM_LOOP)); /* loop on syntax errors, return on EOF */
@@ -3898,15 +3909,14 @@ int hush_main(int argc, char **argv)

	if (argv[optind] == NULL) {
	opt = parse_and_run_file(stdin);
-	goto final_return;
+	} else {
+	debug_printf("\nrunning script '%s'\n", argv[optind]);
+	global_argv = argv + optind;
+	global_argc = argc - optind;
+	input = xfopen(argv[optind], "r");
+	opt = parse_and_run_file(input);
	}

-	debug_printf("\nrunning script '%s'\n", argv[optind]);
-	global_argv = argv + optind;
-	global_argc = argc - optind;
-	input = xfopen(argv[optind], "r");
-	opt = parse_and_run_file(input);
-
	final_return:

	#if ENABLE_FEATURE_CLEAN_UP

shell/hush_doc.txt+39 -0

@@ -0,0 +1,39 @@
+	This is how hush runs commands:
+
+	/* callsite: process_command_subs */
+	generate_stream_from_list(struct pipe *head) - handles `cmds`
+	create UNIX pipe
+	[v]fork
+	child:
+	redirect pipe output to stdout
+	_exit(run_list(head)); /* leaks memory */
+	parent:
+	return UNIX pipe's output fd
+	/* head is freed by the caller */
+
+	/* callsite: parse_and_run_stream */
+	run_and_free_list(struct pipe *)
+	run_list(struct pipe *)
+	free_pipe_list(struct pipe *)
+
+	/* callsites: generate_stream_from_list, run_and_free_list, pseudo_exec, run_pipe */
+	run_list(struct pipe *) - handles "cmd; cmd2 && cmd3", while/for/do loops
+	run_pipe - for every pipe in list
+
+	/* callsite: run_list */
+	run_pipe - runs "cmd1 \| cmd2 \| cmd3 [&]"
+	run_list - used if only one cmd and it is of the form "{ cmd4; cmd5 && cmd6; }"
+	forks for every cmd if more than one cmd or if & is there
+	pseudo_exec - runs each "cmdN" (handles builtins etc)
+
+	/* callsite: run_pipe_real */
+	pseudo_exec - runs "cmd" (handles builtins etc)
+	exec - execs external programs
+	run_list - used if cmdN is "(cmds)" or "{cmds;}"
+	/* problem: putenv's malloced strings into environ -
+	** with vfork they will leak into parent process
+	*/
+	/* problem with ENABLE_FEATURE_SH_STANDALONE:
+	** run_applet_no_and_exit(a, argv) uses exit - this can interfere
+	** with vfork - switch to _exit there?
+	*/

shell/hush_test/run-all+4 -1

@@ -1,6 +1,9 @@
	#!/bin/sh

-	test -x hush \|\| { echo "No ./hush?!"; exit; }
+	test -x hush \|\| {
+	echo "No ./hush?! Perhaps you want to run 'ln -s ../../busybox hush'"
+	exit
+	}

	PATH="$PWD:$PATH" # for hush and recho/zecho/printenv
	export PATH

shell/hush_test/zbad2+19 -0

@@ -0,0 +1,19 @@
+	## TODO: fix and add to testsuite
+
+	## # bash zbad2
+	## ZVAR=z.map
+	## *.map
+	## # hush zbad2
+	## ZVAR=z.map
+	## z.map <====== !!!
+
+	## hush does globbing for "VAR=val" too!
+	## it should do it only for non-assignments.
+	## even if word looks like assignment, it can be non-assignemnt:
+	## ZVAR=.map /bin/echo ZVAR=.map
+	## ^dont_glob ^glob
+
+	>ZVAR=z.map
+	ZVAR=.map /bin/echo ZVAR=.map
+	ZVAR=*.map
+	echo "$ZVAR"