b72baeb00
Denys Vlasenko
2011-02-02
Subject
hush: use FEATURE_SH_NOFORK to enable NOFORK trick
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docs/nofork_noexec.txt+23 -4
| @@ -44,9 +44,11 @@ NOEXEC trick is disabled for NOMMU build. | |
| NOFORK | |
| NOFORK applet should work correctly if another applet simply runs | |
| - | <applet>_main(argc,argv) and then continues with its business (xargs, |
| - | find, shells can do it). This poses much more serious limitations |
| - | on what applet can/cannot do: |
| + | <applet>_main(argc,argv) and then continues with its business. |
| + | xargs, find, shells do it (grep for "spawn_and_wait" and |
| + | "run_nofork_applet" to find more users). |
| + | |
| + | This poses much more serious limitations on what applet can do: |
| * all NOEXEC limitations apply. | |
| * do not ever exit() or exec(). | |
| @@ -56,7 +58,7 @@ on what applet can/cannot do: | |
| is taken from xfunc_error_retval. | |
| - fflush_stdout_and_exit(n) is ok to use. | |
| * do not use shared global data, or save/restore shared global data | |
| - | prior to returning. (e.g. bb_common_bufsiz1 is off-limits). |
| + | (e.g. bb_common_bufsiz1) prior to returning. |
| - getopt32() is ok to use. You do not need to save/restore option_mask32, | |
| it is already done by core code. | |
| * if you allocate memory, you can use xmalloc() only on the very first | |
| @@ -77,3 +79,20 @@ script loops. Applets which mess with signal handlers, termios etc | |
| are probably not worth the effort. | |
| Any NOFORK applet is also a NOEXEC applet. | |
| + | |
| + | |
| + | Relevant CONFIG options |
| + | |
| + | FEATURE_PREFER_APPLETS |
| + | BB_EXECVP(cmd, argv) will try to exec /proc/self/exe |
| + | if command's name matches some applet name |
| + | applet tables will contain NOFORK/NOEXEC bits |
| + | spawn_and_wait(argv) will do NOFORK/NOEXEC tricks |
| + | |
| + | FEATURE_SH_STANDALONE (needs FEATURE_PREFER_APPLETS=y) |
| + | shells will try to exec /proc/self/exe if command's name matches |
| + | some applet name |
| + | shells will do NOEXEC trick on NOEXEC applets |
| + | |
| + | FEATURE_SH_NOFORK (needs FEATURE_PREFER_APPLETS=y) |
| + | shells will do NOFORK trick on NOFORK applets |
include/libbb.h+1 -0
| @@ -859,6 +859,7 @@ void FAST_FUNC update_utmp(pid_t pid, int new_type, const char *tty_name, const | |
| # define update_utmp(pid, new_type, tty_name, username, hostname) ((void)0) | |
| #endif | |
| + | |
| int execable_file(const char *name) FAST_FUNC; | |
| char *find_execable(const char *filename, char **PATHp) FAST_FUNC; | |
| int exists_execable(const char *filename) FAST_FUNC; | |
shell/Config.src+5 -4
| @@ -123,9 +123,9 @@ config FEATURE_SH_NOFORK | |
| default n | |
| depends on (HUSH || ASH) && FEATURE_PREFER_APPLETS | |
| help | |
| - | This option causes busybox shells [currently only ash] |
| - | to not execute typical fork/exec/wait sequence, but call <applet>_main |
| - | directly, if possible. (Sometimes it is not possible: for example, |
| + | This option causes busybox shells to not execute typical |
| + | fork/exec/wait sequence, but call <applet>_main directly, |
| + | if possible. (Sometimes it is not possible: for example, |
| this is not possible in pipes). | |
| This will be done only for some applets (those which are marked | |
| @@ -133,6 +133,7 @@ config FEATURE_SH_NOFORK | |
| This may significantly speed up some shell scripts. | |
| - | This feature is relatively new. Use with care. |
| + | This feature is relatively new. Use with care. Report bugs |
| + | to project mailing list. |
| endmenu | |
shell/hush.c+5 -6
| @@ -6615,7 +6615,7 @@ static int checkjobs_and_fg_shell(struct pipe *fg_pipe) | |
| * cmd ; ... { list } ; ... | |
| * cmd && ... { list } && ... | |
| * cmd || ... { list } || ... | |
| - | * If it is, then we can run cmd as a builtin, NOFORK [do we do this?], |
| + | * If it is, then we can run cmd as a builtin, NOFORK, |
| * or (if SH_STANDALONE) an applet, and we can run the { list } | |
| * with run_list. If it isn't one of these, we fork and exec cmd. | |
| * | |
| @@ -6797,13 +6797,12 @@ static NOINLINE int run_pipe(struct pipe *pi) | |
| } | |
| /* Expand the rest into (possibly) many strings each */ | |
| - | if (0) {} |
| #if ENABLE_HUSH_BASH_COMPAT | |
| - | else if (command->cmd_type == CMD_SINGLEWORD_NOGLOB) { |
| + | if (command->cmd_type == CMD_SINGLEWORD_NOGLOB) { |
| argv_expanded = expand_strvec_to_strvec_singleword_noglob(argv + command->assignment_cnt); | |
| - | } |
| + | } else |
| #endif | |
| - | else { |
| + | { |
| argv_expanded = expand_strvec_to_strvec(argv + command->assignment_cnt); | |
| } | |
| @@ -6865,7 +6864,7 @@ static NOINLINE int run_pipe(struct pipe *pi) | |
| return rcode; | |
| } | |
| - | if (ENABLE_FEATURE_SH_STANDALONE) { |
| + | if (ENABLE_FEATURE_SH_NOFORK) { |
| int n = find_applet_by_name(argv_expanded[0]); | |
| if (n >= 0 && APPLET_IS_NOFORK(n)) { | |
| rcode = redirect_and_varexp_helper(&new_env, &old_vars, command, squirrel, argv_expanded); | |