diff options
| author | Denys Vlasenko <vda.linux@googlemail.com> | 2017-08-06 14:03:27 +0200 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2017-08-06 14:03:27 +0200 |
| commit | fbecca1bed1b6daf10341304af2156baabc7af57 (patch) | |
| tree | 8ede3ecea0ce8de7c033b093954c049b1ba7a0c0 /docs/nofork_noexec.txt | |
| parent | 9a58cc0f7fbdf967c159588e0de5f3a8dfd87db5 (diff) | |
| download | busybox-w32-fbecca1bed1b6daf10341304af2156baabc7af57.tar.gz busybox-w32-fbecca1bed1b6daf10341304af2156baabc7af57.tar.bz2 busybox-w32-fbecca1bed1b6daf10341304af2156baabc7af57.zip | |
Tweak outdated documentation and comments
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'docs/nofork_noexec.txt')
| -rw-r--r-- | docs/nofork_noexec.txt | 53 |
1 files changed, 27 insertions, 26 deletions
diff --git a/docs/nofork_noexec.txt b/docs/nofork_noexec.txt index b45a4be89..9d210a1c9 100644 --- a/docs/nofork_noexec.txt +++ b/docs/nofork_noexec.txt | |||
| @@ -10,13 +10,8 @@ of reimplemented Unix commands, and we can do the same trick | |||
| 10 | for speeding up busybox shells, and more. NOEXEC and NOFORK applets | 10 | for speeding up busybox shells, and more. NOEXEC and NOFORK applets |
| 11 | are exactly those applets which are eligible for these tricks. | 11 | are exactly those applets which are eligible for these tricks. |
| 12 | 12 | ||
| 13 | Applet will be subject to NOFORK/NOEXEC tricks if it is marked as such | 13 | Applet will be subject to NOFORK/NOEXEC tricks only if it is marked |
| 14 | in applets.h. FEATURE_PREFER_APPLETS is a config option which | 14 | as such in applets.src.h or in their inline "//applet:" directives. |
| 15 | globally enables usage of NOFORK/NOEXEC tricks. | ||
| 16 | If it is enabled, FEATURE_SH_STANDALONE can be enabled too, | ||
| 17 | and then shells will use NOFORK/NOEXEC tricks for ordinary commands. | ||
| 18 | NB: shell builtins use these tricks regardless of FEATURE_SH_STANDALONE | ||
| 19 | or FEATURE_PREFER_APPLETS. | ||
| 20 | 15 | ||
| 21 | In C, if you want to call a program and wait for it, use | 16 | In C, if you want to call a program and wait for it, use |
| 22 | spawn_and_wait(argv), BB_EXECVP(prog,argv) or BB_EXECLP(prog,argv0,...). | 17 | spawn_and_wait(argv), BB_EXECVP(prog,argv) or BB_EXECLP(prog,argv0,...). |
| @@ -24,6 +19,31 @@ They check whether program name is an applet name and optionally | |||
| 24 | do NOFORK/NOEXEC thing depending on configuration. | 19 | do NOFORK/NOEXEC thing depending on configuration. |
| 25 | 20 | ||
| 26 | 21 | ||
| 22 | Relevant CONFIG options | ||
| 23 | |||
| 24 | FEATURE_PREFER_APPLETS | ||
| 25 | Globally enables NOFORK/NOEXEC tricks for such programs as xargs | ||
| 26 | and find: | ||
| 27 | BB_EXECVP(cmd, argv) will try to exec /proc/self/exe | ||
| 28 | if command's name matches some applet name; | ||
| 29 | spawn_and_wait(argv) will do NOFORK/NOEXEC tricks | ||
| 30 | |||
| 31 | //TODO: the above two things probably should have separate options? | ||
| 32 | |||
| 33 | FEATURE_SH_STANDALONE | ||
| 34 | shells will try to exec /proc/self/exe if command's name matches | ||
| 35 | some applet name; shells will do NOEXEC trick on NOEXEC applets | ||
| 36 | |||
| 37 | //TODO: split (same as for PREFER_APPLETS) | ||
| 38 | |||
| 39 | FEATURE_SH_NOFORK | ||
| 40 | shells will do NOFORK trick on NOFORK applets | ||
| 41 | |||
| 42 | NB: shell builtins use these tricks regardless of FEATURE_SH_STANDALONE, | ||
| 43 | FEATURE_PREFER_APPLETS or FEATURE_SH_NOFORK. In effect, builtins | ||
| 44 | are "always NOFORK". | ||
| 45 | |||
| 46 | |||
| 27 | NOEXEC | 47 | NOEXEC |
| 28 | 48 | ||
| 29 | NOEXEC applet should work correctly if another applet forks and then | 49 | NOEXEC applet should work correctly if another applet forks and then |
| @@ -121,22 +141,3 @@ option_mask32 getting trashed. | |||
| 121 | It's the same trusty spawn_and_wait(argv). If FEATURE_PREFER_APPLETS=y, | 141 | It's the same trusty spawn_and_wait(argv). If FEATURE_PREFER_APPLETS=y, |
| 122 | it does NOEXEC trick. It resets xfunc_error_retval = 1 and | 142 | it does NOEXEC trick. It resets xfunc_error_retval = 1 and |
| 123 | logmode = LOGMODE_STDIO in the child. | 143 | logmode = LOGMODE_STDIO in the child. |
| 124 | |||
| 125 | |||
| 126 | Relevant CONFIG options | ||
| 127 | |||
| 128 | FEATURE_PREFER_APPLETS | ||
| 129 | BB_EXECVP(cmd, argv) will try to exec /proc/self/exe | ||
| 130 | if command's name matches some applet name; | ||
| 131 | spawn_and_wait(argv) will do NOFORK/NOEXEC tricks | ||
| 132 | |||
| 133 | //TODO: the above two things probably should have separate options? | ||
| 134 | |||
| 135 | FEATURE_SH_STANDALONE | ||
| 136 | shells will try to exec /proc/self/exe if command's name matches | ||
| 137 | some applet name; shells will do NOEXEC trick on NOEXEC applets | ||
| 138 | |||
| 139 | //TODO: split (same as for PREFER_APPLETS) | ||
| 140 | |||
| 141 | FEATURE_SH_NOFORK | ||
| 142 | shells will do NOFORK trick on NOFORK applets | ||