diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/nofork_noexec.txt | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/docs/nofork_noexec.txt b/docs/nofork_noexec.txt index c58f5a83f..2fb184a03 100644 --- a/docs/nofork_noexec.txt +++ b/docs/nofork_noexec.txt @@ -33,6 +33,7 @@ roughly are: * do not expect shared global variables/buffers to be in their "initialized" state. Examples: xfunc_error_retval can be != 1, bb_common_bufsiz1 can be scribbled over, ... + (although usually xfunc_error_retval's state is not a problem). * do not expect that stdio wasn't used before. Calling set[v]buf() can be disastrous. * ... @@ -81,18 +82,37 @@ are probably not worth the effort. Any NOFORK applet is also a NOEXEC applet. + Calling NOFORK applets + +API to call NOFORK applets is two functions: + + run_nofork_applet(appno, argv) + spawn_and_wait(argv) // only if FEATURE_PREFER_APPLETS=y + +First one is directly used by shells if FEATURE_SH_NOFORK=y. +Second one is used by many applets, but main users are xargs and find. +It itself calls run_nofork_applet(), if argv[0] turned out to be a name +of a NOFORK applet. + +run_nofork_applet() saves/inits/restores option parsing, xfunc_error_retval, +applet_name. Thus, for example, caller does not need to worry about +option_mask32 getting trashed. + + 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 + if command's name matches some applet name; spawn_and_wait(argv) will do NOFORK/NOEXEC tricks -FEATURE_SH_STANDALONE (needs FEATURE_PREFER_APPLETS=y) +//TODO: the above two things probably should have separate options? + +FEATURE_SH_STANDALONE shells will try to exec /proc/self/exe if command's name matches - some applet name - shells will do NOEXEC trick on NOEXEC applets + some applet name; shells will do NOEXEC trick on NOEXEC applets + +//TODO: split (same as for PREFER_APPLETS) -FEATURE_SH_NOFORK (needs FEATURE_PREFER_APPLETS=y) +FEATURE_SH_NOFORK shells will do NOFORK trick on NOFORK applets |