ash: disable sleep as builtin, closes 15619

Has a few annoying problems:
* sleepcmd() -> sleep_main(), the parsing of bad arguments exits the shell.
* sleep_for_duration() in sleep_main() has to be interruptible for
  ^C traps to work, which may be a problem for other users
  of sleep_for_duration().
* BUT, if sleep_for_duration() is interruptible, then SIGCHLD interrupts it
  as well (try "/bin/sleep 1 & sleep 10").
* sleep_main() must not allocate anything as ^C in ash longjmp's.
  (currently, allocations are only on error paths, in message printing).

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 17 insertions, 5 deletions

diff --git a/shell/ash.c b/shell/ash.c
index e91566994..e154cc6cc 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -134,11 +134,23 @@
 //config:       default y
 //config:       depends on SHELL_ASH
 //config:
-//config:config ASH_SLEEP
-//config:       bool "sleep builtin"
-//config:       default y
-//config:       depends on SHELL_ASH
-//config:
+//
+////config:config ASH_SLEEP
+////config:     bool "sleep builtin"
+////config:     default y
+////config:     depends on SHELL_ASH
+////config:
+//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//Disabled for now. Has a few annoying problems:
+// * sleepcmd() -> sleep_main(), the parsing of bad arguments exits the shell.
+// * sleep_for_duration() in sleep_main() has to be interruptible for
+//   ^C traps to work, which may be a problem for other users
+//   of sleep_for_duration().
+// * BUT, if sleep_for_duration() is interruptible, then SIGCHLD interrupts it
+//   as well (try "/bin/sleep 1 & sleep 10").
+// * sleep_main() must not allocate anything as ^C in ash longjmp's.
+//   (currently, allocations are only on error paths, in message printing).
+//
 //config:config ASH_HELP
 //config:       bool "help builtin"
 //config:       default y