> > (trap "echo WORKS" EXIT; touch x)
> > (trap "echo WORKS" EXIT && touch x)
> > bash -c 'trap "echo WORKS" EXIT; true'
> > bash -c 'trap "echo WORKS" EXIT; false'
> > bash -c 'trap "echo WORKS" EXIT; touch x && a'
> > bash -c 'trap "echo WORKS" EXIT; touch x; a'
> >
> > They all produce the output "WORKS" as the trap runs on exit. (Where "a"
> > is not a command or in the path and produces an error.)
> >
> > Now consider this command:
> >
> > bash -c 'trap "echo WORKS" EXIT && touch x'
> >
> > On newer versions of bash, it produces no output. Substituting different
> > commands in the trap or tracing it seems to indicate that the trap never
> > runs.
>
> It's a case of bash being too aggressive optimizing the last command in
> the AND_OR list. Here's a patch that disables that optimization attempt
> while I look at alternatives.
Here's a better patch that doesn't just disable the fork optimization. Please
let me know how it works in your testing.
Chet
*** ../bash-5.0-patched/command.h 2018-07-20 21:16:31.000000000 -0400
--- command.h 2019-02-20 11:09:36.000000000 -0500
***************
*** 187,190 ****
--- 188,192 ----
#define CMD_LASTPIPE 0x2000
#define CMD_STDPATH 0x4000 /* use standard path for command lookup
*/
+ #define CMD_TRY_OPTIMIZING 0x8000 /* try to optimize this simple command
*/
/* What a command looks like. */
*** ../bash-5.0-patched/builtins/evalstring.c 2018-12-26 11:19:21.000000000
-0500
--- builtins/evalstring.c 2019-01-29 14:15:19.000000000 -0500
***************
*** 101,104 ****
--- 101,113 ----
}
+ int
+ can_optimize_connection (command)
+ COMMAND *command;
+ {
+ return (*bash_input.location.string == '\0' &&
+ (command->value.Connection->connector == AND_AND ||
command->value.Connection->connector == OR_OR ||
command->value.Connection->connector == ';') &&
+ command->value.Connection->second->type == cm_simple);
+ }
+
void
optimize_fork (command)
***************
*** 106,110 ****
{
if (command->type == cm_connection &&
! (command->value.Connection->connector == AND_AND ||
command->value.Connection->connector == OR_OR) &&
should_suppress_fork (command->value.Connection->second))
{
--- 115,120 ----
{
if (command->type == cm_connection &&
! (command->value.Connection->connector == AND_AND ||
command->value.Connection->connector == OR_OR ||
command->value.Connection->connector == ';') &&
! (command->value.Connection->second->flags & CMD_TRY_OPTIMIZING) &&
should_suppress_fork (command->value.Connection->second))
{
***************
*** 413,418 ****
command->value.Simple->flags |= CMD_NO_FORK;
}
! else if (command->type == cm_connection)
! optimize_fork (command);
#endif /* ONESHOT */
--- 423,438 ----
command->value.Simple->flags |= CMD_NO_FORK;
}
!
! /* Can't optimize forks out here execept for simple commands.
! This knows that the parser sets up commands as left-side heavy
! (&& and || are left-associative) and after the single parse,
! if we are at the end of the command string, the last in a
! series of connection commands is
! command->value.Connection->second. */
! else if (command->type == cm_connection &&
can_optimize_connection (command))
! {
! command->value.Connection->second->flags |=
CMD_TRY_OPTIMIZING;
! command->value.Connection->second->value.Simple->flags |=
CMD_TRY_OPTIMIZING;
! }
#endif /* ONESHOT */
*** ../bash-5.0-patched/execute_cmd.c 2018-12-05 09:05:14.000000000 -0500
--- execute_cmd.c 2019-01-25 15:59:00.000000000 -0500
***************
*** 2768,2771 ****
--- 2768,2773 ----
(exec_result != EXECUTION_SUCCESS)))
{
+ optimize_fork (command);
+
second = command->value.Connection->second;
if (ignore_return && second)
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU c...@case.edu http://tiswww.cwru.edu/~chet/
