src-test2/bin/sh/expand.h, branch releng/11.2

sh: Perform pathname generation during the first expansion phases.

2015-12-31T18:47:54Z

This avoids the need to add and remove CTLESC bytes if pathname generation will not be performed (set -f). Side effect: the order of operations is slightly different: pathname generation in ${$+* $(CMD)} will not see filesystem changes from CMD.

sh: Avoid copying argv for simple commands.

2015-11-01T22:07:40Z

Add dummy entries before and after so arglist's array is directly usable as argv.

sh: Make struct arglist an array instead of a linked list.

2015-10-11T21:33:00Z

This simplifies the code (e.g. allowing use of qsort(3) instead of a hand-rolled mergesort) and should have better cache properties. The waste of unused args arrays after resizes is approximately the same as the savings from getting rid of the next pointers. At the same time, remove a piece of global state and move some duplicated code into a function.

sh: Remove EXP_REDIR.

2014-12-21T22:18:30Z

EXP_REDIR was supposed to generate pathnames in redirection if exactly one file matches, as permitted but not required by POSIX in interactive mode. It is unlikely this will be implemented. No functional change is intended. MFC after: 1 week

sh: Make expari() static.

2014-02-26T21:38:42Z

sh: Expand here documents in the current process.

2013-02-03T15:54:57Z

Expand here documents at the same point other redirections are expanded but use a non-fork subshell environment (like simple command substitutions) for compatibility. Substitition errors result in an empty here document like before. As a result, a fork is avoided for short (<4K) expanded here documents. Unexpanded here documents (with quoted end marker after <<) are not affected by this change. They already only forked when >4K. Side effects: * Order of expansion is slightly different. * Slow expansions are not executed in parallel with the redirected command. * A non-fork subshell environment is subtly different from a forked process.

sh: Make various functions static.

2012-01-01T22:17:12Z

sh: Fix duplicate prototypes for builtins.

2011-06-13T21:03:27Z

Have mkbuiltins write the prototypes for the *cmd functions to builtins.h instead of builtins.c and include builtins.h in more .c files instead of duplicating prototypes for *cmd functions in other headers.

sh: Save/restore changed variables in optimized command substitution.

2011-06-12T23:06:04Z

In optimized command substitution, save and restore any variables changed by expansions (${var=value} and $((var=assigned))), instead of trying to determine if an expansion may cause such changes. If $! is referenced in optimized command substitution, do not cause jobs to be remembered longer. This fixes $(jobs $!) again, simplifies the man page and shortens the code.

sh: Don't do optimized command substitution if expansions have side effects.

2010-12-28T21:27:08Z

Before considering to execute a command substitution in the same process, check if any of the expansions may have a side effect; if so, execute it in a new process just like happens if it is not a single simple command. Although the check happens at run time, it is a static check that does not depend on current state. It is triggered by: - expanding $! (which may cause the job to be remembered) - ${var=value} default value assignment - assignment operators in arithmetic - parameter substitutions in arithmetic except ${#param}, $$, $# and $? - command substitutions in arithmetic This means that $((v+1)) does not prevent optimized command substitution, whereas $(($v+1)) does, because $v might expand to something containing assignment operators. Scripts should not depend on these exact details for correctness. It is also imaginable to have the shell fork if and when a side effect is encountered or to create a new temporary namespace for variables. Due to the $! change, the construct $(jobs $!) no longer works. The value of $! should be stored in a variable outside command substitution first.