8a9a96192a
Import a whole set of tree evaluation enhancements from FreeBSD.
With these, before forking, the shell predicts (often) when all it will
have to do after forking (in the parent) is wait for the child and then
exit with the status from the child, and in such a case simply does not
fork, but rather allows the child to take over the parent's role.
This turns out to handle the particular test case from PR bin/48875 in
such a way that it works as hoped, rather than as it did (the delay there
was caused by an extra copy of the shell hanging around waiting for the
background child to complete ... and keeping the command substitution
stdout open, so the "real" parent had to wait in case more output appeared).
As part of doing this, redirection processing for compound commands gets
moved out of evalsubshell() and into a new evalredir(), which allows us
to properly handle errors occurring while performing those redirects,
and not mishandle (as in simply forget) fd's which had been moved out
of the way temporarily.
evaltree() has its degree of recursion reduced by making it loop to
handle the subsequent operation: that is instead of (for any binop
like ';' '&&' (etc)) where it used to
evaltree(node->left);
evaltree(node->right);
return;
it now does (kind of)
next = node;
while ((node = next) != NULL) {
next = NULL;
if (node is a binary op) {
evaltree(node->left);
if appropriate /* if && test for success, etc */
next = node->right;
continue;
}
/* similar for loops, etc */
}
which can be a good saving, as while the left side (now) tends to be
(usually) a simple (or simpleish) command, the right side can be many
commands (in a command sequence like a; b; c; d; ... the node at the
top of the tree will now have "a" as its left node, and the tree for
b; c; d; ... as its right node - until now everything was evaluated
recursively so it made no difference, and the tree was constructed
the other way).
if/while/... statements are done similarly, recurse to evaluate the
condition, then if the (or one of the) body parts is to be evaluated,
set next to that, and loop (previously it recursed).
There is more to do in this area (particularly in the way that case
statements are processed - we can avoid recursion there as well) but
that can wait for another day.
While doing all of this we keep much better track of when the shell is
just going to exit once the current tree is evaluated (with a new
predicate at_eof() to tell us that we have, for sure, reached the end
of the input stream, that is, this shell will, for certain, not be reading
more command input) and use that info to avoid unneeded forks. For that
we also need another new predicate (have_traps()) to determine of there
are any caught traps which might occur - if there are, we need to remain
to (potentially) handle them, so these optimisations will not occur (to
make the issue in PR 48875 appear again, run the same code, but with a
trap set to execute some code when a signal (or EXIT) occurs - note that
the trap must be set in the appropriate level of sub-shell to have this
effect, any caught traps are cleared in a subshell whenever one is created).
There is still work to be done to handle traps properly, whatever
weirdness they do (some of which is related to some of this.)
These changes do not need man page updates, but 48875 does - an update
to sh.1 will be forthcoming once it is decided what it should say...
Once again, all the heavy lifting for this set of changes comes directly
(with thanks) from the FreeBSD shell.
XXX pullup-8 (but not very soon)
121 lines
4.4 KiB
C
121 lines
4.4 KiB
C
/* $NetBSD: error.h,v 1.21 2018/08/19 23:50:27 kre Exp $ */
|
|
|
|
/*-
|
|
* Copyright (c) 1991, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* This code is derived from software contributed to Berkeley by
|
|
* Kenneth Almquist.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)error.h 8.2 (Berkeley) 5/4/95
|
|
*/
|
|
|
|
#include <stdarg.h>
|
|
|
|
/*
|
|
* Types of operations (passed to the errmsg routine).
|
|
*/
|
|
|
|
#define E_OPEN 01 /* opening a file */
|
|
#define E_CREAT 02 /* creating a file */
|
|
#define E_EXEC 04 /* executing a program */
|
|
|
|
|
|
/*
|
|
* We enclose jmp_buf in a structure so that we can declare pointers to
|
|
* jump locations. The global variable handler contains the location to
|
|
* jump to when an exception occurs, and the global variable exception
|
|
* contains a code identifying the exeception. To implement nested
|
|
* exception handlers, the user should save the value of handler on entry
|
|
* to an inner scope, set handler to point to a jmploc structure for the
|
|
* inner scope, and restore handler on exit from the scope.
|
|
*/
|
|
|
|
#include <setjmp.h>
|
|
|
|
struct jmploc {
|
|
jmp_buf loc;
|
|
};
|
|
|
|
extern struct jmploc *handler;
|
|
extern int exception;
|
|
extern int exerrno; /* error for EXEXEC */
|
|
|
|
/* exceptions */
|
|
#define EXINT 0 /* SIGINT received */
|
|
#define EXERROR 1 /* a generic error */
|
|
#define EXSHELLPROC 2 /* execute a shell procedure */
|
|
#define EXEXEC 3 /* command execution failed */
|
|
#define EXEXIT 4 /* shell wants to exit(exitstatus) */
|
|
|
|
|
|
/*
|
|
* These macros allow the user to suspend the handling of interrupt signals
|
|
* over a period of time. This is similar to SIGHOLD to or sigblock, but
|
|
* much more efficient and portable. (But hacking the kernel is so much
|
|
* more fun than worrying about efficiency and portability. :-))
|
|
*/
|
|
|
|
extern volatile int suppressint;
|
|
extern volatile int intpending;
|
|
|
|
#define INTOFF suppressint++
|
|
#define INTON do { if (--suppressint == 0 && intpending) onint(); } while (0)
|
|
#define FORCEINTON do { suppressint = 0; if (intpending) onint(); } while (0)
|
|
#define CLEAR_PENDING_INT (intpending = 0)
|
|
#define int_pending() intpending
|
|
|
|
#if ! defined(SHELL_BUILTIN)
|
|
void exraise(int) __dead;
|
|
void onint(void);
|
|
void error(const char *, ...) __dead __printflike(1, 2);
|
|
void exerror(int, const char *, ...) __dead __printflike(2, 3);
|
|
const char *errmsg(int, int);
|
|
#endif /* ! SHELL_BUILTIN */
|
|
|
|
void sh_err(int, const char *, ...) __dead __printflike(2, 3);
|
|
void sh_verr(int, const char *, va_list) __dead __printflike(2, 0);
|
|
void sh_errx(int, const char *, ...) __dead __printflike(2, 3);
|
|
void sh_verrx(int, const char *, va_list) __dead __printflike(2, 0);
|
|
void sh_warn(const char *, ...) __printflike(1, 2);
|
|
void sh_vwarn(const char *, va_list) __printflike(1, 0);
|
|
void sh_warnx(const char *, ...) __printflike(1, 2);
|
|
void sh_vwarnx(const char *, va_list) __printflike(1, 0);
|
|
|
|
void sh_exit(int) __dead;
|
|
|
|
|
|
/*
|
|
* BSD setjmp saves the signal mask, which violates ANSI C and takes time,
|
|
* so we use _setjmp instead.
|
|
*/
|
|
|
|
#if defined(BSD) && !defined(__SVR4)
|
|
#define setjmp(jmploc) _setjmp(jmploc)
|
|
#define longjmp(jmploc, val) _longjmp(jmploc, val)
|
|
#endif
|