freebsd-skq/bin/sh/nodetypes
jilles 6fa139d56e sh: Expand here documents in the current process.
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.
2013-02-03 15:54:57 +00:00

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#-
# 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.
# 4. 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.
#
# @(#)nodetypes 8.2 (Berkeley) 5/4/95
# $FreeBSD$
# This file describes the nodes used in parse trees. Unindented lines
# contain a node type followed by a structure tag. Subsequent indented
# lines specify the fields of the structure. Several node types can share
# the same structure, in which case the fields of the structure should be
# specified only once.
#
# A field of a structure is described by the name of the field followed
# by a type. The currently implemented types are:
# nodeptr - a pointer to a node
# nodelist - a pointer to a list of nodes
# string - a pointer to a nul terminated string
# int - an integer
# other - any type that can be copied by assignment
# temp - a field that doesn't have to be copied when the node is copied
# The last two types should be followed by the text of a C declaration for
# the field.
NSEMI nbinary # two commands separated by a semicolon
type int
ch1 nodeptr # the first child
ch2 nodeptr # the second child
NCMD ncmd # a simple command
type int
args nodeptr # the arguments
redirect nodeptr # list of file redirections
NPIPE npipe # a pipeline
type int
backgnd int # set to run pipeline in background
cmdlist nodelist # the commands in the pipeline
NREDIR nredir # redirection (of a compex command)
type int
n nodeptr # the command
redirect nodeptr # list of file redirections
NBACKGND nredir # run command in background
NSUBSHELL nredir # run command in a subshell
NAND nbinary # the && operator
NOR nbinary # the || operator
NIF nif # the if statement. Elif clauses are handled
type int # using multiple if nodes.
test nodeptr # if test
ifpart nodeptr # then ifpart
elsepart nodeptr # else elsepart
NWHILE nbinary # the while statement. First child is the test
NUNTIL nbinary # the until statement
NFOR nfor # the for statement
type int
args nodeptr # for var in args
body nodeptr # do body; done
var string # the for variable
NCASE ncase # a case statement
type int
expr nodeptr # the word to switch on
cases nodeptr # the list of cases (NCLIST nodes)
NCLIST nclist # a case ending with ;;
type int
next nodeptr # the next case in list
pattern nodeptr # list of patterns for this case
body nodeptr # code to execute for this case
NCLISTFALLTHRU nclist # a case ending with ;&
NDEFUN narg # define a function. The "next" field contains
# the body of the function.
NARG narg # represents a word
type int
next nodeptr # next word in list
text string # the text of the word
backquote nodelist # list of commands in back quotes
NTO nfile # fd> fname
NFROM nfile # fd< fname
NFROMTO nfile # fd<> fname
NAPPEND nfile # fd>> fname
NCLOBBER nfile # fd>| fname
type int
next nodeptr # next redirection in list
fd int # file descriptor being redirected
fname nodeptr # file name, in a NARG node
expfname temp char *expfname # actual file name
NTOFD ndup # fd<&dupfd
NFROMFD ndup # fd>&dupfd
type int
next nodeptr # next redirection in list
fd int # file descriptor being redirected
dupfd int # file descriptor to duplicate
vname nodeptr # file name if fd>&$var
NHERE nhere # fd<<\!
NXHERE nhere # fd<<!
type int
next nodeptr # next redirection in list
fd int # file descriptor being redirected
doc nodeptr # input to command (NARG node)
expdoc temp char *expdoc # actual document (for NXHERE)
NNOT nnot # ! command (actually pipeline)
type int
com nodeptr