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eaf9436b08
Upstream commit:
Date: Thu, 27 May 2010 14:21:17 +0800
[REDIR] Move null redirect checks into caller
The null redirect checks were added as an optimisation to avoid
unnecessary memory allocations. However, we could avoid this
completely by simply making the caller avoid making a redirection
unless it is not null.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
function old new delta
evaltree 784 809 +25
evalcommand 1251 1261 +10
hashvar 59 62 +3
dotcmd 321 319 -2
clearredir 37 30 -7
popredir 183 162 -21
redirect 1264 1233 -31
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(add/remove: 0/0 grow/shrink: 4/4 up/down: 63/-61) Total: -23 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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| .. | ||
| ash_test | ||
| hush_test | ||
| ash_doc.txt | ||
| ash_ptr_hack.c | ||
| ash.c | ||
| brace.txt | ||
| Config.src | ||
| cttyhack.c | ||
| hush_doc.txt | ||
| hush_leaktool.sh | ||
| hush.c | ||
| Kbuild.src | ||
| match.c | ||
| match.h | ||
| math.c | ||
| math.h | ||
| random.c | ||
| random.h | ||
| README | ||
| README.job | ||
| shell_common.c | ||
| shell_common.h | ||
http://www.opengroup.org/onlinepubs/9699919799/ Open Group Base Specifications Issue 7 http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap01.html Shell & Utilities It says that any of the standard utilities may be implemented as a regular shell built-in. It gives a list of utilities which are usually implemented that way (and some of them can only be implemented as built-ins, like "alias"): alias bg cd command false fc fg getopts jobs kill newgrp pwd read true umask unalias wait http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html Shell Command Language It says that shell must implement special built-ins. Special built-ins differ from regular ones by the fact that variable assignments done on special builtin are *PRESERVED*. That is, VAR=VAL special_builtin; echo $VAR should print VAL. (Another distinction is that an error in special built-in should abort the shell, but this is not such a critical difference, and moreover, at least bash's "set" does not follow this rule, which is even codified in autoconf configure logic now...) List of special builtins: . file : [argument...] break [n] continue [n] eval [argument...] exec [command [argument...]] exit [n] export name[=word]... export -p readonly name[=word]... readonly -p return [n] set [-abCefhmnuvx] [-o option] [argument...] set [+abCefhmnuvx] [+o option] [argument...] set -- [argument...] set -o set +o shift [n] times trap n [condition...] trap [action condition...] unset [-fv] name... In practice, no one uses this obscure feature - none of these builtins gives any special reasons to play such dirty tricks. However. This section also says that *function invocation* should act similar to special built-in. That is, variable assignments done on function invocation should be preserved after function invocation. This is significant: it is not unthinkable to want to run a function with some variables set to special values. But because of the above, it does not work: variable will "leak" out of the function.