From: Eric Blake Date: Thu, 19 Feb 2009 21:32:36 +0000 (-0700) Subject: Use m4_translit more efficiently in AS_ESCAPE. X-Git-Tag: v2.63b~19 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4da1abd28bae9bbe54e49159929f33628476fc9a;p=thirdparty%2Fautoconf.git Use m4_translit more efficiently in AS_ESCAPE. * lib/m4sugar/m4sh.m4 (_AS_ESCAPE): Alter API to take first byte of set separately from rest. (AS_ESCAPE, _AS_QUOTE_MODERN, AS_TR_SH, AS_VAR_GET): Adjust callers. * lib/autoconf/autoheader.m4 (AH_VERBATIM): Avoid duplicate characters in translit request. * doc/autoconf.texi (Common Shell Constructs) : Document the macro. * NEWS: Likewise. Signed-off-by: Eric Blake --- diff --git a/ChangeLog b/ChangeLog index 79b6740ef..c68d1b5de 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,16 @@ 2009-02-19 Eric Blake + Use m4_translit more efficiently in AS_ESCAPE. + * lib/m4sugar/m4sh.m4 (_AS_ESCAPE): Alter API to take first byte + of set separately from rest. + (AS_ESCAPE, _AS_QUOTE_MODERN, AS_TR_SH, AS_VAR_GET): Adjust + callers. + * lib/autoconf/autoheader.m4 (AH_VERBATIM): Avoid duplicate + characters in translit request. + * doc/autoconf.texi (Common Shell Constructs) : + Document the macro. + * NEWS: Likewise. + Mention recently documented macros. * NEWS: Update list of new documentation. diff --git a/NEWS b/NEWS index a1f0a607b..34b438071 100644 --- a/NEWS +++ b/NEWS @@ -80,8 +80,8 @@ GNU Autoconf NEWS - User visible changes. ** The following m4sh macros are documented now, but in some cases with slightly different semantics than what the previous undocumented version had: - AS_ECHO AS_ECHO_N AS_EXIT AS_LITERAL_IF AS_UNSET AS_VAR_IF - AS_VAR_POPDEF AS_VAR_PUSHDEF AS_VAR_SET AS_VAR_SET_IF + AS_ECHO AS_ECHO_N AS_ESCAPE AS_EXIT AS_LITERAL_IF AS_UNSET + AS_VAR_IF AS_VAR_POPDEF AS_VAR_PUSHDEF AS_VAR_SET AS_VAR_SET_IF AS_VAR_TEST_SET AS_VERSION_COMPARE ** The m4sh macros AS_IF and AS_CASE can now be used in shell lists. diff --git a/doc/autoconf.texi b/doc/autoconf.texi index 958830139..dcf591d28 100644 --- a/doc/autoconf.texi +++ b/doc/autoconf.texi @@ -12338,6 +12338,51 @@ for portability, should not include more than one newline. The bytes of Redirections can be placed outside the macro invocation. @end defmac +@defmac AS_ESCAPE (@var{string}, @dvar{chars, `\"$}) +@asindex{ESCAPE} +Expands to @var{string}, with any characters in @var{chars} escaped with +a backslash (@samp{\}). @var{chars} should be at most four bytes long, +and only contain characters from the set @samp{`\"$}; however, +characters may be safely listed more than once in @var{chars} for the +sake of syntax highlighting editors. The current implementation expands +@var{string} after adding escapes; if @var{string} contains macro calls +that have text that needs quoting, you can use +@code{AS_ESCAPE(m4_dquote(m4_expand([string])))}. + +The default for @var{chars} (@samp{\"$`}) is the set of characters +needing escapes when @var{string} will be used literally within double +quotes. One common variant is the set of characters to protect when +@var{string} will be used literally within back-ticks or an unquoted +here-doc (@samp{\$`}). Another common variant is @samp{""}, which can +be used to form a double-quoted string containing the same expansions +that would have occurred if @var{string} were expanded in an unquoted +here-doc; however, when using this variant, care must be taken that +@var{string} does not use double quotes within complex variable +expansions (such as @samp{$@{foo-`echo "hi"`@}}) that would be broken +with improper escapes. + +This macro is often used with @code{AS_ECHO}. For example, this snippet +will produce shell code that outputs the four lines @samp{"$foo" = +"bar"}, @samp{macro}, @samp{a, b}, and @samp{a, \b}: + +@example +foo=bar +AS_ECHO(["AS_ESCAPE(["$foo" = ])AS_ESCAPE(["$foo"], [""])"]) +m4_define([macro], [a, [\b]]) +AS_ECHO(["AS_ESCAPE([[macro]])"]) +AS_ECHO(["AS_ESCAPE([macro])"]) +AS_ECHO(["AS_ESCAPE(m4_dquote(m4_expand([macro])))"]) +@end example + +@comment Should we add AS_ESCAPE_SINGLE? If we do, we can optimize in +@comment the case of @var{string} that does not contain '. +To escape a string that will be placed within single quotes, use: + +@example +m4_bpatsubst([[@var{string}]], ['], ['\\'']) +@end example +@end defmac + @defmac AS_EXIT (@dvar{status, $?}) @asindex{EXIT} Emit code to exit the shell with @var{status}, defaulting to @samp{$?}. diff --git a/lib/autoconf/autoheader.m4 b/lib/autoconf/autoheader.m4 index dfc5f77d7..8e109cca2 100644 --- a/lib/autoconf/autoheader.m4 +++ b/lib/autoconf/autoheader.m4 @@ -2,7 +2,7 @@ # Interface with autoheader. # Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001, -# 2002, 2008 Free Software Foundation, Inc. +# 2002, 2008, 2009 Free Software Foundation, Inc. # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by @@ -68,7 +68,7 @@ m4_define([AH_OUTPUT], []) # Quote for Perl '' strings, which are those used by Autoheader. m4_define([AH_VERBATIM], [AS_LITERAL_IF([$1], - [AH_OUTPUT([$1], AS_ESCAPE([[$2]], [\\'']))])]) + [AH_OUTPUT([$1], AS_ESCAPE([[$2]], [\']))])]) # AH_TEMPLATE(KEY, DESCRIPTION) diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4 index 2e17a9de7..e03306382 100644 --- a/lib/m4sugar/m4sh.m4 +++ b/lib/m4sugar/m4sh.m4 @@ -680,18 +680,33 @@ m4_define([AS_MESSAGE_LOG_FD]) m4_define([AS_ORIGINAL_STDIN_FD], [0]) -# AS_ESCAPE(STRING, [CHARS = $"`\]) +# AS_ESCAPE(STRING, [CHARS = `\"$]) # --------------------------------- -# Escape the CHARS in STRING. +# Add backslash escaping to the CHARS in STRING. In an effort to +# optimize use of this macro inside double-quoted shell constructs, +# the behavior is intentionally undefined if CHARS is longer than 4 +# bytes, or contains bytes outside of the set [`\"$]. However, +# repeated bytes within the set are permissible (AS_ESCAPE([$1], [""]) +# being a common way to be nice to syntax highlighting). # # Avoid the m4_bpatsubst if there are no interesting characters to escape. # _AS_ESCAPE bypasses argument defaulting. m4_define([AS_ESCAPE], -[_$0([$1], m4_default([$2], [\"$`]))]) +[_$0([$1], m4_if([$2], [], [[`], [\"$]], [m4_substr([$2], [0], [1]), [$2]]))]) + +# _AS_ESCAPE(STRING, KEY, SET) +# ---------------------------- +# Backslash-escape all instances of the singly byte KEY or up to four +# bytes in SET occurring in STRING. Although a character can occur +# multiple times, optimum efficiency occurs when KEY and SET are +# distinct, and when SET does not exceed two bytes. These particular +# semantics allow for the fewest number of parses of STRING, as well +# as taking advantage of newer m4's optimizations when m4_translit is +# passed SET of size 2 or smaller. m4_define([_AS_ESCAPE], -[m4_if(m4_len([$1]), - m4_len(m4_translit([[$1]], [$2])), - [$1], [m4_bpatsubst([$1], [[$2]], [\\\&])])]) +[m4_if(m4_index(m4_translit([[$1]], [$3], [$2$2$2$2]), [$2]), [-1], + [$0_], [m4_bpatsubst])([$1], [[$2$3]], [\\\&])]) +m4_define([_AS_ESCAPE_], [$1]) # _AS_QUOTE(STRING) @@ -722,7 +737,7 @@ m4_define([_AS_QUOTE], [_AS_QUOTE_MODERN])([$1])]) m4_define([_AS_QUOTE_MODERN], -[_AS_ESCAPE([$1], [`""])]) +[_AS_ESCAPE([$1], [`], [""])]) m4_define([_AS_QUOTE_OLD], [m4_warn([obsolete], @@ -1725,7 +1740,8 @@ m4_defun_init([AS_TR_SH], m4_dquote(m4_dquote(m4_defn([m4_cr_not_symbols2])))[[, [pp[]]]]dnl m4_dquote(m4_dquote(m4_for(,1,255,,[[_]])))[[)], - [`AS_ECHO(["_AS_ESCAPE(m4_dquote(m4_expand([$1])), [\`])"]) | $as_tr_sh`])]) + [`AS_ECHO(["_AS_ESCAPE(m4_dquote(m4_expand([$1])), + [`], [\])"]) | $as_tr_sh`])]) # _AS_TR_CPP_PREPARE @@ -1883,7 +1899,7 @@ m4_define([AS_VAR_COPY], m4_define([AS_VAR_GET], [AS_LITERAL_IF([$1], [$$1], - [`eval 'as_val=${'_AS_ESCAPE([[$1]], [\`])'};AS_ECHO(["$as_val"])'`])]) + [`eval 'as_val=${'_AS_ESCAPE([[$1]], [`], [\])'};AS_ECHO(["$as_val"])'`])]) # AS_VAR_IF(VARIABLE, VALUE, IF-TRUE, IF-FALSE)