--- /dev/null
+--
+-- features.lua
+--
+-- $Id$
+--
+-- Lua 5.2 module providing a mingw-get setup hook for configuration of
+-- the user's MinGW GCC compiler <features.h> preferences.
+--
+-- Written by Keith Marshall <keithmarshall@users.sourceforge.net>
+-- Copyright (C) 2019, MinGW.org Project
+--
+--
+-- Permission is hereby granted, free of charge, to any person obtaining a
+-- copy of this software and associated documentation files (the "Software"),
+-- to deal in the Software without restriction, including without limitation
+-- the rights to use, copy, modify, merge, publish, distribute, sublicense,
+-- and/or sell copies of the Software, and to permit persons to whom the
+-- Software is furnished to do so, subject to the following conditions:
+--
+-- The above copyright notice and this permission notice shall be included
+-- in all copies or substantial portions of the Software.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+-- OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+-- THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+-- FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+-- DEALINGS IN THE SOFTWARE.
+--
+--
+-- We begin by initializing a container, for construction of a Lua module
+-- to encapsulate the content of this source file.
+--
+ local M = {}
+--
+-- mingw-get passes the MinGW installation root directory path, in the
+-- $MINGW32_SYSROOT environment variable; from this, we deduce the path
+-- name for the working copy of the features.h file...
+--
+ local function syspath( varname )
+--
+-- ...using this local helper function to ensure that the path name
+-- string, returned from the environment, is free from insignificant
+-- trailing directory name separators, and that all internal sequences
+-- of directory name separators are normalized to a single '/'.
+--
+ local pathname = os.getenv( varname )
+ if pathname
+ then
+ pathname = string.gsub( pathname, "[/\\]+", "/" )
+ pathname = string.match( pathname, "(.*[^/])/*$" )
+ end
+ return pathname
+ end
+ local sysroot = syspath( "MINGW32_SYSROOT" )
+ if not sysroot
+ then
+ error( "environment variable MINGW32_SYSROOT may not be set", 0 )
+ end
+ local config_file_name = sysroot .. "/include/features.h"
+--
+-- Define a template, whence the default features configuration may be
+-- deduced when writing the initial content of the <features.h> file.
+--
+ local config_default =
+ { '/*',
+ ' * features.h',
+ ' *',
+ ' * Features configuration for MinGW.org GCC implementation; users may',
+ ' * customize this file, to establish their preferred default behaviour.',
+ ' * Projects may provide an alternative, package-specific configuration,',
+ ' * either by placing their own customized <features.h> in the package',
+ ' * -I path, ahead of the system default, or by assignment of their',
+ ' * preferred alternative to the _MINGW_FEATURES_HEADER macro.',
+ ' *',
+ ' *',
+ ' * $'..'Id$',
+ ' *',
+ ' * Template written by Keith Marshall <keith@users.osdn.me>',
+ ' * Copyright (C) 2019, MinGW.org Project.',
+ ' *',
+ ' *',
+ ' * Permission is hereby granted, free of charge, to any person obtaining a',
+ ' * copy of this software and associated documentation files (the "Software"),',
+ ' * to deal in the Software without restriction, including without limitation',
+ ' * the rights to use, copy, modify, merge, publish, distribute, sublicense,',
+ ' * and/or sell copies of the Software, and to permit persons to whom the',
+ ' * Software is furnished to do so, subject to the following conditions:',
+ ' *',
+ ' * The above copyright notice, this permission notice, and the following',
+ ' * disclaimer shall be included in all copies or substantial portions of',
+ ' * the Software.',
+ ' *',
+ ' * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS',
+ ' * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,',
+ ' * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL',
+ ' * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER',
+ ' * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING',
+ ' * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OF OR OTHER',
+ ' * DEALINGS IN THE SOFTWARE.',
+ ' *',
+ ' */',
+ '#ifndef __MINGW_FEATURES__',
+ '#pragma GCC system_header',
+ '',
+ '/* Users are expected to customize this header, but it remains subject to',
+ ' * automatic updates by system software. To ensure that any customisation',
+ ' * is not ovewritten, during such updates, it MUST observe the following:',
+ ' *',
+ ' * This header MUST define __MINGW_FEATURES__; the definition MUST begin',
+ ' * with "#define __MINGW_FEATURES__ (__MINGW_FEATURES_BEGIN__) \\"; it MUST',
+ ' * extend over multiple lines, and terminate with "__MINGW_FEATURES_END__";',
+ ' * intervening lines may enumerate any defined features, one per line, and',
+ ' * each specified as an argument to either the __MINGW_FEATURE_ENABLE__(),',
+ ' * or the __MINGW_FEATURE_IGNORE__() macro, (ensuring that at least one',
+ ' * space separates either of these macro names from its parenthesized',
+ ' * argument name).',
+ ' *',
+ ' * CAUTION:',
+ ' * If customizing this features configuration, ALWAYS refer to features',
+ ' * using their designated symbolic constant names; NEVER usurp the use of',
+ ' * these symbolic constants for any other purpose, and NEVER assume that',
+ ' * any such constant has a specific value ... their definitions may vary',
+ ' * between distinct MinGW Runtime Library software releases!',
+ ' */',
+ '#define __MINGW_FEATURES__ (__MINGW_FEATURES_BEGIN__) \\',
+ ' __MINGW_FEATURE_IGNORE__ (__MINGW_ANSI_STDIO__) \\',
+ ' __MINGW_FEATURE_IGNORE__ (__MINGW_LC_MESSAGES__) \\',
+ ' __MINGW_FEATURE_IGNORE__ (__MINGW_LC_ENVVARS__) \\',
+ ' __MINGW_FEATURES_END__',
+ '',
+ '#endif /* !__MINGW_FEATURES__: $'..'RCSfile$: end of file */'
+ }
+--
+ local function defines( name )
+--
+-- A local helper function, to generate a string.match
+-- pattern for identification of any C #define statement,
+-- which defines a specified symbol "name"
+--
+ return "^%s*#%s*define%s+" .. name
+ end
+--
+ local function feature( value )
+--
+-- A local helper function, to generate a string.match
+-- pattern for identification of a specified parenthesized
+-- value field, within a C #define statement.
+--
+ return "%s+%(%s*" .. value .. "%s*%)%s*"
+ end
+--
+ local function begins_definition( line, name, value )
+--
+-- A local helper function to check whether any input "line"
+-- represents the first of a multiline C #define for the "name"
+-- symbol, with its initial field matching the parenthesized
+-- "value" token (default: "__MINGW_FEATURES_BEGIN__").
+--
+ if not value then value = "__MINGW_FEATURES_BEGIN__" end
+ return string.match( line, defines( name ) .. feature( value ) .. "\\$" )
+ end
+--
+-- In the event that a features configuration has already been
+-- specified for this installation, capture this into internal
+-- "as built" configuration tables...
+--
+ local current_config, current_features
+ local config = io.open( config_file_name )
+ if config
+ then
+-- ...always starting collection into table "current_config"...
+--
+ current_config = {}
+ local active_list = current_config
+--
+-- ...reading the existing configuration file, line by line...
+--
+ for line in config:lines()
+ do if active_list == current_features
+ and string.match( line, "^%s*__MINGW_FEATURES_END__%s*$" )
+ then
+-- ...noting that actual configuration options will have
+-- been diverted to the "current_features" table; when all
+-- such options have been captured, redirect any residual
+-- content to the "current_config" table.
+--
+ active_list = current_config
+ end
+--
+-- Capture the current configuration record, into whichever
+-- diversion is currently active.
+--
+ table.insert( active_list, line )
+--
+ if begins_definition( line, "__MINGW_FEATURES__" )
+ then
+-- When we find the first line of a (possibly) well-formed
+-- features configuration, divert capture of its subsequent
+-- lines to a new "current_features" table.
+--
+ current_features = {}
+ active_list = current_features
+ end
+ end
+--
+-- When capture is complete, ensure that the input stream file
+-- is closed; (we may want to reopen it later, to rewrite it).
+--
+ io.close( config )
+--
+-- Before we go any further, check for well-formedness of the
+-- configuration which we have just captured; effectively...
+--
+ if not current_features
+ or active_list == current_features
+ then
+-- ...when no "current_features" diversion has been created,
+-- or such a diversion remains open for capture, then an error
+-- has occurred, and the configuration is not well-formed.
+--
+ local function config_error( reason )
+ error( config_file_name .." ".. reason, 0 )
+ end
+ for ref, line in next, current_config
+ do if string.match( line, defines( "__MINGW_FEATURES__" ) )
+ then
+-- In this case, a "__MINGW_FEATURES__" definition is
+-- present, but it is not well-formed; (note that, here,
+-- we rescan the "current_config" table, using a less
+-- rigorous criterion for detection of a definition of
+-- of "__MINGW_FEATURES__" than that which is required
+-- to open the "current_features" diversion)...
+--
+ config_error( "has malformed __MINGW_FEATURES__ definition" )
+ end
+ end
+-- ...while in this case, no "__MINGW_FEATURES__" definition
+-- was found, (well-formed, or otherwise).
+--
+ config_error( "does not define __MINGW_FEATURES__" )
+ end
+ end
+--
+--
+ local function update_configuration( stream_file, template, current )
+--
+-- A function to write a features configuration to a designated output
+-- stream, based on a specified template, reproducing and encapsulating
+-- any existing configuration which may also have been specified...
+--
+ local function stream_file_writeln( line )
+--
+-- ...using this helper function to write each line.
+--
+ stream_file:write( line .. "\n" )
+ end
+--
+ if current
+ then
+-- An existing configuration header is to be updated. An image of
+-- its original content has already been loaded into "current"; copy
+-- it back to the original file, line by line...
+--
+ for ref, line in next, current
+ do if begins_definition( line, "__MINGW_FEATURES__" )
+ then
+-- ...until we reach the first active configuration record.
+-- We now wish to merge any new configuration options from the
+-- template, into the existing configuration; work through the
+-- template, line by line, ignoring all lines...
+--
+ local merge = false
+ for ref, sub in next, template
+ do if begins_definition( sub, "__MINGW_FEATURES__" )
+ then
+-- ...until we find the first line of a (possibly)
+-- well-formed features configuration record; when we
+-- find this, we decompose and reassemble it, so that
+-- we may preserve a tabulation format matching the
+-- longer of the template and actual configuration
+-- records.
+--
+ local def = string.match( sub, "^[^(]*" )
+ local usr = string.match( line, "^[^(]*" )
+ if string.len( usr ) > string.len( def )
+ then
+ def = usr
+ end
+ usr = string.match( line, "%(.*" )
+ sub = string.match( sub, "%(.*" )
+ if string.len( usr ) > string.len( sub )
+ then
+ sub = usr
+ end
+--
+-- Write out the reassembled features configuration
+-- start record, and activate the features merge.
+--
+ stream_file_writeln( def .. sub )
+ merge = true
+--
+-- During the merge operation, when we find the record
+-- terminator within the template...
+--
+ elseif string.match( sub, "^%s*__MINGW_FEATURES_END__%s*$" )
+ then
+-- ...we immediately write out any additional option
+-- specifications, which remain in the user specified
+-- configuration...
+--
+ for ref, sub in next, current_features
+ do
+ stream_file_writeln( sub )
+ end
+--
+-- ...and break out of the merge cycle.
+--
+ break
+--
+ elseif merge
+ then
+-- While we remain within the merge cycle, we extract
+-- the identification of each configuration option from
+-- the template, comparing it with all entries in the
+-- "current_features" table...
+--
+ tag = string.match( sub, "%(.*%)" )
+ for ref, usr in next, current_features
+ do if string.match( usr, tag )
+ then
+--
+-- ...and, when we find a match, we favour the
+-- existing configuration record over that from
+-- the template...
+--
+ sub = usr
+--
+-- ...remove the corresponding entry from the
+-- "current_features" table, and break out of
+-- the inner matching loop, before...
+--
+ table.remove( current_features, ref )
+ break
+ end
+ end
+--
+-- ...in either event, writing out a copy of each
+-- selected configuration record.
+--
+ stream_file_writeln( sub )
+ end
+ end
+ else
+--
+-- For every line in the existing configuration file, outside
+-- the scope of the "__MINGW_FEATURES__" definition itself, we
+-- simply write out a verbatim copy of each line.
+--
+ stream_file_writeln( line )
+ end
+ end
+ else
+--
+-- There is no existing configuration header, so we simply reproduce
+-- the template, processing it line by line...
+--
+ for ref, line in next, template
+ do
+-- ...and writing out each line individually.
+--
+ stream_file_writeln( line )
+ end
+ end
+ end
+--
+--
+ function M.pathname( suffix )
+--
+-- An exported utility function, to facilitate identification of
+-- the full MS-Windows path name for the features.h configuration
+-- file, as appropriate to the current installation...
+--
+ if suffix
+ then
+-- ...appending any suffix which may have been specified, (e.g.
+-- to specify a reference to the features.h.sample file)...
+--
+ return config_file_name .. suffix
+ end
+--
+-- ...otherwise, specifying a reference to features.h itself.
+--
+ return config_file_name
+ end
+--
+--
+ function M.initialize( stream_file )
+--
+-- Primary initialization function; overwrites any existing features
+-- configuration header, opened for writing as "stream_file"...
+--
+ if not stream_file
+ then
+-- ...or falling back to "io.stderr", in the event that no output
+-- stream file has been opened...
+--
+ stream_file = io.stdout
+ end
+--
+-- ...replacing any existing configuration with an exact copy of the
+-- "config_default" content specified within this module.
+--
+ update_configuration( stream_file, config_default )
+ end
+--
+--
+ function M.update( stream_file )
+--
+-- Primary API function, exported for use by mingw-get (or any other
+-- client); overwrites any existing configuration header file, which
+-- has been opened for writing as "stream_file"...
+--
+ if not stream_file
+ then
+-- ...or falling back to "io.stderr", in the event that no output
+-- stream file has been opened...
+--
+ stream_file = io.stdout
+ end
+--
+-- ...preserving any existing configuration, with the addition of
+-- any configuration options which have been included in the default
+-- template, but which do not yet appear in the existing header.
+--
+ update_configuration( stream_file, config_default, current_config )
+ end
+--
+-- Since this source file is intended to be loaded as a Lua module, we
+-- must ultimately return a reference handle for it.
+--
+ return M
+--
+-- $RCSfile$: end of file */
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