N.B. If you're interested in building Midipix using this script, please join the project's IRC channel #midipix on Libera and ask for the address of the internal repositories required in order to build Midipix.

N.B. Due to the present state of the (largely) automated package upstream updates integration script and, despite frequent contributions, lack of human resources, it bears mentioning that the 3rd party packages built and distributed by this script are often not up to date with their resp. upstream and may hence be insecure. It is advised that this be taken into account when deploying and using Midipix distributions.

Table of Contents

1. What is Midipix, and how is it different?
2. Building and deployment
   2.1. Building, installing, and using a Midipix distribution
   2.1.1. Build-time dependencies
   2.1.1.1. Alpine-specific notate bene
   2.2. Deployment
   2.3. System requirements
   2.4. Troubleshooting
3. Common concepts and tasks
   3.1. Common tasks
   3.2. Adding a package
   3.3. Addressing build failure
   3.4. Package archive files and Git repositories
   3.5. Patches and vars files
4. Reference
   4.1. Build steps
   4.2. Build variables
   4.3. File installation DSL
   4.4. Package variables
   4.4.1. Package variable types
   4.4.2. Package variables
   4.5. Fault-tolerant & highly optimised 3D laser show-equipped usage screen
   4.6. pkgtool.sh
   4.7. Bourne shell coding rules
5. References

1. What is Midipix, and how is it different?

midipix is a development environment that lets you create programs for Windows using the standard C and POSIX APIs. No compromises made, no shortcuts taken.

If you are interested in cross-platform programming that reclaims the notion of write once, compile everywhere; if you believe that the 'standard' in the C Standard Library should not be a null signifier; and if you like cooking your code without #ifdef hell and low-level minutiae, then this page is for you.

midipix makes cross-platform programming better, simpler and faster, specifically by bringing a modern, conforming C Runtime Library to the Windows platform. While the idea itself is not new, the approach taken in midipix to code portability is radically different from that found in other projects.

(reproduced from [2])

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2. Building and deployment

2.1. Building, installing and using a Midipix distribution

A Midipix distribution consists of the following:

• the native Midipix toolchain, consisting of perk, gcc, its dependencies, and binutils,
• musl, a lightweight, fast, simple, and free libc[1] used by Midipix,
• the Midipix runtime components that bridge the gap between the libc and the executive subsystems of all Windows NT-derived Windows OS starting with and including Windows XP, and
• a steadily increasing number of 3rd party open source packages, as expected in any modern POSIX-compliant *nix environment, including GNU coreutils, shells, libraries such as ncurses, libressl, as well as Perl and Python.

Install the build-time dependencies listed in section 2.1.1, clone this repository (e.g. git clone https://dev.midipix.org/build/midipix_build) and run the following command line:

./build.sh -a nt64 -b release -D zipdist -P -v

By default, the build will take place within ${HOME}/midipix/nt64/release and package archive files and/or Git repositores will be downloaded into ${HOME}/midipix/dlcache. Consult sections 4.2 and 4.4 for the list of available build/package variables and how to override them.
Parallelisation is enabled by the above command line for both packages that can be built independently of each other and make(1) via -j, limited to the amount of logical processors on the build host divided by two (2).

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2.1.1. Build-time dependencies

• Alpine Linux: binutils bison bzip2 cmake coreutils curl findutils g++ gawk gcc git grep gzip libc-dev linux-headers lzip m4 make musl-dev net-tools patch perl perl-xml-parser procps sed tar util-linux wget xz zip
• Arch Linux: binutils bison bzip2 cmake coreutils curl findutils gawk gcc git grep gzip lzip m4 make net-tools patch perl perl-xml-parser procps-ng sed tar util-linux wget xz zip
• Debian/-derived Linux: binutils bison bzip2 cmake coreutils curl findutils g++ gawk gcc git grep gzip hostname libc6-dev libxml-parser-perl lzip m4 make patch perl procps sed tar util-linux wget xz-utils zip
• Gentoo Linux: binutils bison bzip2 cmake coreutils curl findutils gawk =gcc-7.5.0-r1 dev-vcs/git grep gzip lzip m4 make patch perl dev-perl/XML-Parser procps sed tar util-linux wget xz-utils zip
• OpenSUSE Linux: binutils bison bzip2 cmake coreutils curl findutils gawk gcc gcc-c++ git grep gzip hostname linux-glibc-devel lzip m4 make patch perl perl-XML-Parser procps sed tar util-linux wget xz zip

The distro matrix:

N.B. Busybox is not supported. Awk implementations other than GNU Awk are not supported.

N.B. clang is not supported.

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2.1.1.1. Alpine-specific notate bene

Some packages (coreutils, grep, and tar, among others) override Alpine's BusyBox utilities of the same name, as the latter are either non-conformant or defective.

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2.2. Deployment

On successful completion of the build, a ZIP archive containing the Midipix distribution will be created inside ${PREFIX} (see section 4.2.) Create a directory on the target machine and extract the contents of the distribution ZIP archive into it, run bash.bat, and then /install.sh inside the resulting self-contained Midipix installation shell window.

Make sure to consult the notate bene below:

N.B. The pathname of the target directory containing bash.bat and all other distribution files must not contain whitespaces.

N.B. The Midipix installer defaults to /dev/fs/c/midipix (C:\midipix). If left unchanged, the distribution ZIP archive must not be extracted into a directory of the same pathname.

N.B. The user installing and using Midipix must have been delegated the SeCreateSymbolicLinkPrivilege ("Create symbolic links") privilege[3] and additionally be a non-administrator account owing to the UAC-related filtering policy of tokens introduced by Windows Vista[4].

N.B. On Windows 10 and 11, Windows Defender as well as SmartScreen must be disabled.

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2.3. System requirements

The following build-time system requirements are assessed on build hosts equipped with the following hardware at minimum:

• Intel(R) Xeon(R) CPU W3520 @ 2.67GHz (8 cores)
• 7200 RPM SATA 3.1 HDD
• 6 GB RAM

Package archive files and/or Git repositories additionally consume at least 1.82 GB.

(last update: Thu, 05 Mar 2020 09:25:41 +0000)

These are the Midipix distribution disk space system requirements:

The installation directory and archive file may be safely deleted post-installation.

(last update: Thu, 07 Jan 2021 18:20:06 +0000)

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2.4. Troubleshooting

Midipix presently provides, inter alia, strace-like functionality via ntctty's logging capabilities. This is available both through the regular strace(1) command as distributed, which however must be provided with an absolute pathname without consideration for ${PATH}, as well as directly via ntctty.exe for a session by running ntctty.exe with the --log-level 7 option, e.g.:

$ #strace ls -la /        # (incorrect, relative pathname)
$ strace /bin/ls -la /    # (correct, absolute pathname)
$ ntctty.exe --log-level 7 -e /bin/ls -la /
$ ntctty.exe --log-level=7 -e /bin/ls -la /
$ ntctty.exe --log-level 7 -e /bin/sh -c "ls -la /"
$ ntctty.exe --log-level=7 -e /bin/sh -c "ls -la /"

By default, ntctty.exe log files are written into the /var/log/ntctty directory; this may be adjusted with the --log-dir and/or --log-file options. strace(1) logs to stderr by default.

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3. Common concepts and tasks

3.1. Common tasks

Rebuild set of packages in isolation:

./build.sh [ ... ] -r mc,zsh

Restart the @install (shorthand alias) step, with implicit finish, of the mc and zsh packages.

./build.sh [ ... ] -r mc,zsh:@install

Rebuild set of packages along w/ their dependencies, if any, as needed, or forcibly, respectively:

./build.sh [ ... ] -r \*mc,zsh
./build.sh [ ... ] -r \*\*mc,zsh

Forcibly rebuild all reverse dependencies of a set of packages:

./build.sh [ ... ] -r \*\*\*glib,libflac

Restart the @configure, @build, and @install (shorthand alias) steps of the coreutils package:

./build.sh -r coreutils:@configure,@build,@install

Rebuild entire build groups including or excluding group dependencies, respectively:

./build.sh [ ... ] -r ALL native_runtime
./build.sh [ ... ] -r ALL =native_runtime

Forcibly (re)download all archive files and/or Git repositories associated with all packages:

./build.sh [ ... ] -r ALL:@fetch

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3.2. Adding a package

Packages are grouped into build groups according to sets of common package variable defaults, such as ${PKG_CFLAGS_CONFIGURE}, ${PKG_LDFLAGS_CONFIGURE} and ${PKG_CONFIGURE_ARGS}, and semantic interrelatedness, such as the native_runtime build group comprising the Midipix runtime components. Packages may belong to more than one build group such as when subsumed by a shorthand build group e.g. the dev_packages build group, as long as the default set of build groups or as overriden on the command line does not entail group membership conflicts.

Build groups files beneath groups/ named [0-9][0-9][0-9].<group name>.group contain package variable defaults, the alphabetically sorted list of contained packages in <upper case group name>_PACKAGES, and their package variables sorted alphabetically with the exception of ${PKG_DEPENDS} (if present,) ${PKG_SHA256SUM}, ${PKG_URL}, and ${PKG_VERSION}, and/or ${PKG_URLS_GIT}, which are specified in this order.

Pick a build group according to the criteria mentioned, add the package to the build group's list of contained packages in its corresponding file, and add the set of package variables required (see above and section 4.4.)
Consult section 3.5 if the package to be added requires patches or additional code amending or replacing package build steps or the entire package build. Consult section 4.1 for a list of package build steps and how they are overriden.

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3.3. Addressing build failure

During package build, standard error and output are redirected into a log file beneath ${BUILD_WORKDIR} named ${PKG_NAME}_stderrout.log, following a package variable dump. If -V build was specified, package logs will additionally be printed to standard output. If -V xtrace was specified, xtrace will be set during package builds for rudimentary debugging purposes. Additionally, packages using GNU autotools will, if package configuration failed or appears relevant, log the configuration process in detail in, most usually, ${PKG_BUILD_DIR}/config.log.

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3.4. Package archive files and Git repositories

Packages may have either or both of a SHA-256 message digest checked and to be extracted tarball (set in ${PKG_URL}, ${PKG_FNAME}, and ${PKG_SHA256SUM}) and/or Git repository or set thereof (set in ${PKG_URLS_GIT}.) Complementing these, an implicitly inferred or, in the presence of both, explicit primary source directory is specified for each package in ${PKG_SUBDIR}. Furthermore, these may be subject to download caching and/or setting up as well as maintaining mirrors, including automatic cleanup as well as deduplication in both cases.

A list of pertinent package variables and their formats follows:

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3.5. Patches and vars files

Package patches are applied prior and/or subsequent to (GNU autotools or similar) package configuration during the configure_patch_pre and/or configure_patch build steps, respectively (see section 4.1.) Patch files are searched for beneath patches/ with the following globs and in-order: * ${PKG_NAME}-${PKG_VERSION}_pre.local.patch or ${PKG_NAME}_pre.local.patch (for packages lacking ${PKG_VERSION}) * ${PKG_NAME}-${PKG_VERSION}_pre.local@${BUILD_HNAME}.patch or ${PKG_NAME}_pre.local@${BUILD_HNAME}.patch (for packages lacking ${PKG_VERSION}) * ${PKG_NAME}/*.patch * ${PKG_NAME}-${PKG_VERSION}.local.patch or ${PKG_NAME}.local.patch (for packages lacking ${PKG_VERSION}) * ${PKG_NAME}-${PKG_VERSION}.local@${BUILD_HNAME}.patch or ${PKG_NAME}.local@${BUILD_HNAME}.patch (for packages lacking ${PKG_VERSION}) * ${PKG_PATCHES_EXTRA} (if set)

If the default set of package build steps does not suffice, such as if additional commands must be executed after package configuration or prior to building, or if an entire or all build step must be replaced, overrides may be specified in the form of functions in the package's vars/${PKG_NAME}.vars vars file. Consult section 4.1 for a list of package build steps and how they are overriden.

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4. Reference

4.1. Build steps

Package builds are divided up into consecutively executed build steps until completion or aborted on failure unless relaxed mode is enabled by passing -R.

Each build step corresponds to a function in the corresponding subr/pkg_*.subr script and may be overriden entirely by a function named pkg_<package name>_<build step>() or composed in terms of prior and/or subsequent execution by a function named pkg_<package name>_<build step>_pre() and/or pkg_<package name>_<build step>_post(), respectively, in the package's vars file. If a function named pkg_<package name>_all() exists, it will override all build steps.

Build step functions receive the following arguments in the order specified:

Build step status is tracked on a per-package basis by state files beneath ${BUILD_WORKDIR} following the format .<package name>.<build step>; package build completion corresponds to the pseudo-build step finish.

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4.2. Build variables

The following variables are primarily defined in midipix.env and may be overriden on a per-build basis on the command-line, the environment, and/or ${HOME}/midipix_build.vars, ${HOME}/.midipix_build.vars, and/or ../midipix_build.vars, e.g.:

./build.sh -a nt64 -b release -D minipix,zipdist -P -v PREFIX_ROOT="${HOME}/midipix_tmp"
env ARCH=nt64 BUILD_KIND=release PREFIX_ROOT="${HOME}/midipix_tmp" ./build.sh -D minipix,zipdist -P -v

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4.3. File installation DSL

File and directory installation, comprising e.g. copying, moving, creating symbolic links, setting owner and/or permission metadata, are expressed in a descriptive domain-specific language and integrated with package building via the package variable ${PKG_INSTALL_FILES_V2}, applying during install_files after the install_make build step, and ${PKG_INSTALL_FILES_DESTDIR} and ${PKG_INSTALL_FILES_DESTDIR_EXTRA} during install_subdirs. The ${PKG_INSTALL_FILES_V2} must adhere to the following syntax specified in EBNF:

(*
SH_GLOB_PATTERN      = any valid portable shell pattern (see sh(1)); superset of PATHNAME
SH_SUBSTRING_PATTERN = any valid portable substring processing shell pattern (see sh(1));
                       superset of PATHNAME
PARAMETER            = any valid portable shell variable name except that [0-9] may occur
                       the beginning
PATHNAME             = any valid filename, directory name, relative or absolute pathname
                       excluding the characters NUL and NL
 *)

spec                 = { op_flag, } op_unary, "=", op_spec, "\n", { spec } ;
                     | { op_flag, } op_binary, op_spec, "=" op_spec, "\n", { spec } ;
                     | "#" COMMENT ;
op_unary             = "-" | "/" | "t" ;
op_binary            = ":" | "!" | "@" | "+" | "g" | "m" | "o" | "T" ;
op_flag              = "?" ;
op_spec              = pattern_spec | PATHNAME | expr_spec | op_spec ;

pattern_spec         = "%<", SH_GLOB_PATTERN, ">" ;

expr_spec            = "%[", expr, { sexpr_spec }, "%]" ;
expr                 = [ "@" ], "0" .. "9" | "DNAME" | "FNAME" | "ITEM" | PARAMETER ;

sexpr_spec           = sexpr_op_unary, SH_SUBSTRING_PATTERN, { sexpr } ;
sexpr_op_unary       = "##" | "#" | "%%" | "%" ;

Single "=" characters in spec, the "%<" and "%[" character sequences in pattern_spec and expr_spec, resp., and the sexpr_op_unary as well as sexpr_op_binary characters or character sequences may be escaped with a single backslash ("\".) SH_SUBSTRING_PATTERN differs from SH_GLOB_PATTERN solely in that any of sexpr_op_unary and sexpr_op_binary occuring at the beginning of or in the former must be escaped with a single backslash ("\",) e.g. "#\#pattern" and "%\%pattern", etc. and "#pat\%ern" and ``%patt#ern", etc., resp.

Named parameters (PARAMETER) are supplied via the -p name=value argument to rtl_install(), whereas numbered parameters are for internal usage only; the "DNAME", "FNAME", and "ITEM" parameters lazily evaluate to the directory name, file (aka base) name, and full pathname of the current item being processed relative to a specification with a pattern in it.

The following parameters are defined by default during install_files:

The following operation flags are defined:

The following operations are defined:

The following expression modifiers are defined:

The following subexpression operators are defined:

#
# Examples:
# 

#
# Create directory %[_minipix]/bin and copy all files
# in %[_minipix_dist]/bin/ to %[_minipix]/bin/ with
# identical file names.
/=%[_minipix]/bin
?%[_minipix_dist]/bin/%<*>=%[_minipix]/bin/%[FNAME]

#
# Rename all files in share/info/ matching *.info to
# their filenames with the `.info' postfix removed and
# `-2.64.info' appended and all files in share/man/man1/
# matching *.1 with the `.1' postfix removed and -2.64.1
# appended.
!share/info/%<*.info>=share/info/%[FNAME%.info]-2.64.info
!share/man/man1/%<*.1>=share/man/man1/%[FNAME%.1]-2.64.1

#
# Create/update symbolic links named include/ffi.h and
# include/ffitarget.h with ../lib/libffi-3.2.1/include/ffi.h
# and ../lib/libffi-3.2.1/include/ffitarget.h as targets, resp.
@../lib/libffi-3.2.1/include/ffi.h=include/ffi.h
@../lib/libffi-3.2.1/include/ffitarget.h=include/ffitarget.h

#
# Manual invocation:
PKG_INSTALL_FILES_V2="
        [ ... ]
";
rtl_install                                                     \
                -p "_builddir=${PKG_BASE_DIR}/${PKG_BUILD_DIR}" \
                -p "_minipix=${PREFIX_MINIPIX##*/}"             \
                -p "_minipix_dist=${PREFIX}/minipix_dist"       \
                -p "_native=${PREFIX_NATIVE##*/}"               \
                -p "_subdir=${PKG_BASE_DIR}/${PKG_SUBDIR}"      \
                -p "_target=${PKG_TARGET}"                      \
                -n -- "${PREFIX}"                               \
                "${PKG_INSTALL_FILES_V2}"; then
        return 1;
fi;

#
# Usage screen:
usage: rtl_install [-i] [-I ifs] [-n] [-p name=val] [-v] prefix spec_list
       -i...........: continue on soft errors
       -I ifs.......: process spec_list with ifs instead of NL
       -n...........: perform dry run
       -p name=val..: set named parameter
       -v...........: increase verbosity
       prefix.......: pathname prefix
       spec_list....: ifs-separated list of specs

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4.4. Package variables

The following variables are package-specific and receive their value from either top-level defaults defined in midipix.env, build group-specific defaults from the build group the package pertains to and defined in its corresponding file beneath groups/, or package-specific overrides defined either in the latter and/or in its corresponding file beneath vars/, with one of the following prefixes:

Additionally, overrides may be specified on a per-build basis on the command- line, with each variable prefixed w/ PKG_, e.g.: ./build.sh [ ... ] PKG_ZSH_CC="/usr/bin/clang".

The minimum set of package variables that must be provided is SHA256SUM, URL, VERSION and/or URLS_GIT, respectively.

4.4.1 Package variable types

4.4.2 Package variables

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4.5. Fault-tolerant & highly optimised 3D laser show-equipped usage screen

usage: ./build.sh [-a nt32|nt64]  [-b debug|release]    [-C dir[,..]]  [-D kind[,..]]
                  [-F ipv4|ipv6|offline]    [-h|--help] [-p jobs|-P]    [-r ALL|LAST]
                  [-r [*[*[*]]]name[,..][:ALL|LAST|[^|<|<=|>|>=]step,..]]        [-R]
                  [-v] [-V [+]tag|pat[,..]]

                  [--as-needed] [--ccache]  [--debug-minipix]  [--reset-state] [--roar]
                  [--theme theme] [[=]<group>|<variable name>=<variable override>[ ..]]

        -a nt32|nt64        Selects 32-bit or 64-bit architecture; defaults to nt64.
        -b debug|release    Selects debug or release build kind; defaults to debug.
        -C dir[,..]         Clean build directory (build,) ${PREFIX} before processing build
                            scripts (prefix,) source directory (src,) and/or destination
                            directory (dest) after successful package builds.
        -D kind[,..]        Produce minimal midipix distribution directory (minipix,) RPM
                            binary packages (rpm,) and/or deployable distribution ZIP
                            archive (zipdist.) zipdist implies minipix.
        -F ipv4|ipv6|offline
                            Force IPv4 (ipv4) or IPv6 (ipv6) when downloading package
                            archives and/or Git repositories or don't download either at all
                            (offline.)
        -h|--help           Show short/full help screen, respectively.
        -p jobs|-P          Enables parallelisation at group-level, whenever applicable.
                            The maximum count of jobs defaults to the number of logical
                            processors on the host system divided by two (2.)

                            If -R is not specified and at least one (1) package fails to
                            build, all remaining package builds will be forcibly aborted.

        -r ALL|LAST         Restart all packages or the last failed package and resume
                            build, resp.
        -r [*[*[*]]]name[,..][:ALL|LAST|[^|<|<=|>|>=]step,..]
                            Restart the specified comma-separated package(s) w/ inhibition
                            of package build step state resetting completely (`ALL',) starting
                            at the resp. last successfully executed build steps (`LAST',) or the
                            specified comma-separated list of build steps, optionally subject
                            concerning package name(s) and/or build step(s) to the below modifiers:

                            Prepend name w/ `*' to automatically include dependencies, `**'
                            to forcibly rebuild all dependencies, and `***' to forcibly
                            rebuild all packages that depend on the specified package(s).

                            Prepend step w/ `^' to filter build steps with, `<' or `<='
                            to constrain build steps to below or below or equal with, resp.,
                            `>' or `>=' to constrain build steps to above or above or equal
                            with, resp.

                            Currently defined build steps are:
                            fetch_clean, fetch_download, fetch_extract, configure_clean,
                            configure_patch_pre, configure_autotools, configure_patch,
                            configure, build_clean, build, install_clean, install_subdirs,
                            install_make, install_files, install, install_rpm, and clean.

                            Additionally, the following virtual steps are provided:
                            @fetch, @configure, @build, @install, @clean, and finish.

        -R                  Ignore build failures, skip printing package logs, and continue
                            building (relaxed mode.)

        -v                  Increase logging verbosity.
        -V [+]tag|pat[,..]  Enable logging for messages with tag or pattern matching tags of:
                            + (prefix)..: initialise tags with normal verbosity (implies normal) (see etc/build.theme,)
                            all.........: log everything (see etc/build.theme,)
                            clear|none..: log nothing,
                            normal......: log at normal verbosity (see etc/build.theme,)
                            verbose.....: log at increased verbosity (implies normal) (see etc/build.theme) (-v,)

                            build.......: log package build logs,
                            fileops.....: log RTL file operations,
                            install.....: log RTL installation DSL operations,
                            zipdist.....: log deployable distribution ZIP archive operations,
                            xtrace......: set xtrace during package builds,

                            fatal.......: fatal, unrecoverable errors,
                            info........: informational messages,
                            verbose.....: verbose informational messages,
                            warning.....: warning messages possibly relating to imminent fatal, unrecoverable errors,

                            build_*.....: general build messages (viz.: begin, finish, finish_time, vars,)
                            group_*.....: build group messages (viz.: begin, finish,)
                            pkg_*.......: package build messages (viz.: begin, finish, msg, skip, step, strip.)

        --as-needed         Don't build unless the midipix_build repository has received
                            new commits.
        --ccache            Build w/ ccache(1) in $PATH.
        --debug-minipix     Don't strip(1) minipix binaries to facilitate debugging minipix.
        --reset-state       Reset package build step state on exit.
        --theme theme       Set theme.

        <group>[ ..]        One of: dev_packages, dist, host_deps, host_deps_rpm,
                            host_toolchain, host_tools, minipix, native_packages,
                            native_runtime, native_toolchain, native_tools.

                            Prepend w/ `=' to inhibit group-group dependency expansion.

        <variable name>=<variable override>[ ..]
                            Override build or package variable.

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4.6. pkgtool.sh

usage: ./pkgtool.sh [-a nt32|nt64] [-b debug|release] [-i|-m <dname> -M <dname>|-p|-r|-R|-t]
                    [--theme theme] [-v]
                    [<variable name>=<variable override>[ ..]] name[,name..]

        -a nt32|nt64      Selects 32-bit or 64-bit architecture; defaults to nt64.
        -b debug|release  Selects debug or release build kind; defaults to debug.
        -e                Edit package group file of single named package with ${EDITOR}.
        -i                List package variables and dependencies of named package(s).
        -m <dname>        Setup package archives mirror in <dname> and/or
        -M <dname>        Setup Git repositories mirror in <dname>
                          Specify "" or '' as <dname> to default to the defaults in
                          ${HOME}/pkgtool.vars, if present.
        -p <log_fname>    Profile last build.
        -r                List reverse dependencies of single named package.
        -R                List recursive reverse dependencies of single named package.
        -t                Produce tarball of package build root directory and build log
                          file for the purpose of distribution given build failure.
        -v                Increase verbosity.

        <variable name>=<variable override>[ ..]
                          Override build or package variable.

N.B. When using pkgtool.sh on a build w/ build variables (see section 4.2) overriden on the command line or via the environment, ensure that they are included in the pkgtool.sh command line, preceding the package name, or exported, respectively.

N.B. pkgtool.sh will source the ${HOME}/pkgtool.vars file, if present, on startup where the following option arguments may be set: -a nt32|nt64 by setting ARCH=..., -b debug|release by setting BUILD_KIND=..., -m <dname> by setting ARG_MIRROR_DNAME=..., and -M <dname> by setting ARG_MIRROR_DNAME_GIT=....

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4.7. Bourne shell coding rules

If no rationale is specified for any specific point, the rationale is avoidance of undefined behaviour and/or implicit behaviour contingent on often subtle special cases, both of which are prone to cause hard to debug or even diagnose bugs.

Shell options

1) The noglob option is set at all times except for when globbing is required, e.g.: set +o noglob; files=*; set -o noglob 2) The nounset option is set at all times; if a parameter is to be expanded that may be unset, use the ${parameter:-word} expansion format. 3) The errexit option is unset at all times except for top-level subshell code that does not engage in conditional evaluation, e.g. ([...] set -o errexit; [...]) & due to its implicit unsetting when a/any function is subject to conditional evaluation, e.g.: [...] set -o errexit; [...] if some_function; then [ ... ] fi

Quoting and brace-enclosing

4) Quoting with single quotes or double quotes is mandatory at all times except for when field splitting subsequent to parameter expansion, etc. is required, e.g.: params="a b c"; param="single parameter"; fn ${params} "${param}" 5) Enclosing parameter names in braces is mandatory at all times, e.g.: ${parameter_name123}

Checking parameter status

6) Checking for whether a parameter is set/non-empty or unset/empty is expressed with the following the idiom: [ "${parameter:+1}" = 1 ] and [ "${parameter:+1}" != 1 ]

This is necessary to avoid the potentially costly expansion of a parameter's value when only its
status of being set/non-empty or unset/empty is of concern, particularly when this is done repeatedly.

Functions

7) Functions must explicitly return either 0 or 1 at all times except for when specific return exit statuses are specified according to the function's interface contract. 8) Function names must have namespace prefixes followed by a p in the topmost namespace prefix field in private functions, e.g.: rtlp_log_do_something() { [...] } 9) The non-POSIX but extremely widely available local command must be used at at all times in functions on all function-local variables.

This is necessary in order to avoid polluting the (global) parameter namespace.

10) Function-local variables must be lower case and prefixed with a _, a prefix comprised of the initial letters of each word in the function's name plus, in private functions, the p topmost namespace prefix field postfix, and a _, where words are separated by _ characters, e.g.: rtlp_log_do_something() { local _rplds_parameter=""; [...] } and ex_something() { local _es_parameter=""; [ ...] }

This is necessary in order to prevent implicit conflicts between two or more functions that share
a call path and would otherwise use the same variables names, such as `function1() { local
list="${1}"; function2 "${list}"; }; function2() { local list="${2}"; }`, particularly when those
functions acess and/or mutate each other's variables. Additionally, local variables are thus marked
with a `_` prefix and by being lower case.

eval rules

11) The following special characters must be escaped with a backslash at all times in eval expressions: <newline>, ", ', [, \, ], <backtick>, $ 12) If parameter expansion is to be evaluated with respect to a parameter reference, the following idiom must be used at all times: eval [...]\${${rparameter[...]}} 13) If quoting with single quotes or double quotes is required - see 4) - or brace-enclosing - see 5) - and with respect to 11), viz. the single quotes or double quotes have been escaped with a backslash, something must be evaluated as a single field, then that field must be doubly quoted with single or double quotes, where the second set of quotes must not be escaped with a backslash, e.g.: rparameter=parameter; eval ${rparameter}="\"a b c\"". This is very rarely required.

Passing arguments

14) The fork/exec/write-read pattern where a parameter is set to the result of a command substitution expression which is executed in a subshell process, e.g.: parameter="$(function)" is prohibited at all times except when an actual external command is invoked, e.g. sort(1) or sed(1).

This is necessary due to the very significant cost of the mentioned pattern, particularly concerning
primitive e.g. list or string processing functions with high contention.

15) If a function is to return, produce, evaluate to, etc. an arbitrary value apart from the exit status, it shall do so by receiving references to the target variables in the callers' scope from the caller prefixed with a single $ character, e.g. function \$parameter and function() { local _fn_rparameter="${1#\$}"; [..]; } which are then set with eval expressions: function() { local _fn_rparameter="${1#\$}"; [...]; eval ${_fn_rparameter}=\'a b c\'; }; Refer to 11)-13) for the rules concerning eval.

This is necessary due to 14) as well as the absence of any other calling convention other than using
implicit global variables, e.g.: `function1() { VARIABLE=; function2; }; function2() { VARIABLE=1;
}`

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5. References

• Sun, 25 Apr 2016 09:04:08 +0000 [1]musl FAQ
• Wed, 04 Mar 2020 13:36:19 +0000 [2]midipix - what is midipix, and how is it different?
• Wed, 29 Apr 2020 23:33:34 +0100 [3]User Rights Assignment (Windows 10) - Windows security | Microsoft Docs
• Wed, 29 Apr 2020 23:33:50 +0100 [4]Windows Vista Application Development Requirements for User Account Control Compatibility | Microsoft Docs

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