Implements extended -r syntax.

build.sh:buildp_ast(): only reset package build step state if ${ARG_RESET_PKG} is 1.
etc/{build.usage,README.md}: updated.
etc/build.usage.short, subr/build_init.subr: implement short help screen.
midipix.env: correctly escape multi-line variable assignment expressions.
subr.rtl/rtl_list.subr: updated.
subr.rtl/rtl_state.subr:rtl_state_set(): correctly implement invalidation.
subr.rtl/rtl_state.subr:rtl_state_test(): honour `LAST'.
subr/build_init.subr:buildp_init_getopts(): implements --reset-pkg.
subr/build_init.subr:buildp_{expand_restart_{at,recursive},process_restart_spec}(): initial implementation.
subr/ex_pkg_{dispatch,env}.subr: updated.
subr/ex_pkg_exec.subr:ex_pkg_exec(): honour `ALL' and `LAST'.
vars/gcc.vars: updated.

3 files changed, 147 insertions, 46 deletions

diff --git a/etc/README.md b/etc/README.md
index 06e205f7..582a5da6 100644
--- a/etc/README.md
+++ b/etc/README.md
@@ -210,6 +210,12 @@ 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.
+```shell
+./build.sh [ ... ] -r mc,zsh:@install
+```
+  
 Rebuild set of packages along w/ their dependencies, if any, as needed, or forcibly,
 respectively:
 ```shell
@@ -222,10 +228,10 @@ Forcibly rebuild all reverse dependencies of a set of packages:
 ./build.sh [ ... ] -r \*\*\*glib,libflac
 ```
   
-Restart the ``configure``, ``build``, and ``install`` steps of the ``coreutils``
-package:
+Restart the ``@configure``, ``@build``, and ``@install`` (shorthand alias) steps of the
+``coreutils`` package:
 ```shell
-./build.sh -r coreutils:configure,build,install
+./build.sh -r coreutils:@configure,@build,@install
 ```
   
 Rebuild entire build groups including or excluding group dependencies, respectively:
@@ -243,9 +249,9 @@ Rebuild entire build groups including or excluding group dependencies, respectiv
 ```
 usage: ./build.sh [-a nt32|nt64]  [-b debug|release]   [-C dir[,..]]  [-D kind[,..]]
                   [-F ipv4|ipv6|offline]   [-h]   [-p jobs]     [-P]   [-r ALL|LAST]
-                  [-r [*[*[*]]]name[,..][:step,..]] [-R] [-v[v[v[v]]]] [--as-needed]
-                  [--debug-minipix] [--dump-on-abort] [--roar]
-                  [[=]<group>|<variable name>=<variable override>[ ..]]
+                  [-r [*[*[*]]]name[,..][:[^|<|<=|>|>=]step,..]]  [-R] [-v[v[v[v]]]]
+                  [--as-needed] [--debug-minipix] [--dump-on-abort]  [--reset-state]
+                  [--roar]     [[=]<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.
@@ -269,19 +275,31 @@ usage: ./build.sh [-a nt32|nt64]  [-b debug|release]   [-C dir[,..]]  [-D kind[,
 
         -r ALL|LAST       Restart all packages or the last failed package and resume
                           build, resp.
-        -r [*[*[*]]]name[,..][:step,..]
-                          Restart the specified comma-separated package(s) completely or
-                          at optionally specified comma-separated list of build steps.
-
-                          Prepend w/ `*' to automatically include dependencies, `**' to
-                          forcibly rebuild all dependencies, and `***` to forcibly rebuild
-                          all packages that depend on the specified package(s).
+        -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_wget, fetch_git, fetch_extract, configure_patch_pre,
+                          fetch_download, fetch_extract, configure_patch_pre,
                           configure_autotools, configure_patch, configure, build,
                           install_subdirs, install_make, install_files, install_libs,
-                          install, and install_rpm.
+                          install, install_rpm, and clean.
+
+                          Additionally, the following shorthand aliases and pseudo-steps are provided:
+                          @fetch, @configure, @build, @install, and @clean, and
+                          start and finish.
 
         -R                Ignore build failures, skip printing package logs, and continue
                           building (relaxed mode.)
@@ -292,6 +310,7 @@ usage: ./build.sh [-a nt32|nt64]  [-b debug|release]   [-C dir[,..]]  [-D kind[,
         --debug-minipix   Don't strip(1) minipix binaries to facilitate debugging minipix.
         --dump-on-abort   Produce package environment dump files on build failure to be
                           used in conjuction with pkg_shell.sh script (excludes -R.)
+        --reset-state     Reset package build step state on exit.
         <group>[ ..]      One of: dev_packages, dist, host_deps, host_deps_rpm,
                           host_toolchain, host_tools, minipix, native_packages,
                           native_runtime, native_toolchain, native_tools.
@@ -384,26 +403,78 @@ for a list of package build steps and how they are overriden.
 ## 3.5. ``pkgtool.sh``
 
 ```
-usage: ./pkgtool.sh [-a nt32|nt64] [-b debug|release] [-i|-m <dname> -M <dname>|-r|-s|-t] [-v]
-                    [<variable name>=<variable override>[ ..]] 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.
-        -i                    List package variables and dependencies of single named package.
-        -m <dname>            Setup package archives mirror in <dname> and/or
-        -M <dname>            Setup Git repositories mirror in <dname>
-        -r                    List reverse dependencies of single named package.
-        -s                    Enter interactive package build shell environment for single
-                              named package; requires a package dump file. If the package
-                              has not been built yet or built successfully, it will be rebuilt
-                              at build steps up until, by default, the `build' build step and
-                              forcibly aborted and dumped prior to enterting the shell.
-        -t                    Produce tarball of package build root directory and build log
-                              file for the purpose of distribution given build failure.
-        -v                    Increase verbosity.
+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[,..][:[^|<|<=|>|>=]step,..]]  [-R] [-v[v[v[v]]]]
+                  [--as-needed] [--debug-minipix] [--dump-on-abort]  [--reset-state]
+                  [--roar]     [[=]<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           Enables parallelisation at group-level, whenever applicable.
+        -P                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_download, fetch_extract, configure_patch_pre,
+                          configure_autotools, configure_patch, configure, build,
+                          install_subdirs, install_make, install_files, install_libs,
+                          install, install_rpm, and clean.
+
+                          Additionally, the following shorthand aliases and pseudo-steps are provided:
+                          @fetch, @configure, @build, @install, and @clean, and
+                          start and finish.
+
+        -R                Ignore build failures, skip printing package logs, and continue
+                          building (relaxed mode.)
+        -v[v[v[v]]]       Be verbose; -vv: always print package logs; -vvv: set xtrace
+                          during package builds; -vvvv: logs fileops.
+        --as-needed       Don't build unless the midipix_build repository has received
+                          new commits.
+        --debug-minipix   Don't strip(1) minipix binaries to facilitate debugging minipix.
+        --dump-on-abort   Produce package environment dump files on build failure to be
+                          used in conjuction with pkg_shell.sh script (excludes -R.)
+        --reset-state     Reset package build step state on exit.
+        <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 variable.
+                          Override build or package variable.
 ```
   
 > N.B. When using ``pkgtool.sh`` on a build w/ build variables (see section [4](#4-build-variables))
diff --git a/etc/build.usage b/etc/build.usage
index 1537bb33..aeb775b3 100644
--- a/etc/build.usage
+++ b/etc/build.usage
@@ -1,8 +1,8 @@
 usage: ./build.sh [-a nt32|nt64]  [-b debug|release]   [-C dir[,..]]  [-D kind[,..]]
-                  [-F ipv4|ipv6|offline]   [-h]   [-p jobs]     [-P]   [-r ALL|LAST]
-                  [-r [*[*[*]]]name[,..][:step,..]] [-R] [-v[v[v[v]]]] [--as-needed]
-                  [--debug-minipix] [--dump-on-abort] [--roar]
-                  [[=]<group>|<variable name>=<variable override>[ ..]]
+                  [-F ipv4|ipv6|offline] [-h|--help|  [-p jobs]  [-P]  [-r ALL|LAST]
+                  [-r [*[*[*]]]name[,..][:[^|<|<=|>|>=]step,..]]  [-R] [-v[v[v[v]]]]
+                  [--as-needed] [--debug-minipix] [--dump-on-abort]  [--reset-state]
+                  [--roar]     [[=]<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.
@@ -16,7 +16,7 @@ usage: ./build.sh [-a nt32|nt64]  [-b debug|release]   [-C dir[,..]]  [-D kind[,
                           Force IPv4 (ipv4) or IPv6 (ipv6) when downloading package
                           archives and/or Git repositories or don't download either at all
                           (offline.)
-        -h                Show this screen.
+        -h|--help         Show short/full help screen, respectively.
         -p jobs           Enables parallelisation at group-level, whenever applicable.
         -P                The maximum count of jobs defaults to the number of logical
                           processors on the host system divided by two (2.)
@@ -26,19 +26,31 @@ usage: ./build.sh [-a nt32|nt64]  [-b debug|release]   [-C dir[,..]]  [-D kind[,
 
         -r ALL|LAST       Restart all packages or the last failed package and resume
                           build, resp.
-        -r [*[*[*]]]name[,..][:step,..]
-                          Restart the specified comma-separated package(s) completely or
-                          at optionally specified comma-separated list of build steps.
+        -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 w/ `*' to automatically include dependencies, `**' to
-                          forcibly rebuild all dependencies, and `***` to forcibly rebuild
-                          all packages that depend on the specified package(s).
+                          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_wget, fetch_git, fetch_extract, configure_patch_pre,
+                          fetch_download, fetch_extract, configure_patch_pre,
                           configure_autotools, configure_patch, configure, build,
                           install_subdirs, install_make, install_files, install_libs,
-                          install, and install_rpm.
+                          install, install_rpm, and clean.
+
+                          Additionally, the following shorthand aliases and pseudo-steps are provided:
+                          @fetch, @configure, @build, @install, and @clean, and
+                          start and finish.
 
         -R                Ignore build failures, skip printing package logs, and continue
                           building (relaxed mode.)
@@ -49,6 +61,7 @@ usage: ./build.sh [-a nt32|nt64]  [-b debug|release]   [-C dir[,..]]  [-D kind[,
         --debug-minipix   Don't strip(1) minipix binaries to facilitate debugging minipix.
         --dump-on-abort   Produce package environment dump files on build failure to be
                           used in conjuction with pkg_shell.sh script (excludes -R.)
+        --reset-state     Reset package build step state on exit.
         <group>[ ..]      One of: dev_packages, dist, host_deps, host_deps_rpm,
                           host_toolchain, host_tools, minipix, native_packages,
                           native_runtime, native_toolchain, native_tools.
diff --git a/etc/build.usage.short b/etc/build.usage.short
new file mode 100644
index 00000000..f89b75ff
--- /dev/null
+++ b/etc/build.usage.short
@@ -0,0 +1,17 @@
+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[,..][:[^|<|<=|>|>=]step,..]]  [-R] [-v[v[v[v]]]]
+                  [--as-needed] [--debug-minipix] [--dump-on-abort]  [--reset-state]
+                  [--roar]     [[=]<group>|<variable name>=<variable override>[ ..]]
+
+        -h|--help         Show short/full help screen, respectively.
+        -v[v[v[v]]]       Be verbose; -vv: always print package logs; -vvv: set xtrace
+
+        <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.