util: add specialized github-handler to acquire

notwa-util/Dockerfile

@@ -6,6 +6,7 @@ RUN apk add --no-cache xz
 COPY --chmod=0755 acquire cosmocc dedupe quickconf shed \
     /usr/local/bin/
 RUN ln -s /usr/local/bin /nu
+WORKDIR /media/common
 
 FROM partial as downloader
 # this demonstrates how to use the `acquire` script.
@@ -13,9 +14,8 @@ ENV BUSYBOX_VERSION=1.35.0
 ENV BUSYBOX_SHA256=faeeb244c35a348a334f4a59e44626ee870fb07b6884d68c10ae8bc19f83a694
 RUN --mount=type=cache,id=common,target=/media/common,sharing=locked \
     --mount=type=tmpfs,target=/tmp : \
- && cd /media/common \
  && name=busybox \
- && export remote_fn="$name-$BUSYBOX_VERSION.tar.bz2" \
+ && remote_fn="$name-$BUSYBOX_VERSION.tar.bz2" \
  && export local_fn="$remote_fn" \
  && export remote_url="http://busybox.net/downloads/$remote_fn" \
  && export dest=/root/$name \

notwa-util/acquire

@@ -1,17 +1,75 @@
 #!/usr/bin/env sh
 
 : \
- && die() \
+ && warn() { printf >&2 '\033[1m%s:\033[m %s\n' acquire "$*" ;} \
+ && die() { warn "$@"; exit 64 ;} \
+ && missing()
 { : \
-     && printf '\033[1m%s:\033[m %s\n' acquire "$@" \
+ && [ ${#3} != 0 ] \
-     && exit 64 \
+ || { warn "missing a required $1: $2"; ok=0 ;} \
  ;} \
+ && ok=1 from= repo= commit= checksum= \
+\
+ &&  if [ "$#" != 0 ] \
+    ;then : \
+     && for arg in "$@" \
+        ;do : \
+         && rhs="${arg#*=}" \
+         && a="${arg%"$rhs"}" \
+         && b="${a%=}" \
+         &&  if [ ${#a} = ${#b} ] \
+             || [ ${#b} = 0 ] \
+            ;then : \
+             && warn "ignoring bare argument: $arg" \
+             && continue \
+            ;fi \
+         && lhs="${b#*[!-0-9A-Z_a-z]}" \
+         &&  if [ ${#lhs} != ${#b} ] \
+            ;then : \
+             && warn "ignoring invalid key: $b" \
+             && warn "it became invalid at: ${b#"${b%?"$lhs"}"}" \
+             && continue \
+            ;fi \
+         && case "$lhs" in \
+            (from) from="$rhs" ;; \
+            (repo) repo="$rhs" ;; \
+            (dest) dest="$rhs" ;; \
+            (commit) commit="$rhs" ;; \
+            (checksum) checksum="$rhs" ;; \
+            (*) warn "ignoring unknown key: $lhs" ;; \
+            esac \
+         || exit \
+        ;done \
+     && { [ "${#from}" != 0 ] || die "missing a required key: from" ;} \
+     &&  if [ "$from" = github ] \
+        ;then : \
+         && missing key repo "$repo" \
+         && missing key commit "$commit" \
+         && missing key checksum "$checksum" \
+         && { [ $ok = 1 ] || exit 64 ;} \
+         && username="${repo%%/*}" && project="${repo##*/}" \
+         &&  if [ ".$username/$project" != ".$repo" ] \
+            ;then : \
+             && warn "invalid value for key: repo=$repo" \
+             && die "expected format: repo=username/project" \
+            ;fi \
+         && remote_fn="$commit.tar.gz" \
+         && local_fn="$username!$project-$remote_fn" \
+         && remote_url="https://github.com/$repo/archive/$remote_fn" \
+         && sha256="$checksum" \
+         && { [ "${#dest}" != 0 ] || dest="${repo##*/}" ;} \
+        ;else : \
+         && die "unknown value specified for \"from\": $from" \
+        ;fi \
+     || exit \
+    ;fi \
+\
  && { [ -d "/tmp" ] || die '/tmp must be mounted (or just exist)' ;} \
- && { [ -n "$dest" ] || die 'dest must be set' ;} \
+ && missing variable dest "$dest" \
- && { [ -n "$local_fn" ] || die 'local_fn must be set' ;} \
+ && missing variable local_fn "$local_fn" \
- && { [ -n "$remote_fn" ] || die 'remote_fn must be set' ;} \
+ && missing variable remote_url "$remote_url" \
- && { [ -n "$remote_url" ] || die 'remote_url must be set' ;} \
+ && missing variable sha256 "$sha256" \
- && { [ -n "$sha256" ] || die 'sha256 must be set' ;} \
+ && { [ $ok = 1 ] || exit 64 ;} \
  && { : \
      && printf '%s  %s\n' "$sha256" "$local_fn" | sha256sum -c - >/dev/null 2>&1 \
      || wget -q "$remote_url" -O "$local_fn" \