[__download] support multiple checksum formats and download utilities, add --onchange and other minor changes

cdist/conf/type/__download/explorer/state

@@ -2,19 +2,71 @@
 
 dst="/$__object_id"
 
-# shellcheck disable=SC2059
+if [ ! -f "$dst" ]
-cmd="$( printf "$( cat "$__object/parameter/cmd-sum" )" "$dst" )"
-
-sum="$( cat "$__object/parameter/sum" )"
-
-if [ -f "$dst" ]
 then
-    if [ "$( eval "$cmd" )" = "$sum" ]
-    then
-        echo 'present'
-    else
-        echo 'mismatch'
-    fi
-else
     echo 'absent'
+    exit 0
+fi
+
+sum_should="$( cat "$__object/parameter/sum" )"
+
+if [ -f "$__object/parameter/cmd-sum" ]
+then
+    # shellcheck disable=SC2059
+    sum_is="$( eval "$( printf \
+        "$( cat "$__object/parameter/cmd-sum" )" \
+        "$dst" )" )"
+else
+    os="$( "$__explorer/os" )"
+
+    if echo "$sum_should" | grep -Eq '^[0-9]+\s[0-9]+$'
+    then
+        sum_is="$( cksum "$dst" | awk '{print $1" "$2}' )"
+
+    elif echo "$sum_should" | grep -Eiq '^md5:[a-f0-9]{32}$'
+    then
+        case "$os" in
+            freebsd)
+                sum_is="md5:$( md5 -q "$dst" )"
+            ;;
+            *)
+                sum_is="md5:$( md5sum "$dst" | awk '{print $1}' )"
+            ;;
+        esac
+
+    elif echo "$sum_should" | grep -Eiq '^sha1:[a-f0-9]{40}$'
+    then
+        case "$os" in
+            freebsd)
+                sum_is="sha1:$( sha1 -q "$dst" )"
+            ;;
+            *)
+                sum_is="sha1:$( sha1sum "$dst" | awk '{print $1}' )"
+            ;;
+        esac
+
+    elif echo "$sum_should" | grep -Eiq '^sha256:[a-f0-9]{64}$'
+    then
+        case "$os" in
+            freebsd)
+                sum_is="sha256:$( sha256 -q "$dst" )"
+            ;;
+            *)
+                sum_is="sha256:$( sha256sum "$dst" | awk '{print $1}' )"
+            ;;
+        esac
+    fi
+fi
+
+if [ -z "$sum_is" ]
+then
+    echo 'no checksum from target' >&2
+    exit 1
+fi
+
+if [ "$sum_is" = "$sum_should" ]
+then
+    echo 'present'
+else
+    echo 'mismatch'
 fi

cdist/conf/type/__download/gencode-local

@@ -9,12 +9,31 @@ fi
 
 url="$( cat "$__object/parameter/url" )"
 
-cmd="$( cat "$__object/parameter/cmd-get" )"
-
 tmp="$( mktemp )"
 
 dst="/$__object_id"
 
+if [ -f "$__object/parameter/cmd-get" ]
+then
+    cmd="$( cat "$__object/parameter/cmd-get" )"
+
+elif command -v wget > /dev/null
+then
+    cmd="wget -O - '%s'"
+
+elif command -v curl > /dev/null
+then
+    cmd="curl -o - '%s'"
+
+elif command -v fetch > /dev/null
+then
+    cmd="fetch -o - '%s'"
+
+else
+    echo 'no usable locally installed utility for downloading' >&2
+    exit 1
+fi
+
 printf "$cmd > %s\n" \
     "$url" \
     "$tmp"
@@ -33,3 +52,5 @@ printf '%s %s %s:%s\n' \
     "$dst"
 
 echo "rm -f '$tmp'"
+
+echo 'downloaded' > "$__messages_out"

cdist/conf/type/__download/gencode-remote

@@ -0,0 +1,7 @@
+#!/bin/sh -e
+
+if [ -f "$__object/parameter/onchange" ] \
+    && grep -Fq "$__object_id:downloaded" "$__messages_in"
+then
+    cat "$__object/parameter/onchange"
+fi

cdist/conf/type/__download/man.rst

@@ -10,7 +10,13 @@ DESCRIPTION
 -----------
 You must use persistent storage in target host for destination file
 (``$__object_id``) because it will be used for checksum calculation
-in order to decide if file must be downloaded.
+in order to decide if file must be (re-)downloaded.
+
+By default type will try to use following locally installed utilities
+for downloading (in order): ``wget``, ``curl`` or ``fetch``.
+
+Environment variables like ``{http,https,ftp}_proxy`` etc can be used on
+cdist execution (``http_proxy=foo cdist config ...``).
 
 
 REQUIRED PARAMETERS
@@ -19,20 +25,29 @@ url
    URL from which to download the file.
 
 sum
-   Checksum of downloaded file.
+   Checksum of file going to be downloaded.
+   By default output of ``cksum`` without filename is expected.
+   Other hash formats supported with prefixes: ``md5:``, ``sha1:`` and ``sha256:``.
+
+onchange
+   Execute this command after download.
 
 
 OPTIONAL PARAMETERS
 -------------------
 cmd-get
    Command used for downloading.
-   Default is ``wget -O- '%s'``.
    Command must output to ``stdout``.
+   Parameter will be used for ``printf`` and must include only one
+   variable ``%s`` which will become URL.
+   For example: ``wget -O - '%s'``.
 
 cmd-sum
    Command used for checksum calculation.
-   Default is ``md5sum '%s' | awk '{print $1}'``.
    Command output and ``--sum`` parameter must match.
+   Parameter will be used for ``printf`` and must include only one
+   variable ``%s`` which will become destination.
+   For example: ``md5sum '%s' | awk '{print $1}'``.
 
 
 EXAMPLES
@@ -45,7 +60,7 @@ EXAMPLES
     require='__directory/opt/cpma' \
         __download /opt/cpma/cnq3.zip \
             --url https://cdn.playmorepromode.com/files/cnq3/cnq3-1.51.zip \
-            --sum 46da3021ca9eace277115ec9106c5b46
+            --sum md5:46da3021ca9eace277115ec9106c5b46
 
     require='__download/opt/cpma/cnq3.zip' \
         __unpack /opt/cpma/cnq3.zip \

cdist/conf/type/__download/parameter/default/cmd-get

@@ -1 +0,0 @@
-wget -O- '%s'

cdist/conf/type/__download/parameter/default/cmd-sum

@@ -1 +0,0 @@
-md5sum '%s' | awk '{print $1}'

cdist/conf/type/__download/parameter/optional

@@ -1,2 +1,3 @@
 cmd-get
 cmd-sum
+onchange