Merge commit '6455a7f85522fd319caa8cb7cffa93b4ee9ca4b9'

[confetti] / cgilite / storage.sh

diff --git a/cgilite/storage.sh b/cgilite/storage.sh
new file mode 100755 (executable)
index 0000000..355bd56
--- /dev/null
+++ b/cgilite/storage.sh
@@ -0,0 +1,207 @@
+#!/bin/sh
+
+# Copyright 2018, 2019 Paul Hänsch
+#
+# This is a file format helper, part of CGIlite.
+# 
+# CGIlite is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# CGIlite is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+# 
+# You should have received a copy of the GNU Affero General Public License
+# along with CGIlite.  If not, see <http://www.gnu.org/licenses/>. 
+
+[ -n "$include_storage" ] && return 0
+include_storage="$0"
+
+CR="\r"
+BR='
+'
+
+LOCK(){
+  local lock timeout block
+  lock="${1}.lock"
+  timeout="${2-20}"
+  if [ \! -w "${lock%/*}" ] || [ -e "$lock" -a \! -d "$lock" ]; then
+    debug "Impossible to get lock: $lock"
+    return 1
+  fi
+
+  while ! mkdir "$lock" 2>&-; do
+    block="$(cat "$lock/pid" || printf 1)"
+    if ! { ps -eo pid |grep -qwF "$block"; }; then
+      debug "Overriding stale lock: $lock"
+      break
+    fi
+    if [ $timeout -le 0 ]; then
+      debug "Timeout while trying to get lock: $lock"
+      return 1
+    fi
+    timeout=$((timeout - 1))
+    sleep 1
+  done
+  printf '%i\n' $$ >"${lock}/pid"
+  return 0
+}
+
+RELEASE(){
+  local lock
+  lock="${1}.lock"
+  if [ "$(cat "$lock/pid")" = "$$" ]; then
+    rm "$lock/pid"
+    if ! rmdir "$lock"; then
+      debug "Cannot remove tainted lock: $lock"
+      printf '%i\n' $$ >"${lock}/pid"
+      return 1
+    fi
+    return 0
+  else
+    debug "Refusing to release foreign lock: $lock"
+    return 1
+  fi
+}
+
+# STRING='
+#   s;\\;\\\\;g; s;\t;\\t;g;
+#   s;\n;\\n;g;  s;\r;\\r;g;
+#   s;\+;\\+;g;  s; ;+;g;
+# '
+STRING(){
+  local in out=''
+  [ $# -gt 0 ] && in="$*" || in="$(cat)"
+  while [ "$in" ]; do case $in in
+    \\*) out="${out}\\\\"; in="${in#\\}" ;;
+    "$BR"*) out="${out}\\n"; in="${in#${BR}}" ;;
+    "$CR"*) out="${out}\\r"; in="${in#${CR}}" ;;
+    "  "*) out="${out}\\t"; in="${in#  }" ;;
+    +*) out="${out}\\+"; in="${in#+}" ;;
+    " "*) out="${out}+"; in="${in# }" ;;
+    *) out="${out}${in%%[\\${CR}${BR}  + ]*}"; in="${in#"${in%%[\\${BR}${CR}   + ]*}"}" ;;
+  esac; done
+  printf '%s' "$out"
+}
+
+UNSTRING='
+  :UNSTRING_X
+  s;((^|[^\\])(\\\\)*)\\n;\1\n;g;
+  s;((^|[^\\])(\\\\)*)\\t;\1\t;g;
+  s;((^|[^\\])(\\\\)*)\\r;\1\r;g;
+  s;((^|[^\\])(\\\\)*)\+;\1 ;g;
+  tUNSTRING_X;
+  s;((^|[^\\])(\\\\)*)\\\+;\1+;g;
+  s;\\\\;\\;g;
+'
+UNSTRING(){
+  local in out=''
+  [ $# -gt 0 ] && in="$*" || in="$(cat)"
+  while [ "$in" ]; do case $in in
+    \\\\*) out="${out}\\"; in="${in#\\\\}" ;;
+    \\n*) out="${out}${BR}"; in="${in#\\n}" ;;
+    \\r*) out="${out}${CR}"; in="${in#\\r}" ;;
+    \\t*) out="${out}  "; in="${in#\\t}" ;;
+    \\+*) out="${out}+"; in="${in#\\+}" ;;
+    +*) out="${out} "; in="${in#+}" ;;
+    \\*) in="${in#\\}" ;;
+    *) out="${out}${in%%[\\+]*}"; in="${in#"${in%%[\\+]*}"}" ;;
+  esac; done
+  printf '%s' "$out"
+}
+
+DBM() {
+  local file="$1" cmd="$2"
+  local k v key value
+  shift 2;
+
+  case "$cmd" in
+    check|contains)
+      key="$(STRING "$1")"
+      while read -r k v; do if [ "$k" = "$key" ]; then
+        return 0
+      fi; done <"$file" 2>&-
+      return 1
+      ;;
+    get)
+      key="$(STRING "$1")"
+      while read -r k v; do if [ "$k" = "$key" ]; then
+        UNSTRING "$v"
+        return 0
+      fi; done <"$file" 2>&-
+      return 1
+      ;;
+    set|store)
+      key="$(STRING "$1")" value="$(STRING "$2")"
+      LOCK "$file" || return 1
+      { while read -r k v; do
+          [ "$k" = "$key" ] || printf '%s\t%s\n' "$k" "$v"
+        done <"$file" 2>&-
+        printf '%s\t%s\n' "$key" "$value"
+      } >"${file}.$$.tmp"
+      mv "${file}.$$.tmp" "${file}"
+      RELEASE "$file"
+      return 0
+      ;;
+    add|insert)
+      k="$1" key="$(STRING "$1")" value="$(STRING "$2")"
+      LOCK "$file" || return 1
+      if DBM "$file" check "$k"; then
+        RELEASE "$file"
+        return 1
+      else
+        printf '%s\t%s\n' "$key" "$value" >>"${file}"
+        RELEASE "$file"
+        return 0
+      fi
+      ;;
+    update|replace)
+      k="$1" key="$(STRING "$1")" value="$(STRING "$2")"
+      LOCK "$file" || return 1
+      if ! DBM check "$k"; then
+        RELEASE "$file"
+        return 1
+      fi
+      { while read -r k v; do
+          [ "$k" = "$key" ] \
+          && printf '%s\t%s\n' "$key" "$value" \
+          || printf '%s\t%s\n' "$k" "$v"
+        done <"$file" 2>&-
+      } >"${file}.$$.tmp"
+      mv "${file}.$$.tmp" "${file}"
+      RELEASE "$file"
+      return 0
+      ;;
+    append)
+      key="$(STRING "$1")" value="$(STRING "$2")"
+      LOCK "$file" || return 1
+      if ! DBM check "$1"; then
+        RELEASE "$file"
+        return 1
+      fi
+      { while read -r k v; do
+          [ "$k" = "$key" ] \
+          && printf '%s\t%s\n' "$key" "$v$value" \
+          || printf '%s\t%s\n' "$k" "$v"
+        done <"$file" 2>&-
+      } >"${file}.$$.tmp"
+      mv "${file}.$$.tmp" "${file}"
+      RELEASE "$file"
+      return 0
+      ;;
+    delete|remove)
+      key="$(STRING "$1")"
+      LOCK "$file" || return 1
+      { while read -r k v; do
+          [ "$k" = "$key" ] || printf '%s\t%s\n' "$k" "$v"
+        done <"$file" 2>&-
+      } >"${file}.$$.tmp"
+      mv "${file}.$$.tmp" "${file}"
+      RELEASE "$file"
+      return 0
+      ;;
+  esac
+}