Add GitHub Actions file health workflow

.github/workflows/file_health.sh

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+#!/usr/bin/env zsh
+
+set -o nounset
+
+# Assumption: file names don't contain `:` (for the `cut` invocation).
+# Safe to assume, as such a character in a filename would cause trouble on Windows, a platform we support
+
+# any regression turn this non-zero
+regressions=0
+
+# exclusions (these are just grep extended regular expressions to match against paths relative to the root of the repository)
+exclusions_nonutf8='(.*(7z|gif|ic(ns|o)|png|qm|zip))'
+exclusions_bom='src/base/unicodestrings.h'
+exclusions_tw='(*.ts)|src/webui/www/private/scripts/lib/mootools-1.2-more.js'
+exclusions_no_lf='(*.ts)|(.*svg)|compile_commands.json|src/webui/www/private/scripts/lib/mootools-1.2-(core-yc.js|more.js)'
+
+echo -e "*** Detect files not encoded in UTF-8 ***\n"
+
+find . -path ./build -prune -false -o -path ./.git -prune -false -o -type f -exec file --mime {} \; | sort \
+    | grep -v -e "charset=us-ascii" -e "charset=utf-8" | cut -d ":" -f 1 \
+    | grep -E -v -e "${exclusions_nonutf8}" \
+    | tee >(echo -e "\n--> Files not encoded in UTF-8: found" "$(wc -l < /dev/stdin)" "regression(s)") \
+    | xargs -I my_input -0 bash -c 'echo "my_input"; test "$(echo -n "my_input" | wc -l)" -eq 0'
+regressions=$((regressions+$?))
+
+echo -e "*** Detect files encoded in UTF-8 with BOM ***\n"
+
+grep --exclude-dir={.git,build} -rIl $'\xEF\xBB\xBF' | sort \
+    | grep -E -v -e "${exclusions_bom}" \
+    | tee >(echo -e "\n--> Files encoded in UTF-8 with BOM: found" "$(wc -l < /dev/stdin)" "regression(s)") \
+    | xargs -I my_input -0 bash -c 'echo "my_input"; test "$(echo -n "my_input" | wc -l)" -eq 0'
+regressions=$((regressions+$?))
+
+echo -e "*** Detect usage of CR byte ***\n"
+
+grep --exclude-dir={.git,build} -rIlU $'\x0D' | sort \
+    | tee >(echo -e "\n--> Usage of CR byte: found" "$(wc -l < /dev/stdin)" "regression(s)") \
+    | xargs -I my_input -0 bash -c 'echo "my_input"; test "$(echo -n "my_input" | wc -l)" -eq 0'
+regressions=$((regressions+$?))
+
+echo -e "*** Detect trailing whitespace in lines ***\n"
+
+grep --exclude-dir={.git,build} -rIl "[[:blank:]]$" | sort \
+    | grep -E -v -e "${exclusions_tw}" \
+    | tee >(echo -e "\n--> Trailing whitespace in lines: found" "$(wc -l < /dev/stdin)" "regression(s)") \
+    | xargs -I my_input -0 bash -c 'echo "my_input"; test "$(echo -n "my_input" | wc -l)" -eq 0';
+regressions=$((regressions+$?))
+
+echo -e "*** Detect too many trailing newlines ***\n"
+
+find . -path ./build -prune -false -o -path ./.git -prune -false -o -type f -exec file --mime {} \; | sort \
+    | grep -e "charset=us-ascii" -e "charset=utf-8" | cut -d ":" -f 1 \
+    | xargs -L1 -I my_input bash -c 'test "$(tail -q -c2 "my_input" | hexdump -C | grep "0a 0a")" && echo "my_input"' \
+    | tee >(echo -e "\n--> Too many trailing newlines: found" "$(wc -l < /dev/stdin)" "regression(s)") \
+    | xargs -I my_input -0 bash -c 'echo "my_input"; test "$(echo -n "my_input" | wc -l)" -eq 0'
+regressions=$((regressions+$?))
+
+echo -e "*** Detect no trailing newline ***\n"
+
+find . -path ./build -prune -false -o -path ./.git -prune -false -o -type f -exec file --mime {} \; | sort \
+    | grep -e "charset=us-ascii" -e "charset=utf-8" |  cut -d ":" -f 1 \
+    | grep -E -v -e "${exclusions_no_lf}" \
+    | xargs -L1 -I my_input bash -c 'test "$(tail -q -c1 "my_input" | hexdump -C | grep "0a")" || echo "my_input"' \
+    | tee >(echo -e "\n--> No trailing newline: found" "$(wc -l < /dev/stdin)" "regression(s)") \
+    | xargs -I my_input -0 bash -c 'echo "my_input"; test "$(echo -n "my_input" | wc -l)" -eq 0'
+regressions=$((regressions+$?))
+
+if [ "$regressions" -ne 0 ]; then
+    regressions=1
+    echo "File health regressions found. Please fix them (or add them as exclusions)."
+else
+    echo "All OK, no file health regressions found."
+fi
+
+exit $regressions;

.github/workflows/file_health.yaml

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+name: GitHub Actions file health check
+
+on:
+  push:
+    branches: [ '**' ]
+  pull_request:
+    types: [edited, opened, reopened, synchronize]
+    branches: [ '**' ]
+
+jobs:
+  check_file_health:
+    name: Check file health
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: checkout repository
+      uses: actions/checkout@v2.3.3
+
+    - name: install zsh
+      run: |
+        sudo apt update
+        sudo apt install zsh
+
+    - name: run check file health script
+      run: |
+        ./.github/workflows/file_health.sh