src/save: Avoid writing CopyFile whenever possible

src/common.bash

@@ -1441,6 +1441,7 @@ function AconfNeedPackageFile() {
 			do
 				if sudo test -d "$dir"
 				then
+					local file
 					sudo find "$dir" -type f -name "$filemask" -not -name '*.sig' -print0 | \
 						while read -r -d $'\0' file
 						do
@@ -1844,6 +1845,21 @@ function SuperCat() {
 	fi
 }
 
+function ChooseHeredocTerminator() {
+	local src="$1" delim=EOF
+
+	while grep -q "^$delim" "$src"; do delim="$delim$delim"; done
+
+	echo $delim
+}
+
+# determine if a file can be inlined into the config when saving
+function AconfIsFileInlinable() {
+	# implicitly inhibit errexit:
+	LC_ALL=C awk '/[\x00-\x09\x0B\x0C\x0E-\x1F\x7F]/{exit 1;}' "$1" && true
+	return $?
+}
+
 if ! ( empty_array=() ; : "${empty_array[@]}" )
 then
 	# Old bash versions treat substitution of an empty array

src/save.bash

@@ -134,6 +134,7 @@ function AconfSave() {
 	then
 		LogEnter 'Found %s new and %s changed files.\n' "$(Color G ${#system_only_files[@]})" "$(Color G ${#changed_files[@]})"
 		printf '\n\n# %s - New / changed files\n\n\n' "$(date)" >> "$config_save_target"
+		local file
 		( Print0Array system_only_files ; Print0Array changed_files ) | \
 			while read -r -d $'\0' file
 			do
@@ -147,7 +148,8 @@ function AconfSave() {
 				# shellcheck disable=SC2174
 				mkdir --mode=700 --parents "$config_dir"/files/"$dir"
 
-				local func args props suffix=''
+				unset func suffix heredoc_src prefix_to_expand # remove the previous values
+				local func suffix heredoc_src prefix_to_expand args=() props=()
 
 				local output_file="$output_dir"/files/"$file"
 				local system_file="$system_dir"/files/"$file"
@@ -185,23 +187,85 @@ function AconfSave() {
 					args=("$file")
 					props=(mode owner group)
 				else
-					local size
-					size=$(LC_ALL=C stat --format=%s "$system_file")
+					local size package
+					size="$(LC_ALL=C stat --format=%s "$system_file")"
+					package="$(pacman -Qoq "$file" 2>/dev/null || true)"
 					if [[ $size -eq 0 ]]
 					then
 						func=CreateFile
+						args=("$file")
+						props=(mode owner group)
 						suffix=' > /dev/null'
 
 						if [[ -h "$output_file" || -e "$output_file" ]]
 						then
 							printf 'RemoveFile %q\n' "$file" >> "$config_save_target"
 						fi
+					elif [[ $(wc -w <<<"$package") -le 1 ]] && AconfIsFileInlinable "$system_file"
+					then
+						AconfNeedProgram diff diffutils n
+						if [[ -n "$package" ]]
+						then
+							AconfNeedPackageFile "$package" >/dev/null
+							function GetOutputFileElsePackageFile() {
+								if [[ -f "$output_file" ]]
+								then
+									cat "$output_file"
+								else
+									AconfGetPackageOriginalFile "$package" "$file"
+								fi
+							}
+							{
+								# the output should contain a quoted command expansion
+								# shellcheck disable=SC2016
+								printf 'patch --no-backup-if-mismatch "$(GetPackageOriginalFile --no-clobber %s %q)" <<"EOF"\n' "$package" "$file"
+ 								diff --unified=5 --label "output/$file" --label "system/$file" \
+									<(GetOutputFileElsePackageFile) "$system_file" || true;
+ 								printf 'EOF\n'
+								# we didn't have to worry about heredoc delimiter collisions because
+								# unified diff lines always begin with space, plus or minus
+							} >> "$config_save_target"
+						elif [[ -f "$output_file" ]]
+						then
+							{
+								# the output should contain a quoted command expansion
+								# shellcheck disable=SC2016
+								printf 'patch --no-backup-if-mismatch "$(CreateFile --no-clobber %q)" <<"EOF"\n' "$file"
+								diff --unified=5 --label "output/$file" --label "system/$file" \
+									"$output_file" "$system_file" || true;
+								printf 'EOF\n'
+								# we didn't have to worry about heredoc delimiter collisions because
+								# unified diff lines always begin with space, plus or minus
+							} >> "$config_save_target"
+						else
+							func=CreateFile
+							args=("$file")
+							props=(mode owner group)
+							prefix_to_expand='cat >'
+ 							if [[ -f "$output_file" ]]
+							then
+								heredoc_src="$output_file"
+							else
+								heredoc_src="$system_file"
+							fi
+							local contents
+							case "$(head -n2 "$heredoc_src" | wc -l)" in
+								0|1)
+									contents=$(<"$heredoc_src")
+									unset heredoc_src
+									prefix_to_expand="printf -- '%s\n' ${contents@Q} >"
+								;;&
+								0)
+									prefix_to_expand="printf -- '%s' ${contents@Q} >"
+								;;
+							esac
+						fi
 					else
 						cp "$system_file" "$config_dir"/files/"$file"
 						func=CopyFile
+						args=("$file")
+						props=(mode owner group)
 					fi
-					args=("$file")
-					props=(mode owner group)
 				fi
 
 				# Calculate the optional function parameters
@@ -220,12 +284,34 @@ function AconfSave() {
 				done
 
 				# Trim redundant blank parameters
-				while [[ -z "${args[-1]}" ]]
+				while [[ "${#args[*]}" -gt 0 && -z "${args[-1]}" ]]
 				do
 					unset 'args[${#args[@]}-1]'
 				done
 
-				printf '%s%s%s\n' "$func" "$(printf ' %q' "${args[@]}")" "$suffix" >> "$config_save_target"
+				if [[ -v func ]]
+				then
+					if [[ -v prefix_to_expand ]]
+					then
+						if [[ -v heredoc_src ]]
+						then
+							local heredoc_delim
+							heredoc_delim="$(ChooseHeredocTerminator "$heredoc_src")"
+							# the output should contain a quoted command expansion
+							# shellcheck disable=SC2016
+							printf '%s "$(%s%s%s)" <<"%s"\n' "$prefix_to_expand" "$func" "$(printf ' %q' "${args[@]}")" "${suffix:-}" "$heredoc_delim"
+							# use sed to enforce trailing newline, via https://unix.stackexchange.com/a/31955
+							# shellcheck disable=SC1003
+							sed -e '$a\' "$heredoc_src"
+							printf '%s\n' "$heredoc_delim"
+						else
+							# shellcheck disable=SC2016
+							printf '%s "$(%s%s%s)"\n' "$prefix_to_expand" "$func" "$(printf ' %q' "${args[@]}")" "${suffix:-}"
+						fi
+					else
+						printf '%s%s%s\n' "$func" "$(printf ' %q' "${args[@]}")" "${suffix:-}"
+					fi >> "$config_save_target"
+				fi
 			done
 		modified=y
 		LogLeave

test/t/t-1_save-2_files-1_stray-1_file.sh

@@ -10,10 +10,8 @@ TestPhase_Run #################################################################
 AconfSave
 
 TestPhase_Check ###############################################################
-TestExpectConfig <<EOF
-CopyFile /strayfile.txt
+TestExpectConfig <<"EOF"
+printf -- '%s' 'Stray file contents' > "$(CreateFile /strayfile.txt)"
 EOF
 
-diff -u "$config_dir"/files/strayfile.txt <(printf "Stray file contents")
-
 TestDone ######################################################################

test/t/t-1_save-2_files-1_stray-5_dirfile.sh

@@ -11,10 +11,9 @@ TestPhase_Run #################################################################
 AconfSave
 
 TestPhase_Check ###############################################################
-TestExpectConfig <<EOF
-CopyFile /dir/strayfile.txt
+TestExpectConfig <<"EOF"
+printf -- '%s' 'Stray file contents' > "$(CreateFile /dir/strayfile.txt)"
 EOF
 
-diff -u "$config_dir"/files/dir/strayfile.txt <(printf "Stray file contents")
 
 TestDone ######################################################################

test/t/t-1_save-2_files-1_stray-6_props.sh

@@ -10,10 +10,8 @@ TestPhase_Run #################################################################
 AconfSave
 
 TestPhase_Check ###############################################################
-TestExpectConfig <<EOF
-CopyFile /strayfile.txt 777 billy wheel
+TestExpectConfig <<"EOF"
+printf -- '%s' 'Stray file contents' > "$(CreateFile /strayfile.txt 777 billy wheel)"
 EOF
 
-diff -u "$config_dir"/files/strayfile.txt <(printf "Stray file contents")
-
 TestDone ######################################################################

test/t/t-1_save-2_files-2_modified-2_skipchecksums_hitdiffsize.sh

@@ -20,8 +20,8 @@ AconfSave
 
 TestPhase_Check ###############################################################
 
-TestExpectConfig <<EOF
-CopyFile /badfile.txt
+TestExpectConfig <<"EOF"
+printf -- '%s' 'Not original file' > "$(CreateFile /badfile.txt)"
 EOF
 
 TestDone ######################################################################

test/t/t-1_save-2_files-2_modified-3_skipchecksums_hitdiffmtime.sh

@@ -20,8 +20,8 @@ AconfSave
 
 TestPhase_Check ###############################################################
 
-TestExpectConfig <<EOF
-CopyFile /badfile.txt
+TestExpectConfig <<"EOF"
+printf -- '%s' 'Another file!' > "$(CreateFile /badfile.txt)"
 EOF
 
 TestDone ######################################################################

test/t/t-1_save-2_files-4_ignored-2_shellpatterns.sh

@@ -33,11 +33,11 @@ TestPhase_Run #################################################################
 AconfSave
 
 TestPhase_Check ###############################################################
-TestExpectConfig <<EOF
-CopyFile /strayfile\ e\ y\ ff.txt
-CopyFile /strayfile-three.txt
-CopyFile /strayfilex.txt
-CopyFile /strayfilez.txt
+TestExpectConfig <<"EOF"
+printf -- '%s' 'Stray file contents' > "$(CreateFile /strayfile\ e\ y\ ff.txt)"
+printf -- '%s' 'Stray file contents' > "$(CreateFile /strayfile-three.txt)"
+printf -- '%s' 'Stray file contents' > "$(CreateFile /strayfilex.txt)"
+printf -- '%s' 'Stray file contents' > "$(CreateFile /strayfilez.txt)"
 EOF
 
 TestDone ######################################################################