Improve and harden alt file regeneration

Improvements include:

1. Skip writing a temporary file if the file contents are unchanged
2. Better error reporting if templating program fails
3. Better error reporting/handling if file creation, mv, or chmod fail
4. Quiet logs by not outputing "Creating output..." line twice (debug & loud)
This commit is contained in:
Ross Smith II 2023-10-11 14:10:21 -07:00
parent f163130609
commit 95d7bae7b3
No known key found for this signature in database
GPG Key ID: A05F962FB6A849D2
1 changed files with 86 additions and 43 deletions

129
yadm
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@ -363,7 +363,6 @@ function choose_template_cmd() {
function template_default() {
input="$1"
output="$2"
temp_file="${output}.$$.$RANDOM"
# the explicit "space + tab" character class used below is used because not
# all versions of awk seem to support the POSIX character classes [[:blank:]]
@ -452,7 +451,10 @@ function conditions() {
}
EOF
"${AWK_PROGRAM[0]}" \
local source_dir=$(dirname "$input")
local yadm_classes out
yadm_classes="$(join_string $'\n' "${local_classes[@]}")"
out=$("${AWK_PROGRAM[0]}" \
-v class="$local_class" \
-v arch="$local_arch" \
-v os="$local_system" \
@ -461,20 +463,20 @@ EOF
-v distro="$local_distro" \
-v distro_family="$local_distro_family" \
-v source="$input" \
-v source_dir="$(dirname "$input")" \
-v classes="$(join_string $'\n' "${local_classes[@]}")" \
-v source_dir="$source_dir" \
-v classes="$yadm_classes" \
"$awk_pgm" \
"$input" > "$temp_file" || rm -f "$temp_file"
"$input")
move_file "$input" "$output" "$temp_file"
move_file "$input" "$output" "$out"
}
function template_j2cli() {
input="$1"
output="$2"
temp_file="${output}.$$.$RANDOM"
YADM_CLASS="$local_class" \
local input="$1"
local output="$2"
local yadm_classes out
yadm_classes="$(join_string $'\n' "${local_classes[@]}")"
out=$(YADM_CLASS="$local_class" \
YADM_ARCH="$local_arch" \
YADM_OS="$local_system" \
YADM_HOSTNAME="$local_host" \
@ -482,18 +484,18 @@ function template_j2cli() {
YADM_DISTRO="$local_distro" \
YADM_DISTRO_FAMILY="$local_distro_family" \
YADM_SOURCE="$input" \
YADM_CLASSES="$(join_string $'\n' "${local_classes[@]}")" \
"$J2CLI_PROGRAM" "$input" -o "$temp_file"
YADM_CLASSES="$yadm_classes" \
"$J2CLI_PROGRAM" "$input")
move_file "$input" "$output" "$temp_file"
move_file "$input" "$output" "$out" "$?"
}
function template_envtpl() {
input="$1"
output="$2"
temp_file="${output}.$$.$RANDOM"
YADM_CLASS="$local_class" \
local input="$1"
local output="$2"
local yadm_classes out
yadm_classes="$(join_string $'\n' "${local_classes[@]}")"
out=$(YADM_CLASS="$local_class" \
YADM_ARCH="$local_arch" \
YADM_OS="$local_system" \
YADM_HOSTNAME="$local_host" \
@ -501,19 +503,19 @@ function template_envtpl() {
YADM_DISTRO="$local_distro" \
YADM_DISTRO_FAMILY="$local_distro_family" \
YADM_SOURCE="$input" \
YADM_CLASSES="$(join_string $'\n' "${local_classes[@]}")" \
"$ENVTPL_PROGRAM" --keep-template "$input" -o "$temp_file"
YADM_CLASSES="$yadm_classes" \
"$ENVTPL_PROGRAM" --keep-template "$input")
move_file "$input" "$output" "$temp_file"
move_file "$input" "$output" "$out" "$?"
}
function template_esh() {
input="$1"
output="$2"
temp_file="${output}.$$.$RANDOM"
local input="$1"
local output="$2"
YADM_CLASSES="$(join_string $'\n' "${local_classes[@]}")" \
"$ESH_PROGRAM" -o "$temp_file" "$input" \
local yadm_classes out
yadm_classes="$(join_string $'\n' "${local_classes[@]}")"
out=$("$ESH_PROGRAM" "$input" \
YADM_CLASS="$local_class" \
YADM_ARCH="$local_arch" \
YADM_OS="$local_system" \
@ -521,25 +523,61 @@ function template_esh() {
YADM_USER="$local_user" \
YADM_DISTRO="$local_distro" \
YADM_DISTRO_FAMILY="$local_distro_family" \
YADM_SOURCE="$input"
YADM_SOURCE="$input" \
YADM_CLASSES="$yadm_classes")
move_file "$input" "$output" "$temp_file"
move_file "$input" "$output" "$out" "$?"
}
function move_file() {
local input=$1
local output=$2
local temp_file=$3
local input="$1"
local output="$2"
local new="$3"
local err="${4:-}"
[ ! -f "$temp_file" ] && return
if [[ -s "$input" && -z "$new" ]]; then
debug "Failed to create $output from template $input: error $err"
return 1
fi
# if the output files already exists as read-only, change it to be writable.
# there are some environments in which a read-only file will prevent the move
# from being successful.
[[ -e "$output" && ! -w "$output" ]] && chmod u+w "$output"
if [[ -r "$output" ]]; then
local old
old=$(< "$output")
mv -f "$temp_file" "$output"
copy_perms "$input" "$output"
if [[ "$old" == "$new" ]]; then
debug "Not rewriting file as contents have not changed: $output"
return 0
fi
# if the output files already exists as read-only, change it to be writable.
# there are some environments in which a read-only file will prevent the move
# from being successful.
if [[ ! -w "$output" ]]; then
if ! chmod u+w "$output"; then
debug "Unable to make '$output' writeable"
fi
fi
fi
if [ -n "$loud" ]; then
echo "Creating $output from template $input"
else
debug "Creating $output from template $input"
fi
local temp_file="${output}.$$.$RANDOM"
if printf '%s' "${new}" >"$temp_file"; then
if mv -f "$temp_file" "$output"; then
copy_perms "$input" "$output"
return
fi
debug "Failed to rename '$temp_file' to '$output'"
rm -f "$temp_file" &>/dev/null
else
debug "Failed to create '$temp_file' to generate '$output'"
fi
return 1
}
# ****** yadm Commands ******
@ -707,8 +745,6 @@ function alt_linking() {
template_cmd="${alt_template_cmds[$index]}"
if [ -n "$template_cmd" ]; then
# a template is defined, process the template
debug "Creating $tgt from template $src"
[ -n "$loud" ] && echo "Creating $tgt from template $src"
# ensure the destination path exists
assert_parent "$tgt"
# remove any existing symlink before processing template
@ -2111,7 +2147,7 @@ function get_mode {
# only accept results if they are octal
if [[ ! $mode =~ ^[0-7]+$ ]] ; then
mode=""
return
fi
echo "$mode"
@ -2121,7 +2157,14 @@ function copy_perms {
local source="$1"
local dest="$2"
mode=$(get_mode "$source")
[ -n "$mode" ] && chmod "$mode" "$dest"
if [[ -z "$mode" ]]; then
debug "Unable to get mode for '$source'"
return 1
fi
if ! chmod "$mode" "$dest"; then
debug "Unable to set mode to '$mode' on '$dest'"
return 1
fi
return 0
}