Hi Rafał,
thanks for taking are of this. Please find some comments below.
Am 2/26/24 um 15:14 schrieb Rafał Miłecki:
From: Jo-Philipp Wich <j...@mein.io>
This allows building uncompressed tar archives from shell scripts (and
compressing them later if needed)
Signed-off-by: Rafał Miłecki <ra...@milecki.pl>
---
package/base-files/files/lib/upgrade/tar.sh | 84 +++++++++++++++++++++
1 file changed, 84 insertions(+)
create mode 100644 package/base-files/files/lib/upgrade/tar.sh
diff --git a/package/base-files/files/lib/upgrade/tar.sh
b/package/base-files/files/lib/upgrade/tar.sh
new file mode 100644
index 0000000000..00057dd760
--- /dev/null
+++ b/package/base-files/files/lib/upgrade/tar.sh
@@ -0,0 +1,84 @@
+# SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+__tar_print_padding() {
+ [ $1 -eq 0 ] || dd if=/dev/zero bs=$1 count=1 2>/dev/null
+}
+
+__tar_make_member() {
+ local name="$1"
+ local content="$2"
+ local username="$3"
+ local groupname="$4"
+ local mtime="$5"
+ local mode=644
I think the uid and gid values should correspond to the given username
and groupname values. Something like this would probably work:
local uid=$(id -u "$username")
local gid=$(sed -rne "s#^$groupname:[^:]*:([0-9]+):.*\$#\1#p" /etc/group)
+ local uid=0
+ local gid=0
+ local size=${#content}
+ local type=0
+ local link=""
+
+ # 100 byte of padding bytes, using 0x01 since the shell does not tolate
null bytes in strings
+ local
pad=$'\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1'
+
+ # validate name
+ if [ "${name:0:1}" = "/" ]; then
+ name="${name:1}"
+ fi
+
+ # truncate string header values to their maximum length
+ name=${name:0:100}
+ link=${link:0:100}
+ username=${username:0:32}
+ groupname=${groupname:0:32}
+
+ # construct header part before checksum field
+ local header1="${name}${pad:0:$((100 - ${#name}))}"
+ header1="${header1}$(printf '%07d\1' $mode)"
+ header1="${header1}$(printf '%07o\1' $uid)"
+ header1="${header1}$(printf '%07o\1' $gid)"
+ header1="${header1}$(printf '%011o\1' $size)"
+ header1="${header1}$(printf '%011o\1' $mtime)"
+
+ # construct header part after checksum field
+ local header2="$(printf '%d' $type)"
+ header2="${header2}${link}${pad:0:$((100 - ${#link}))}"
+ header2="${header2}ustar ${pad:0:1}"
+ header2="${header2}${username}${pad:0:$((32 - ${#username}))}"
+ header2="${header2}${groupname}${pad:0:$((32 - ${#groupname}))}"
+
+ # calculate checksum over header fields
+ local checksum=0
+ for byte in $(printf '%s%8s%s' "$header1" "" "$header2" | tr '\1' '\0' | hexdump
-ve '1/1 "%u "'); do
+ checksum=$((checksum + byte))
+ done
+
+ # print member header, padded to 512 byte
+ printf '%s%06o\0 %s' "$header1" $checksum "$header2" | tr '\1' '\0'
+ __tar_print_padding 183
I checked and noticed that `dd` accepts a `count` value of 0, so we can
inline `__tar_print_padding()` (whose sole purpose was the != 0 check)
and get rid of the extra function:
dd if=/dev/zero bs=183 count=1 2>/dev/null
+
+ # print content data, padded to multiple of 512 byte
+ printf "%s" "$content"
+ __tar_print_padding $((512 - (size % 512)))
Inline this `__tar_print_padding()` as (count may be zero):
dd if=/dev/zero bs=1 count=$((512 - (size % 512))) 2>/dev/null
+}
+
+tar_make_member_from_file() {
+ local name="$1"
+ local username="$(ls -l "$1" | tr -s ' ' | cut -d ' ' -f 3)"
+ local groupname="$(ls -l "$1" | tr -s ' ' | cut -d ' ' -f 4)"
+
+ __tar_make_member "$name" "$(cat $name)" "$username" "$groupname" "$(date +%s -r
"$1")"
+}
+
+tar_make_member_inline() {
+ local name="$1"
+ local content="$2"
+ local username="${3:-root}"
+ local groupname="${4:-root}"
+ local mtime="${5:-$(date +%s)}"
+
+ __tar_make_member "$name" "$content" "$username" "$groupname" "$mtime"
+}
+
+tar_close() {
+ __tar_print_padding 1024
Inline this `__tar_print_padding()` as:
dd if=/dev/zero bs=1024 count=1 2>/dev/null
+}
~ Jo
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