[pacman-dev] [PATCH] makepkg: add PACMAN_AUTH configurable setting for sudo elevation

[Eli Schwartz]

On 3/24/21 9:20 PM, Allan McRae wrote:
> On 22/3/21 1:14 pm, Eli Schwartz wrote:
>> If specified, this will be used no matter what. If not, then we check if
>> sudo exists and use that, or else fall back on su.
>>
>> Implements FS#32621
>>
>> Signed-off-by: Eli Schwartz <eschwartz at archlinux.org>
>> ---
>>  doc/makepkg.conf.5.asciidoc |  8 ++++++++
>>  etc/makepkg.conf.in         |  7 +++++++
>>  scripts/makepkg.sh.in       | 13 ++++++++++---
>>  3 files changed, 25 insertions(+), 3 deletions(-)
>>
>> diff --git a/doc/makepkg.conf.5.asciidoc b/doc/makepkg.conf.5.asciidoc
>> index 2c7a54dbf..398529158 100644
>> --- a/doc/makepkg.conf.5.asciidoc
>> +++ b/doc/makepkg.conf.5.asciidoc
>> @@ -278,6 +278,14 @@ Options
>>  	`.tar.lzo`, `.tar.lrz`, `.tar.lz4`, `.tar.lz` and `.tar.Z`, or
>>  	simply `.tar` to disable compression entirely.
>>  
>> +**PACMAN_AUTH=()**::
>> +	Specify a command prefix for running pacman as root. If unset, makepkg will
>> +	check for the presence of sudo(8) and su(1) in turn, and try the first one
>> +	it finds.
>> +	+
>> +	If present, `%q` will be replaced with the shell-quoted form of the command
>> +	to run. Otherwise, the command to run is appended to the auth command.
> 
> I found "%q" a weird choice for the command when reading this, then got
> even more confused with the "printf '%q ' " in the code, which is a
> different %q!   Would %c be better?

I forget why I picked it (but now it seems weird to me too), and don't
much care what we use. Sure.

>>  See Also
>> diff --git a/etc/makepkg.conf.in b/etc/makepkg.conf.in
>> index 43a69df66..fff5b8eb2 100644
>> --- a/etc/makepkg.conf.in
>> +++ b/etc/makepkg.conf.in
>> @@ -147,3 +147,10 @@ COMPRESSLZ=(lzip -c -f)
>>  #
>>  PKGEXT='@PKGEXT@'
>>  SRCEXT='@SRCEXT@'
>> +
>> +#########################################################################
>> +# OTHER
>> +#########################################################################
>> +#
>> +#-- Command used to run pacman as root, instead of trying sudo and su
>> +PACMAN_AUTH=()
>> diff --git a/scripts/makepkg.sh.in b/scripts/makepkg.sh.in
>> index f4a2de7d4..a0cd1a4fb 100644
>> --- a/scripts/makepkg.sh.in
>> +++ b/scripts/makepkg.sh.in
>> @@ -225,15 +225,22 @@ missing_source_file() {
>>  }
>>  
>>  run_pacman() {
>> -	local cmd
>> +	local cmd cmdescape
>>  	if [[ $1 = -@(T|Q)*([[:alpha:]]) ]]; then
>>  		cmd=("$PACMAN_PATH" "$@")
>>  	else
>>  		cmd=("$PACMAN_PATH" "${PACMAN_OPTS[@]}" "$@")
>> -		if type -p sudo >/dev/null; then
>> +		cmdescape="$(printf '%q ' "${cmd[@]}")"
>> +		if (( ${#PACMAN_AUTH[@]} )); then
>> +			if in_array '%q' "${PACMAN_AUTH[@]}"; then
>> +				cmd=("${PACMAN_AUTH[@]/\%q/$cmdescape}")
>> +			else
>> +				cmd=("${PACMAN_AUTH[@]}" "${cmd[@]}")
>> +			fi
>> +		elif type -p sudo >/dev/null; then
> 
> Can we just put sudo in PACMAN_PATH in our makepkg.conf by deafult.
> Then we can get rid of the sudo path and just have su -c as a fallback.
> 
> We probably want a check for the binary at the start of the PACMAN_AUTH
> instead of sudo in scripts/libmakepkg/executable/sudo.sh.in too.

The current implementation was supposed to assume that the users know
what they are doing in setting PACMAN_AUTH to non-default values, and
refrain from second-guessing them by erroring rather than trying su as a
fallback (they explicitly asked for it, don't try something else instead).

sudo is our attempt to gracefully pick our recommended tool
automatically, if needed/available.

That being said, I guess at a minimum, executable_sudo() should not warn
you if:
- sudo is not installed
- PACMAN_AUTH is set to something you installed

>>  			cmd=(sudo "${cmd[@]}")
>>  		else
>> -			cmd=(su root -c "$(printf '%q ' "${cmd[@]}")")
>> +			cmd=(su root -c "$cmdescape")
>>  		fi
>>  		local lockfile="$(pacman-conf DBPath)/db.lck"
>>  		while [[ -f $lockfile ]]; do
>>


-- 
Eli Schwartz
Bug Wrangler and Trusted User

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