Re: [PATCH v2] scripts/make-gpt.sh: allow setting partition size

[Demi Marie Obenour <demiobenour@gmail.com>]

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On 11/28/25 16:14, Alyssa Ross wrote:
> Demi Marie Obenour <demiobenour@gmail.com> writes:
> 
>> On 11/28/25 08:22, Alyssa Ross wrote:
>>> We want non-minimally-sized partitions to leave space for updates.
>>> All such partitions will also be labelled, so we can just add another
>>> optional field at the end.
>>>
>>> Since we don't parse partition specifications in sh, we can't keep a
>>> running total any more, so instead we just go through the table at the
>>> end and add up all the sizes, taking advantage of our knowledge that
>>> the size will always be the last thing in each line in our tables.
>>>
>>> Signed-off-by: Alyssa Ross <hi@alyssa.is>
>>> Message-ID: <20251127174054.2056835-2-hi@alyssa.is>
>>> ---
>>> v2: fix conflicts after applying Demi's optimization, and avoid awk
>>>     to sum partition sizes, taking inspiration from the same.
>>> v1: https://spectrum-os.org/lists/archives/spectrum-devel/20251127174054.2056835-2-hi@alyssa.is/
>>>
>>>  scripts/make-gpt.sh      | 30 ++++++++++++++++++------------
>>>  scripts/sfdisk-field.awk | 22 +++++++++++++++++-----
>>>  2 files changed, 35 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/scripts/make-gpt.sh b/scripts/make-gpt.sh
>>> index 3cae441..cb19868 100755
>>> --- a/scripts/make-gpt.sh
>>> +++ b/scripts/make-gpt.sh
>>> @@ -1,10 +1,10 @@
>>>  #!/bin/sh -eu
>>>  #
>>> -# SPDX-FileCopyrightText: 2021-2023 Alyssa Ross <hi@alyssa.is>
>>> +# SPDX-FileCopyrightText: 2021-2023, 2025 Alyssa Ross <hi@alyssa.is>
>>>  # SPDX-FileCopyrightText: 2022 Unikie
>>>  # SPDX-License-Identifier: EUPL-1.2+
>>>  #
>>> -# usage: make-gpt.sh GPT_PATH PATH:PARTTYPE[:PARTUUID[:PARTLABEL]]...
>>> +# usage: make-gpt.sh GPT_PATH PATH:PARTTYPE[:PARTUUID[:PARTLABEL[:PARTMiB]]]...
>>>  
>>>  ONE_MiB=1048576
>>>  
>>> @@ -33,21 +33,27 @@ scriptsDir="$(dirname "$0")"
>>>  out="$1"
>>>  shift
>>>  
>>> -nl='
>>> -'
>>> -table="label: gpt"
>>> +table=$(for partition; do
>>> +	awk -f "$scriptsDir/sfdisk-field.awk" \
>>> +		-v partition="$partition" \
>>> +		-v size="$(sizeMiB "${partition%%:*}")"
>>> +done)
>>
>> $(sizeMiB) should be moved into a separate command.  Shellcheck can
>> catch this if you enable SC2312.
> 
> Good catch, thanks.  Feel free to suggest other optional shellcheck
> things we should enable.  (Although I've just noticed
> release/checks/shellcheck.nix doesn't seem to be reading the
> .shellcheckrc file properly so don't use that for testing.)

I'll look later.

>>>  # Keep 1MiB free at the start, and 1MiB free at the end.
>>> -gptBytes=$((ONE_MiB * 2))
>>> -for partition; do
>>> -	sizeMiB="$(sizeMiB "${partition%%:*}")"
>>> -	table="$table${nl}size=${sizeMiB}MiB,$(awk -f "$scriptsDir/sfdisk-field.awk" -v partition="$partition")"
>>> -	gptBytes="$((gptBytes + sizeMiB * ONE_MiB))"
>>> -done
>>> +gptMiB=2
>>> +while read -r partition; do
>>> +	# Here we rely on sfdisk-field.awk always putting size last.
>>> +	: $((gptMiB += ${partition##*=}))
>>> +done <<EOF
>>> +$table
>>> +EOF
>>
>> Nit: should ${partition##*=} be in double quotes?
> 
> I tried changing it, but it is apparently an "arithmetic syntax error"
> to use double quotes here.

I'd use a separate variable then.
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)

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