[PATCH v12 00/24] Modernize U-Boot shell

Francis Laniel
2023-12-08T22:30:55Z

Hi.

During 2021 summer, Sean Anderson wrote a contribution to add a new shell, based
on LIL, to U-Boot [1, 2].
While one of the goals of this contribution was to address the fact actual
U-Boot shell, which is based on Busybox hush, is old there was a discussion
about adding a new shell versus updating the actual one [3, 4].

So, in this series, with Harald Seiler, we updated the actual U-Boot shell to
reflect what is currently in Busybox source code.
Basically, this contribution is about taking a snapshot of Busybox shell/hush.c
file (as it exists in commit 37460f5da) and adapt it to suit U-Boot needs.

This contribution was written to be as backward-compatible as possible to avoid
breaking the existing.
So, the modern hush flavor offers the same as the actual, that is to say:
1. Variable expansion.
2. Instruction lists (;, && and ||).
3. If, then and else.
4. Loops (for, while and until).
No new features offered by Busybox hush were implemented (e.g. functions).

It is possible to change the parser at runtime using the "cli" command:
=> cli print
old
=> cli set modern
=> cli print
modern
=> cli set old
The default parser is the old one.
Note that to use both parser, you would need to set both
CONFIG_HUSH_MODERN_PARSER and CONFIG_HUSH_OLD_PARSER.

In terms of testing, new unit tests were added to ut to ensure the new behavior
is the same as the old one and it does not add regression.
Nonetheless, if old behavior was buggy and fixed upstream, the fix is then added
to U-Boot [5].
In sandbox, all of these tests pass smoothly:
=> printenv board
board=sandbox
=> ut hush
Running 20 hush tests
...
Failures: 0
=> cli set modern
=> ut hush
Running 20 hush tests
...
Failures: 0

Thanks to the effort of Harald Seiler, I was successful booting a board:
=> printenv fdtfile
fdtfile=amlogic/meson-gxl-s905x-libretech-cc.dtb
=> cli get
old
=> boot
...
root@lepotato:~#
root@lepotato:~# reboot
...
=> cli set modern
=> cli get
modern
=> printenv fdtfile
fdtfile=amlogic/meson-gxl-s905x-libretech-cc.dtb
=> boot
...
root@lepotato:~#

This contribution indeed adds a lot of code and there were concern about its
size [6, 7].
With regard to the amount of code added, the cli_hush_upstream.c is 13030 lines
long but it seems a smaller subset is really used:
gcc -D__U_BOOT__ -E common/cli_hush_upstream.c | wc -l
2870
Despite this, it is better to still have the whole upstream code for the sake of
easing maintenance.
With regard to memory size, I conducted some experiments for version 8 of this
series and for a subset of arm64 boards and found the worst case to be 4K [8].
Tom Rini conducted more research on this and also found the increase to be
acceptable [9].

If you want to review it - your review will really be appreciated - here are
some information regarding the commits:
* commits marked as "test:" deal with unit tests.
* commit "cli: Add Busybox upstream hush.c file." copies Busybox shell/hush.c
into U-Boot tree, this explain why this commit contains around 12000 additions.
* commit "cli: Port Busybox 2021 hush to U-Boot." modifies previously added file
to permit us to use this as new shell.
The really good idea of #include'ing Busybox code into a wrapper file to define
some particular functions while minimizing modifications to upstream code comes
from Harald Seiler.
* commit "cmd: Add new parser command" adds a new command which permits
selecting parser at runtime.
I am not really satisfied with the fact it calls cli_init() and cli_loop() each
time the parser is set, so your reviews would be welcomed.
* Other commits focus on enabling features we need (e.g. if).

Changes since:
v2:
* Added a small fix to compile sandbox with NO_SDL=1.
* Added a command to change parser at runtime.
* Added 2021 parser function to all run_command*().
v3:
* Various bug fixes pointed by the CI.
* Added upstream busybox hush commits until 6th February 2022.
v4:
* Various cleaning.
* Modified python test to accept failure output when the test are designed to
fail.
* Bumped upstream busybox hush commits until 24h March 2022.
v5:
* Bumped upstream busybox hush commits until 30th January 2023.
* Fix how hush interprets '<' and '>', indeed we needed to escape them but I
removed this behavior as tests are handled by test command and not hush
itself. This permitted to have the ut fdt to pass.
* Fix a problem with how exit was handled. This was reported by the ut exit
test.
v6:
* There was no v6 and I got mixed up with version.
v7:
* Bumped upstream busybox hush commits until 9th May 2023.
* Renamed parser command to change parser at runtime to cli and added
documentation.
* Added better separation of patches.
* Removed code about __gnu_thumb1_case_si as it was merged in another series.
* Various cleaning.
v8:
* Bumped upstream busybox hush commits until 25th May 2023.
v9:
* Bumped upstream busybox hush commits until 2nd October 2023.
v10:
* Fixed a build error in commit adding cli command.
* Add new CONFIG_HUSH_SELECTABLE to only build cli command if the two shell
flavors are selected.
v11:
* Renamed everything containing 2021 to modern.
* Fixed cmd Kconfig indentation.
* Set modern parser as default for majority of boards except some.

Francis Laniel (24):
test: Add framework to test hush behavior
test: hush: Test hush if/else
test/py: hush_if_test: Remove the test file
test: hush: Test hush variable expansion
test: hush: Test hush commands list
test: hush: Test hush loops
cli: Add Busybox upstream hush.c file
cli: Port upstream Busybox hush to U-Boot
cli: Add menu for hush parser
global_data.h: add GD_FLG_HUSH_OLD_PARSER flag
cmd: Add new cli command
cli: Enables using modern hush parser as command line parser
cli: hush_modern: Enable variables expansion for modern hush
cli: hush_modern: Add functions to be called from run_command()
cli: add modern hush as parser for run_command*()
test: hush: Fix instructions list tests for modern hush
test: hush: Fix variable expansion tests for modern hush
cli: hush_modern: Enable using < and > as string compare operators
cli: hush_modern: Enable if keyword
cli: hush_modern: Enable loops
test: hush: Fix loop tests for modern hush
cli: modern_hush: Add upstream commits up to 2nd October 2023.
cmd: Set modern hush as default shell
configs: Use old hush for several boards

cmd/Kconfig | 21 +
cmd/Makefile | 2 +
cmd/cli.c | 134 +
common/Makefile | 3 +-
common/cli.c | 82 +-
common/cli_hush_modern.c | 324 +
common/cli_hush_upstream.c | 13030 +++++++++++++++++++++++
configs/kmcent2_defconfig | 1 +
configs/kmcoge5ne_defconfig | 1 +
configs/kmeter1_defconfig | 1 +
configs/kmopti2_defconfig | 1 +
configs/kmsupx5_defconfig | 1 +
configs/kmtepr2_defconfig | 1 +
configs/pg_wcom_expu1_defconfig | 1 +
configs/pg_wcom_expu1_update_defconfig | 1 +
configs/pg_wcom_seli8_defconfig | 1 +
configs/pg_wcom_seli8_update_defconfig | 1 +
configs/socfpga_secu1_defconfig | 1 +
configs/tuge1_defconfig | 1 +
configs/tuxx1_defconfig | 1 +
doc/usage/cmd/cli.rst | 74 +
doc/usage/index.rst | 1 +
include/asm-generic/global_data.h | 8 +
include/cli_hush.h | 51 +-
include/test/hush.h | 15 +
include/test/suites.h | 1 +
test/Makefile | 3 +
test/cmd_ut.c | 6 +
test/hush/Makefile | 10 +
test/hush/cmd_ut_hush.c | 20 +
test/hush/dollar.c | 226 +
test/hush/if.c | 316 +
test/hush/list.c | 140 +
test/hush/loop.c | 91 +
test/py/tests/test_hush_if_test.py | 197 -
test/py/tests/test_ut.py | 8 +-
36 files changed, 14565 insertions(+), 211 deletions(-)
create mode 100644 cmd/cli.c
create mode 100644 common/cli_hush_modern.c
create mode 100644 common/cli_hush_upstream.c
create mode 100644 doc/usage/cmd/cli.rst
create mode 100644 include/test/hush.h
create mode 100644 test/hush/Makefile
create mode 100644 test/hush/cmd_ut_hush.c
create mode 100644 test/hush/dollar.c
create mode 100644 test/hush/if.c
create mode 100644 test/hush/list.c
create mode 100644 test/hush/loop.c
delete mode 100644 test/py/tests/test_hush_if_test.py

Best regards and thank you in advance.
---
[1] https://lists.denx.de/pipermail/u-boot/2021-July/453347.html
[2] https://runtimeterror.com/tech/lil/
[3] https://lists.denx.de/pipermail/u-boot/2021-July/453790.html
[4] https://lists.denx.de/pipermail/u-boot/2021-July/453848.html
[5] https://lists.denx.de/pipermail/u-boot/2021-August/458569.html
[6] https://lists.denx.de/pipermail/u-boot/2023-November/536768.html
[7] https://lists.denx.de/pipermail/u-boot/2023-May/518140.html
[8] https://lists.denx.de/pipermail/u-boot/2023-May/518147.html
[9] https://lists.denx.de/pipermail/u-boot/2023-November/536952.html
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