Re: Meson build leaks host 'sh' path to target build when cross-compiled

> On Sun, Feb 09, 2025 at 01:30:27PM +0100, Peter Seiderer wrote:
> [snip]
> >   The meson build tries to execute the non-existent '/usr/bin/sh' (instead of
> >   '/bin/sh' as the autoconf build), 'which sh' on the host returns
> >   '/usr/bin/sh'...
> >
> >   From meson.build
> >
> >    [...]
> >    186 shell = find_program('sh', dirs: program_path)
> >    [...]
> >    685   '-DSHELL_PATH="' + fs.as_posix(shell.full_path()) + '"',
> >
> >   Do not use the result of 'find_program('sh',...)' for '-DSHELL_PATH='
> >   (at least not for cross-compile), use fix '/bin/sh' instead or make it
> >   configurable via a meson option?
>
> Hm, very true. We're mixing up concerns here by treating the build
> environment and the target environment the same.
>
> I guess the proper fix is to wire up the "native:" parameter when we
> call `find_program()`, which allows us to tell Meson whether it should
> find an executable for the build or the target host. And then, for those
> binaries where we actually need to know about both the build and target
> host's locations, we'd end up calling `find_program()` twice.
>
> For executables that are supposed to be used on the target host Meson
> would then know to first consult the cross file, which could look like
> this:
>
>     [binaries]
>     sh = '/target/path/to/sh'
>     perl = '/target/path/to/perl'
>
> Meson would then pick up that file via `meson setup --cross-file
> <CROSSFILE_PATH> <BUILDDIR>`.

>
> The patch should look somewhat like the attached patch, but it conflicts
> with my in-flight patch series at [1]. I'll wait for that series to be
> merged to `next` before sending out the fix.
>
> Thanks for your report!
>
> Patrick
>
> [1]: <20250129-b4-pks-meson-improvements-v1-0-ab709f0be12c@pks.im>
>
> -- >8 --
>
> diff --git a/Documentation/meson.build b/Documentation/meson.build
> index c6117366ff..b033f4a93a 100644
> --- a/Documentation/meson.build
> +++ b/Documentation/meson.build
> @@ -206,9 +206,9 @@ manpages = {
>
>  docs_backend = get_option('docs_backend')
>  if docs_backend == 'auto'
> -  if find_program('asciidoc', dirs: program_path, required: false).found()
> +  if find_program('asciidoc', dirs: program_path, native: true, required: false).found()
>      docs_backend = 'asciidoc'
> -  elif find_program('asciidoctor', dirs: program_path, required: false).found()
> +  elif find_program('asciidoctor', dirs: program_path, native: true, required: false).found()
>      docs_backend = 'asciidoctor'
>    else
>      error('Neither asciidoc nor asciidoctor were found.')
> @@ -216,7 +216,7 @@ if docs_backend == 'auto'
>  endif
>
>  if docs_backend == 'asciidoc'
> -  asciidoc = find_program('asciidoc', dirs: program_path)
> +  asciidoc = find_program('asciidoc', native: true, dirs: program_path)
>    asciidoc_html = 'xhtml11'
>    asciidoc_docbook = 'docbook'
>    xmlto_extra = [ ]
> @@ -245,7 +245,7 @@ if docs_backend == 'asciidoc'
>      asciidoc_conf,
>    ]
>  elif docs_backend == 'asciidoctor'
> -  asciidoctor = find_program('asciidoctor', dirs: program_path)
> +  asciidoctor = find_program('asciidoctor', native: true, dirs: program_path)
>    asciidoc_html = 'xhtml5'
>    asciidoc_docbook = 'docbook5'
>    xmlto_extra = [
> @@ -283,7 +283,7 @@ elif docs_backend == 'asciidoctor'
>    ]
>  endif
>
> -xmlto = find_program('xmlto', dirs: program_path)
> +xmlto = find_program('xmlto', dirs: program_path, native: true)
>
>  cmd_lists = [
>    'cmds-ancillaryinterrogators.txt',
> @@ -404,7 +404,7 @@ if get_option('docs').contains('html')
>      pointing_to: 'git.html',
>    )
>
> -  xsltproc = find_program('xsltproc', dirs: program_path)
> +  xsltproc = find_program('xsltproc', dirs: program_path, native: true)
>
>    user_manual_xml = custom_target(
>      command: asciidoc_common_options + [
> diff --git a/gitweb/meson.build b/gitweb/meson.build
> index 89b403dc9d..88a54b4dc9 100644
> --- a/gitweb/meson.build
> +++ b/gitweb/meson.build
> @@ -1,5 +1,5 @@
>  gitweb_config = configuration_data()
> -gitweb_config.set_quoted('PERL_PATH', perl.full_path())
> +gitweb_config.set_quoted('PERL_PATH', target_perl.full_path())
>  gitweb_config.set_quoted('CSSMIN', '')
>  gitweb_config.set_quoted('JSMIN', '')
>  gitweb_config.set_quoted('GIT_BINDIR', get_option('prefix') / get_option('bindir'))
> diff --git a/meson.build b/meson.build
> index e153a43918..5a5662bc02 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -173,7 +173,7 @@ project('git', 'c',
>    # The version is only of cosmetic nature, so if we cannot find a shell yet we
>    # simply don't set up a version at all. This may be the case for example on
>    # Windows systems, where we first have to bootstrap the host environment.
> -  version: find_program('sh', required: false).found() ? run_command(
> +  version: find_program('sh', native: true, required: false).found() ? run_command(
>      'GIT-VERSION-GEN', meson.current_source_dir(), '--format=@GIT_VERSION@',
>      capture: true,
>      check: true,
> @@ -198,16 +198,18 @@ elif host_machine.system() == 'windows'
>    program_path = [ 'C:/Program Files/Git/bin', 'C:/Program Files/Git/usr/bin' ]
>  endif
>
> -cygpath = find_program('cygpath', dirs: program_path, required: false)
> -diff = find_program('diff', dirs: program_path)
> -git = find_program('git', dirs: program_path, required: false)
> -sed = find_program('sed', dirs: program_path)
> -shell = find_program('sh', dirs: program_path)
> -tar = find_program('tar', dirs: program_path)
> +cygpath = find_program('cygpath', dirs: program_path, native: true, required: false)
> +diff = find_program('diff', dirs: program_path, native: true)
> +git = find_program('git', dirs: program_path, native: true, required: false)
> +sed = find_program('sed', dirs: program_path, native: true)
> +shell = find_program('sh', dirs: program_path, native: true)
> +tar = find_program('tar', dirs: program_path, native: true)
> +
> +target_shell = find_program('sh', dirs: program_path, native: false)
>
>  # Sanity-check that programs required for the build exist.
>  foreach tool : ['cat', 'cut', 'grep', 'sort', 'tr', 'uname']
> -  find_program(tool, dirs: program_path)
> +  find_program(tool, dirs: program_path, native: true)
>  endforeach
>
>  script_environment = environment()
> @@ -758,6 +760,7 @@ endif
>  build_options_config.set_quoted('X', executable_suffix)
>
>  python = import('python').find_installation('python3', required: get_option('python'))
> +target_python = find_program('python3', native: false, required: python.found())
>  if python.found()
>    build_options_config.set('NO_PYTHON', '')
>  else
> @@ -775,7 +778,8 @@ endif
>
>  # Note that we only set NO_PERL if the Perl features were disabled by the user.
>  # It may not be set when we have found Perl, but only use it to run tests.
> -perl = find_program('perl', version: '>=5.8.1', dirs: program_path, required: perl_required)
> +perl = find_program('perl', version: '>=5.8.1', dirs: program_path, native: true, required: perl_required)
> +target_perl = find_program('perl', version: '>=5.8.1', native: false, required: perl.found())
>  perl_features_enabled = perl.found() and get_option('perl').allowed()
>  if perl_features_enabled
>    build_options_config.set('NO_PERL', '')
> @@ -825,7 +829,7 @@ else
>    build_options_config.set('NO_PTHREADS', '1')
>  endif
>
> -msgfmt = find_program('msgfmt', dirs: program_path, required: false)
> +msgfmt = find_program('msgfmt', dirs: program_path, native: true, required: false)
>  gettext_option = get_option('gettext').disable_auto_if(not msgfmt.found())
>  if not msgfmt.found() and gettext_option.enabled()
>    error('Internationalization via libintl requires msgfmt')
> @@ -1954,9 +1958,9 @@ foreach key, value : {
>    'GIT_TEST_TEMPLATE_DIR': meson.project_build_root() / 'templates',
>    'GIT_TEST_TEXTDOMAINDIR': meson.project_build_root() / 'po',
>    'PAGER_ENV': get_option('pager_environment'),
> -  'PERL_PATH': perl.found() ? perl.full_path() : '',
> -  'PYTHON_PATH': python.found () ? python.full_path() : '',
> -  'SHELL_PATH': shell.full_path(),
> +  'PERL_PATH': target_perl.found() ? target_perl.full_path() : '',
> +  'PYTHON_PATH': target_python.found () ? target_python.full_path() : '',
> +  'SHELL_PATH': target_shell.full_path(),
>    'TAR': tar.full_path(),
>    'TEST_OUTPUT_DIRECTORY': test_output_directory,
>    'TEST_SHELL_PATH': shell.full_path(),
> diff --git a/templates/meson.build b/templates/meson.build
> index 1faf9a44ce..986c2e03be 100644
> --- a/templates/meson.build
> +++ b/templates/meson.build
> @@ -1,6 +1,6 @@
>  template_config = configuration_data()
> -template_config.set('PERL_PATH', perl.found() ? fs.as_posix(perl.full_path()) : '')
> -template_config.set('SHELL_PATH', fs.as_posix(shell.full_path()))
> +template_config.set('PERL_PATH', perl.found() ? fs.as_posix(target_perl.full_path()) : '')