Build flags: Add support for extension builders (#1543394)

This commit is contained in:
Florian Weimer 2018-12-20 11:34:27 +01:00
parent 98ffd5040d
commit e80fa1344a
3 changed files with 61 additions and 1 deletions

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@ -332,3 +332,44 @@ linker flags:
security exploits, redirecting execution). Therefore, it is security exploits, redirecting execution). Therefore, it is
preferable to turn of lazy binding, although it increases startup preferable to turn of lazy binding, although it increases startup
time. time.
# Support for extension builders
Some packages include extension builders that allow users to build
extension modules (which are usually written in C and C++) under the
control of a special-purpose build system. This is a common
functionality provided by scripting languages such as Python and Perl.
Traditionally, such extension builders captured the Fedora build flags
when these extension were built. However, these compiler flags are
adjusted for a specific Fedora release and toolchain version and
therefore do not work with a custom toolchain (e.g., different C/C++
compilers), and users might want to build their own extension modules
with such toolchains.
The macros `%{extension_cflags}`, `%{extension_cxxflags}`,
`%{extension_fflags}`, `%{extension_ldflags}` contain a subset of
flags that have been adjusted for compatibility with alternative
toolchains, while still preserving some of the compile-time security
hardening that the standard Fedora build flags provide.
The current set of differences are:
* No GCC plugins (such as annobin) are activated.
* No GCC spec files (`-specs=` arguments) are used.
Additional flags may be removed in the future if they prove to be
incompatible with alternative toolchains.
Extension builders should detect whether they are performing a regular
RPM build (e.g., by looking for an `RPM_OPT_FLAGS` variable). In this
case, they should use the *current* set of Fedora build flags (that
is, the output from `rpm --eval '%{build_cflags}'` and related
commands). Otherwise, when not performing an RPM build, they can
either use hard-coded extension builder flags (thus avoiding a
run-time dependency on `redhat-rpm-config`), or use the current
extension builder flags (with a run-time dependency on
`redhat-rpm-config`).
As a result, extension modules built for Fedora will use the official
Fedora build flags, while users will still be able to build their own
extension modules with custom toolchains.

16
macros
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@ -57,6 +57,22 @@
FCFLAGS="${FCFLAGS:-%{build_fflags}}" ; export FCFLAGS ; \ FCFLAGS="${FCFLAGS:-%{build_fflags}}" ; export FCFLAGS ; \
LDFLAGS="${LDFLAGS:-%{build_ldflags}}" ; export LDFLAGS LDFLAGS="${LDFLAGS:-%{build_ldflags}}" ; export LDFLAGS
# Internal-only. Do not use. Expand a variable and strip the flags
# not suitable to extension builders.
%__extension_strip_flags() %{lua:
local name = rpm.expand("%{1}")
local value = " " .. rpm.expand("%{build_" .. name .. "}")
local result = string.gsub(value, "%s+-specs=[^%s]+", " ")
print(result)
}
# Variants of CFLAGS, CXXFLAGS, FFLAGS, LDFLAGS for use within
# extension builders.
%extension_cflags %{__extension_strip_flags cflags}
%extension_cxxflags %{__extension_strip_flags cxxflags}
%extension_fflags %{__extension_strip_flags fflags}
%extension_ldflags %{__extension_strip_flags ldflags}
# Deprecated names. For backwards compatibility only. # Deprecated names. For backwards compatibility only.
%__global_cflags %{build_cflags} %__global_cflags %{build_cflags}
%__global_cxxflags %{build_cxxflags} %__global_cxxflags %{build_cxxflags}

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@ -6,7 +6,7 @@
Summary: Red Hat specific rpm configuration files Summary: Red Hat specific rpm configuration files
Name: redhat-rpm-config Name: redhat-rpm-config
Version: 126 Version: 127
Release: 1%{?dist} Release: 1%{?dist}
# No version specified. # No version specified.
License: GPL+ License: GPL+
@ -199,6 +199,9 @@ install -p -m 644 -t %{buildroot}%{_rpmluadir}/fedora/srpm forge.lua
%{_rpmconfigdir}/macros.d/macros.kmp %{_rpmconfigdir}/macros.d/macros.kmp
%changelog %changelog
* Thu Dec 20 2018 Florian Weimer <fweimer@redhat.com> - 127-1
- Build flags: Add support for extension builders (#1543394)
* Mon Dec 17 2018 Panu Matilainen <pmatilai@redhat.com> - 126-1 * Mon Dec 17 2018 Panu Matilainen <pmatilai@redhat.com> - 126-1
- Silence the annoying warning from ldconfig brp-script (#1540971) - Silence the annoying warning from ldconfig brp-script (#1540971)