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Diffstat (limited to 'pkgs/build-support/cc-wrapper/setup-hook-nonlinux.sh')
| -rw-r--r-- | pkgs/build-support/cc-wrapper/setup-hook-nonlinux.sh | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/pkgs/build-support/cc-wrapper/setup-hook-nonlinux.sh b/pkgs/build-support/cc-wrapper/setup-hook-nonlinux.sh new file mode 100644 index 0000000000000..6a913cc4eac72 --- /dev/null +++ b/pkgs/build-support/cc-wrapper/setup-hook-nonlinux.sh @@ -0,0 +1,120 @@ +# CC Wrapper hygiene +# +# For at least cross compilation, we need to depend on multiple cc-wrappers at +# once---specifically up to one per sort of dependency. This follows from having +# different tools targeting different platforms, and different flags for those +# tools. For example: +# +# # Flags for compiling (whether or not linking) C code for the... +# NIX_CFLAGS_COMPILE_FOR_BUILD # ...build platform +# NIX_CFLAGS_COMPILE # ...host platform +# NIX_CFLAGS_COMPILE_FOR_TARGET # ...target platform +# +# Notice that these platforms are the 3 *relative* to the package using +# cc-wrapper, not absolute like `x86_64-pc-linux-gnu`. +# +# The simplest solution would be to have separate cc-wrappers per (3 intended +# use-cases * n absolute concrete platforms). For the use-case axis, we would +# @-splice in 'BUILD_' '' 'TARGET_' to use the write environment variables when +# building the cc-wrapper, and likewise prefix the binaries' names so they didn't +# clobber each other on the PATH. But the need for 3x cc-wrappers, along with +# non-standard name prefixes, is annoying and liable to break packages' build +# systems. +# +# Instead, we opt to have just one cc-wrapper per absolute platform. Matching +# convention, the binaries' names can just be prefixed with their target +# platform. On the other hand, that means packages will depend on not just +# multiple cc-wrappers, but the exact same cc-wrapper derivation multiple ways. +# That means the exact same cc-wrapper derivation must be able to avoid +# conflicting with itself, despite the fact that `setup-hook.sh`, the `addCvars` +# function, and `add-flags.sh` are all communicating with each other with +# environment variables. Yuck. +# +# The basic strategy is: +# +# - Everyone exclusively *adds information* to relative-platform-specific +# environment variables, like `NIX_CFLAGS_COMPILE_FOR_TARGET`, to communicate +# with the wrapped binaries. +# +# - The wrapped binaries will exclusively *read* cc-wrapper-derivation-specific +# environment variables distinguished with with `suffixSalt`, like +# `NIX_CFLAGS_COMPILE_@suffixSalt@`. +# +# - `add-flags`, beyond its old task of reading extra flags stuck inside the +# cc-wrapper derivation, will convert the relative-platform-specific +# variables to cc-wrapper-derivation-specific variables. This conversion is +# the only time all but one of the cc-wrapper-derivation-specific variables +# are set. +# +# This ensures the flow of information is exclusive from +# relative-platform-specific variables to cc-wrapper-derivation-specific +# variables. This allows us to support the general case of a many--many relation +# between relative platforms and cc-wrapper derivations. +# +# For more details, read the individual files where the mechanisms used to +# accomplish this will be individually documented. + +# Skip setup hook if we're neither a build-time dep, nor, temporarily, doing a +# native compile. +# +# TODO(@Ericson2314): No native exception +[[ -z ${strictDeps-} ]] || (( "$hostOffset" < 0 )) || return 0 + +# It's fine that any other cc-wrapper will redefine this. Bash functions close +# over no state, and there's no @-substitutions within, so any redefined +# function is guaranteed to be exactly the same. +ccWrapper_addCVars () { + # See ../setup-hooks/role.bash + local role_post + getHostRoleEnvHook + + if [ -d "$1/include" ]; then + export NIX_CFLAGS_COMPILE${role_post}+=" -isystem $1/include" + fi + + if [ -d "$1/Library/Frameworks" ]; then + export NIX_CFLAGS_COMPILE${role_post}+=" -iframework $1/Library/Frameworks" + fi +} + +# See ../setup-hooks/role.bash +getTargetRole +getTargetRoleWrapper + +# We use the `targetOffset` to choose the right env hook to accumulate the right +# sort of deps (those with that offset). +addEnvHooks "$targetOffset" ccWrapper_addCVars + +# Note 1: these come *after* $out in the PATH (see setup.sh). +# Note 2: phase separation makes this look useless to shellcheck. + +# shellcheck disable=SC2157 +if [ -n "@cc@" ]; then + addToSearchPath _PATH @cc@/bin +fi + +# shellcheck disable=SC2157 +if [ -n "@libc_bin@" ]; then + addToSearchPath _PATH @libc_bin@/bin +fi + +# shellcheck disable=SC2157 +if [ -n "@coreutils_bin@" ]; then + addToSearchPath _PATH @coreutils_bin@/bin +fi + +# Export tool environment variables so various build systems use the right ones. + +export NIX_CC${role_post}=@out@ + +export CC${role_post}=@named_cc@ +export CXX${role_post}=@named_cxx@ +export CC${role_post}=@named_cc@ +export CXX${role_post}=@named_cxx@ + +# If unset, assume the default hardening flags. +: ${NIX_HARDENING_ENABLE="fortify stackprotector pic strictoverflow format relro bindnow"} +export NIX_HARDENING_ENABLE + +# No local scope in sourced file +unset -v role_post |