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LibCrypt: Link the SHA2 hash implementation into LibCrypt privately

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Previously, we linked LibCrypt against LibCrypto. This creates a
circular symbol dependency between LibCore, LibCrypto and LibCrypt.
LibCrypto uses Core::DateTime, LibCrypt uses Crypto::SHA2, and LibCore
uses crypt in Core::Account. The GNU toolchain massages the DT_NEEDED
lines of each library and applications that use each library such that
the Loader finds all the symbols as necessary. However, when using the
Clang toolchain, the circular library dependency is not as tolerated.
We get a symbol not found error in the Loader at runtime, and the app in
question crashes.

Now, we build the SHA2.cpp implementation file into LibCrypt using an
object library and `-fvisibility=hidden -fvisibility-hidden-inlines`.
This adds the implementation in a way that only creates STB_LOCAL
symbols and should avoid nasty ODR problems in the future.

An alternative approach to resolving this dependency would be to move
Core::DateTime to AK, or to make Crypto::ASN1::parse_utc_date return a
struct tm instead of a Core::DateTime. One of those approaches to
remove the LibCore dependency from LibCrypto should probabably be
investigated further in the future.

The net effect of removing this circular library dependency is that one
can now build and run the python3 port with the Clang toolchain :^)
This commit is contained in:
Andrew Kaster 2022-01-08 05:55:32 -07:00 committed by Linus Groh
parent 3ff7b76502
commit e687e5ba74
Notes: sideshowbarker 2024-07-17 21:25:20 +09:00 
Author: https://github.com/ADKaster
Commit: https://github.com/SerenityOS/serenity/commit/e687e5ba747
Pull-request: https://github.com/SerenityOS/serenity/pull/11722
Reviewed-by: https://github.com/BertalanD
Reviewed-by: https://github.com/linusg
1 changed files with 9 additions and 1 deletions
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10
Userland/Libraries/LibCrypt/CMakeLists.txt
View file

@ -1,6 +1,14 @@
# HACK ALERT!
# To avoid a circular dependency chain with LibCrypt --> LibCrypto --> LibCore --> LibCrypt
# We include the SHA2 implementation from LibCrypto here manually
add_library(LibCryptSHA2 OBJECT ../LibCrypto/Hash/SHA2.cpp)
set_target_properties(LibCryptSHA2 PROPERTIES CXX_VISIBILITY_PRESET hidden)
set_target_properties(LibCryptSHA2 PROPERTIES VISIBILITY_INLINES_HIDDEN ON)
set(SOURCES
crypt.cpp
)
serenity_libc(LibCrypt crypt)
target_link_libraries(LibCrypt LibC LibCrypto)
target_link_libraries(LibCrypt LibC LibCryptSHA2)