Our in-tree SHA-1 wrappers all define platform_SHA_CTX and related
macros to point at the opaque "context" type, init, update, and similar
functions for each specific implementation.
In hash.h, we use these platform_ variables to set up the function
pointers for, e.g., the_hash_algo->init_fn(), etc.
But while these header files have a header-specific macro that prevents
them declaring their structs / functions multiple times, they
unconditionally define the platform variables, making it impossible to
load multiple SHA-1 implementations at once.
As a prerequisite for loading a separate SHA-1 implementation for
non-cryptographic uses, only define the platform_ variables if they have
not already been defined.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
OpenSSL 3+ deprecates the SHA1_Init, SHA1_Update, and SHA1_Final
functions, leading to errors when building with `DEVELOPER=1'.
Use the newer EVP_* API with OpenSSL 3+ (only) despite being more
error-prone and less efficient due to heap allocations.
Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
