Re: [PATCH 7/9] meson: make the CSPRNG backend configurable

diff --git a/meson.build b/meson.build
index 5e1373f6a52a91beb527d00d8fd5c55d377c718b..cb352ce6fd50616e3281a776104692c5b2bfa5b2 100644
--- a/meson.build
+++ b/meson.build

@@ -1325,6 +1325,7 @@ if not meson.is_cross_build() and fs.exists('/dev/tty')

@@ -1421,18 +1422,28 @@ else
   error('Unhandled SHA256 backend ' + sha256_backend)
 endif
 
-if compiler.has_header_symbol('stdlib.h', 'arc4random_buf')
+if csprng_backend in ['auto', 'arc4random'] and compiler.has_header_symbol('stdlib.h', 'arc4random_buf', required: csprng_backend == 'arc4random')
   libgit_c_args += '-DHAVE_ARC4RANDOM'
-elif compiler.has_header_symbol('bsd/stdlib.h', 'arc4random_buf')
+  csprng_backend = 'arc4random'
+elif csprng_backend in ['auto', 'arc4random_bsd'] and compiler.has_header_symbol('bsd/stdlib.h', 'arc4random_buf', required: csprng_backend == 'arc4random_bsd')
   libgit_c_args += '-DHAVE_ARC4RANDOM_BSD'
-elif compiler.has_function('getrandom', prefix: '#include <sys/random.h>')
+  csprng_backend = 'arc4random_bsd'
+elif csprng_backend in ['auto', 'getrandom'] and compiler.has_function('getrandom', prefix: '#include <sys/random.h>', required: csprng_backend == 'getrandom')
   libgit_c_args += '-DHAVE_GETRANDOM'
-elif compiler.has_function('getentropy', prefix: '#include <unistd.h>')
+  csprng_backend = 'getrandom'
+elif csprng_backend in ['auto', 'getentropy'] and compiler.has_function('getentropy', prefix: '#include <unistd.h>', required: csprng_backend == 'getentropy')
   libgit_c_args += '-DHAVE_GETENTROPY'
-elif compiler.has_function('RtlGenRandom', prefix: '#include <windows.h>\n#include <ntsecapi.h>')
+  csprng_backend = 'getentropy'
+elif csprng_backend in ['auto', 'rtlgenrandom'] and compiler.has_function('RtlGenRandom', prefix: '#include <windows.h>\n#include <ntsecapi.h>', required: csprng_backend == 'rtlgenrandom')
   libgit_c_args += '-DHAVE_RTLGENRANDOM'
-elif openssl.found()
+  csprng_backend = 'rtlgenrandom'
+elif csprng_backend in ['auto', 'openssl'] and openssl.found()
   libgit_c_args += '-DHAVE_OPENSSL_CSPRNG'
+  csprng_backend = 'openssl'
+elif csprng_backend in ['auto', 'urandom']
+  csprng_backend = 'urandom'
+else
+  error('Unsupported CSPRNG backend: ' + csprng_backend)
 endif
 
 if get_option('runtime_prefix')