Document and fix the MBEDTLS_xxx_ALT logic for the full config
The intended logic around MBEDTLS_xxx_ALT is to exclude them from full
because they require the alternative implementation of one or more
library functions, except that MBEDTLS_PLATFORM_xxx_ALT are different:
they're alternative implementations of a platform function and they
have a built-in default, so they should be included in full. Document
this.
Fix a bug whereby MBEDTLS_PLATFORM_xxx_ALT didn't catch symbols where
xxx contains an underscore. As a consequence,
MBEDTLS_PLATFORM_GMTIME_R_ALT and MBEDTLS_PLATFORM_NV_SEED_ALT are now
enabled in the full config. Explicitly exclude
MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT because it behaves like the
non-platform ones, requiring an extra build-time dependency.
Explicitly exclude MBEDTLS_PLATFORM_NV_SEED_ALT from baremetal
because it requires MBEDTLS_ENTROPY_NV_SEED, and likewise explicitly
unset it from builds that unset MBEDTLS_ENTROPY_NV_SEED.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/scripts/config.pl b/scripts/config.pl
index 83e3055..fc85bb2 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -104,15 +104,20 @@
MBEDTLS_MEMORY_BUFFER_ALLOC_C
MBEDTLS_NET_C
MBEDTLS_PLATFORM_FPRINTF_ALT
+MBEDTLS_PLATFORM_NV_SEED_ALT
MBEDTLS_PLATFORM_TIME_ALT
MBEDTLS_THREADING_C
MBEDTLS_THREADING_PTHREAD
MBEDTLS_TIMING_C
);
-# Things that should be enabled in "full" even if they match @excluded
+# Things that should be enabled in "full" even if they match @excluded.
+# Platform ALTs enable global variables that allow configuring the behavior
+# but default to the default behavior, except for PLATFORM_SETUP_TEARDOWN_ALT
+# which requires the application to provide relevant functions like
+# non-platform ALTs.
my @non_excluded = qw(
-PLATFORM_[A-Z0-9]+_ALT
+PLATFORM_(?!SETUP_TEARDOWN_)[A-Z_0-9]+_ALT
);
# Things that should be enabled in "baremetal"