expat asks for entropy the graph has - #451
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`lib/expat_config.h` is one static header shared by every target, and it
carried `#define HAVE_ARC4RANDOM_BUF 1` from a glibc configure run. Over
openkal-musl the member stopped at
xmlparse.c:977:3: error: call to undeclared function 'arc4random_buf'
musl 1.2.5 has no arc4random at all --- its `src/prng/` is the rand48 family,
and the name appears in no header. This is therefore a recipe that claims a
function for hosts that do not have it, not a gap in the C library.
THE MACRO SHORT-CIRCUITS THE WHOLE CHAIN, which is why the fallbacks below it
never ran. `generate_hash_secret_salt` reads:
#if defined(HAVE_ARC4RANDOM_BUF)
arc4random_buf(&entropy, sizeof(entropy));
#elif defined(HAVE_ARC4RANDOM)
#else
/* Try high quality providers first .. */
# elif defined(HAVE_GETRANDOM) || defined(HAVE_SYSCALL_GETRANDOM)
Undefined, the chain falls to `HAVE_GETRANDOM`, already defined in this same
header and provided by both musl and glibc, and then to `XML_DEV_URANDOM`. No
target loses a high-quality entropy source; the glibc hosts that were reaching
arc4random_buf reach getrandom instead.
Verified against the published stack --- openkal-linux 0.15.0, openkal-musl
0.18.0, openkal-llvm-runtime 0.13.0 --- with this checkout as a live index:
expat 2.7.1 compiles and the program links and runs, and the artefact
references no arc4random symbol.
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The defect
lib/expat_config.his one static header shared by every target, and it carried#define HAVE_ARC4RANDOM_BUF 1from a glibc configure run. Over openkal-musl the member stopped at:musl 1.2.5 has no arc4random at all — its
src/prng/is the rand48 family, and the name appears in no header. So this is a recipe claiming a function for hosts that do not have it, not a gap in the C library. (The measurement had it filed under the latter; reading musl settled it.)Why the fallbacks never ran
The macro short-circuits the whole chain:
Undefined, the chain falls to
HAVE_GETRANDOM— already defined in this same header, and provided by both musl and glibc — then toXML_DEV_URANDOM. No target loses a high-quality entropy source.Verification
Built against the published stack (openkal-linux 0.15.0, openkal-musl 0.18.0, openkal-llvm-runtime 0.13.0) with this checkout as a live index:
nm -uon the artefact shows no arc4random symbol