Remove dependency to OpenSSL's RAND_bytes

build-static.sh

@@ -22,6 +22,16 @@ RUN apt-get update && \
   rm -rf /var/lib/apt/lists/*
 EOF
 
+LDFLAGS='-fuse-ld=lld -static'
+
+# libstdc++'s `std::__glibcxx_rwlock_rdlock` refers these symbols
+# as weak symbols, although they need to be defined. Otherwise,
+# the program crashes after juping to address 0.
+# So, we force loading symbols as a workaround.
+LDFLAGS="$LDFLAGS -Wl,-u,pthread_rwlock_rdlock"
+LDFLAGS="$LDFLAGS -Wl,-u,pthread_rwlock_unlock"
+LDFLAGS="$LDFLAGS -Wl,-u,pthread_rwlock_wrlock"
+
 docker run -it --rm -v `pwd`:/mold -u $(id -u):$(id -g) \
   mold-build-ubuntu20 \
-  make -C /mold -j$(nproc) EXTRA_LDFLAGS='-fuse-ld=lld -static'
+  make -C /mold -j$(nproc) EXTRA_LDFLAGS="$LDFLAGS"

elf/output-chunks.cc

@@ -1,6 +1,5 @@
 #include "mold.h"
 
-#include <openssl/rand.h>
 #include <shared_mutex>
 #include <sys/mman.h>
 #include <tbb/parallel_for_each.h>
@@ -1665,8 +1664,13 @@ static void compute_sha256(Context<E> &ctx, i64 offset) {
 template <typename E>
 static std::vector<u8> get_uuid_v4(Context<E> &ctx) {
   std::vector<u8> buf(16);
-  if (!RAND_bytes(buf.data(), buf.size()))
-    Fatal(ctx) << "RAND_bytes failed";
+
+  FILE *fp = fopen("/dev/urandom", "r");
+  if (!fp)
+    Fatal(ctx) << "cannot open /dev/urandom: " << strerror(errno);
+  if (fread(buf.data(), buf.size(), 1, fp) != 1)
+    Fatal(ctx) << "fread on /dev/urandom: short read";
+  fclose(fp);
 
   // Indicate that this is UUIDv4.
   buf[6] &= 0b00001111;