From 4d22949f71f7e59440d0c6340b6766f019204612 Mon Sep 17 00:00:00 2001
From: Alex Shinn <alexshinn@gmail.com>
Date: Tue, 27 Apr 2021 18:30:43 +0900
Subject: [PATCH] disable fileno unification by default

---
 include/chibi/features.h   | 17 +++++++++++++++++
 sexp.c                     | 10 +++++-----
 tests/build/build-opts.txt |  1 +
 3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/include/chibi/features.h b/include/chibi/features.h
index e5b5b924..a4c22954 100644
--- a/include/chibi/features.h
+++ b/include/chibi/features.h
@@ -64,6 +64,15 @@
 /*   if you suspect a bug in the native GC. */
 /* #define SEXP_USE_BOEHM 1 */
 
+/* uncomment this to enable automatic file descriptor unification */
+/*   File descriptors as returned by C functions are raw integers, */
+/*   which are convereted to GC'ed first-class objects on the Scheme */
+/*   side.  By default we assume that each fd is new, however if this */
+/*   option is enabled and an fd is returned which matches an existing */
+/*   open fd, they are assumed to refer to the same descriptor and */
+/*   unified. */
+/* #define SEXP_USE_UNIFY_FILENOS_BY_NUMBER 1 */
+
 /* uncomment this to disable weak references */
 /* #define SEXP_USE_WEAK_REFERENCES 0 */
 
@@ -464,9 +473,17 @@
 #define SEXP_USE_BOEHM 0
 #endif
 
+#ifdef SEXP_USE_UNIFY_FILENOS_BY_NUMBER
+#define SEXP_USE_UNIFY_FILENOS_BY_NUMBER 0
+#endif
+
 #ifndef SEXP_USE_WEAK_REFERENCES
+#if SEXP_USE_UNIFY_FILENOS_BY_NUMBER
+#define SEXP_USE_WEAK_REFERENCES 1
+#else
 #define SEXP_USE_WEAK_REFERENCES ! SEXP_USE_NO_FEATURES
 #endif
+#endif
 
 #ifndef SEXP_USE_FIXED_CHUNK_SIZE_HEAPS
 #define SEXP_USE_FIXED_CHUNK_SIZE_HEAPS 0
diff --git a/sexp.c b/sexp.c
index 9b83c5ba..7baa0fee 100644
--- a/sexp.c
+++ b/sexp.c
@@ -1806,7 +1806,7 @@ sexp sexp_open_output_file_descriptor (sexp ctx, sexp self, sexp_sint_t n, sexp
   return res;
 }
 
-#if SEXP_USE_WEAK_REFERENCES
+#if SEXP_USE_UNIFY_FILENOS_BY_NUMBER
 sexp sexp_make_ephemeron_op(sexp ctx, sexp self, sexp_sint_t n, sexp key, sexp value) {
   sexp res = sexp_alloc_type(ctx, pair, SEXP_EPHEMERON);
   if (!sexp_exceptionp(res)) {
@@ -1878,13 +1878,13 @@ static void sexp_insert_fileno(sexp ctx, sexp fileno) {
     n++;
   sexp_global(ctx, SEXP_G_NUM_FILE_DESCRIPTORS) = sexp_make_fixnum(n);
 }
-#endif
+#endif  /* SEXP_USE_UNIFY_FILENOS_BY_NUMBER */
 
 sexp sexp_make_fileno_op (sexp ctx, sexp self, sexp_sint_t n, sexp fd, sexp no_closep) {
   sexp_gc_var1(res);
   sexp_assert_type(ctx, sexp_fixnump, SEXP_FIXNUM, fd);
   if (sexp_unbox_fixnum(fd) < 0) return SEXP_FALSE;
-#if SEXP_USE_WEAK_REFERENCES
+#if SEXP_USE_UNIFY_FILENOS_BY_NUMBER
   res = sexp_lookup_fileno(ctx, sexp_unbox_fixnum(fd));
   if (sexp_filenop(res)) {
     sexp_fileno_no_closep(res) = sexp_truep(no_closep);
@@ -1898,7 +1898,7 @@ sexp sexp_make_fileno_op (sexp ctx, sexp self, sexp_sint_t n, sexp fd, sexp no_c
     sexp_fileno_fd(res) = sexp_unbox_fixnum(fd);
     sexp_fileno_openp(res) = 1;
     sexp_fileno_no_closep(res) = sexp_truep(no_closep);
-#if SEXP_USE_WEAK_REFERENCES
+#if SEXP_USE_UNIFY_FILENOS_BY_NUMBER
     sexp_insert_fileno(ctx, res);
 #endif
   }
@@ -1925,7 +1925,7 @@ sexp sexp_make_input_port (sexp ctx, FILE* in, sexp name) {
 #if SEXP_USE_FOLD_CASE_SYMS
   sexp_port_fold_casep(p) = sexp_truep(sexp_global(ctx, SEXP_G_FOLD_CASE_P));
 #endif
-#if SEXP_USE_WEAK_REFERENCES
+#if SEXP_USE_UNIFY_FILENOS_BY_NUMBER
   /* if the fd was previously opened by a non-stream port, preserve it */
   /* here to avoid gc timing issues */
   if (in && fileno(in) >= 0) {
diff --git a/tests/build/build-opts.txt b/tests/build/build-opts.txt
index 93431524..279a53d5 100644
--- a/tests/build/build-opts.txt
+++ b/tests/build/build-opts.txt
@@ -25,6 +25,7 @@ CPPFLAGS=-DSEXP_USE_2010_EPOCH=0
 CPPFLAGS=-DSEXP_USE_CHECK_STACK=0
 CPPFLAGS=-DSEXP_USE_EXTENDED_FCALL=0
 CPPFLAGS=-DSEXP_USE_WEAK_REFERENCES=0
+CPPFLAGS=-DSEXP_USE_UNIFY_FILENOS_BY_NUMBER=1
 CPPFLAGS=-DSEXP_USE_OBJECT_BRACE_LITERALS=0
 CPPFLAGS=-DSEXP_USE_TAIL_JUMPS=0
 CPPFLAGS=-DSEXP_USE_RESERVE_OPCODE=0