From c37a465897c3bf6663140858ca82e9dd04f9c036 Mon Sep 17 00:00:00 2001
From: Xavier Leroy <xavier.leroy@college-de-france.fr>
Date: Sun, 10 Dec 2023 19:24:38 +0100
Subject: [PATCH 1/3] Fail when unmarshaling would produce non-canonical big
 integers

Fixes: #148
---
 caml_z.c                |  12 ++++
 tests/Makefile          |   8 +++
 tests/extern.data32     | Bin 0 -> 23522 bytes
 tests/extern.data64     | Bin 0 -> 21510 bytes
 tests/extern.ml         |  14 +++++
 tests/intern.ml         |  24 ++++++++
 tests/intern.output3232 | 127 ++++++++++++++++++++++++++++++++++++++++
 tests/intern.output3264 | 127 ++++++++++++++++++++++++++++++++++++++++
 tests/intern.output6432 | 127 ++++++++++++++++++++++++++++++++++++++++
 tests/intern.output6464 | 127 ++++++++++++++++++++++++++++++++++++++++
 10 files changed, 566 insertions(+)
 create mode 100644 tests/extern.data32
 create mode 100644 tests/extern.data64
 create mode 100644 tests/extern.ml
 create mode 100644 tests/intern.ml
 create mode 100644 tests/intern.output3232
 create mode 100644 tests/intern.output3264
 create mode 100644 tests/intern.output6432
 create mode 100644 tests/intern.output6464

diff --git a/caml_z.c b/caml_z.c
index 02e758d..c0b11c4 100644
--- a/caml_z.c
+++ b/caml_z.c
@@ -3398,6 +3398,10 @@ static void ml_z_custom_serialize(value v,
 /* XXX: serializing a large (i.e., > 2^31) int on a 64-bit machine and
    deserializing on a 32-bit machine will fail (instead of returning a
    block).
+   YYY: serializing a large (i.e., > 2^31 and < 2^62) int on a
+   32-bit machine and deserializing on a 64-bit machine must fail
+   (instead of returning a block containing a non-normalized big integer)
+   (issue #148).
  */
 static uintnat ml_z_custom_deserialize(void * dst)
 {
@@ -3444,6 +3448,14 @@ static uintnat ml_z_custom_deserialize(void * dst)
 #if Z_PERFORM_CHECK
   d[szw] = 0xDEADBEEF ^ szw;
   szw++;
+#endif
+#if Z_USE_NATINT
+  if (i == 0 ||
+      (i == 1 && (d[0] <= Z_MAX_INT || (d[0] == -Z_MIN_INT && sign)))) {
+    /* Issue #148: this is not a canonical representation,
+       so we raise a Failure */
+    caml_deserialize_error("Z.t value produced on a 32-bit platform cannot be read on a 64-bit platform");
+  }
 #endif
   return (szw+1) * sizeof(mp_limb_t);
 }
diff --git a/tests/Makefile b/tests/Makefile
index 760294b..80762cc 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -50,6 +50,14 @@ test:: tst_extract.exe
 	@echo "Testing extract..."
 	@if ./tst_extract.exe; then echo "tst_extract: passed"; else echo "tst_extract: FAILED"; exit 2; fi
 
+test:: intern.exe
+	@echo "Testing unmarshaling..."
+	@if ./intern.exe extern.data32 | cmp -s intern.output32$(WORDSIZE) -; then echo "intern 32: passed"; else echo "intern 32: failed"; exit 2; fi
+	@if ./intern.exe extern.data64 | cmp -s intern.output64$(WORDSIZE) -; then echo "intern 64: passed"; else echo "intern 64: failed"; exit 2; fi
+
+extern.data$(WORDSIZE): extern.exe
+	./extern.exe extern.data$(WORDSIZE)
+
 tofloat.exe: tofloat.ml setround.o ../zarith.cmxa
 	ocamlopt -I .. -ccopt "-L.." zarith.cmxa -o tofloat.exe \
            setround.o tofloat.ml
diff --git a/tests/extern.data32 b/tests/extern.data32
new file mode 100644
index 0000000000000000000000000000000000000000..60d155d7ed0ac761c3dec73daeceb444125bc32b
GIT binary patch
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diff --git a/tests/extern.data64 b/tests/extern.data64
new file mode 100644
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GIT binary patch
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literal 0
HcmV?d00001

diff --git a/tests/extern.ml b/tests/extern.ml
new file mode 100644
index 0000000..33819a8
--- /dev/null
+++ b/tests/extern.ml
@@ -0,0 +1,14 @@
+(* Marshal some interesting big integers to the given file *)
+
+let _ =
+  let file = Sys.argv.(1) in
+  let oc = open_out_bin file in
+  for nbits = 2 to 128 do
+    let x = Z.shift_left Z.one nbits in
+    output_value oc x;
+    output_value oc (Z.pred x);
+    output_value oc (Z.neg x);
+    output_value oc (Z.neg (Z.pred x))
+  done;
+  close_out oc
+
diff --git a/tests/intern.ml b/tests/intern.ml
new file mode 100644
index 0000000..cd359c2
--- /dev/null
+++ b/tests/intern.ml
@@ -0,0 +1,24 @@
+(* Unmarshal big integers from the given file, and report errors *)
+
+open Printf
+
+let expect ic n =
+  try
+    let m = (input_value ic : Z.t) in
+    if Z.equal m n then printf " OK" else printf " Wrong"
+  with Failure _ ->
+    printf " Fail"
+
+let _ =
+  let file = Sys.argv.(1) in
+  let ic = open_in_bin file in
+  for nbits = 2 to 128 do
+    printf "%d:" nbits;
+    let x = Z.shift_left Z.one nbits in
+    expect ic x;
+    expect ic (Z.pred x);
+    expect ic (Z.neg x);
+    expect ic (Z.neg (Z.pred x));
+    print_newline()
+  done;
+  close_in ic
diff --git a/tests/intern.output3232 b/tests/intern.output3232
new file mode 100644
index 0000000..b2c34a1
--- /dev/null
+++ b/tests/intern.output3232
@@ -0,0 +1,127 @@
+2: OK OK OK OK
+3: OK OK OK OK
+4: OK OK OK OK
+5: OK OK OK OK
+6: OK OK OK OK
+7: OK OK OK OK
+8: OK OK OK OK
+9: OK OK OK OK
+10: OK OK OK OK
+11: OK OK OK OK
+12: OK OK OK OK
+13: OK OK OK OK
+14: OK OK OK OK
+15: OK OK OK OK
+16: OK OK OK OK
+17: OK OK OK OK
+18: OK OK OK OK
+19: OK OK OK OK
+20: OK OK OK OK
+21: OK OK OK OK
+22: OK OK OK OK
+23: OK OK OK OK
+24: OK OK OK OK
+25: OK OK OK OK
+26: OK OK OK OK
+27: OK OK OK OK
+28: OK OK OK OK
+29: OK OK OK OK
+30: OK OK OK OK
+31: OK OK OK OK
+32: OK OK OK OK
+33: OK OK OK OK
+34: OK OK OK OK
+35: OK OK OK OK
+36: OK OK OK OK
+37: OK OK OK OK
+38: OK OK OK OK
+39: OK OK OK OK
+40: OK OK OK OK
+41: OK OK OK OK
+42: OK OK OK OK
+43: OK OK OK OK
+44: OK OK OK OK
+45: OK OK OK OK
+46: OK OK OK OK
+47: OK OK OK OK
+48: OK OK OK OK
+49: OK OK OK OK
+50: OK OK OK OK
+51: OK OK OK OK
+52: OK OK OK OK
+53: OK OK OK OK
+54: OK OK OK OK
+55: OK OK OK OK
+56: OK OK OK OK
+57: OK OK OK OK
+58: OK OK OK OK
+59: OK OK OK OK
+60: OK OK OK OK
+61: OK OK OK OK
+62: OK OK OK OK
+63: OK OK OK OK
+64: OK OK OK OK
+65: OK OK OK OK
+66: OK OK OK OK
+67: OK OK OK OK
+68: OK OK OK OK
+69: OK OK OK OK
+70: OK OK OK OK
+71: OK OK OK OK
+72: OK OK OK OK
+73: OK OK OK OK
+74: OK OK OK OK
+75: OK OK OK OK
+76: OK OK OK OK
+77: OK OK OK OK
+78: OK OK OK OK
+79: OK OK OK OK
+80: OK OK OK OK
+81: OK OK OK OK
+82: OK OK OK OK
+83: OK OK OK OK
+84: OK OK OK OK
+85: OK OK OK OK
+86: OK OK OK OK
+87: OK OK OK OK
+88: OK OK OK OK
+89: OK OK OK OK
+90: OK OK OK OK
+91: OK OK OK OK
+92: OK OK OK OK
+93: OK OK OK OK
+94: OK OK OK OK
+95: OK OK OK OK
+96: OK OK OK OK
+97: OK OK OK OK
+98: OK OK OK OK
+99: OK OK OK OK
+100: OK OK OK OK
+101: OK OK OK OK
+102: OK OK OK OK
+103: OK OK OK OK
+104: OK OK OK OK
+105: OK OK OK OK
+106: OK OK OK OK
+107: OK OK OK OK
+108: OK OK OK OK
+109: OK OK OK OK
+110: OK OK OK OK
+111: OK OK OK OK
+112: OK OK OK OK
+113: OK OK OK OK
+114: OK OK OK OK
+115: OK OK OK OK
+116: OK OK OK OK
+117: OK OK OK OK
+118: OK OK OK OK
+119: OK OK OK OK
+120: OK OK OK OK
+121: OK OK OK OK
+122: OK OK OK OK
+123: OK OK OK OK
+124: OK OK OK OK
+125: OK OK OK OK
+126: OK OK OK OK
+127: OK OK OK OK
+128: OK OK OK OK
diff --git a/tests/intern.output3264 b/tests/intern.output3264
new file mode 100644
index 0000000..5327d0a
--- /dev/null
+++ b/tests/intern.output3264
@@ -0,0 +1,127 @@
+2: OK OK OK OK
+3: OK OK OK OK
+4: OK OK OK OK
+5: OK OK OK OK
+6: OK OK OK OK
+7: OK OK OK OK
+8: OK OK OK OK
+9: OK OK OK OK
+10: OK OK OK OK
+11: OK OK OK OK
+12: OK OK OK OK
+13: OK OK OK OK
+14: OK OK OK OK
+15: OK OK OK OK
+16: OK OK OK OK
+17: OK OK OK OK
+18: OK OK OK OK
+19: OK OK OK OK
+20: OK OK OK OK
+21: OK OK OK OK
+22: OK OK OK OK
+23: OK OK OK OK
+24: OK OK OK OK
+25: OK OK OK OK
+26: OK OK OK OK
+27: OK OK OK OK
+28: OK OK OK OK
+29: OK OK OK OK
+30: Fail OK OK OK
+31: Fail Fail Fail Fail
+32: Fail Fail Fail Fail
+33: Fail Fail Fail Fail
+34: Fail Fail Fail Fail
+35: Fail Fail Fail Fail
+36: Fail Fail Fail Fail
+37: Fail Fail Fail Fail
+38: Fail Fail Fail Fail
+39: Fail Fail Fail Fail
+40: Fail Fail Fail Fail
+41: Fail Fail Fail Fail
+42: Fail Fail Fail Fail
+43: Fail Fail Fail Fail
+44: Fail Fail Fail Fail
+45: Fail Fail Fail Fail
+46: Fail Fail Fail Fail
+47: Fail Fail Fail Fail
+48: Fail Fail Fail Fail
+49: Fail Fail Fail Fail
+50: Fail Fail Fail Fail
+51: Fail Fail Fail Fail
+52: Fail Fail Fail Fail
+53: Fail Fail Fail Fail
+54: Fail Fail Fail Fail
+55: Fail Fail Fail Fail
+56: Fail Fail Fail Fail
+57: Fail Fail Fail Fail
+58: Fail Fail Fail Fail
+59: Fail Fail Fail Fail
+60: Fail Fail Fail Fail
+61: Fail Fail Fail Fail
+62: OK Fail Fail Fail
+63: OK OK OK OK
+64: OK OK OK OK
+65: OK OK OK OK
+66: OK OK OK OK
+67: OK OK OK OK
+68: OK OK OK OK
+69: OK OK OK OK
+70: OK OK OK OK
+71: OK OK OK OK
+72: OK OK OK OK
+73: OK OK OK OK
+74: OK OK OK OK
+75: OK OK OK OK
+76: OK OK OK OK
+77: OK OK OK OK
+78: OK OK OK OK
+79: OK OK OK OK
+80: OK OK OK OK
+81: OK OK OK OK
+82: OK OK OK OK
+83: OK OK OK OK
+84: OK OK OK OK
+85: OK OK OK OK
+86: OK OK OK OK
+87: OK OK OK OK
+88: OK OK OK OK
+89: OK OK OK OK
+90: OK OK OK OK
+91: OK OK OK OK
+92: OK OK OK OK
+93: OK OK OK OK
+94: OK OK OK OK
+95: OK OK OK OK
+96: OK OK OK OK
+97: OK OK OK OK
+98: OK OK OK OK
+99: OK OK OK OK
+100: OK OK OK OK
+101: OK OK OK OK
+102: OK OK OK OK
+103: OK OK OK OK
+104: OK OK OK OK
+105: OK OK OK OK
+106: OK OK OK OK
+107: OK OK OK OK
+108: OK OK OK OK
+109: OK OK OK OK
+110: OK OK OK OK
+111: OK OK OK OK
+112: OK OK OK OK
+113: OK OK OK OK
+114: OK OK OK OK
+115: OK OK OK OK
+116: OK OK OK OK
+117: OK OK OK OK
+118: OK OK OK OK
+119: OK OK OK OK
+120: OK OK OK OK
+121: OK OK OK OK
+122: OK OK OK OK
+123: OK OK OK OK
+124: OK OK OK OK
+125: OK OK OK OK
+126: OK OK OK OK
+127: OK OK OK OK
+128: OK OK OK OK
diff --git a/tests/intern.output6432 b/tests/intern.output6432
new file mode 100644
index 0000000..5327d0a
--- /dev/null
+++ b/tests/intern.output6432
@@ -0,0 +1,127 @@
+2: OK OK OK OK
+3: OK OK OK OK
+4: OK OK OK OK
+5: OK OK OK OK
+6: OK OK OK OK
+7: OK OK OK OK
+8: OK OK OK OK
+9: OK OK OK OK
+10: OK OK OK OK
+11: OK OK OK OK
+12: OK OK OK OK
+13: OK OK OK OK
+14: OK OK OK OK
+15: OK OK OK OK
+16: OK OK OK OK
+17: OK OK OK OK
+18: OK OK OK OK
+19: OK OK OK OK
+20: OK OK OK OK
+21: OK OK OK OK
+22: OK OK OK OK
+23: OK OK OK OK
+24: OK OK OK OK
+25: OK OK OK OK
+26: OK OK OK OK
+27: OK OK OK OK
+28: OK OK OK OK
+29: OK OK OK OK
+30: Fail OK OK OK
+31: Fail Fail Fail Fail
+32: Fail Fail Fail Fail
+33: Fail Fail Fail Fail
+34: Fail Fail Fail Fail
+35: Fail Fail Fail Fail
+36: Fail Fail Fail Fail
+37: Fail Fail Fail Fail
+38: Fail Fail Fail Fail
+39: Fail Fail Fail Fail
+40: Fail Fail Fail Fail
+41: Fail Fail Fail Fail
+42: Fail Fail Fail Fail
+43: Fail Fail Fail Fail
+44: Fail Fail Fail Fail
+45: Fail Fail Fail Fail
+46: Fail Fail Fail Fail
+47: Fail Fail Fail Fail
+48: Fail Fail Fail Fail
+49: Fail Fail Fail Fail
+50: Fail Fail Fail Fail
+51: Fail Fail Fail Fail
+52: Fail Fail Fail Fail
+53: Fail Fail Fail Fail
+54: Fail Fail Fail Fail
+55: Fail Fail Fail Fail
+56: Fail Fail Fail Fail
+57: Fail Fail Fail Fail
+58: Fail Fail Fail Fail
+59: Fail Fail Fail Fail
+60: Fail Fail Fail Fail
+61: Fail Fail Fail Fail
+62: OK Fail Fail Fail
+63: OK OK OK OK
+64: OK OK OK OK
+65: OK OK OK OK
+66: OK OK OK OK
+67: OK OK OK OK
+68: OK OK OK OK
+69: OK OK OK OK
+70: OK OK OK OK
+71: OK OK OK OK
+72: OK OK OK OK
+73: OK OK OK OK
+74: OK OK OK OK
+75: OK OK OK OK
+76: OK OK OK OK
+77: OK OK OK OK
+78: OK OK OK OK
+79: OK OK OK OK
+80: OK OK OK OK
+81: OK OK OK OK
+82: OK OK OK OK
+83: OK OK OK OK
+84: OK OK OK OK
+85: OK OK OK OK
+86: OK OK OK OK
+87: OK OK OK OK
+88: OK OK OK OK
+89: OK OK OK OK
+90: OK OK OK OK
+91: OK OK OK OK
+92: OK OK OK OK
+93: OK OK OK OK
+94: OK OK OK OK
+95: OK OK OK OK
+96: OK OK OK OK
+97: OK OK OK OK
+98: OK OK OK OK
+99: OK OK OK OK
+100: OK OK OK OK
+101: OK OK OK OK
+102: OK OK OK OK
+103: OK OK OK OK
+104: OK OK OK OK
+105: OK OK OK OK
+106: OK OK OK OK
+107: OK OK OK OK
+108: OK OK OK OK
+109: OK OK OK OK
+110: OK OK OK OK
+111: OK OK OK OK
+112: OK OK OK OK
+113: OK OK OK OK
+114: OK OK OK OK
+115: OK OK OK OK
+116: OK OK OK OK
+117: OK OK OK OK
+118: OK OK OK OK
+119: OK OK OK OK
+120: OK OK OK OK
+121: OK OK OK OK
+122: OK OK OK OK
+123: OK OK OK OK
+124: OK OK OK OK
+125: OK OK OK OK
+126: OK OK OK OK
+127: OK OK OK OK
+128: OK OK OK OK
diff --git a/tests/intern.output6464 b/tests/intern.output6464
new file mode 100644
index 0000000..b2c34a1
--- /dev/null
+++ b/tests/intern.output6464
@@ -0,0 +1,127 @@
+2: OK OK OK OK
+3: OK OK OK OK
+4: OK OK OK OK
+5: OK OK OK OK
+6: OK OK OK OK
+7: OK OK OK OK
+8: OK OK OK OK
+9: OK OK OK OK
+10: OK OK OK OK
+11: OK OK OK OK
+12: OK OK OK OK
+13: OK OK OK OK
+14: OK OK OK OK
+15: OK OK OK OK
+16: OK OK OK OK
+17: OK OK OK OK
+18: OK OK OK OK
+19: OK OK OK OK
+20: OK OK OK OK
+21: OK OK OK OK
+22: OK OK OK OK
+23: OK OK OK OK
+24: OK OK OK OK
+25: OK OK OK OK
+26: OK OK OK OK
+27: OK OK OK OK
+28: OK OK OK OK
+29: OK OK OK OK
+30: OK OK OK OK
+31: OK OK OK OK
+32: OK OK OK OK
+33: OK OK OK OK
+34: OK OK OK OK
+35: OK OK OK OK
+36: OK OK OK OK
+37: OK OK OK OK
+38: OK OK OK OK
+39: OK OK OK OK
+40: OK OK OK OK
+41: OK OK OK OK
+42: OK OK OK OK
+43: OK OK OK OK
+44: OK OK OK OK
+45: OK OK OK OK
+46: OK OK OK OK
+47: OK OK OK OK
+48: OK OK OK OK
+49: OK OK OK OK
+50: OK OK OK OK
+51: OK OK OK OK
+52: OK OK OK OK
+53: OK OK OK OK
+54: OK OK OK OK
+55: OK OK OK OK
+56: OK OK OK OK
+57: OK OK OK OK
+58: OK OK OK OK
+59: OK OK OK OK
+60: OK OK OK OK
+61: OK OK OK OK
+62: OK OK OK OK
+63: OK OK OK OK
+64: OK OK OK OK
+65: OK OK OK OK
+66: OK OK OK OK
+67: OK OK OK OK
+68: OK OK OK OK
+69: OK OK OK OK
+70: OK OK OK OK
+71: OK OK OK OK
+72: OK OK OK OK
+73: OK OK OK OK
+74: OK OK OK OK
+75: OK OK OK OK
+76: OK OK OK OK
+77: OK OK OK OK
+78: OK OK OK OK
+79: OK OK OK OK
+80: OK OK OK OK
+81: OK OK OK OK
+82: OK OK OK OK
+83: OK OK OK OK
+84: OK OK OK OK
+85: OK OK OK OK
+86: OK OK OK OK
+87: OK OK OK OK
+88: OK OK OK OK
+89: OK OK OK OK
+90: OK OK OK OK
+91: OK OK OK OK
+92: OK OK OK OK
+93: OK OK OK OK
+94: OK OK OK OK
+95: OK OK OK OK
+96: OK OK OK OK
+97: OK OK OK OK
+98: OK OK OK OK
+99: OK OK OK OK
+100: OK OK OK OK
+101: OK OK OK OK
+102: OK OK OK OK
+103: OK OK OK OK
+104: OK OK OK OK
+105: OK OK OK OK
+106: OK OK OK OK
+107: OK OK OK OK
+108: OK OK OK OK
+109: OK OK OK OK
+110: OK OK OK OK
+111: OK OK OK OK
+112: OK OK OK OK
+113: OK OK OK OK
+114: OK OK OK OK
+115: OK OK OK OK
+116: OK OK OK OK
+117: OK OK OK OK
+118: OK OK OK OK
+119: OK OK OK OK
+120: OK OK OK OK
+121: OK OK OK OK
+122: OK OK OK OK
+123: OK OK OK OK
+124: OK OK OK OK
+125: OK OK OK OK
+126: OK OK OK OK
+127: OK OK OK OK
+128: OK OK OK OK

From 8c6a5d7c42665e5ce8043bd489d657a65fa3f1e5 Mon Sep 17 00:00:00 2001
From: Xavier Leroy <xavier.leroy@college-de-france.fr>
Date: Wed, 3 Jan 2024 10:19:25 +0100
Subject: [PATCH 2/3] Reword comment about delicate points of unmarshaling

---
 caml_z.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/caml_z.c b/caml_z.c
index c0b11c4..85563eb 100644
--- a/caml_z.c
+++ b/caml_z.c
@@ -3395,14 +3395,17 @@ static void ml_z_custom_serialize(value v,
 #endif
 }
 
-/* XXX: serializing a large (i.e., > 2^31) int on a 64-bit machine and
-   deserializing on a 32-bit machine will fail (instead of returning a
-   block).
-   YYY: serializing a large (i.e., > 2^31 and < 2^62) int on a
-   32-bit machine and deserializing on a 64-bit machine must fail
-   (instead of returning a block containing a non-normalized big integer)
-   (issue #148).
- */
+/* There are two issues with integers that are tagged ints on a 64-bit
+   machine but boxed bigints on a 32-bit machine, namely integers in the
+   [2^30, 2^62) and [-2^62, -2^30) ranges:
+   - Serializing such an integer on a 64-bit machine and
+     deserializing on a 32-bit machine will fail in the generic unmarshaler.
+     The correct behavior would be to return a boxed integer.
+   - Serializing such an integer on a 32-bit machine and
+     deserializing on a 64-bit machine must fail.
+     The wrong behavior would be to return a block containing a
+     non-normalized, boxed integer (issue #148).
+*/
 static uintnat ml_z_custom_deserialize(void * dst)
 {
   mp_limb_t* d = ((mp_limb_t*)dst) + 1;

From d1193ab562653b8b866558cdc757dfa68a60c52d Mon Sep 17 00:00:00 2001
From: Xavier Leroy <xavier.leroy@college-de-france.fr>
Date: Wed, 3 Jan 2024 14:08:42 +0100
Subject: [PATCH 3/3] Cleaned up the extern/intern test

---
 tests/extern.data32     | Bin 23522 -> 22300 bytes
 tests/extern.data64     | Bin 21510 -> 20292 bytes
 tests/extern.ml         |   8 ++++----
 tests/intern.ml         |   8 ++++----
 tests/intern.output3232 |  14 --------------
 tests/intern.output3264 |  18 ++----------------
 tests/intern.output6432 |  18 ++----------------
 tests/intern.output6464 |  14 --------------
 8 files changed, 12 insertions(+), 68 deletions(-)

diff --git a/tests/extern.data32 b/tests/extern.data32
index 60d155d7ed0ac761c3dec73daeceb444125bc32b..003164380b9f39c6d2c612ee7d827f049868dfd1 100644
GIT binary patch
literal 22300
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diff --git a/tests/extern.data64 b/tests/extern.data64
index 096750b0952b63b33181f8220c1803e4f13a813a..6d0c104c5f689800432dc3c101c5d765f9111664 100644
GIT binary patch
literal 20292
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literal 21510
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diff --git a/tests/extern.ml b/tests/extern.ml
index 33819a8..247677b 100644
--- a/tests/extern.ml
+++ b/tests/extern.ml
@@ -3,12 +3,12 @@
 let _ =
   let file = Sys.argv.(1) in
   let oc = open_out_bin file in
-  for nbits = 2 to 128 do
+  for nbits = 16 to 128 do
     let x = Z.shift_left Z.one nbits in
-    output_value oc x;
-    output_value oc (Z.pred x);
+    output_value oc (Z.pred (Z.neg x));
     output_value oc (Z.neg x);
-    output_value oc (Z.neg (Z.pred x))
+    output_value oc (Z.pred x);
+    output_value oc x
   done;
   close_out oc
 
diff --git a/tests/intern.ml b/tests/intern.ml
index cd359c2..c7940ae 100644
--- a/tests/intern.ml
+++ b/tests/intern.ml
@@ -12,13 +12,13 @@ let expect ic n =
 let _ =
   let file = Sys.argv.(1) in
   let ic = open_in_bin file in
-  for nbits = 2 to 128 do
+  for nbits = 16 to 128 do
     printf "%d:" nbits;
     let x = Z.shift_left Z.one nbits in
-    expect ic x;
-    expect ic (Z.pred x);
+    expect ic (Z.pred (Z.neg x));
     expect ic (Z.neg x);
-    expect ic (Z.neg (Z.pred x));
+    expect ic (Z.pred x);
+    expect ic x;
     print_newline()
   done;
   close_in ic
diff --git a/tests/intern.output3232 b/tests/intern.output3232
index b2c34a1..9029dd2 100644
--- a/tests/intern.output3232
+++ b/tests/intern.output3232
@@ -1,17 +1,3 @@
-2: OK OK OK OK
-3: OK OK OK OK
-4: OK OK OK OK
-5: OK OK OK OK
-6: OK OK OK OK
-7: OK OK OK OK
-8: OK OK OK OK
-9: OK OK OK OK
-10: OK OK OK OK
-11: OK OK OK OK
-12: OK OK OK OK
-13: OK OK OK OK
-14: OK OK OK OK
-15: OK OK OK OK
 16: OK OK OK OK
 17: OK OK OK OK
 18: OK OK OK OK
diff --git a/tests/intern.output3264 b/tests/intern.output3264
index 5327d0a..bcacdfb 100644
--- a/tests/intern.output3264
+++ b/tests/intern.output3264
@@ -1,17 +1,3 @@
-2: OK OK OK OK
-3: OK OK OK OK
-4: OK OK OK OK
-5: OK OK OK OK
-6: OK OK OK OK
-7: OK OK OK OK
-8: OK OK OK OK
-9: OK OK OK OK
-10: OK OK OK OK
-11: OK OK OK OK
-12: OK OK OK OK
-13: OK OK OK OK
-14: OK OK OK OK
-15: OK OK OK OK
 16: OK OK OK OK
 17: OK OK OK OK
 18: OK OK OK OK
@@ -26,7 +12,7 @@
 27: OK OK OK OK
 28: OK OK OK OK
 29: OK OK OK OK
-30: Fail OK OK OK
+30: Fail OK OK Fail
 31: Fail Fail Fail Fail
 32: Fail Fail Fail Fail
 33: Fail Fail Fail Fail
@@ -58,7 +44,7 @@
 59: Fail Fail Fail Fail
 60: Fail Fail Fail Fail
 61: Fail Fail Fail Fail
-62: OK Fail Fail Fail
+62: OK Fail Fail OK
 63: OK OK OK OK
 64: OK OK OK OK
 65: OK OK OK OK
diff --git a/tests/intern.output6432 b/tests/intern.output6432
index 5327d0a..bcacdfb 100644
--- a/tests/intern.output6432
+++ b/tests/intern.output6432
@@ -1,17 +1,3 @@
-2: OK OK OK OK
-3: OK OK OK OK
-4: OK OK OK OK
-5: OK OK OK OK
-6: OK OK OK OK
-7: OK OK OK OK
-8: OK OK OK OK
-9: OK OK OK OK
-10: OK OK OK OK
-11: OK OK OK OK
-12: OK OK OK OK
-13: OK OK OK OK
-14: OK OK OK OK
-15: OK OK OK OK
 16: OK OK OK OK
 17: OK OK OK OK
 18: OK OK OK OK
@@ -26,7 +12,7 @@
 27: OK OK OK OK
 28: OK OK OK OK
 29: OK OK OK OK
-30: Fail OK OK OK
+30: Fail OK OK Fail
 31: Fail Fail Fail Fail
 32: Fail Fail Fail Fail
 33: Fail Fail Fail Fail
@@ -58,7 +44,7 @@
 59: Fail Fail Fail Fail
 60: Fail Fail Fail Fail
 61: Fail Fail Fail Fail
-62: OK Fail Fail Fail
+62: OK Fail Fail OK
 63: OK OK OK OK
 64: OK OK OK OK
 65: OK OK OK OK
diff --git a/tests/intern.output6464 b/tests/intern.output6464
index b2c34a1..9029dd2 100644
--- a/tests/intern.output6464
+++ b/tests/intern.output6464
@@ -1,17 +1,3 @@
-2: OK OK OK OK
-3: OK OK OK OK
-4: OK OK OK OK
-5: OK OK OK OK
-6: OK OK OK OK
-7: OK OK OK OK
-8: OK OK OK OK
-9: OK OK OK OK
-10: OK OK OK OK
-11: OK OK OK OK
-12: OK OK OK OK
-13: OK OK OK OK
-14: OK OK OK OK
-15: OK OK OK OK
 16: OK OK OK OK
 17: OK OK OK OK
 18: OK OK OK OK