Merge commit 'a60e1366a63bd05f0fa1199d6f15b21acc32f90e' as 'src/simplicity'

Author: roconnor-blockstream

src/simplicity/Makefile

@@ -0,0 +1,40 @@
+OBJS := bitstream.o dag.o deserialize.o eval.o frame.o jets.o jets-secp256k1.o rsort.o sha256.o type.o typeInference.o primitive/elements/env.o primitive/elements/exec.o primitive/elements/ops.o primitive/elements/jets.o primitive/elements/primitive.o
+TEST_OBJS := test.o hashBlock.o schnorr0.o schnorr6.o primitive/elements/checkSigHashAllTx1.o
+
+# From https://fastcompression.blogspot.com/2019/01/compiler-warnings.html
+CWARN := -Werror -Wall -Wextra -Wcast-qual -Wcast-align -Wstrict-aliasing -Wpointer-arith -Winit-self -Wshadow -Wswitch-enum -Wstrict-prototypes -Wmissing-prototypes -Wredundant-decls -Wfloat-equal -Wundef -Wconversion
+
+ifneq ($(doCheck), 1)
+CPPFLAGS := $(CPPFLAGS) -DNDEBUG
+endif
+
+CFLAGS := -I include
+
+# libsecp256k1 is full of conversion warnings, so we compile jets-secp256k1.c separately.
+jets-secp256k1.o: jets-secp256k1.c
+	$(CC) -c $(CFLAGS) $(CWARN) -Wno-conversion $(CPPFLAGS) -o $@ $<
+
+primitive/elements/jets.o: primitive/elements/jets.c
+	$(CC) -c $(CFLAGS) $(CWARN) -Wno-switch-enum -Wswitch $(CPPFLAGS) -o $@ $<
+
+%.o: %.c
+	$(CC) -c $(CFLAGS) $(CWARN) $(CPPFLAGS) -o $@ $<
+
+libElementsSimplicity.a: $(OBJS)
+	ar rcs $@ $^
+
+test: $(TEST_OBJS) libElementsSimplicity.a
+	$(CC) $^ -o $@ $(LDFLAGS)
+
+install: libElementsSimplicity.a
+	mkdir -p $(out)/lib
+	cp $^ $(out)/lib/
+	cp -R include $(out)/include
+
+check: test
+	./test
+
+clean:
+	-rm -f test libElementsSimplicity.a $(TEST_OBJS) $(OBJS)
+
+.PHONY: install check clean

src/simplicity/bitstream.c

@@ -0,0 +1,230 @@
+#include "bitstream.h"
+
+#include <assert.h>
+#include <limits.h>
+#include <stdlib.h>
+
+/* Closes a bitstream by consuming all remaining bits.
+ * Returns false if CHAR_BIT or more bits remain in the stream or if any remaining bits are non-zero.
+ *
+ * Precondition: NULL != stream
+ */
+bool closeBitstream(bitstream* stream) {
+  if (1 < stream->len) return false; /* If there is more than one byte remaining. */
+  if (1 == stream->len &&                                  /* If there is one byte remaining */
+      (0 == stream->offset ||                              /* and either no bits have been consumed */
+       0 != (*stream->arr & (UCHAR_MAX >> stream->offset)) /* or any of the unconsumed bits are non-zero */
+     )) return false;
+  /* Otherwise there are either 0 bits remaining or there are between 1 and CHAR_BITS-1 bits remaining and they are all zero. */
+  *stream = (bitstream){0};
+  return true;
+}
+
+/* Fetches up to 31 bits from 'stream' as the 'n' least significant bits of return value.
+ * The 'n' bits are set from the MSB to the LSB.
+ * Returns 'SIMPLICITY_ERR_BITSTREAM_EOF' if not enough bits are available.
+ *
+ * Precondition: 0 <= n < 32
+ *               NULL != stream
+ */
+int32_t readNBits(int n, bitstream* stream) {
+  assert(0 <= n && n < 32);
+
+  uint32_t result = 0;
+  while (CHAR_BIT <= stream->offset + n) {
+    if (!stream->len) return SIMPLICITY_ERR_BITSTREAM_EOF;
+    n -= CHAR_BIT - stream->offset;
+    result |= (uint32_t)(*stream->arr & (UCHAR_MAX >> stream->offset)) << n;
+    stream->arr++; stream->len--; stream->offset = 0;
+  }
+  /* stream->offset + n < CHAR_BIT */
+  if (n) {
+    if (!stream->len) return SIMPLICITY_ERR_BITSTREAM_EOF;
+    stream->offset += (unsigned char)n;
+    result |= (*stream->arr >> (CHAR_BIT - stream->offset)) & ((UCHAR_MAX >> (CHAR_BIT - n)));
+  }
+  return (int32_t)result;
+}
+/* Decode an encoded bitstring up to length 1.
+ * If successful returns the length of the bitstring and 'result' contains the decoded bits.
+ * The decoded bitstring is stored in the LSBs of 'result', with the LSB being the last bit decoded.
+ * Any remaining bits in 'result' are reset to 0.
+ * If the decoded bitstring would be too long 'SIMPLICITY_ERR_DATA_OUT_OF_RANGE' is returned ('result' may be modified).
+ * If more bits are needed than available in the 'stream', 'SIMPLICITY_ERR_BITSTRING_EOF' is returned ('result' may be modified).
+ * If an I/O error occurs when reading from the 'stream', 'SIMPLICITY_ERR_BISTRING_ERROR' is returned ('result' may be modified).
+ *
+ * Precondition: NULL != result
+ *               NULL != stream
+ */
+static int32_t decodeUpto1Bit(int32_t* result, bitstream* stream) {
+  *result = read1Bit(stream);
+  if (*result <= 0) return *result;
+
+  *result = read1Bit(stream);
+  if (*result < 0) return *result;
+  if (0 != *result) return SIMPLICITY_ERR_DATA_OUT_OF_RANGE;
+
+  *result = read1Bit(stream);
+  if (*result < 0) return *result;
+  return 1;
+}
+
+/* Decode an encoded number between 1 and 3 inclusive.
+ * When successful returns the decoded result.
+ * If the decoded value would be too large, 'SIMPLICITY_ERR_DATA_OUT_OF_RANGE' is returned.
+ * If more bits are needed than available in the 'stream', 'SIMPLICITY_ERR_BITSTRING_EOF' is returned.
+ * If an I/O error occurs when reading from the 'stream', 'SIMPLICITY_ERR_BISTRING_ERROR' is returned.
+ *
+ * Precondition: NULL != stream
+ */
+static int32_t decodeUpto3(bitstream* stream) {
+  int32_t result;
+  int32_t len = decodeUpto1Bit(&result, stream);
+  if (len < 0) return len;
+  result |= 1 << len;
+  return result;
+}
+
+/* Decode an encoded bitstring up to length 3.
+ * If successful returns the length of the bitstring and 'result' contains the decoded bits.
+ * The decoded bitstring is stored in the LSBs of 'result', with the LSB being the last bit decoded.
+ * Any remaining bits in 'result' are reset to 0.
+ * If the decoded bitstring would be too long 'SIMPLICITY_ERR_DATA_OUT_OF_RANGE' is returned ('result' may be modified).
+ * If more bits are needed than available in the 'stream', 'SIMPLICITY_ERR_BITSTRING_EOF' is returned ('result' may be modified).
+ * If an I/O error occurs when reading from the 'stream', 'SIMPLICITY_ERR_BISTRING_ERROR' is returned ('result' may be modified).
+ *
+ * Precondition: NULL != result
+ *               NULL != stream
+ */
+static int32_t decodeUpto3Bits(int32_t* result, bitstream* stream) {
+  int32_t bit = read1Bit(stream);
+  if (bit < 0) return bit;
+
+  *result = 0;
+  if (0 == bit) {
+    return 0;
+  } else {
+    int32_t n = decodeUpto3(stream);
+    if (0 <= n) {
+      *result = readNBits(n, stream);
+      if (*result < 0) return *result;
+    }
+    return n;
+  }
+}
+
+/* Decode an encoded number between 1 and 15 inclusive.
+ * When successful returns the decoded result.
+ * If the decoded value would be too large, 'SIMPLICITY_ERR_DATA_OUT_OF_RANGE' is returned.
+ * If more bits are needed than available in the 'stream', 'SIMPLICITY_ERR_BITSTRING_EOF' is returned.
+ * If an I/O error occurs when reading from the 'stream', 'SIMPLICITY_ERR_BISTRING_ERROR' is returned.
+ *
+ * Precondition: NULL != stream
+ */
+static int32_t decodeUpto15(bitstream* stream) {
+  int32_t result;
+  int32_t len = decodeUpto3Bits(&result, stream);
+  if (len < 0) return len;
+  result |= 1 << len;
+  return result;
+}
+
+/* Decode an encoded bitstring up to length 15.
+ * If successful returns the length of the bitstring and 'result' contains the decoded bits.
+ * The decoded bitstring is stored in the LSBs of 'result', with the LSB being the last bit decoded.
+ * Any remaining bits in 'result' are reset to 0.
+ * If the decoded bitstring would be too long 'SIMPLICITY_ERR_DATA_OUT_OF_RANGE' is returned ('result' may be modified).
+ * If more bits are needed than available in the 'stream', 'SIMPLICITY_ERR_BITSTRING_EOF' is returned ('result' may be modified).
+ * If an I/O error occurs when reading from the 'stream', 'SIMPLICITY_ERR_BISTRING_ERROR' is returned ('result' may be modified).
+ *
+ * Precondition: NULL != result
+ *               NULL != stream
+ */
+static int32_t decodeUpto15Bits(int32_t* result, bitstream* stream) {
+  int32_t bit = read1Bit(stream);
+  if (bit < 0) return bit;
+
+  *result = 0;
+  if (0 == bit) {
+    return 0;
+  } else {
+    int32_t n = decodeUpto15(stream);
+    if (0 <= n) {
+      *result = readNBits(n, stream);
+      if (*result < 0) return *result;
+    }
+    return n;
+  }
+}
+
+/* Decode an encoded number between 1 and 65535 inclusive.
+ * When successful returns the decoded result.
+ * If the decoded value would be too large, 'SIMPLICITY_ERR_DATA_OUT_OF_RANGE' is returned.
+ * If more bits are needed than available in the 'stream', 'SIMPLICITY_ERR_BITSTRING_EOF' is returned.
+ * If an I/O error occurs when reading from the 'stream', 'SIMPLICITY_ERR_BISTRING_ERROR' is returned.
+ *
+ * Precondition: NULL != stream
+ */
+static int32_t decodeUpto65535(bitstream* stream) {
+  int32_t result;
+  int32_t len = decodeUpto15Bits(&result, stream);
+  if (len < 0) return len;
+  result |= 1 << len;
+  return result;
+}
+
+/* Decode an encoded number between 1 and 2^31 - 1 inclusive.
+ * When successful returns the decoded result.
+ * If the decoded value would be too large, 'SIMPLICITY_ERR_DATA_OUT_OF_RANGE' is returned.
+ * If more bits are needed than available in the 'stream', 'SIMPLICITY_ERR_BITSTRING_EOF' is returned.
+ * If an I/O error occurs when reading from the 'stream', 'SIMPLICITY_ERR_BISTRING_ERROR' is returned.
+ *
+ * Precondition: NULL != stream
+ */
+int32_t decodeUptoMaxInt(bitstream* stream) {
+  int32_t bit = read1Bit(stream);
+  if (bit < 0) return bit;
+  if (0 == bit) {
+    return 1;
+  } else {
+    int32_t n = decodeUpto65535(stream);
+    if (n < 0) return n;
+    if (30 < n) return SIMPLICITY_ERR_DATA_OUT_OF_RANGE;
+    {
+      int32_t result = readNBits(n, stream);
+      if (result < 0) return result;
+      return ((1 << n) | result);
+    }
+  }
+}
+
+/* Fills a 'bitstring' containing 'n' bits from 'stream'.
+ * Returns 'SIMPLICITY_ERR_BITSTREAM_EOF' if not enough bits are available.
+ * If successful, '*result' is set to a bitstring with 'n' bits read from 'stream' and 0 is returned.
+ *
+ * If an error is returned '*result' might be modified.
+ *
+ * Precondition: NULL != result
+ *               n <= 2^31
+ *               NULL != stream
+ */
+int32_t readBitstring(bitstring* result, size_t n, bitstream* stream) {
+  static_assert(0x8000u + 2*(CHAR_BIT - 1) <= SIZE_MAX, "size_t needs to be at least 32-bits");
+  assert(n <= 0x8000u);
+  size_t total_offset = n + stream->offset;
+  /* |= stream->len * CHAR_BIT < total_offset iff stream->len < (total_offset + (CHAR_BIT - 1)) / CHAR_BIT */
+  if (stream->len < (total_offset + (CHAR_BIT - 1)) / CHAR_BIT) return SIMPLICITY_ERR_BITSTREAM_EOF;
+  /* total_offset <= stream->len * CHAR_BIT */
+  *result = (bitstring)
+          { .arr = stream->arr
+          , .offset = stream->offset
+          , .len = n
+          };
+  {
+    size_t delta = total_offset / CHAR_BIT;
+    stream->arr += delta; stream->len -= delta;
+    stream->offset = total_offset % CHAR_BIT;
+    /* Note that if 0 == stream->len then 0 == stream->offset. */
+  }
+  return 0;
+}

src/simplicity/bitstream.h

@@ -0,0 +1,78 @@
+/* This module provides functions for initializing and reading from a stream of bits from a 'FILE'. */
+#ifndef SIMPLICITY_BITSTREAM_H
+#define SIMPLICITY_BITSTREAM_H
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include "bitstring.h"
+#include "errorCodes.h"
+
+/* :TODO: consider adding an 'invalid' state that can be set when parsing has failed and should not be resumed. */
+/* Datatype representing a bit stream.
+ * Bits are streamed from MSB to LSB.
+ *
+ * Invariant: unsigned char arr[len]
+ *            0 <= offset < CHAR_BIT
+ *            0 == len implies 0 == offset
+ */
+typedef struct bitstream {
+  const unsigned char *arr;  /* Underlying byte array */
+  size_t len;                /* Length of arr (in bytes) */
+  unsigned char offset;      /* Number of bits parsed from the beginning of arr */
+} bitstream;
+
+/* Initialize a bit stream, 'stream', from a given byte array.
+ * Precondition: unsigned char arr[len];
+ */
+static inline bitstream initializeBitstream(const unsigned char* arr, size_t len) {
+  return (bitstream){ .arr = arr, .len = len };
+}
+
+/* Closes a bitstream by consuming all remaining bits.
+ * Returns false if CHAR_BIT or more bits remain in the stream or if any remaining bits are non-zero.
+ *
+ * Precondition: NULL != stream
+ */
+bool closeBitstream(bitstream* stream);
+
+/* Fetches up to 31 bits from 'stream' as the 'n' least significant bits of return value.
+ * The 'n' bits are set from the MSB to the LSB.
+ * Returns 'SIMPLICITY_ERR_BITSTREAM_EOF' if not enough bits are available.
+ *
+ * Precondition: 0 <= n < 32
+ *               NULL != stream
+ */
+int32_t readNBits(int n, bitstream* stream);
+
+/* Returns one bit from 'stream', 0 or 1.
+ * Returns 'SIMPLICITY_ERR_BITSTREAM_EOF' if no bits are available.
+ *
+ * Precondition: NULL != stream
+ */
+static inline int32_t read1Bit(bitstream* stream) {
+  return readNBits(1, stream);
+}
+
+/* Decode an encoded number between 1 and 2^31 - 1 inclusive.
+ * When successful returns the decoded result.
+ * If the decoded value would be too large, 'SIMPLICITY_ERR_DATA_OUT_OF_RANGE' is returned.
+ * If more bits are needed than available in the 'stream', 'SIMPLICITY_ERR_BITSTRING_EOF' is returned.
+ * If an I/O error occurs when reading from the 'stream', 'SIMPLICITY_ERR_BISTRING_ERROR' is returned.
+ *
+ * Precondition: NULL != stream
+ */
+int32_t decodeUptoMaxInt(bitstream* stream);
+
+/* Fills a 'bitstring' containing 'n' bits from 'stream'.
+ * Returns 'SIMPLICITY_ERR_BITSTREAM_EOF' if not enough bits are available.
+ * If successful, '*result' is set to a bitstring with 'n' bits read from 'stream' and 0 is returned.
+ *
+ * If an error is returned '*result' might be modified.
+ *
+ * Precondition: NULL != result
+ *               n <= 2^31
+ *               NULL != stream
+ */
+int32_t readBitstring(bitstring* result, size_t n, bitstream* stream);
+#endif

src/simplicity/bitstring.h

@@ -0,0 +1,35 @@
+/* This modules defines a structure representing bit strings. */
+#ifndef SIMPLICITY_BITSTRING_H
+#define SIMPLICITY_BITSTRING_H
+
+#include <assert.h>
+#include <limits.h>
+#include <stdbool.h>
+
+/* Represents a bitstring of length 'len' bits using an array of unsigned char.
+ * The bit at index 'n', where 0 <= 'n' < 'len', is located at bit '1 << (CHAR_BIT - 1 - (offset + n) % CHAR_BIT)' of
+ * array element 'arr[(offset + n) / CHAR_BIT]'.
+ * Other bits in the array may be any value.
+ *
+ * Invariant: len <= 2^31
+ *            offset + length <= SIZE_MAX
+ *            0 < len implies unsigned char arr[(offset + len - 1) / CHAR_BIT + 1];
+ */
+typedef struct bitstring {
+  const unsigned char* arr;
+  size_t len;
+  size_t offset;
+} bitstring;
+
+/* Return the nth bit from a bitstring.
+ *
+ * Precondition: NULL != s
+ *               n < s->len;
+ */
+static inline bool getBit(const bitstring *s, size_t n) {
+  size_t total_offset = s->offset + n;
+  assert(n < s->len);
+  return 1 & (s->arr[total_offset / CHAR_BIT] >> (CHAR_BIT - 1 - (total_offset % CHAR_BIT)));
+}
+
+#endif