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/****************************************************************************
**
** Copyright (C) 2021 Intel Corporation
**
** Permission is hereby granted, free of charge, to any person obtaining a copy
** of this software and associated documentation files (the "Software"), to deal
** in the Software without restriction, including without limitation the rights
** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
** copies of the Software, and to permit persons to whom the Software is
** furnished to do so, subject to the following conditions:
**
** The above copyright notice and this permission notice shall be included in
** all copies or substantial portions of the Software.
**
** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
** OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
** THE SOFTWARE.
**
****************************************************************************/
#define _BSD_SOURCE 1
#define _DEFAULT_SOURCE 1
#ifndef __STDC_LIMIT_MACROS
# define __STDC_LIMIT_MACROS 1
#endif
#include "cbor.h"
#include "cborinternal_p.h"
#include "compilersupport_p.h"
#include "utf8_p.h"
#include <inttypes.h>
#include <string.h>
/**
* \defgroup CborPretty Converting CBOR to text
* \brief Group of functions used to convert CBOR to text form.
*
* This group contains two functions that can be used to convert a \ref
* CborValue object to a text representation. This module attempts to follow
* the recommendations from RFC 7049 section 6 "Diagnostic Notation", though it
* has a few differences. They are noted below.
*
* TinyCBOR does not provide a way to convert from the text representation back
* to encoded form. To produce a text form meant to be parsed, CborToJson is
* recommended instead.
*
* Either of the functions in this section will attempt to convert exactly one
* CborValue object to text. Those functions may return any error documented
* for the functions for CborParsing. In addition, if the C standard library
* stream functions return with error, the text conversion will return with
* error CborErrorIO.
*
* These functions also perform UTF-8 validation in CBOR text strings. If they
* encounter a sequence of bytes that is not permitted in UTF-8, they will return
* CborErrorInvalidUtf8TextString. That includes encoding of surrogate points
* in UTF-8.
*
* \warning The output type produced by these functions is not guaranteed to
* remain stable. A future update of TinyCBOR may produce different output for
* the same input and parsers may be unable to handle it.
*
* \sa CborParsing, CborToJson, cbor_parser_init()
*/
/**
* \addtogroup CborPretty
* @{
* <h2 class="groupheader">Text format</h2>
*
* As described in RFC 7049 section 6 "Diagnostic Notation", the format is
* largely borrowed from JSON, but modified to suit CBOR's different data
* types. TinyCBOR makes further modifications to distinguish different, but
* similar values.
*
* CBOR values are currently encoded as follows:
* \par Integrals (unsigned and negative)
* Base-10 (decimal) text representation of the value
* \par Byte strings:
* <tt>"h'"</tt> followed by the Base16 (hex) representation of the binary data, followed by an ending quote (')
* \par Text strings:
* C-style escaped string in quotes, with C11/C++11 escaping of Unicode codepoints above U+007F.
* \par Tags:
* Tag value, with the tagged value in parentheses. No special encoding of the tagged value is performed.
* \par Simple types:
* <tt>"simple(nn)"</tt> where \c nn is the simple value
* \par Null:
* \c null
* \par Undefined:
* \c undefined
* \par Booleans:
* \c true or \c false
* \par Floating point:
* If NaN or infinite, the actual words \c NaN or \c infinite.
* Otherwise, the decimal representation with as many digits as necessary to ensure no loss of information.
* By default, float values are suffixed by "f" and half-float values suffixed by "f16" (doubles have no suffix).
* If the CborPrettyNumericEncodingIndicators flag is active, the values instead are encoded following the
* Section 6 recommended encoding indicators: float values are suffixed with "_2" and half-float with "_1".
* A decimal point is always present.
* \par Arrays:
* Comma-separated list of elements, enclosed in square brackets ("[" and "]").
* \par Maps:
* Comma-separated list of key-value pairs, with the key and value separated
* by a colon (":"), enclosed in curly braces ("{" and "}").
*
* The CborPrettyFlags enumerator contains flags to control some aspects of the
* encoding:
* \par String fragmentation
* When the CborPrettyShowStringFragments option is active, text and byte
* strings that are transmitted in fragments are shown instead inside
* parentheses ("(" and ")") with no preceding number and each fragment is
* displayed individually. If a tag precedes the string, then the output
* will contain a double set of parentheses. If the option is not active,
* the fragments are merged together and the display will not show any
* difference from a string transmitted with determinate length.
* \par Encoding indicators
* Numbers and lengths in CBOR can be encoded in multiple representations.
* If the CborPrettyIndicateOverlongNumbers option is active, numbers
* and lengths that are transmitted in a longer encoding than necessary
* will be indicated, by appending an underscore ("_") to either the
* number or the opening bracket or brace, followed by a number
* indicating the CBOR additional information: 0 for 1 byte, 1 for 2
* bytes, 2 for 4 bytes and 3 for 8 bytes.
* If the CborPrettyIndicateIndeterminateLength option is active, maps,
* arrays and strings encoded with indeterminate length will be marked by
* an underscore after the opening bracket or brace or the string (if not
* showing fragments), without a number after it.
*/
/**
* \enum CborPrettyFlags
* The CborPrettyFlags enum contains flags that control the conversion of CBOR to text format.
*
* \value CborPrettyNumericEncodingIndicators Use numeric encoding indicators instead of textual for float and half-float.
* \value CborPrettyTextualEncodingIndicators Use textual encoding indicators for float ("f") and half-float ("f16").
* \value CborPrettyIndicateIndeterminateLength (default) Indicate when a map or array has indeterminate length.
* \value CborPrettyIndicateOverlongNumbers Indicate when a number or length was encoded with more bytes than needed.
* \value CborPrettyShowStringFragments If the byte or text string is transmitted in chunks, show each individually.
* \value CborPrettyMergeStringFragment Merge all chunked byte or text strings and display them in a single entry.
* \value CborPrettyDefaultFlags Default conversion flags.
*/
#ifndef CBOR_NO_FLOATING_POINT
static inline bool convertToUint64(double v, uint64_t *absolute)
{
double supremum;
v = fabs(v);
/* C11 standard section 6.3.1.4 "Real floating and integer" says:
*
* 1 When a finite value of real floating type is converted to an integer
* type other than _Bool, the fractional part is discarded (i.e., the
* value is truncated toward zero). If the value of the integral part
* cannot be represented by the integer type, the behavior is undefined.
*
* So we must perform a range check that v <= UINT64_MAX, but we can't use
* UINT64_MAX + 1.0 because the standard continues:
*
* 2 When a value of integer type is converted to a real floating type, if
* the value being converted can be represented exactly in the new type,
* it is unchanged. If the value being converted is in the range of
* values that can be represented but cannot be represented exactly, the
* result is either the nearest higher or nearest lower representable
* value, chosen in an implementation-defined manner.
*/
supremum = -2.0 * INT64_MIN; /* -2 * (- 2^63) == 2^64 */
if (v >= supremum)
return false;
/* Now we can convert, these two conversions cannot be UB */
*absolute = v;
return *absolute == v;
}
#endif
static void printRecursionLimit(CborStreamFunction stream, void *out)
{
stream(out, "<nesting too deep, recursion stopped>");
}
static CborError hexDump(CborStreamFunction stream, void *out, const void *ptr, size_t n)
{
const uint8_t *buffer = (const uint8_t *)ptr;
CborError err = CborNoError;
while (n-- && !err)
err = stream(out, "%02" PRIx8, *buffer++);
return err;
}
/* This function decodes buffer as UTF-8 and prints as escaped UTF-16.
* On UTF-8 decoding error, it returns CborErrorInvalidUtf8TextString */
static CborError utf8EscapedDump(CborStreamFunction stream, void *out, const void *ptr, size_t n)
{
const uint8_t *buffer = (const uint8_t *)ptr;
const uint8_t * const end = buffer + n;
CborError err = CborNoError;
while (buffer < end && !err) {
uint32_t uc = get_utf8(&buffer, end);
if (uc == ~0U)
return CborErrorInvalidUtf8TextString;
if (uc < 0x80) {
/* single-byte UTF-8 */
unsigned char escaped = (unsigned char)uc;
if (uc < 0x7f && uc >= 0x20 && uc != '\\' && uc != '"') {
err = stream(out, "%c", (char)uc);
continue;
}
/* print as an escape sequence */
switch (uc) {
case '"':
case '\\':
break;
case '\b':
escaped = 'b';
break;
case '\f':
escaped = 'f';
break;
case '\n':
escaped = 'n';
break;
case '\r':
escaped = 'r';
break;
case '\t':
escaped = 't';
break;
default:
goto print_utf16;
}
err = stream(out, "\\%c", escaped);
continue;
}
/* now print the sequence */
if (uc > 0xffffU) {
/* needs surrogate pairs */
err = stream(out, "\\u%04" PRIX32 "\\u%04" PRIX32,
(uc >> 10) + 0xd7c0, /* high surrogate */
(uc % 0x0400) + 0xdc00);
} else {
print_utf16:
/* no surrogate pair needed */
err = stream(out, "\\u%04" PRIX32, uc);
}
}
return err;
}
static const char *resolve_indicator(const CborValue *it, int flags)
{
static const char indicators[8][3] = {
"_0", "_1", "_2", "_3",
"", "", "", /* these are not possible */
"_"
};
const char *no_indicator = indicators[5]; /* empty string */
uint8_t additional_information;
uint8_t expected_information;
uint64_t value;
CborError err;
if (!read_bytes(it, &additional_information, 0, 1))
return NULL; /* CborErrorUnexpectedEOF */
additional_information &= SmallValueMask;
if (additional_information < Value8Bit)
return no_indicator;
/* determine whether to show anything */
if ((flags & CborPrettyIndicateIndeterminateLength) &&
additional_information == IndefiniteLength)
return indicators[IndefiniteLength - Value8Bit];
if ((flags & CborPrettyIndicateOverlongNumbers) == 0)
return no_indicator;
err = extract_number_checked(it, &value, NULL);
if (err)
return NULL; /* CborErrorUnexpectedEOF */
expected_information = Value8Bit - 1;
if (value >= Value8Bit)
++expected_information;
if (value > 0xffU)
++expected_information;
if (value > 0xffffU)
++expected_information;
if (value > 0xffffffffU)
++expected_information;
return expected_information == additional_information ?
no_indicator :
indicators[additional_information - Value8Bit];
}
static const char *get_indicator(const CborValue *it, int flags)
{
return resolve_indicator(it, flags);
}
static CborError value_to_pretty(CborStreamFunction stream, void *out, CborValue *it, int flags, int recursionsLeft);
static CborError container_to_pretty(CborStreamFunction stream, void *out, CborValue *it, CborType containerType,
int flags, int recursionsLeft)
{
const char *comma = "";
CborError err = CborNoError;
if (!recursionsLeft) {
printRecursionLimit(stream, out);
return err; /* do allow the dumping to continue */
}
while (!cbor_value_at_end(it) && !err) {
err = stream(out, "%s", comma);
comma = ", ";
if (!err)
err = value_to_pretty(stream, out, it, flags, recursionsLeft);
if (containerType == CborArrayType)
continue;
/* map: that was the key, so get the value */
if (!err)
err = stream(out, ": ");
if (!err)
err = value_to_pretty(stream, out, it, flags, recursionsLeft);
}
return err;
}
static CborError value_to_pretty(CborStreamFunction stream, void *out, CborValue *it, int flags, int recursionsLeft)
{
CborError err = CborNoError;
CborType type = cbor_value_get_type(it);
switch (type) {
case CborArrayType:
case CborMapType: {
/* recursive type */
CborValue recursed;
const char *indicator = get_indicator(it, flags);
const char *space = *indicator ? " " : indicator;
err = stream(out, "%c%s%s", type == CborArrayType ? '[' : '{', indicator, space);
if (err)
return err;
err = cbor_value_enter_container(it, &recursed);
if (err) {
copy_current_position(it, &recursed);
return err; /* parse error */
}
err = container_to_pretty(stream, out, &recursed, type, flags, recursionsLeft - 1);
if (err) {
copy_current_position(it, &recursed);
return err; /* parse error */
}
err = cbor_value_leave_container(it, &recursed);
if (err)
return err; /* parse error */
return stream(out, type == CborArrayType ? "]" : "}");
}
case CborIntegerType: {
uint64_t val;
cbor_value_get_raw_integer(it, &val); /* can't fail */
if (cbor_value_is_unsigned_integer(it)) {
err = stream(out, "%" PRIu64, val);
} else {
/* CBOR stores the negative number X as -1 - X
* (that is, -1 is stored as 0, -2 as 1 and so forth) */
if (++val) { /* unsigned overflow may happen */
err = stream(out, "-%" PRIu64, val);
} else {
/* overflown
* 0xffff`ffff`ffff`ffff + 1 =
* 0x1`0000`0000`0000`0000 = 18446744073709551616 (2^64) */
err = stream(out, "-18446744073709551616");
}
}
if (!err)
err = stream(out, "%s", get_indicator(it, flags));
break;
}
case CborByteStringType:
case CborTextStringType: {
size_t n = 0;
const void *ptr;
bool showingFragments = (flags & CborPrettyShowStringFragments) && !cbor_value_is_length_known(it);
const char *separator = "";
char close = '\'';
char open[3] = "h'";
const char *indicator = NULL;
if (type == CborTextStringType) {
close = open[0] = '"';
open[1] = '\0';
}
if (showingFragments)
err = stream(out, "(_ ");
else
err = stream(out, "%s", open);
if (!err)
err = cbor_value_begin_string_iteration(it);
while (!err) {
if (showingFragments || indicator == NULL) {
/* any iteration, except the second for a non-chunked string */
indicator = resolve_indicator(it, flags);
}
err = _cbor_value_get_string_chunk(it, &ptr, &n, it);
if (err == CborErrorNoMoreStringChunks) {
err = cbor_value_finish_string_iteration(it);
break;
}
if (!err && showingFragments)
err = stream(out, "%s%s", separator, open);
if (!err)
err = (type == CborByteStringType ?
hexDump(stream, out, ptr, n) :
utf8EscapedDump(stream, out, ptr, n));
if (!err && showingFragments) {
err = stream(out, "%c%s", close, indicator);
separator = ", ";
}
}
if (!err) {
if (showingFragments)
err = stream(out, ")");
else
err = stream(out, "%c%s", close, indicator);
}
return err;
}
case CborTagType: {
CborTag tag;
cbor_value_get_tag(it, &tag); /* can't fail */
err = stream(out, "%" PRIu64 "%s(", tag, get_indicator(it, flags));
if (!err)
err = cbor_value_advance_fixed(it);
if (!err && recursionsLeft)
err = value_to_pretty(stream, out, it, flags, recursionsLeft - 1);
else if (!err)
printRecursionLimit(stream, out);
if (!err)
err = stream(out, ")");
return err;
}
case CborSimpleType: {
/* simple types can't fail and can't have overlong encoding */
uint8_t simple_type;
cbor_value_get_simple_type(it, &simple_type);
err = stream(out, "simple(%" PRIu8 ")", simple_type);
break;
}
case CborNullType:
err = stream(out, "null");
break;
case CborUndefinedType:
err = stream(out, "undefined");
break;
case CborBooleanType: {
bool val;
cbor_value_get_boolean(it, &val); /* can't fail */
err = stream(out, val ? "true" : "false");
break;
}
#ifndef CBOR_NO_FLOATING_POINT
case CborDoubleType: {
const char *suffix;
double val;
int r;
uint64_t ival;
if (false) {
float f;
case CborFloatType:
cbor_value_get_float(it, &f);
val = f;
suffix = flags & CborPrettyNumericEncodingIndicators ? "_2" : "f";
} else if (false) {
uint16_t f16;
case CborHalfFloatType:
#ifndef CBOR_NO_HALF_FLOAT_TYPE
cbor_value_get_half_float(it, &f16);
val = decode_half(f16);
suffix = flags & CborPrettyNumericEncodingIndicators ? "_1" : "f16";
#else
(void)f16;
err = CborErrorUnsupportedType;
break;
#endif
} else {
cbor_value_get_double(it, &val);
suffix = "";
}
if ((flags & CborPrettyNumericEncodingIndicators) == 0) {
r = fpclassify(val);
if (r == FP_NAN || r == FP_INFINITE)
suffix = "";
}
if (convertToUint64(val, &ival)) {
/* this double value fits in a 64-bit integer, so show it as such
* (followed by a floating point suffix, to disambiguate) */
err = stream(out, "%s%" PRIu64 ".%s", val < 0 ? "-" : "", ival, suffix);
} else {
/* this number is definitely not a 64-bit integer */
err = stream(out, "%." DBL_DECIMAL_DIG_STR "g%s", val, suffix);
}
break;
}
#else
case CborDoubleType:
case CborFloatType:
case CborHalfFloatType:
err = CborErrorUnsupportedType;
break;
#endif /* !CBOR_NO_FLOATING_POINT */
case CborInvalidType:
err = stream(out, "invalid");
if (err)
return err;
return CborErrorUnknownType;
}
if (!err)
err = cbor_value_advance_fixed(it);
return err;
}
/**
* Converts the current CBOR type pointed by \a value to its textual
* representation and writes it to the stream by calling the \a streamFunction.
* If an error occurs, this function returns an error code similar to
* \ref CborParsing.
*
* The textual representation can be controlled by the \a flags parameter (see
* \ref CborPrettyFlags for more information).
*
* If no error ocurred, this function advances \a value to the next element.
* Often, concatenating the text representation of multiple elements can be
* done by appending a comma to the output stream in between calls to this
* function.
*
* The \a streamFunction function will be called with the \a token value as the
* first parameter and a printf-style format string as the second, with a variable
* number of further parameters.
*
* \sa cbor_value_to_pretty(), cbor_value_to_json_advance()
*/
CborError cbor_value_to_pretty_stream(CborStreamFunction streamFunction, void *token, CborValue *value, int flags)
{
return value_to_pretty(streamFunction, token, value, flags, CBOR_PARSER_MAX_RECURSIONS);
}
/** @} */