libpqxx 7.9.0
util.hxx
1/* Various utility definitions for libpqxx.
2 *
3 * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/util instead.
4 *
5 * Copyright (c) 2000-2024, Jeroen T. Vermeulen.
6 *
7 * See COPYING for copyright license. If you did not receive a file called
8 * COPYING with this source code, please notify the distributor of this
9 * mistake, or contact the author.
10 */
11#ifndef PQXX_H_UTIL
12#define PQXX_H_UTIL
13
14#if !defined(PQXX_HEADER_PRE)
15# error "Include libpqxx headers as <pqxx/header>, not <pqxx/header.hxx>."
16#endif
17
18#include <cassert>
19#include <cctype>
20#include <cerrno>
21#include <cstdio>
22#include <cstring>
23#include <functional>
24#include <iterator>
25#include <limits>
26#include <memory>
27#include <stdexcept>
28#include <string>
29#include <string_view>
30#include <type_traits>
31#include <typeinfo>
32#include <utility>
33#include <vector>
34
35#include "pqxx/except.hxx"
36#include "pqxx/types.hxx"
37#include "pqxx/version.hxx"
38
39
41namespace pqxx
42{}
43
44#include <pqxx/internal/libpq-forward.hxx>
45
46
47// C++23: Retire wrapper.
48#if defined(PQXX_HAVE_UNREACHABLE)
50# define PQXX_UNREACHABLE std::unreachable()
51#else
52# define PQXX_UNREACHABLE assert(false)
53#endif
54
55
57namespace pqxx::internal
58{
59
60// C++20: Retire wrapper.
62template<typename LEFT, typename RIGHT>
63inline constexpr bool cmp_less(LEFT lhs, RIGHT rhs) noexcept
64{
65#if defined(PQXX_HAVE_CMP)
66 return std::cmp_less(lhs, rhs);
67#else
68 // We need a variable just because lgtm.com gives off a false positive
69 // warning when we compare the values directly. It considers that a
70 // "self-comparison."
71 constexpr bool left_signed{std::is_signed_v<LEFT>};
72 if constexpr (left_signed == std::is_signed_v<RIGHT>)
73 return lhs < rhs;
74 else if constexpr (std::is_signed_v<LEFT>)
75 return (lhs <= 0) ? true : (std::make_unsigned_t<LEFT>(lhs) < rhs);
76 else
77 return (rhs <= 0) ? false : (lhs < std::make_unsigned_t<RIGHT>(rhs));
78#endif
79}
80
81
82// C++20: Retire wrapper.
84template<typename LEFT, typename RIGHT>
85inline constexpr bool cmp_greater(LEFT lhs, RIGHT rhs) noexcept
86{
87#if defined(PQXX_HAVE_CMP)
88 return std::cmp_greater(lhs, rhs);
89#else
90 return cmp_less(rhs, lhs);
91#endif
92}
93
94
95// C++20: Retire wrapper.
97template<typename LEFT, typename RIGHT>
98inline constexpr bool cmp_less_equal(LEFT lhs, RIGHT rhs) noexcept
99{
100#if defined(PQXX_HAVE_CMP)
101 return std::cmp_less_equal(lhs, rhs);
102#else
103 return not cmp_less(rhs, lhs);
104#endif
105}
106
107
108// C++20: Retire wrapper.
110template<typename LEFT, typename RIGHT>
111inline constexpr bool cmp_greater_equal(LEFT lhs, RIGHT rhs) noexcept
112{
113#if defined(PQXX_HAVE_CMP)
114 return std::cmp_greater_equal(lhs, rhs);
115#else
116 return not cmp_less(lhs, rhs);
117#endif
118}
119
120
122
125[[nodiscard]] inline std::string cat2(std::string_view x, std::string_view y)
126{
127 std::string buf;
128 auto const xs{std::size(x)}, ys{std::size(y)};
129 buf.resize(xs + ys);
130 x.copy(std::data(buf), xs);
131 y.copy(std::data(buf) + xs, ys);
132 return buf;
133}
134} // namespace pqxx::internal
135
136
137namespace pqxx
138{
139using namespace std::literals;
140
142template<typename... T> inline constexpr void ignore_unused(T &&...) noexcept
143{}
144
145
147
150template<typename TO, typename FROM>
151inline TO check_cast(FROM value, std::string_view description)
152{
153 static_assert(std::is_arithmetic_v<FROM>);
154 static_assert(std::is_arithmetic_v<TO>);
155 static_assert(std::is_integral_v<FROM> == std::is_integral_v<TO>);
156
157 // The rest of this code won't quite work for bool, but bool is trivially
158 // convertible to other arithmetic types as far as I can see.
159 if constexpr (std::is_same_v<FROM, bool>)
160 return static_cast<TO>(value);
161
162 // Depending on our "if constexpr" conditions, this parameter may not be
163 // needed. Some compilers will warn.
164 ignore_unused(description);
165
166 using from_limits = std::numeric_limits<decltype(value)>;
167 using to_limits = std::numeric_limits<TO>;
168 if constexpr (std::is_signed_v<FROM>)
169 {
170 if constexpr (std::is_signed_v<TO>)
171 {
172 if (value < to_limits::lowest())
173 throw range_error{internal::cat2("Cast underflow: "sv, description)};
174 }
175 else
176 {
177 // FROM is signed, but TO is not. Treat this as a special case, because
178 // there may not be a good broader type in which the compiler can even
179 // perform our check.
180 if (value < 0)
182 "Casting negative value to unsigned type: "sv, description)};
183 }
184 }
185 else
186 {
187 // No need to check: the value is unsigned so can't fall below the range
188 // of the TO type.
189 }
190
191 if constexpr (std::is_integral_v<FROM>)
192 {
193 using unsigned_from = std::make_unsigned_t<FROM>;
194 using unsigned_to = std::make_unsigned_t<TO>;
195 constexpr auto from_max{static_cast<unsigned_from>((from_limits::max)())};
196 constexpr auto to_max{static_cast<unsigned_to>((to_limits::max)())};
197 if constexpr (from_max > to_max)
198 {
199 if (internal::cmp_greater(value, to_max))
200 throw range_error{internal::cat2("Cast overflow: "sv, description)};
201 }
202 }
203 else if constexpr ((from_limits::max)() > (to_limits::max)())
204 {
205 if (value > (to_limits::max)())
206 throw range_error{internal::cat2("Cast overflow: ", description)};
207 }
208
209 return static_cast<TO>(value);
210}
211
212
234inline PQXX_PRIVATE void check_version() noexcept
235{
236 // There is no particular reason to do this here in @ref connection, except
237 // to ensure that every meaningful libpqxx client will execute it. The call
238 // must be in the execution path somewhere or the compiler won't try to link
239 // it. We can't use it to initialise a global or class-static variable,
240 // because a smart compiler might resolve it at compile time.
241 //
242 // On the other hand, we don't want to make a useless function call too
243 // often for performance reasons. A local static variable is initialised
244 // only on the definition's first execution. Compilers will be well
245 // optimised for this behaviour, so there's a minimal one-time cost.
246 static auto const version_ok{internal::PQXX_VERSION_CHECK()};
247 ignore_unused(version_ok);
248}
249
250
252
254struct PQXX_LIBEXPORT thread_safety_model
255{
257 bool safe_libpq = false;
258
260
266 bool safe_kerberos = false;
267
269 std::string description;
270};
271
272
274[[nodiscard]] PQXX_LIBEXPORT thread_safety_model describe_thread_safety();
275
276
277#if defined(PQXX_HAVE_CONCEPTS)
278# define PQXX_POTENTIAL_BINARY_ARG pqxx::potential_binary
279#else
280# define PQXX_POTENTIAL_BINARY_ARG typename
281#endif
282
284
288struct byte_char_traits : std::char_traits<char>
289{
290 using char_type = std::byte;
291
292 static void assign(std::byte &a, const std::byte &b) noexcept { a = b; }
293 static bool eq(std::byte a, std::byte b) { return a == b; }
294 static bool lt(std::byte a, std::byte b) { return a < b; }
295
296 static int compare(const std::byte *a, const std::byte *b, std::size_t size)
297 {
298 return std::memcmp(a, b, size);
299 }
300
302 /* This is nonsense: we can't determine the length of a random sequence of
303 * bytes. There is no terminating zero like there is for C strings.
304 *
305 * But `std::char_traits` requires us to provide this function, so we
306 * declare it without defining it.
307 */
308 static size_t length(const std::byte *data);
309
310 static const std::byte *
311 find(const std::byte *data, std::size_t size, const std::byte &value)
312 {
313 return static_cast<const std::byte *>(
314 std::memchr(data, static_cast<int>(value), size));
315 }
316
317 static std::byte *
318 move(std::byte *dest, const std::byte *src, std::size_t size)
319 {
320 return static_cast<std::byte *>(std::memmove(dest, src, size));
321 }
322
323 static std::byte *
324 copy(std::byte *dest, const std::byte *src, std::size_t size)
325 {
326 return static_cast<std::byte *>(std::memcpy(dest, src, size));
327 }
328
329 static std::byte *assign(std::byte *dest, std::size_t size, std::byte value)
330 {
331 return static_cast<std::byte *>(
332 std::memset(dest, static_cast<int>(value), size));
333 }
334
336 static int_type not_eof(int_type value);
337
338 static std::byte to_char_type(int_type value) { return std::byte(value); }
339
340 static int_type to_int_type(std::byte value) { return int_type(value); }
341
342 static bool eq_int_type(int_type a, int_type b) { return a == b; }
343
345 static int_type eof();
346};
347
348template<typename TYPE, typename = void>
349struct has_generic_char_traits : std::false_type
350{};
351
352template<typename TYPE>
354 TYPE, std::void_t<decltype(std::char_traits<TYPE>::eof)>> : std::true_type
355{};
356
357inline constexpr bool has_generic_bytes_char_traits =
359
360// Supress warnings from potentially using a deprecated generic
361// std::char_traits.
362// Necessary for libc++ 18.
363#include "pqxx/internal/ignore-deprecated-pre.hxx"
364
365// C++20: Change this type.
367/* Required to support standard libraries without a generic implementation for
368 * `std::char_traits<std::byte>`.
369 * @warn Will change to `std::vector<std::byte>` in the next major release.
370 */
371using bytes = std::conditional<
372 has_generic_bytes_char_traits, std::basic_string<std::byte>,
373 std::basic_string<std::byte, byte_char_traits>>::type;
374
375// C++20: Change this type.
377/* Required to support standard libraries without a generic implementation for
378 * `std::char_traits<std::byte>`.
379 * @warn Will change to `std::span<std::byte>` in the next major release.
380 */
381using bytes_view = std::conditional<
382 has_generic_bytes_char_traits, std::basic_string_view<std::byte>,
383 std::basic_string_view<std::byte, byte_char_traits>>::type;
384
385#include "pqxx/internal/ignore-deprecated-post.hxx"
386
387
389
406template<PQXX_POTENTIAL_BINARY_ARG TYPE>
407bytes_view binary_cast(TYPE const &data)
408{
409 static_assert(sizeof(value_type<TYPE>) == 1);
410 // C++20: Use std::as_bytes.
411 return {
412 reinterpret_cast<std::byte const *>(
413 const_cast<strip_t<decltype(*std::data(data))> const *>(
414 std::data(data))),
415 std::size(data)};
416}
417
418
419#if defined(PQXX_HAVE_CONCEPTS)
420template<typename CHAR>
421concept char_sized = (sizeof(CHAR) == 1);
422# define PQXX_CHAR_SIZED_ARG char_sized
423#else
424# define PQXX_CHAR_SIZED_ARG typename
425#endif
426
428
434template<PQXX_CHAR_SIZED_ARG CHAR, typename SIZE>
435bytes_view binary_cast(CHAR const *data, SIZE size)
436{
437 static_assert(sizeof(CHAR) == 1);
438 return {
439 reinterpret_cast<std::byte const *>(data),
440 check_cast<std::size_t>(size, "binary data size")};
441}
442
443
445constexpr oid oid_none{0};
446} // namespace pqxx
447
448
450
459namespace pqxx::internal
460{
461using namespace std::literals;
462
463
465
469template<typename CHAR> inline constexpr bool is_digit(CHAR c) noexcept
470{
471 return (c >= '0') and (c <= '9');
472}
473
474
476
478[[nodiscard]] std::string
479describe_object(std::string_view class_name, std::string_view name);
480
481
483
495 void const *old_guest, std::string_view old_class, std::string_view old_name,
496 void const *new_guest, std::string_view new_class,
497 std::string_view new_name);
498
499
501
505 void const *old_guest, std::string_view old_class, std::string_view old_name,
506 void const *new_guest, std::string_view new_class,
507 std::string_view new_name);
508
509
511
514inline constexpr std::size_t size_esc_bin(std::size_t binary_bytes) noexcept
515{
516 return 2 + (2 * binary_bytes) + 1;
517}
518
519
521
523inline constexpr std::size_t size_unesc_bin(std::size_t escaped_bytes) noexcept
524{
525 return (escaped_bytes - 2) / 2;
526}
527
528
529// TODO: Use actual binary type for "data".
531
536void PQXX_LIBEXPORT esc_bin(bytes_view binary_data, char buffer[]) noexcept;
537
538
540std::string PQXX_LIBEXPORT esc_bin(bytes_view binary_data);
541
542
544void PQXX_LIBEXPORT
545unesc_bin(std::string_view escaped_data, std::byte buffer[]);
546
547
549bytes PQXX_LIBEXPORT unesc_bin(std::string_view escaped_data);
550
551
553template<typename T> auto ssize(T const &c)
554{
555#if defined(PQXX_HAVE_SSIZE)
556 return std::ssize(c);
557#else
558 using signed_t = std::make_signed_t<decltype(std::size(c))>;
559 return static_cast<signed_t>(std::size(c));
560#endif // PQXX_HAVE_SSIZe
561}
562
563
565
569template<typename RETURN, typename... ARGS>
570std::tuple<ARGS...> args_f(RETURN (&func)(ARGS...));
571
572
574
578template<typename RETURN, typename... ARGS>
579std::tuple<ARGS...> args_f(std::function<RETURN(ARGS...)> const &);
580
581
583
587template<typename CLASS, typename RETURN, typename... ARGS>
588std::tuple<ARGS...> member_args_f(RETURN (CLASS::*)(ARGS...));
589
590
592
596template<typename CLASS, typename RETURN, typename... ARGS>
597std::tuple<ARGS...> member_args_f(RETURN (CLASS::*)(ARGS...) const);
598
599
601
607template<typename CALLABLE>
608auto args_f(CALLABLE const &f)
609 -> decltype(member_args_f(&CALLABLE::operator()));
610
611
613template<typename CALLABLE>
614using args_t = decltype(args_f(std::declval<CALLABLE>()));
615
616
618
621template<typename... TYPES>
622std::tuple<strip_t<TYPES>...> strip_types(std::tuple<TYPES...> const &);
623
624
626template<typename... TYPES>
627using strip_types_t = decltype(strip_types(std::declval<TYPES...>()));
628
629
631inline constexpr char unescape_char(char escaped) noexcept
632{
633 switch (escaped)
634 {
635 case 'b': // Backspace.
636 PQXX_UNLIKELY return '\b';
637 case 'f': // Form feed
638 PQXX_UNLIKELY return '\f';
639 case 'n': // Line feed.
640 return '\n';
641 case 'r': // Carriage return.
642 return '\r';
643 case 't': // Horizontal tab.
644 return '\t';
645 case 'v': // Vertical tab.
646 return '\v';
647 default: break;
648 }
649 // Regular character ("self-escaped").
650 return escaped;
651}
652
653
654// C++20: std::span?
656template<std::size_t BYTES>
657char const *PQXX_COLD
658error_string(int err_num, std::array<char, BYTES> &buffer)
659{
660 // Not entirely clear whether strerror_s will be in std or global namespace.
661 using namespace std;
662
663#if defined(PQXX_HAVE_STERROR_S) || defined(PQXX_HAVE_STRERROR_R)
664# if defined(PQXX_HAVE_STRERROR_S)
665 auto const err_result{strerror_s(std::data(buffer), BYTES, err_num)};
666# else
667 auto const err_result{strerror_r(err_num, std::data(buffer), BYTES)};
668# endif
669 if constexpr (std::is_same_v<pqxx::strip_t<decltype(err_result)>, char *>)
670 {
671 // GNU version of strerror_r; returns the error string, which may or may
672 // not reside within buffer.
673 return err_result;
674 }
675 else
676 {
677 // Either strerror_s or POSIX strerror_r; returns an error code.
678 // Sorry for being lazy here: Not reporting error string for the case
679 // where we can't retrieve an error string.
680 if (err_result == 0)
681 return std::data(buffer);
682 else
683 return "Compound errors.";
684 }
685
686#else
687 // Fallback case, hopefully for no actual platforms out there.
688 pqxx::ignore_unused(err_num, buffer);
689 return "(No error information available.)";
690#endif
691}
692} // namespace pqxx::internal
693
694
696{
698PQXX_LIBEXPORT void pqfreemem(void const *) noexcept;
699} // namespace pqxx::internal::pq
700#endif
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:33
std::remove_cv_t< std::remove_reference_t< TYPE > > strip_t
Remove any constness, volatile, and reference-ness from a type.
Definition: types.hxx:78
bytes_view binary_cast(TYPE const &data)
Cast binary data to a type that libpqxx will recognise as binary.
Definition: util.hxx:407
strip_t< decltype(*std::begin(std::declval< CONTAINER >()))> value_type
The type of a container's elements.
Definition: types.hxx:94
void check_version() noexcept
Definition: util.hxx:234
thread_safety_model describe_thread_safety()
Describe thread safety available in this build.
Definition: util.cxx:35
constexpr void ignore_unused(T &&...) noexcept
Suppress compiler warning about an unused item.
Definition: util.hxx:142
constexpr bool has_generic_bytes_char_traits
Definition: util.hxx:357
std::conditional< has_generic_bytes_char_traits, std::basic_string< std::byte >, std::basic_string< std::byte, byte_char_traits > >::type bytes
Type alias for a container containing bytes.
Definition: util.hxx:373
std::conditional< has_generic_bytes_char_traits, std::basic_string_view< std::byte >, std::basic_string_view< std::byte, byte_char_traits > >::type bytes_view
Type alias for a view of bytes.
Definition: util.hxx:383
constexpr oid oid_none
The "null" oid.
Definition: util.hxx:445
TO check_cast(FROM value, std::string_view description)
Cast a numeric value to another type, or throw if it underflows/overflows.
Definition: util.hxx:151
Internal items for libpqxx' own use. Do not use these yourself.
Definition: composite.hxx:84
void unesc_bin(std::string_view escaped_data, std::byte buffer[])
Reconstitute binary data from its escaped version.
Definition: util.cxx:165
int PQXX_VERSION_CHECK() noexcept
Library version check stub.
Definition: version.cxx:23
char const *PQXX_COLD error_string(int err_num, std::array< char, BYTES > &buffer)
Get error string for a given errno value.
Definition: util.hxx:658
constexpr std::size_t size_esc_bin(std::size_t binary_bytes) noexcept
Compute buffer size needed to escape binary data for use as a BYTEA.
Definition: util.hxx:514
std::tuple< ARGS... > member_args_f(RETURN(CLASS::*)(ARGS...))
Helper for determining a member function's parameter types.
constexpr bool cmp_less(LEFT lhs, RIGHT rhs) noexcept
Same as std::cmp_less, or a workaround where that's not available.
Definition: util.hxx:63
void check_unique_unregister(void const *old_guest, std::string_view old_class, std::string_view old_name, void const *new_guest, std::string_view new_class, std::string_view new_name)
Like check_unique_register, but for un-registering a guest.
Definition: util.cxx:80
void esc_bin(bytes_view binary_data, char buffer[]) noexcept
Hex-escape binary data into a buffer.
Definition: util.cxx:133
decltype(strip_types(std::declval< TYPES... >())) strip_types_t
Take a tuple type and apply strip_t to its component types.
Definition: util.hxx:627
void check_unique_register(void const *old_guest, std::string_view old_class, std::string_view old_name, void const *new_guest, std::string_view new_class, std::string_view new_name)
Check validity of registering a new "guest" in a "host.".
Definition: util.cxx:63
std::tuple< strip_t< TYPES >... > strip_types(std::tuple< TYPES... > const &)
Helper: Apply strip_t to each of a tuple type's component types.
std::string describe_object(std::string_view class_name, std::string_view name)
Describe an object for humans, based on class name and optional name.
Definition: util.cxx:53
std::tuple< ARGS... > args_f(RETURN(&func)(ARGS...))
Helper for determining a function's parameter types.
constexpr bool cmp_greater(LEFT lhs, RIGHT rhs) noexcept
C++20 std::cmp_greater, or workaround if not available.
Definition: util.hxx:85
decltype(args_f(std::declval< CALLABLE >())) args_t
A callable's parameter types, as a tuple.
Definition: util.hxx:614
constexpr bool is_digit(CHAR c) noexcept
A safer and more generic replacement for std::isdigit.
Definition: util.hxx:469
constexpr char unescape_char(char escaped) noexcept
Return original byte for escaped character.
Definition: util.hxx:631
constexpr bool cmp_greater_equal(LEFT lhs, RIGHT rhs) noexcept
C++20 std::cmp_greater_equal, or workaround if not available.
Definition: util.hxx:111
std::string cat2(std::string_view x, std::string_view y)
Efficiently concatenate two strings.
Definition: util.hxx:125
constexpr bool cmp_less_equal(LEFT lhs, RIGHT rhs) noexcept
C++20 std::cmp_less_equal, or workaround if not available.
Definition: util.hxx:98
auto ssize(T const &c)
Transitional: std::ssize(), or custom implementation if not available.
Definition: util.hxx:553
constexpr std::size_t size_unesc_bin(std::size_t escaped_bytes) noexcept
Compute binary size from the size of its escaped version.
Definition: util.hxx:523
Definition: util.hxx:696
void pqfreemem(void const *) noexcept
Wrapper for PQfreemem(), with C++ linkage.
Definition: util.cxx:205
Something is out of range, similar to std::out_of_range.
Definition: except.hxx:326
Descriptor of library's thread-safety model.
Definition: util.hxx:255
std::string description
A human-readable description of any thread-safety issues.
Definition: util.hxx:269
Custom std::char_trast if the compiler does not provide one.
Definition: util.hxx:289
static std::byte * move(std::byte *dest, const std::byte *src, std::size_t size)
Definition: util.hxx:318
static const std::byte * find(const std::byte *data, std::size_t size, const std::byte &value)
Definition: util.hxx:311
static std::byte * copy(std::byte *dest, const std::byte *src, std::size_t size)
Definition: util.hxx:324
static size_t length(const std::byte *data)
Deliberately undefined: "guess" the length of an array of bytes.
static void assign(std::byte &a, const std::byte &b) noexcept
Definition: util.hxx:292
static std::byte to_char_type(int_type value)
Definition: util.hxx:338
static int_type not_eof(int_type value)
Declared but not defined: makes no sense for binary data.
static bool eq(std::byte a, std::byte b)
Definition: util.hxx:293
static int_type eof()
Declared but not defined: makes no sense for binary data.
static bool lt(std::byte a, std::byte b)
Definition: util.hxx:294
static std::byte * assign(std::byte *dest, std::size_t size, std::byte value)
Definition: util.hxx:329
static int_type to_int_type(std::byte value)
Definition: util.hxx:340
static bool eq_int_type(int_type a, int_type b)
Definition: util.hxx:342
std::byte char_type
Definition: util.hxx:290
static int compare(const std::byte *a, const std::byte *b, std::size_t size)
Definition: util.hxx:296
Definition: util.hxx:350