1 //===-- Implementation of a class for mapping errors to strings -----------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "error_to_string.h"
10 #include "platform_errors.h"
11
12 #include "src/__support/CPP/span.h"
13 #include "src/__support/CPP/string_view.h"
14 #include "src/__support/CPP/stringstream.h"
15 #include "src/__support/StringUtil/message_mapper.h"
16 #include "src/__support/integer_to_string.h"
17 #include "src/__support/macros/attributes.h"
18 #include "src/__support/macros/config.h"
19
20 #include <stddef.h>
21
22 namespace LIBC_NAMESPACE_DECL {
23 namespace internal {
24
max_buff_size()25 constexpr size_t max_buff_size() {
26 constexpr size_t unknown_str_len = sizeof("Unknown error");
27 // the buffer should be able to hold "Unknown error" + ' ' + num_str
28 return (unknown_str_len + 1 + IntegerToString<int>::buffer_size()) *
29 sizeof(char);
30 }
31
32 // This is to hold error strings that have to be custom built. It may be
33 // rewritten on every call to strerror (or other error to string function).
34 constexpr size_t ERR_BUFFER_SIZE = max_buff_size();
35 LIBC_THREAD_LOCAL char error_buffer[ERR_BUFFER_SIZE];
36
37 constexpr size_t TOTAL_STR_LEN = total_str_len(PLATFORM_ERRORS);
38
39 // Since the StringMappings array is a map from error numbers to their
40 // corresponding strings, we have to have an array large enough we can use the
41 // error numbers as indexes. The current linux configuration has 132 values with
42 // the maximum value being 133 (41 and 58 are skipped). If other platforms use
43 // negative numbers or discontiguous ranges, then the array should be turned
44 // into a proper hashmap.
45 constexpr size_t ERR_ARRAY_SIZE = max_key_val(PLATFORM_ERRORS) + 1;
46
47 constexpr MessageMapper<ERR_ARRAY_SIZE, TOTAL_STR_LEN>
48 ERROR_MAPPER(PLATFORM_ERRORS);
49
50 constexpr MessageMapper<ERR_ARRAY_SIZE, TOTAL_STR_LEN>
51 ERRNO_NAME_MAPPER(PLATFORM_ERRNO_NAMES);
52
build_error_string(int err_num,cpp::span<char> buffer)53 cpp::string_view build_error_string(int err_num, cpp::span<char> buffer) {
54 // if the buffer can't hold "Unknown error" + ' ' + num_str, then just
55 // return "Unknown error".
56 if (buffer.size() <
57 (sizeof("Unknown error") + 1 + IntegerToString<int>::buffer_size()))
58 return const_cast<char *>("Unknown error");
59
60 cpp::StringStream buffer_stream(
61 {const_cast<char *>(buffer.data()), buffer.size()});
62 buffer_stream << "Unknown error" << ' ' << err_num << '\0';
63 return buffer_stream.str();
64 }
65
66 } // namespace internal
67
get_error_string(int err_num)68 cpp::string_view get_error_string(int err_num) {
69 return get_error_string(err_num,
70 {internal::error_buffer, internal::ERR_BUFFER_SIZE});
71 }
72
get_error_string(int err_num,cpp::span<char> buffer)73 cpp::string_view get_error_string(int err_num, cpp::span<char> buffer) {
74 auto opt_str = internal::ERROR_MAPPER.get_str(err_num);
75 if (opt_str)
76 return *opt_str;
77 else
78 return internal::build_error_string(err_num, buffer);
79 }
80
try_get_errno_name(int err_num)81 cpp::optional<cpp::string_view> try_get_errno_name(int err_num) {
82 return internal::ERRNO_NAME_MAPPER.get_str(err_num);
83 }
84
85 } // namespace LIBC_NAMESPACE_DECL
86