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| 1 | //===-- Strerror Converter for printf ---------------------------*- C++ -*-===// |
|---|---|
| 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 | #ifndef LLVM_LIBC_SRC_STDIO_PRINTF_CORE_STRERROR_CONVERTER_H |
| 10 | #define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_STRERROR_CONVERTER_H |
| 11 | |
| 12 | #include "src/__support/StringUtil/error_to_string.h" |
| 13 | #include "src/__support/macros/config.h" |
| 14 | #include "src/stdio/printf_core/core_structs.h" |
| 15 | #include "src/stdio/printf_core/int_converter.h" |
| 16 | #include "src/stdio/printf_core/string_converter.h" |
| 17 | #include "src/stdio/printf_core/writer.h" |
| 18 | |
| 19 | namespace LIBC_NAMESPACE_DECL { |
| 20 | namespace printf_core { |
| 21 | |
| 22 | template <WriteMode write_mode> |
| 23 | LIBC_INLINE int convert_strerror(Writer<write_mode> *writer, |
| 24 | const FormatSection &to_conv) { |
| 25 | FormatSection new_conv = to_conv; |
| 26 | const int error_num = static_cast<int>(to_conv.conv_val_raw); |
| 27 | |
| 28 | // The %m conversion takes no arguments passes the result of strerror(errno) |
| 29 | // to a string conversion (including all options). If the alternate form flag |
| 30 | // is set, then if errno is a valid error number the string of the errno macro |
| 31 | // is passed to a string conversion, else the integer value of errno is passed |
| 32 | // to an integer conversion. |
| 33 | |
| 34 | // It's assumed that errno is passed in to_conv.conv_val_raw. |
| 35 | |
| 36 | // normal form |
| 37 | if ((to_conv.flags & FormatFlags::ALTERNATE_FORM) == 0) { |
| 38 | char strerror_buff[64]; |
| 39 | auto strerror_result = get_error_string(error_num, strerror_buff); |
| 40 | new_conv.conv_val_ptr = |
| 41 | reinterpret_cast<void *>(const_cast<char *>(strerror_result.data())); |
| 42 | new_conv.conv_name = 's'; |
| 43 | return convert_string(writer, new_conv); |
| 44 | } else { |
| 45 | // alt form |
| 46 | |
| 47 | // The handling of errno = 0 is in alt form weird. The rule for %m in alt |
| 48 | // form is "named macros print their name, else print errno as int." There |
| 49 | // isn't a specific name for errno = 0, but it does have an explicit meaning |
| 50 | // (success). Due to the way the string mappings work, it's easiest to just |
| 51 | // say that 0 is a valid macro with a string of "0". This works fine for |
| 52 | // most cases, but for precision and the int flags it changes the behavior. |
| 53 | // Given that this behavior is so incredibly deep in the weeds I doubt |
| 54 | // anyone would notice, I'm going to leave it as the simplest to implement |
| 55 | // (0 maps to "0"), which also happens to match what other libc |
| 56 | // implementations have done. |
| 57 | |
| 58 | auto errno_name = try_get_errno_name(error_num); |
| 59 | // if there's a name available, use it. |
| 60 | if (errno_name) { |
| 61 | new_conv.conv_val_ptr = |
| 62 | reinterpret_cast<void *>(const_cast<char *>(errno_name->data())); |
| 63 | new_conv.conv_name = 's'; |
| 64 | return convert_string(writer, new_conv); |
| 65 | } else { |
| 66 | // else do an int conversion |
| 67 | new_conv.conv_name = 'd'; |
| 68 | return convert_int(writer, new_conv); |
| 69 | } |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | } // namespace printf_core |
| 74 | } // namespace LIBC_NAMESPACE_DECL |
| 75 | |
| 76 | #endif // LLVM_LIBC_SRC_STDIO_PRINTF_CORE_STRERROR_CONVERTER_H |
| 77 |
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