libc/src/__support/StringUtil/signal_to_string.cpp

   1 //===-- Implementation of a class for mapping signals 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 "signal_to_string.h"
  10 #include "platform_signals.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 <signal.h>
  21 #include <stddef.h>
  22
  23 namespace LIBC_NAMESPACE_DECL {
  24 namespace internal {
  25
  26 constexpr size_t max_buff_size() {
  27   constexpr size_t base_str_len = sizeof("Real-time signal");
  28   // the buffer should be able to hold "Real-time signal" + ' ' + num_str
  29   return (base_str_len + 1 + IntegerToString<int>::buffer_size()) *
  30          sizeof(char);
  31 }
  32
  33 // This is to hold signal strings that have to be custom built. It may be
  34 // rewritten on every call to strsignal (or other signal to string function).
  35 constexpr size_t SIG_BUFFER_SIZE = max_buff_size();
  36 LIBC_THREAD_LOCAL char signal_buffer[SIG_BUFFER_SIZE];
  37
  38 constexpr size_t TOTAL_STR_LEN = total_str_len(PLATFORM_SIGNALS);
  39
  40 constexpr size_t SIG_ARRAY_SIZE = max_key_val(PLATFORM_SIGNALS) + 1;
  41
  42 constexpr MessageMapper<SIG_ARRAY_SIZE, TOTAL_STR_LEN>
  43     signal_mapper(PLATFORM_SIGNALS);
  44
  45 cpp::string_view build_signal_string(int sig_num, cpp::span<char> buffer) {
  46   cpp::string_view base_str;
  47   if (sig_num >= SIGRTMIN && sig_num <= SIGRTMAX) {
  48     base_str = cpp::string_view("Real-time signal");
  49     sig_num -= SIGRTMIN;
  50   } else {
  51     base_str = cpp::string_view("Unknown signal");
  52   }
  53
  54   // if the buffer can't hold "Unknown signal" + ' ' + num_str, then just
  55   // return "Unknown signal".
  56   if (buffer.size() <
  57       (base_str.size() + 1 + IntegerToString<int>::buffer_size()))
  58     return base_str;
  59
  60   cpp::StringStream buffer_stream(
  61       {const_cast<char *>(buffer.data()), buffer.size()});
  62   buffer_stream << base_str << ' ' << sig_num << '\0';
  63   return buffer_stream.str();
  64 }
  65
  66 } // namespace internal
  67
  68 cpp::string_view get_signal_string(int sig_num) {
  69   return get_signal_string(
  70       sig_num, {internal::signal_buffer, internal::SIG_BUFFER_SIZE});
  71 }
  72
  73 cpp::string_view get_signal_string(int sig_num, cpp::span<char> buffer) {
  74   auto opt_str = internal::signal_mapper.get_str(sig_num);
  75   if (opt_str)
  76     return *opt_str;
  77   else
  78     return internal::build_signal_string(sig_num, buffer);
  79 }
  80
  81 } // namespace LIBC_NAMESPACE_DECL