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