OpenTTD Source  20241125-master-g5b02f51e17
extmidi.cpp
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1 /*
2  * This file is part of OpenTTD.
3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
6  */
7 
10 #include "../stdafx.h"
11 #include "../debug.h"
12 #include "../string_func.h"
13 #include "../core/alloc_func.hpp"
14 #include "../sound/sound_driver.hpp"
15 #include "../video/video_driver.hpp"
16 #include "../gfx_func.h"
17 #include "extmidi.h"
18 #include "../base_media_base.h"
19 #include "../thread.h"
20 #include "midifile.hpp"
21 #include <fcntl.h>
22 #include <sys/types.h>
23 #include <sys/wait.h>
24 #include <unistd.h>
25 #include <signal.h>
26 #include <sys/stat.h>
27 
28 #include "../safeguards.h"
29 
30 #ifndef EXTERNAL_PLAYER
32 #define EXTERNAL_PLAYER "timidity"
33 #endif
34 
37 
38 std::optional<std::string_view> MusicDriver_ExtMidi::Start(const StringList &parm)
39 {
40  if (VideoDriver::GetInstance()->GetName() == "allegro" ||
41  SoundDriver::GetInstance()->GetName() == "allegro") {
42  return "the extmidi driver does not work when Allegro is loaded.";
43  }
44 
45  const char *command = GetDriverParam(parm, "cmd");
46 #ifndef MIDI_ARG
47  if (StrEmpty(command)) command = EXTERNAL_PLAYER;
48 #else
49  if (StrEmpty(command)) command = EXTERNAL_PLAYER " " MIDI_ARG;
50 #endif
51 
52  this->command_tokens.clear();
53 
54  std::string_view view = command;
55  for (;;) {
56  auto pos = view.find(' ');
57  this->command_tokens.emplace_back(view.substr(0, pos));
58 
59  if (pos == std::string_view::npos) break;
60  view.remove_prefix(pos + 1);
61  }
62 
63  this->song.clear();
64  this->pid = -1;
65  return std::nullopt;
66 }
67 
69 {
70  this->song.clear();
71  this->DoStop();
72 }
73 
75 {
76  std::string filename = MidiFile::GetSMFFile(song);
77  if (!filename.empty()) {
78  this->song = std::move(filename);
79  this->DoStop();
80  }
81 }
82 
84 {
85  this->song.clear();
86  this->DoStop();
87 }
88 
90 {
91  if (this->pid != -1 && waitpid(this->pid, nullptr, WNOHANG) == this->pid) {
92  this->pid = -1;
93  }
94  if (this->pid == -1 && !this->song.empty()) this->DoPlay();
95  return this->pid != -1;
96 }
97 
99 {
100  Debug(driver, 1, "extmidi: set volume not implemented");
101 }
102 
103 void MusicDriver_ExtMidi::DoPlay()
104 {
105  this->pid = fork();
106  switch (this->pid) {
107  case 0: {
108  close(0);
109  int d = open("/dev/null", O_RDONLY);
110  if (d != -1 && dup2(d, 1) != -1 && dup2(d, 2) != -1) {
111  /* execvp is nasty as it *allows* the passed parameters to be written
112  * for backward compatibility, however we are a fork so do not care. */
113  std::vector<char *> parameters;
114  for (auto &token : this->command_tokens) parameters.emplace_back(token.data());
115  parameters.emplace_back(this->song.data());
116  parameters.emplace_back(nullptr);
117 
118  execvp(parameters[0], parameters.data());
119  }
120  _exit(1);
121  }
122 
123  case -1:
124  Debug(driver, 0, "extmidi: couldn't fork: {}", strerror(errno));
125  [[fallthrough]];
126 
127  default:
128  this->song.clear();
129  break;
130  }
131 }
132 
139 static bool KillWait(pid_t &pid, int signal)
140 {
141  /* First try to stop for about a second;
142  * 1 seconds = 1000 milliseconds, 50 ms per cycle => 20 cycles. */
143  for (int i = 0; i < 20; i++) {
144  kill(pid, signal);
145  if (waitpid(pid, nullptr, WNOHANG) == pid) {
146  /* It has shut down, so we are done */
147  pid = -1;
148  return true;
149  }
150  /* Wait 50 milliseconds. */
151  CSleep(50);
152  }
153 
154  return false;
155 }
156 
157 void MusicDriver_ExtMidi::DoStop()
158 {
159  if (this->pid <= 0) return;
160 
161  if (KillWait(this->pid, SIGINT)) return;
162 
163  if (KillWait(this->pid, SIGTERM)) return;
164 
165  Debug(driver, 0, "extmidi: gracefully stopping failed, trying the hard way");
166  /* Gracefully stopping failed. Do it the hard way
167  * and wait till the process finally died. */
168  kill(this->pid, SIGKILL);
169  waitpid(this->pid, nullptr, 0);
170  this->pid = -1;
171 }
void PlaySong(const MusicSongInfo &song) override
Play a particular song.
Definition: extmidi.cpp:74
void Stop() override
Stop this driver.
Definition: extmidi.cpp:68
std::optional< std::string_view > Start(const StringList &param) override
Start this driver.
Definition: extmidi.cpp:38
std::string_view GetName() const override
Get the name of this driver.
Definition: extmidi.h:36
void StopSong() override
Stop playing the current song.
Definition: extmidi.cpp:83
bool IsSongPlaying() override
Are we currently playing a song?
Definition: extmidi.cpp:89
void SetVolume(uint8_t vol) override
Set the volume, if possible.
Definition: extmidi.cpp:98
static SoundDriver * GetInstance()
Get the currently active instance of the sound driver.
static VideoDriver * GetInstance()
Get the currently active instance of the video driver.
#define Debug(category, level, format_string,...)
Ouptut a line of debugging information.
Definition: debug.h:37
const char * GetDriverParam(const StringList &parm, const char *name)
Get a string parameter the list of parameters.
Definition: driver.cpp:44
static FMusicDriver_ExtMidi iFMusicDriver_ExtMidi
Factory for the midi player that uses external players.
Definition: extmidi.cpp:36
#define EXTERNAL_PLAYER
The default external midi player.
Definition: extmidi.cpp:32
static bool KillWait(pid_t &pid, int signal)
Try to end child process with kill/waitpid for up to 1 second.
Definition: extmidi.cpp:139
Base support for playing music via an external application.
bool StrEmpty(const char *s)
Check if a string buffer is empty.
Definition: string_func.h:57
std::vector< std::string > StringList
Type for a list of strings.
Definition: string_type.h:60
static std::string GetSMFFile(const MusicSongInfo &song)
Get the name of a Standard MIDI File for a given song.
Definition: midifile.cpp:1025
Metadata about a music track.
void CSleep(int milliseconds)
Sleep on the current thread for a defined time.
Definition: thread.h:24