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Try to load posix spawn addclosefrom_np at runtime

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To work around the issue from
https://github.com/robbert-vdh/yabridge/issues/377.
This commit is contained in:
Robbert van der Helm
2024-11-27 23:39:37 +01:00
parent d9286758c0
commit aa5c371c32
2 changed files with 55 additions and 25 deletions
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src/common/process.cpp
+45 -24
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@@ -19,6 +19,7 @@
#include <cassert>
#include <iostream>
#include <dlfcn.h>
#include <spawn.h>
#include <sys/wait.h>
@@ -323,6 +324,48 @@ Process::StatusResult Process::spawn_get_status() const {
}
}
/**
* Add file handle close actions to a `posix_spawn_file_actions_t` that close
* all non-stdio file descriptors.
*
* If the Wine process outlives the host, then it may cause issues if our
* process is still keeping the host's file descriptors alive that. This can
* prevent Ardour from restarting after an unexpected shutdown. Because of this
* we won't use `vfork()`, but instead we'll just manually close all non-STDIO
* file descriptors.
*/
static void close_non_stdio_file_descriptions(
posix_spawn_file_actions_t& actions) {
#if (__GLIBC__ > 2) || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 34)
posix_spawn_file_actions_addclosefrom_np(&actions, STDERR_FILENO + 1);
#else
// NOTE: As of writing, yabridge is compiled on Ubuntu 20.04, where
// `posix_spawn_file_actions_addclosefrom_np()` is not yet available.
// For whatever reason that may be, on Ubuntu 24.10 closing all file
// handles manually becomes very slow and starts to leak memory when
// running yabridge under Ardour. We could bump the minimum Ubuntu
// version supported by the binaries and always use this function, but
// loading the function at runtime should be fine and gives us better
// compatibility even if yabridge is compiled on an older distro.
//
// https://github.com/robbert-vdh/yabridge/issues/377
int (*posix_spawn_file_actions_addclosefrom_np)(posix_spawn_file_actions_t*,
int);
posix_spawn_file_actions_addclosefrom_np =
reinterpret_cast<decltype(posix_spawn_file_actions_addclosefrom_np)>(
dlsym(nullptr, "posix_spawn_file_actions_addclosefrom_np"));
if (posix_spawn_file_actions_addclosefrom_np) {
posix_spawn_file_actions_addclosefrom_np(&actions, STDERR_FILENO + 1);
} else {
const int max_fds = static_cast<int>(sysconf(_SC_OPEN_MAX));
for (int fd = STDERR_FILENO + 1; fd < max_fds; fd++) {
posix_spawn_file_actions_addclose(&actions, fd);
}
}
#endif
}
#ifndef WITHOUT_ASIO
Process::HandleResult Process::spawn_child_piped(
// NOLINTNEXTLINE(bugprone-easily-swappable-parameters)
@@ -348,20 +391,7 @@ Process::HandleResult Process::spawn_child_piped(
posix_spawn_file_actions_adddup2(&actions, stderr_pipe_fds[1],
STDERR_FILENO);
// We'll close the four pipe fds along with the rest of the file descriptors
// NOTE: If the Wine process outlives the host, then it may cause issues if
// our process is still keeping the host's file descriptors alive
// that. This can prevent Ardour from restarting after an unexpected
// shutdown. Because of this we won't use `vfork()`, but instead we'll
// just manually close all non-STDIO file descriptors.
#if (__GLIBC__ > 2) || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 34)
posix_spawn_file_actions_addclosefrom_np(&actions, STDERR_FILENO + 1);
#else
const int max_fds = static_cast<int>(sysconf(_SC_OPEN_MAX));
for (int fd = STDERR_FILENO + 1; fd < max_fds; fd++) {
posix_spawn_file_actions_addclose(&actions, fd);
}
#endif
close_non_stdio_file_descriptions(actions);
pid_t child_pid = 0;
const auto result = posix_spawnp(&child_pid, command_.c_str(), &actions,
@@ -407,16 +437,7 @@ Process::HandleResult Process::spawn_child_redirected(
O_WRONLY | O_CREAT | O_APPEND, 0640);
posix_spawn_file_actions_addopen(&actions, STDERR_FILENO, filename.c_str(),
O_WRONLY | O_CREAT | O_APPEND, 0640);
// See the note in the other function
#if (__GLIBC__ > 2) || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 34)
posix_spawn_file_actions_addclosefrom_np(&actions, STDERR_FILENO + 1);
#else
const int max_fds = static_cast<int>(sysconf(_SC_OPEN_MAX));
for (int fd = STDERR_FILENO + 1; fd < max_fds; fd++) {
posix_spawn_file_actions_addclose(&actions, fd);
}
#endif
close_non_stdio_file_descriptions(actions);
pid_t child_pid = 0;
const auto result = posix_spawnp(&child_pid, command_.c_str(), &actions,