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Merge branch 'srett-child-process-enhancement' into develop

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This commit is contained in:
emeric
2025-06-06 08:45:48 +02:00
parent 4e7bc9c7cc 161d7b6c15
commit 0b0b8a34d1
1 changed files with 25 additions and 26 deletions
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src/libs/core/impl/ChildProcess.cpp
+25 -26
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@@ -19,18 +19,17 @@
#include "ChildProcess.hpp" #include "ChildProcess.hpp"
#include <cerrno>
#include <cstddef>
#include <fcntl.h> #include <fcntl.h>
#include <signal.h> #include <signal.h>
#include <sys/types.h> #include <sys/types.h>
#include <sys/wait.h> #include <sys/wait.h>
#include <system_error>
#include <unistd.h> #include <unistd.h>
#include <algorithm> #include <algorithm>
#include <iostream> #include <cerrno>
#include <cstddef>
#include <mutex> #include <mutex>
#include <system_error>
#include <boost/asio/buffer.hpp> #include <boost/asio/buffer.hpp>
#include <boost/asio/read.hpp> #include <boost/asio/read.hpp>
@@ -63,32 +62,23 @@ namespace lms::core
{ {
// make sure only one thread is executing this part of code // make sure only one thread is executing this part of code
static std::mutex mutex; static std::mutex mutex;
std::unique_lock<std::mutex> lock{ mutex }; const std::scoped_lock lock{ mutex };
int pipefd[2]; int pipefd[2];
// Use 'pipe' instead of 'pipe2', more portable // Use 'pipe' instead of 'pipe2', more portable
if (pipe(pipefd) < 0) if (pipe(pipefd) == -1)
throw SystemException{ std::error_code{ errno, std::generic_category() }, "pipe failed!" }; throw SystemException{ std::error_code{ errno, std::generic_category() }, "pipe failed!" };
// Manually set the O_NONBLOCK and O_CLOEXEC flags for both ends of the pipe // Only set O_NONBLOCK on read end - usually programs don't expect stdout to be non-blocking
if (fcntl(pipefd[0], F_SETFL, O_NONBLOCK) == -1) if (fcntl(pipefd[0], F_SETFL, O_NONBLOCK) == -1)
throw SystemException{ std::error_code{ errno, std::generic_category() }, "fcntl failed to set O_NONBLOCK!" }; throw SystemException{ std::error_code{ errno, std::generic_category() }, "fcntl failed to set O_NONBLOCK!" };
if (fcntl(pipefd[1], F_SETFL, O_NONBLOCK) == -1)
throw SystemException{ std::error_code{ errno, std::generic_category() }, "fcntl failed to set O_NONBLOCK!" };
if (fcntl(pipefd[0], F_SETFD, FD_CLOEXEC) == -1)
throw SystemException{ std::error_code{ errno, std::generic_category() }, "fcntl failed to set FD_CLOEXEC!" };
if (fcntl(pipefd[1], F_SETFD, FD_CLOEXEC) == -1)
throw SystemException{ std::error_code{ errno, std::generic_category() }, "fcntl failed to set FD_CLOEXEC!" };
#if defined(__linux__) && defined(F_SETPIPE_SZ) #if defined(__linux__) && defined(F_SETPIPE_SZ)
for (const int fd : { pipefd[0], pipefd[1] }) for (const int fd : { pipefd[0], pipefd[1] })
{ {
constexpr std::size_t targetPipeSize{ static_cast<long>(65'536) * 4 }; constexpr int targetPipeSize{ 65'536 * 4 };
std::size_t currentPipeSize{ 65'536 }; // common default value int currentPipeSize{ 65'536 }; // common default value
#if defined(F_GETPIPE_SZ) #if defined(F_GETPIPE_SZ)
const int pipeSizeRes{ fcntl(fd, F_GETPIPE_SZ) }; const int pipeSizeRes{ fcntl(fd, F_GETPIPE_SZ) };
if (pipeSizeRes == -1) if (pipeSizeRes == -1)
@@ -112,27 +102,36 @@ namespace lms::core
} }
#endif #endif
int res{ fork() }; const int res{ fork() };
if (res == -1) if (res == -1)
throw SystemException{ std::error_code{ errno, std::generic_category() }, "fork failed!" }; throw SystemException{ std::error_code{ errno, std::generic_category() }, "fork failed!" };
if (res == 0) // CHILD if (res == 0) // CHILD
{ {
close(pipefd[0]); // Never close stdin/out/err, most programs expect these to exist;
close(STDIN_FILENO); // rather connect them to /dev/null if unwanted
close(STDERR_FILENO); const int nullFd{ open("/dev/null", O_RDWR) };
// Ignore errors, worst thing is stderr writes to the same fd as lms
if (nullFd != -1)
{
dup2(nullFd, STDIN_FILENO);
dup2(nullFd, STDERR_FILENO);
close(nullFd);
}
// Replace stdout with pipe write // Replace stdout with pipe write
if (dup2(pipefd[1], STDOUT_FILENO) == -1) if (dup2(pipefd[1], STDOUT_FILENO) == -1)
exit(-1); exit(-1);
// Close pipe: read end not needed, write end was dup2ed
close(pipefd[0]);
close(pipefd[1]);
std::vector<const char*> execArgs; std::vector<const char*> execArgs;
std::transform(std::cbegin(args), std::cend(args), std::back_inserter(execArgs), [](const std::string& arg) { return arg.c_str(); }); std::transform(std::cbegin(args), std::cend(args), std::back_inserter(execArgs), [](const std::string& arg) { return arg.c_str(); });
execArgs.push_back(nullptr); execArgs.push_back(nullptr);
res = execv(path.string().c_str(), (char* const*)&execArgs[0]); execv(path.string().c_str(), (char* const*)&execArgs[0]);
if (res == -1) exit(-1);
exit(-1);
} }
else // PARENT else // PARENT
{ {
@@ -141,7 +140,7 @@ namespace lms::core
boost::system::error_code assignError; boost::system::error_code assignError;
_childStdout.assign(pipefd[0], assignError); _childStdout.assign(pipefd[0], assignError);
if (assignError) if (assignError)
throw SystemException{ assignError, "fork failed!" }; throw SystemException{ assignError, "assigning read end of pipe to asio stream failed!" };
} }
_childPID = res; _childPID = res;
} }