ProcessFile.cxx

// Linux
#include <sys/syscall.h>
 
// libcosmos
#include <cosmos/error/ApiError.hxx>
#include <cosmos/formatting.hxx>
#include <cosmos/private/cosmos.hxx>
#include <cosmos/proc/ProcessFile.hxx>
 
/*
 * sys/pidfd.h contains the declarations for these system calls by now, but
 * glibc still doesn't implement them, so we get linker errors.
 *
 * Implement the wrappers ourselves then here.
 */
 
int pidfd_getfd(int pidfd, int targetfd, unsigned int flags) noexcept(true) {
        return ::syscall(SYS_pidfd_getfd, pidfd, targetfd, flags);
}
 
int pidfd_open(pid_t pid, unsigned int flags) noexcept(true) {
        return ::syscall(SYS_pidfd_open, pid, flags);
}
 
int pidfd_send_signal(int pidfd, int sig, siginfo_t *info, unsigned int flags) noexcept(true) {
        return ::syscall(SYS_pidfd_send_signal, pidfd, sig, info, flags);
}
 
namespace cosmos {
 
ProcessFile::ProcessFile(const ProcessID pid, const OpenFlags flags) {
        auto fd = pidfd_open(to_integral(pid), flags.raw());
 
        if (fd == -1) {
                cosmos_throw (ApiError("pidfd_open()"));
        }
 
        m_fd.setFD(FileNum{fd});
}
 
ProcessFile::~ProcessFile() {
        const auto orig_fd = m_fd.raw();
 
        try {
                close();
        } catch (const std::exception &e) {
                noncritical_error(sprintf("%s: failed to close fd(%d)", __FUNCTION__, to_integral(orig_fd)), e);
        }
}
 
FileDescriptor ProcessFile::dupFD(const FileNum targetfd) const {
        auto fd = pidfd_getfd(to_integral(m_fd.raw()), to_integral(targetfd), 0);
 
        if (fd == -1) {
                cosmos_throw (ApiError("pidfd_getfd()"));
        }
 
        return FileDescriptor{FileNum{fd}};
}
 
} // end ns