Add tcsetpgrp()+tcgetpgrp().

One more step on the path to being able to ^C a runaway process. :^)

Kernel/ProcFileSystem.cpp

@@ -277,10 +277,11 @@ ByteBuffer procfs$summary()
     auto processes = Process::allProcesses();
     auto buffer = ByteBuffer::createUninitialized(processes.size() * 256);
     char* ptr = (char*)buffer.pointer();
-    ptr += ksprintf(ptr, "PID PGP SID  OWNER  STATE      PPID NSCHED     FDS  TTY  NAME\n");
+    ptr += ksprintf(ptr, "PID TPG PGP SID  OWNER  STATE      PPID NSCHED     FDS  TTY  NAME\n");
     for (auto* process : processes) {
-        ptr += ksprintf(ptr, "% 3u % 3u % 3u  % 4u   % 8s   % 3u  % 9u  % 3u  % 4s  %s\n",
+        ptr += ksprintf(ptr, "% 3u % 3u % 3u % 3u  % 4u   % 8s   % 3u  % 9u  % 3u  % 4s  %s\n",
             process->pid(),
+            process->tty() ? process->tty()->pgid() : 0,
             process->pgid(),
             process->sid(),
             process->uid(),

Kernel/Process.cpp

@@ -1249,3 +1249,34 @@ int Process::sys$setpgid(pid_t specified_pid, pid_t specified_pgid)
     process->m_pgid = new_pgid;
     return 0;
 }
+
+pid_t Process::sys$tcgetpgrp(int fd)
+{
+    auto* handle = fileHandleIfExists(fd);
+    if (!handle)
+        return -EBADF;
+    if (!handle->isTTY())
+        return -ENOTTY;
+    auto& tty = *handle->tty();
+    if (&tty != m_tty)
+        return -ENOTTY;
+    return tty.pgid();
+}
+
+int Process::sys$tcsetpgrp(int fd, pid_t pgid)
+{
+    if (pgid < 0)
+        return -EINVAL;
+    if (get_sid_from_pgid(pgid) != m_sid)
+        return -EINVAL;
+    auto* handle = fileHandleIfExists(fd);
+    if (!handle)
+        return -EBADF;
+    if (!handle->isTTY())
+        return -ENOTTY;
+    auto& tty = *handle->tty();
+    if (&tty != m_tty)
+        return -ENOTTY;
+    tty.set_pgid(pgid);
+    return 0;
+}

Kernel/Process.h

@@ -86,6 +86,8 @@ public:
     int sys$setpgid(pid_t pid, pid_t pgid);
     pid_t sys$getpgrp();
     pid_t sys$getpgid(pid_t);
+    pid_t sys$tcgetpgrp(int fd);
+    int sys$tcsetpgrp(int fd, pid_t pgid);
     uid_t sys$getuid();
     gid_t sys$getgid();
     pid_t sys$getpid();

Kernel/Syscall.cpp

@@ -124,6 +124,10 @@ DWORD handle(DWORD function, DWORD arg1, DWORD arg2, DWORD arg3)
         return current->sys$getpgid((pid_t)arg1);
     case Syscall::PosixGetpgrp:
         return current->sys$getpgrp();
+    case Syscall::PosixTcgetpgrp:
+        return current->sys$tcgetpgrp((int)arg1);
+    case Syscall::PosixTcsetpgrp:
+        return current->sys$tcsetpgrp((int)arg1, (pid_t)arg2);
     default:
         kprintf("<%u> int0x80: Unknown function %x requested {%x, %x, %x}\n", current->pid(), function, arg1, arg2, arg3);
         break;

Kernel/Syscall.h

@@ -45,6 +45,8 @@ enum Function {
     PosixGetpgid = 0x2013,
     PosixSetpgid = 0x2014,
     PosixGetpgrp = 0x2015,
+    PosixTcsetpgrp = 0x2016,
+    PosixTcgetpgrp = 0x2017,
 };
 
 void initialize();

Kernel/TTY.h

@@ -12,6 +12,9 @@ public:
 
     virtual String ttyName() const = 0;
 
+    void set_pgid(pid_t pgid) { m_pgid = pgid; }
+    pid_t pgid() const { return m_pgid; }
+
 protected:
     virtual bool isTTY() const final { return true; }
 
@@ -22,5 +25,6 @@ protected:
 
 private:
     Vector<byte> m_buffer;
+    pid_t m_pgid { 0 };
 };
 

LibC/unistd.cpp

@@ -25,9 +25,14 @@ pid_t setsid()
     return Syscall::invoke(Syscall::PosixSetsid);
 }
 
-pid_t sys$getsid(pid_t pid)
+pid_t tcgetpgrp(int fd)
 {
-    return Syscall::invoke(Syscall::PosixSetsid, (dword)pid);
+    return Syscall::invoke(Syscall::PosixTcgetpgrp, (dword)fd);
+}
+
+int tcsetpgrp(int fd, pid_t pgid)
+{
+    return Syscall::invoke(Syscall::PosixTcsetpgrp, (dword)fd, (dword)pgid);
 }
 
 int setpgid(pid_t pid, pid_t pgid)

LibC/unistd.h

@@ -16,6 +16,8 @@ pid_t getpgrp();
 uid_t getuid();
 gid_t getgid();
 pid_t getpid();
+pid_t tcgetpgrp(int fd);
+int tcsetpgrp(int fd, pid_t pgid);
 int open(const char* path, int options);
 ssize_t read(int fd, void* buf, size_t count);
 ssize_t write(int fd, const void* buf, size_t count);

Userland/sh.cpp

@@ -142,10 +142,17 @@ static int runcmd(char* cmd)
         return 1;
     }
 
+    // FIXME: This is racy, since spawn has already started the new process.
+    //        Once I have fork()+exec(), pgrp setup can be done in the child before exec()ing.
+    tcsetpgrp(0, ret);
+
     // FIXME: waitpid should give us the spawned process's exit status
     int wstatus = 0;
     waitpid(ret, &wstatus, 0);
 
+    // FIXME: Racy as mentioned above. Rework once we have fork()+exec().
+    tcsetpgrp(0, getpid());
+
     if (WIFEXITED(wstatus)) {
         //printf("Exited normally with status %d\n", WEXITSTATUS(wstatus));
     } else {
@@ -173,6 +180,8 @@ int main(int, char**)
 {
     g = new GlobalState;
     g->sid = setsid();
+    tcsetpgrp(0, getpgrp());
+
     int rc = gethostname(g->hostname, sizeof(g->hostname));
     if (rc < 0)
         perror("gethostname");

VirtualFileSystem/FileHandle.cpp

@@ -176,6 +176,13 @@ const TTY* FileHandle::tty() const
     return nullptr;
 }
 
+TTY* FileHandle::tty()
+{
+    if (auto* device = m_vnode->characterDevice())
+        return static_cast<TTY*>(device);
+    return nullptr;
+}
+
 int FileHandle::close()
 {
     return 0;

VirtualFileSystem/FileHandle.h

@@ -30,6 +30,7 @@ public:
 
     bool isTTY() const;
     const TTY* tty() const;
+    TTY* tty();
 
     InodeMetadata metadata() const { return m_vnode->metadata(); }