Kernel+LibC: Add sys$set_process_name() for changing the process name

Kernel/API/Syscall.h

@@ -192,7 +192,8 @@ namespace Kernel {
     __ENUMERATE_SYSCALL(minherit)           \
     __ENUMERATE_SYSCALL(sendfd)             \
     __ENUMERATE_SYSCALL(recvfd)             \
-    __ENUMERATE_SYSCALL(sysconf)
+    __ENUMERATE_SYSCALL(sysconf)            \
+    __ENUMERATE_SYSCALL(set_process_name)
 
 namespace Syscall {
 

Kernel/Process.cpp

@@ -4489,6 +4489,18 @@ int Process::sys$get_process_name(char* buffer, int buffer_size)
     return 0;
 }
 
+int Process::sys$set_process_name(const char* user_name, size_t user_name_length)
+{
+    REQUIRE_PROMISE(proc);
+    if (user_name_length > 256)
+        return -ENAMETOOLONG;
+    auto name = validate_and_copy_string_from_user(user_name, user_name_length);
+    if (name.is_null())
+        return -EFAULT;
+    m_name = move(name);
+    return 0;
+}
+
 // We don't use the flag yet, but we could use it for distinguishing
 // random source like Linux, unlike the OpenBSD equivalent. However, if we
 // do, we should be able of the caveats that Linux has dealt with.

Kernel/Process.h

@@ -185,6 +185,7 @@ public:
     int sys$sync();
     int sys$beep();
     int sys$get_process_name(char* buffer, int buffer_size);
+    int sys$set_process_name(const char* user_name, size_t user_name_length);
     int sys$watch_file(const char* path, size_t path_length);
     int sys$dbgputch(u8);
     int sys$dbgputstr(const u8*, int length);

Libraries/LibC/unistd.cpp

@@ -683,6 +683,12 @@ int get_process_name(char* buffer, int buffer_size)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+int set_process_name(const char* name, size_t name_length)
+{
+    int rc = syscall(SC_set_process_name, name, name_length);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
 int chroot(const char* path)
 {
     return chroot_with_mount_flags(path, -1);

Libraries/LibC/unistd.h

@@ -55,6 +55,7 @@ __BEGIN_DECLS
 extern char** environ;
 
 int get_process_name(char* buffer, int buffer_size);
+int set_process_name(const char* name, size_t name_length);
 void dump_backtrace();
 int fsync(int fd);
 void sysbeep();