kernel: add _sys_getprocfs in place of HANDLE_PROCFS

This makes the side-effects more explicit, and feels less hacky than
`HANDLE_PROCFS`. I don't think accessing a handle alone should have
side-effects, even if it's a "special" one.

3 files changed, 17 insertions, 18 deletions

diff --git a/src/kernel/proc.c b/src/kernel/proc.c
index bbf939c..1084f48 100644
--- a/src/kernel/proc.c
+++ b/src/kernel/proc.c
@@ -6,7 +6,6 @@
 #include <kernel/panic.h>
 #include <kernel/proc.h>
 #include <kernel/vfs/mount.h>
-#include <kernel/vfs/procfs.h>
 #include <shared/mem.h>
 #include <stdint.h>
 
@@ -384,7 +383,6 @@ void proc_tryreap(Proc *dead) {
 		return; /* keep the tombstone */
 	}
 
-	handle_close(dead->specialh.procfs);
 	assert(dead->refcount == 0);
 	if (parent) { /* not applicable to init */
 		proc_forget(dead);
@@ -513,18 +511,6 @@ Handle *proc_handle_get(Proc *p, hid_t id) {
 			.refcount = 2, /* never free */
 		};
 		return &h;
-	} else if (id == HANDLE_PROCFS) {
-		if (!p->specialh.procfs) {
-			Handle *h = kmalloc(sizeof *h);
-			proc_ns_create(p);
-			*h = (Handle){
-				.type = HANDLE_FS_FRONT,
-				.backend = procfs_backend(p),
-				.refcount = 1,
-			};
-			p->specialh.procfs = h;
-		}
-		return p->specialh.procfs;
 	} else if (0 <= id && id < HANDLE_MAX) {
 		return p->_handles[id];
 	} else {
diff --git a/src/kernel/proc.h b/src/kernel/proc.h
index 0dffe08..15da852 100644
--- a/src/kernel/proc.h
+++ b/src/kernel/proc.h
@@ -69,9 +69,6 @@ struct Proc {
 	VfsMount *mount;
 	Handle **_handles; /* points to Handle *[HANDLE_MAX] */
 	uint64_t *handles_refcount; /* works just like pages_refcount */
-	struct {
-		Handle *procfs;
-	} specialh;
 
 	// TODO pids should be 64bit. also typedef pid_t
 	uint32_t globalid; /* only for internal use, don't expose to userland */
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 0dda320..b040285 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -8,6 +8,7 @@
 #include <kernel/panic.h>
 #include <kernel/pipe.h>
 #include <kernel/proc.h>
+#include <kernel/vfs/procfs.h>
 #include <shared/mem.h>
 #include <stdint.h>
 
@@ -120,7 +121,6 @@ long _sys_mount(hid_t hid, const char __user *path, long len) {
 	// remove trailing slash
 	// mounting something under `/this` and `/this/` should be equalivent
 	if (path_buf[len - 1] == '/') {
-		if (len == 0) goto fail;
 		len--;
 	}
 
@@ -404,6 +404,21 @@ int _sys_wait2(int pid, int flags, struct sys_wait2 __user *out) {
 	return 0; // dummy
 }
 
+hid_t _sys_getprocfs(int flags) {
+	if (flags != 0) {
+		SYSCALL_RETURN(-ENOSYS);
+	}
+	proc_ns_create(proc_cur);
+
+	Handle *h;
+	hid_t hid = proc_handle_init(proc_cur, HANDLE_FS_FRONT, &h);
+	if (hid < 0) {
+		SYSCALL_RETURN(-EMFILE);
+	}
+	h->backend = procfs_backend(proc_cur);
+	SYSCALL_RETURN(hid);
+}
+
 long _sys_execbuf(void __user *ubuf, size_t len) {
 	if (len == 0) SYSCALL_RETURN(0);
 	if (len > EXECBUF_MAX_LEN)
@@ -458,6 +473,7 @@ long _syscall(long num, long a, long b, long c, long d, long e) {
 		break; case _SYS_GETPID:	_sys_getpid();
 		break; case _SYS_GETPPID:	_sys_getppid();
 		break; case _SYS_WAIT2:	_sys_wait2(a, b, (userptr_t)c);
+		break; case _SYS_GETPROCFS:	_sys_getprocfs(a);
 		break; case _SYS_EXECBUF:	_sys_execbuf((userptr_t)a, b);
 		break; case _SYS_DEBUG_KLOG:	_sys_debug_klog((userptr_t)a, b);
 		break;