process: Detach or orphan provided resources on termination

Fixes #42.

5 files changed, 113 insertions, 24 deletions

diff --git a/src/lib/process.zig b/src/lib/process.zig
index dcb1baa..a4bbb75 100644
--- a/src/lib/process.zig
+++ b/src/lib/process.zig
@@ -7,6 +7,7 @@ const std = @import("std");
 
 const instructions = @import("instructions.zig");
 const paging = @import("paging.zig");
+const sysexchange = @import("sysexchange.zig");
 const time = @import("sbi/time.zig");
 const trap = @import("trap.zig");
 const vfs = @import("vfs.zig");
@@ -171,6 +172,10 @@ pub const Info = struct {
         var node = list.first;
         while (node) |proc_node| : (node = proc_node.next) {
             if (self.shouldRemove(&proc_node.data)) {
+                if (proc_node.data.thread_id != self.thread_id) {
+                    proc_node.data.terminate();
+                }
+
                 list.remove(proc_node);
                 self.allocator.destroy(proc_node);
             }
@@ -194,6 +199,7 @@ pub const Info = struct {
             cleanup_hook.cleanupFn(self, cleanup_hook.buffer, cleanup_hook.copy);
         }
         if (self.term_hook) |term_hook| {
+            sysexchange.frameReturn(void, &self.trap_frame, vfs.Error.Detached);
             term_hook.hookFn(term_hook.context, self);
         }
     }
diff --git a/src/lib/resources.zig b/src/lib/resources.zig
index c79c82e..f73c751 100644
--- a/src/lib/resources.zig
+++ b/src/lib/resources.zig
@@ -67,7 +67,9 @@ fn provideConsole() !void {
                 .writeFn = iofs.debug.write,
             },
         },
-    }, 0);
+    }, 0, .{
+        .reclaimable = false,
+    });
 }
 
 fn provideUserinit() !void {
@@ -110,7 +112,9 @@ fn addFile(path: []const u8, file: File) !void {
                 .initializer = initializer,
             },
         },
-    }, 0);
+    }, 0, .{
+        .reclaimable = false,
+    });
 }
 
 fn addDir(path: []const u8) !void {
@@ -121,7 +125,9 @@ fn addDir(path: []const u8) !void {
     try vfs.provideResource(path, .{
         .tag = .dir,
         .data = .{ .dir = tree },
-    }, 0);
+    }, 0, .{
+        .reclaimable = false,
+    });
 }
 
 fn open(initializer: ?*anyopaque, _: u16) callconv(.C) Result(*anyopaque) {
diff --git a/src/lib/syscall.zig b/src/lib/syscall.zig
index 661c98d..1533cd4 100644
--- a/src/lib/syscall.zig
+++ b/src/lib/syscall.zig
@@ -74,6 +74,7 @@ fn close(proc: *process.Info, trap_frame: *const trap.Frame) void {
 
 // provideStream(
 //     path_c: [*:0]const u8, // fixme: Kernel panic if null pointer
+//     options: *const vfs.Options, // fixme: Kernel panic if null pointer
 //     readFn: ?vfs.Stream.ReadFn,
 //     writeFn: ?vfs.Stream.WriteFn,
 // ) Result(void)
@@ -82,8 +83,9 @@ fn provideStream(proc: *const process.Info, trap_frame: *trap.Frame) void {
     defer paging.setUserMemoryAccess(false);
 
     const path_c: [*:0]const u8 = @ptrFromInt(trap_frame.general_purpose_registers[10]);
-    const readFn: ?vfs.Stream.ReadFn = @ptrFromInt(trap_frame.general_purpose_registers[11]);
-    const writeFn: ?vfs.Stream.WriteFn = @ptrFromInt(trap_frame.general_purpose_registers[12]);
+    const options: *const vfs.Options = @ptrFromInt(trap_frame.general_purpose_registers[11]);
+    const readFn: ?vfs.Stream.ReadFn = @ptrFromInt(trap_frame.general_purpose_registers[12]);
+    const writeFn: ?vfs.Stream.WriteFn = @ptrFromInt(trap_frame.general_purpose_registers[13]);
 
     sysexchange.frameReturn(null, trap_frame, vfs.provideResourceZ(path_c, .{
         .tag = .stream,
@@ -91,11 +93,12 @@ fn provideStream(proc: *const process.Info, trap_frame: *trap.Frame) void {
             .readFn = readFn,
             .writeFn = writeFn,
         } },
-    }, proc.id));
+    }, proc.id, options.*));
 }
 
 // provideFile(
 //     path_c: [*:0]const u8, // fixme: Kernel panic if null pointer
+//     options: *const vfs.Options, // fixme: Kernel panic if null pointer
 //     openFn: vfs.File.OpenFn,
 //     readFn: ?vfs.File.ReadFn,
 //     writeFn: ?vfs.File.WriteFn,
@@ -106,10 +109,11 @@ fn provideFile(proc: *const process.Info, trap_frame: *trap.Frame) void {
     defer paging.setUserMemoryAccess(false);
 
     const path_c: [*:0]const u8 = @ptrFromInt(trap_frame.general_purpose_registers[10]);
-    const openFn: vfs.File.OpenFn = @ptrFromInt(trap_frame.general_purpose_registers[11]);
-    const readFn: ?vfs.File.ReadFn = @ptrFromInt(trap_frame.general_purpose_registers[12]);
-    const writeFn: ?vfs.File.WriteFn = @ptrFromInt(trap_frame.general_purpose_registers[13]);
-    const closeFn: ?vfs.File.CloseFn = @ptrFromInt(trap_frame.general_purpose_registers[14]);
+    const options: *const vfs.Options = @ptrFromInt(trap_frame.general_purpose_registers[11]);
+    const openFn: vfs.File.OpenFn = @ptrFromInt(trap_frame.general_purpose_registers[12]);
+    const readFn: ?vfs.File.ReadFn = @ptrFromInt(trap_frame.general_purpose_registers[13]);
+    const writeFn: ?vfs.File.WriteFn = @ptrFromInt(trap_frame.general_purpose_registers[14]);
+    const closeFn: ?vfs.File.CloseFn = @ptrFromInt(trap_frame.general_purpose_registers[15]);
 
     sysexchange.frameReturn(null, trap_frame, vfs.provideResourceZ(path_c, .{
         .tag = .file,
@@ -120,11 +124,12 @@ fn provideFile(proc: *const process.Info, trap_frame: *trap.Frame) void {
             .closeFn = closeFn,
             .initializer = null,
         } },
-    }, proc.id));
+    }, proc.id, options.*));
 }
 
 // provideHook(
 //     path_c: [*:0]const u8, // fixme: Kernel panic if null pointer
+//     options: *const vfs.Options, // fixme: Kernel panic if null pointer,
 //     callback: vfs.Hook.Callback,
 // ) Result(void)
 fn provideHook(proc: *const process.Info, trap_frame: *trap.Frame) void {
@@ -132,14 +137,15 @@ fn provideHook(proc: *const process.Info, trap_frame: *trap.Frame) void {
     defer paging.setUserMemoryAccess(false);
 
     const path_c: [*:0]const u8 = @ptrFromInt(trap_frame.general_purpose_registers[10]);
-    const callback: vfs.Hook.Callback = @ptrFromInt(trap_frame.general_purpose_registers[11]);
+    const options: *const vfs.Options = @ptrFromInt(trap_frame.general_purpose_registers[11]);
+    const callback: vfs.Hook.Callback = @ptrFromInt(trap_frame.general_purpose_registers[12]);
 
     sysexchange.frameReturn(null, trap_frame, vfs.provideResourceZ(path_c, .{
         .tag = .hook,
         .data = .{ .hook = .{
             .callback = callback,
         } },
-    }, proc.id));
+    }, proc.id, options.*));
 }
 
 // mkdir(
@@ -158,11 +164,14 @@ fn mkdir(proc: *const process.Info, trap_frame: *trap.Frame) void {
     sysexchange.frameReturn(null, trap_frame, vfs.provideResourceZ(path_c, .{
         .tag = .dir,
         .data = .{ .dir = tree },
-    }, proc.id));
+    }, proc.id, .{
+        .reclaimable = false,
+    }));
 }
 
 // provideDirHook(
 //     path_c: [*:0]const u8, // fixme: Kernel panic if null pointer
+//     options: *const vfs.Options, // fixme: Kernel panic if null pointer
 //     provideFn: vfs.DirHook.ProvideFn,
 //     findFn: vfs.DirHook.FindFn,
 //     removeFn: vfs.DirHook.RemoveFn,
@@ -172,9 +181,10 @@ fn provideDirHook(proc: *const process.Info, trap_frame: *trap.Frame) void {
     defer paging.setUserMemoryAccess(false);
 
     const path_c: [*:0]const u8 = @ptrFromInt(trap_frame.general_purpose_registers[10]);
-    const provideFn: vfs.DirHook.ProvideFn = @ptrFromInt(trap_frame.general_purpose_registers[11]);
-    const findFn: vfs.DirHook.FindFn = @ptrFromInt(trap_frame.general_purpose_registers[12]);
-    const removeFn: vfs.DirHook.RemoveFn = @ptrFromInt(trap_frame.general_purpose_registers[13]);
+    const options: *const vfs.Options = @ptrFromInt(trap_frame.general_purpose_registers[11]);
+    const provideFn: vfs.DirHook.ProvideFn = @ptrFromInt(trap_frame.general_purpose_registers[12]);
+    const findFn: vfs.DirHook.FindFn = @ptrFromInt(trap_frame.general_purpose_registers[13]);
+    const removeFn: vfs.DirHook.RemoveFn = @ptrFromInt(trap_frame.general_purpose_registers[14]);
 
     sysexchange.frameReturn(null, trap_frame, vfs.provideResourceZ(path_c, .{
         .tag = .dir_hook,
@@ -183,7 +193,7 @@ fn provideDirHook(proc: *const process.Info, trap_frame: *trap.Frame) void {
             .findFn = findFn,
             .removeFn = removeFn,
         } },
-    }, proc.id));
+    }, proc.id, options.*));
 }
 
 // remove(path_c: [*:0]const u8) Result(void) // fixme: Kernel panic if null pointer
@@ -225,7 +235,15 @@ fn read(proc: *process.Info, trap_frame: *trap.Frame) void {
         sysexchange.frameReturn(usize, trap_frame, process.Error.BadRdHandle);
         return;
     };
-    sysexchange.frameReturn(usize, trap_frame, rd.read(proc, buffer[0..len]));
+
+    const result = rd.read(proc, buffer[0..len]) catch |err| blk: {
+        if (err == vfs.Error.Orphaned) {
+            proc.destroyRdHandle(handle);
+        }
+
+        break :blk err;
+    };
+    sysexchange.frameReturn(usize, trap_frame, result);
 }
 
 // write(handle: usize, bytes: [*]const u8, len: usize) Result(usize)
@@ -241,7 +259,15 @@ fn write(proc: *process.Info, trap_frame: *trap.Frame) void {
         sysexchange.frameReturn(usize, trap_frame, process.Error.BadRdHandle);
         return;
     };
-    sysexchange.frameReturn(usize, trap_frame, rd.write(proc, bytes[0..len]));
+
+    const result = rd.write(proc, bytes[0..len]) catch |err| blk: {
+        if (err == vfs.Error.Orphaned) {
+            proc.destroyRdHandle(handle);
+        }
+
+        break :blk err;
+    };
+    sysexchange.frameReturn(usize, trap_frame, result);
 }
 
 // terminate() noreturn
diff --git a/src/lib/sysexchange.zig b/src/lib/sysexchange.zig
index 3dd93df..c3d7fa4 100644
--- a/src/lib/sysexchange.zig
+++ b/src/lib/sysexchange.zig
@@ -63,6 +63,8 @@ pub const Status = enum(usize) {
     read_not_supported,
     write_not_supported,
     in_use,
+    detached,
+    orphaned,
     unknown = std.math.maxInt(usize),
 
     pub fn fromError(err: anyerror) Status {
@@ -122,6 +124,8 @@ pub const Status = enum(usize) {
             error.ReadNotSupported => .read_not_supported,
             error.WriteNotSupported => .write_not_supported,
             error.InUse => .in_use,
+            error.Detached => .detached,
+            error.Orphaned => .orphaned,
             else => .unknown,
         };
     }
@@ -186,6 +190,8 @@ pub const Status = enum(usize) {
             .read_not_supported => error.ReadNotSupported,
             .write_not_supported => error.WriteNotSupported,
             .in_use => error.InUse,
+            .detached => error.Detached,
+            .orphaned => error.Orphaned,
             .unknown => error.Unknown,
         };
     }
diff --git a/src/lib/vfs.zig b/src/lib/vfs.zig
index f3520be..c8cc552 100644
--- a/src/lib/vfs.zig
+++ b/src/lib/vfs.zig
@@ -10,7 +10,22 @@ const sysexchange = @import("sysexchange.zig");
 
 const mem = std.mem;
 
-var root: Node = .{ .data = .{ .name = "", .inode = .{ .resource = .{ .tag = .dir, .data = .{ .dir = undefined } }, .pid = 0 } } };
+var root: Node = .{
+    .data = .{
+        .name = "",
+        .inode = .{
+            .resource = .{
+                .tag = .dir,
+                .data = .{ .dir = undefined },
+            },
+            .pid = 0,
+            .options = .{
+                .reclaimable = false,
+            },
+            .flags = .{},
+        },
+    },
+};
 
 pub fn treeRoot() *const Tree {
     return root.data.inode.resource.data.dir;
@@ -25,6 +40,8 @@ pub const Error = error{
     ReadNotSupported,
     WriteNotSupported,
     InUse,
+    Detached,
+    Orphaned,
 };
 
 // A stream is a resource that provides a shared data stream with a driver.
@@ -91,6 +108,16 @@ pub const Inode = extern struct {
     resource: Resource,
     refs: usize = 0,
     pid: u16,
+    options: Options,
+    flags: Flags,
+};
+
+pub const Options = extern struct {
+    reclaimable: bool,
+};
+
+pub const Flags = extern struct {
+    detached: bool = false,
 };
 
 pub const DirEntry = struct {
@@ -151,6 +178,13 @@ pub const ResourceDescriptor = struct {
     }
 
     pub fn read(self: ResourceDescriptor, proc: *process.Info, buffer: []u8) !usize {
+        if (self.inode.flags.detached and self.inode.options.reclaimable) {
+            return Error.Detached;
+        }
+        if (self.inode.flags.detached and !self.inode.options.reclaimable) {
+            return Error.Orphaned;
+        }
+
         return switch (self.inode.resource.tag) {
             .stream => {
                 const stream = self.inode.resource.data.stream;
@@ -179,6 +213,13 @@ pub const ResourceDescriptor = struct {
     }
 
     pub fn write(self: ResourceDescriptor, proc: *process.Info, bytes: []const u8) !usize {
+        if (self.inode.flags.detached and self.inode.options.reclaimable) {
+            return Error.Detached;
+        }
+        if (self.inode.flags.detached and !self.inode.options.reclaimable) {
+            return Error.Orphaned;
+        }
+
         return switch (self.inode.resource.tag) {
             .stream => {
                 const stream = self.inode.resource.data.stream;
@@ -256,7 +297,7 @@ pub fn find(path: []const u8) ?*Inode {
     return &root.data.inode;
 }
 
-pub fn provideResource(path: []const u8, resource: Resource, pid: u16) !void {
+pub fn provideResource(path: []const u8, resource: Resource, pid: u16, options: Options) !void {
     if (!std.fs.path.isAbsolutePosix(path)) return Error.RelativePathNotAllowed;
 
     const dirname = std.fs.path.dirnamePosix(path) orelse return Error.NoAbsoluteContainingDirectory;
@@ -271,6 +312,8 @@ pub fn provideResource(path: []const u8, resource: Resource, pid: u16) !void {
                     .inode = .{
                         .resource = resource,
                         .pid = pid,
+                        .options = options,
+                        .flags = .{},
                     },
                 });
             },
@@ -280,6 +323,8 @@ pub fn provideResource(path: []const u8, resource: Resource, pid: u16) !void {
                 break :blk dir_hook.provideFn(basename.ptr, basename.len, .{
                     .resource = resource,
                     .pid = pid,
+                    .options = options,
+                    .flags = .{},
                 }).toErrorUnion();
             },
             else => Error.NotADirectory,
@@ -287,8 +332,8 @@ pub fn provideResource(path: []const u8, resource: Resource, pid: u16) !void {
     } else return Error.NotFound;
 }
 
-pub fn provideResourceZ(path_c: [*:0]const u8, resource: Resource, pid: u16) !void {
-    return provideResource(mem.sliceTo(path_c, 0), resource, pid);
+pub fn provideResourceZ(path_c: [*:0]const u8, resource: Resource, pid: u16, options: Options) !void {
+    return provideResource(mem.sliceTo(path_c, 0), resource, pid, options);
 }
 
 pub fn open(proc: *process.Info, path: []const u8, pid: u16, data: usize) !ResourceDescriptor {