feat: get Device from Card.

example.zig

@@ -5,13 +5,15 @@ pub fn main(init: std.process.Init) !void {
     const io = init.io;
     const gpa = init.gpa;
 
-    const device = drm.Device.getFromDevId(io, gpa, drm.makeDev(226, 0), .{}) catch
-        try drm.Device.getFromDevId(io, gpa, drm.makeDev(226, 1), .{});
+    // const device = drm.Device.getFromDevId(io, gpa, drm.makeDev(226, 0), .{}) catch
+    //     try drm.Device.getFromDevId(io, gpa, drm.makeDev(226, 1), .{});
 
+    // const card = try device.openNode(io);
+
+    const card = try drm.Card.openAuto(io, .primary);
+    const device = try card.getDevice(io, gpa, .{});
     std.log.info("Device node path: {s}.", .{device.nodePath()});
 
-    // const card = try drm.Card.openAuto(io);
-    const card = try device.openNode(io);
     defer card.close(io);
     const res = try card.getModesettingResources(gpa);
     defer res.deinit(gpa);

src/Card.zig

@@ -1,11 +1,12 @@
 const std = @import("std");
 
+const Device = @import("Device.zig");
 const drm = @import("drm.zig");
 const fmt = @import("format.zig");
 const sys = @import("sys.zig");
+const util = @import("util.zig");
 
 const log = std.log.scoped(.drm);
-
 const Card = @This();
 
 handle: std.Io.File,
@@ -24,13 +25,15 @@ pub fn open(io: std.Io, path: []const u8) OpenError!Card {
 
 pub const OpenAutoError = OpenError || std.Io.Dir.Iterator.Error || error{NoDevicesFound};
 
-pub fn openAuto(io: std.Io) OpenAutoError!Card {
+pub fn openAuto(io: std.Io, target_type: ?drm.Device.NodeType) OpenAutoError!Card {
     const dir = try std.Io.Dir.openDirAbsolute(io, "/dev/dri", .{ .iterate = true });
     defer dir.close(io);
 
     var it = dir.iterateAssumeFirstIteration();
-    while (try it.next(io)) |entry| if (entry.kind == .character_device)
-        return Card{ .handle = try dir.openFile(io, entry.name, .{ .mode = .read_write }) };
+    while (try it.next(io)) |entry| if (entry.kind == .character_device) {
+        if (target_type) |t| if (!std.mem.startsWith(u8, entry.name, t.name())) continue;
+        return Card{ .handle = dir.openFile(io, entry.name, .{ .mode = .read_write }) catch continue };
+    };
 
     return error.NoDevicesFound;
 }
@@ -39,6 +42,15 @@ pub fn close(self: Card, io: std.Io) void {
     self.handle.close(io);
 }
 
+pub fn getDevId(self: Card) !std.posix.dev_t {
+    const stat = try util.statFile(self.handle.handle);
+    return drm.makeDev(stat.rdev_major, stat.rdev_minor);
+}
+
+pub fn getDevice(self: Card, io: std.Io, gpa: std.mem.Allocator, flags: Device.Flags) !Device {
+    return .getFromDevId(io, gpa, try self.getDevId(), flags);
+}
+
 pub fn handleEvents(
     self: Card,
     io: std.Io,

src/Device.zig

@@ -4,6 +4,7 @@ const path_max = std.os.linux.PATH_MAX;
 const Card = @import("Card.zig");
 const drm = @import("drm.zig");
 const sys = @import("sys.zig");
+const util = @import("util.zig");
 
 const log = std.log.scoped(.drm);
 const Device = @This();
@@ -183,6 +184,14 @@ pub const NodeType = enum {
     control,
     render,
     pub const max = 3;
+
+    pub fn name(self: NodeType) []const u8 {
+        return switch (self) {
+            .primary => drm.primary_minor_name,
+            .control => drm.control_minor_name,
+            .render => drm.render_minor_name,
+        };
+    }
 };
 
 fn processDevice(
@@ -202,7 +211,7 @@ fn processDevice(
     if (node.len + 1 > max_node_length)
         return error.NodePathTooLong;
 
-    const stat = try statx(node);
+    const stat = try util.statPath(node);
     const major = stat.rdev_major;
     const minor = stat.rdev_minor;
 
@@ -375,7 +384,7 @@ fn parseConfigSysfsFile(io: std.Io, major: u32, minor: u32) !PciDeviceInfo {
 }
 
 fn hasRdev(dev: Device, rdev: std.posix.dev_t) bool {
-    const stat = statx(dev.nodePath()) catch return false;
+    const stat = util.statPath(dev.nodePath()) catch return false;
     return drm.makeDev(stat.rdev_major, stat.rdev_minor) == rdev;
 }
 
@@ -386,13 +395,3 @@ fn getNodeType(name: []const u8) !NodeType {
 
     return error.InvalidName;
 }
-
-fn statx(path: []const u8) !std.os.linux.Statx {
-    const posix_path = try std.posix.toPosixPath(path);
-    var stat_buf: std.os.linux.Statx = undefined;
-    const rc = std.os.linux.statx(std.os.linux.AT.FDCWD, &posix_path, 0, .{}, &stat_buf);
-    return switch (std.posix.errno(rc)) {
-        .SUCCESS => stat_buf,
-        else => |err| std.posix.unexpectedErrno(err),
-    };
-}

src/util.zig

@@ -0,0 +1,28 @@
+const std = @import("std");
+
+pub fn statPath(path: []const u8) !std.os.linux.Statx {
+    const posix_path = try std.posix.toPosixPath(path);
+    return statxInner(std.os.linux.AT.FDCWD, &posix_path, 0);
+}
+
+pub fn statFile(fd: std.posix.fd_t) !std.os.linux.Statx {
+    return statxInner(fd, "", std.os.linux.AT.EMPTY_PATH);
+}
+
+fn statxInner(fd: std.posix.fd_t, path: [*:0]const u8, flags: u32) !std.os.linux.Statx {
+    var stat_buf: std.os.linux.Statx = undefined;
+    const rc = std.posix.system.statx(fd, path, flags, .{}, &stat_buf);
+    return switch (std.posix.errno(rc)) {
+        .SUCCESS => stat_buf,
+        .ACCES => error.PermissionDenied,
+        .LOOP => error.SymLinkLoop,
+        .NAMETOOLONG => error.NameTooLong,
+        .NOENT => error.FileNotFound,
+        .NOMEM => error.SystemResources,
+        .NOTDIR => error.NotADirectory,
+        .BADF => unreachable,
+        .FAULT => unreachable,
+        .INVAL => unreachable,
+        else => |err| std.posix.unexpectedErrno(err),
+    };
+}