feat: open Card for dev_t.

src/Card.zig

@@ -17,7 +17,7 @@ pub fn open(io: std.Io, path: []const u8) OpenError!Card {
     if (std.fs.path.isAbsolute(path))
         return Card{ .handle = try std.Io.Dir.openFileAbsolute(io, path, .{ .mode = .read_write }) };
 
-    const dir = try std.Io.Dir.openDirAbsolute(io, "/dev/dri", .{});
+    const dir = try std.Io.Dir.openDirAbsolute(io, drm.dir_name, .{});
     defer dir.close(io);
 
     return Card{ .handle = try dir.openFile(io, path, .{ .mode = .read_write }) };
@@ -26,7 +26,7 @@ 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, target_type: ?drm.Device.NodeType) OpenAutoError!Card {
-    const dir = try std.Io.Dir.openDirAbsolute(io, "/dev/dri", .{ .iterate = true });
+    const dir = try std.Io.Dir.openDirAbsolute(io, drm.dir_name, .{ .iterate = true });
     defer dir.close(io);
 
     var it = dir.iterateAssumeFirstIteration();
@@ -38,6 +38,21 @@ pub fn openAuto(io: std.Io, target_type: ?drm.Device.NodeType) OpenAutoError!Car
     return error.NoDevicesFound;
 }
 
+pub fn openForDev(io: std.Io, dev: std.posix.dev_t) OpenAutoError!Card {
+    const dir = try std.Io.Dir.openDirAbsolute(io, drm.dir_name, .{ .iterate = true });
+    defer dir.close(io);
+
+    var it = dir.iterateAssumeFirstIteration();
+    while (try it.next(io)) |entry| if (entry.kind == .character_device) {
+        const posix_name = std.posix.toPosixPath(entry.name);
+        const stat = util.stat(dir.handle, &posix_name, 0) catch continue;
+        if (drm.makeDev(stat.rdev_major, stat.rdev_minor) == dev)
+            return Card{ .handle = try dir.openFile(io, entry.name, .{ .mode = .read_write }) };
+    };
+
+    return error.NoDevicesFound;
+}
+
 pub fn close(self: Card, io: std.Io) void {
     self.handle.close(io);
 }

src/util.zig

@@ -2,14 +2,14 @@ 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);
+    return stat(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);
+    return stat(fd, "", std.os.linux.AT.EMPTY_PATH);
 }
 
-fn statxInner(fd: std.posix.fd_t, path: [*:0]const u8, flags: u32) !std.os.linux.Statx {
+pub fn stat(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)) {