DlDynLib

pub const DlDynLib = struct {
    pub const Error = DlDynLibError;

    handle: *anyopaque,

    pub fn open(path: []const u8) Error!DlDynLib {
        const path_c = try posix.toPosixPath(path);
        return openZ(&path_c);
    }

    pub fn openZ(path_c: [*:0]const u8) Error!DlDynLib {
        return .{
            .handle = std.c.dlopen(path_c, .{ .LAZY = true }) orelse {
                return error.FileNotFound;
            },
        };
    }

    pub fn close(self: *DlDynLib) void {
        switch (posix.errno(std.c.dlclose(self.handle))) {
            .SUCCESS => return,
            else => unreachable,
        }
        self.* = undefined;
    }

    pub fn lookup(self: *DlDynLib, comptime T: type, name: [:0]const u8) ?T {
        // dlsym (and other dl-functions) secretly take shadow parameter - return address on stack
        // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66826
        if (@call(.never_tail, std.c.dlsym, .{ self.handle, name.ptr })) |symbol| {
            return @as(T, @ptrCast(@alignCast(symbol)));
        } else {
            return null;
        }
    }

    /// DlDynLib specific
    /// Returns human readable string describing most recent error than occurred from `lookup`
    /// or `null` if no error has occurred since initialization or when `getError` was last called.
    pub fn getError() ?[:0]const u8 {
        return mem.span(std.c.dlerror());
    }
}