diff --git a/io_buffer.c b/io_buffer.c index 87e392b791..abe7832bee 100644 --- a/io_buffer.c +++ b/io_buffer.c @@ -667,18 +667,25 @@ rb_io_buffer_map(VALUE io, size_t size, rb_off_t offset, enum rb_io_buffer_flags * call-seq: IO::Buffer.map(file, [size, [offset, [flags]]]) -> io_buffer * * Create an IO::Buffer for reading from +file+ by memory-mapping the file. - * +file_io+ should be a +File+ instance, opened for reading. + * +file+ should be a +File+ instance, opened for reading or reading and writing. * * Optional +size+ and +offset+ of mapping can be specified. + * Trying to map an empty file or specify +size+ of 0 will raise an error. + * Valid values for +offset+ are system-dependent. * - * By default, the buffer would be immutable (read only); to create a writable - * mapping, you need to open a file in read-write mode, and explicitly pass - * +flags+ argument without IO::Buffer::IMMUTABLE. + * By default, the buffer is writable and expects the file to be writable. + * It is also shared, so several processes can use the same mapping. + * + * You can pass IO::Buffer::READONLY in +flags+ argument to make a read-only buffer; + * this allows to work with files opened only for reading. + * Specifying IO::Buffer::PRIVATE in +flags+ creates a private mapping, + * which will not impact other processes or the underlying file. + * It also allows updating a buffer created from a read-only file. * * File.write('test.txt', 'test') * * buffer = IO::Buffer.map(File.open('test.txt'), nil, 0, IO::Buffer::READONLY) - * # => # + * # => # * * buffer.readonly? # => true * @@ -686,7 +693,7 @@ rb_io_buffer_map(VALUE io, size_t size, rb_off_t offset, enum rb_io_buffer_flags * # => "test" * * buffer.set_string('b', 0) - * # `set_string': Buffer is not writable! (IO::Buffer::AccessError) + * # 'IO::Buffer#set_string': Buffer is not writable! (IO::Buffer::AccessError) * * # create read/write mapping: length 4 bytes, offset 0, flags 0 * buffer = IO::Buffer.map(File.open('test.txt', 'r+'), 4, 0) @@ -708,31 +715,48 @@ io_buffer_map(int argc, VALUE *argv, VALUE klass) // We might like to handle a string path? VALUE io = argv[0]; + rb_off_t file_size = rb_file_size(io); + // Compiler can confirm that we handled file_size <= 0 case: + if (UNLIKELY(file_size <= 0)) { + rb_raise(rb_eArgError, "Invalid negative or zero file size!"); + } + // Here, we assume that file_size is positive: + else if (UNLIKELY((uintmax_t)file_size > SIZE_MAX)) { + rb_raise(rb_eArgError, "File larger than address space!"); + } + size_t size; if (argc >= 2 && !RB_NIL_P(argv[1])) { size = io_buffer_extract_size(argv[1]); + if (UNLIKELY(size == 0)) { + rb_raise(rb_eArgError, "Size can't be zero!"); + } + if (UNLIKELY(size > (size_t)file_size)) { + rb_raise(rb_eArgError, "Size can't be larger than file size!"); + } } else { - rb_off_t file_size = rb_file_size(io); - - // Compiler can confirm that we handled file_size < 0 case: - if (file_size < 0) { - rb_raise(rb_eArgError, "Invalid negative file size!"); - } - // Here, we assume that file_size is positive: - else if ((uintmax_t)file_size > SIZE_MAX) { - rb_raise(rb_eArgError, "File larger than address space!"); - } - else { - // This conversion should be safe: - size = (size_t)file_size; - } + // This conversion should be safe: + size = (size_t)file_size; } // This is the file offset, not the buffer offset: rb_off_t offset = 0; if (argc >= 3) { offset = NUM2OFFT(argv[2]); + if (UNLIKELY(offset < 0)) { + rb_raise(rb_eArgError, "Offset can't be negative!"); + } + if (UNLIKELY(offset >= file_size)) { + rb_raise(rb_eArgError, "Offset too large!"); + } + if (RB_NIL_P(argv[1])) { + // Decrease size if it's set from the actual file size: + size = (size_t)(file_size - offset); + } + else if (UNLIKELY((size_t)(file_size - offset) < size)) { + rb_raise(rb_eArgError, "Offset too large!"); + } } enum rb_io_buffer_flags flags = 0; diff --git a/test/ruby/test_io_buffer.rb b/test/ruby/test_io_buffer.rb index 62c4667888..997ed52640 100644 --- a/test/ruby/test_io_buffer.rb +++ b/test/ruby/test_io_buffer.rb @@ -73,12 +73,64 @@ class TestIOBuffer < Test::Unit::TestCase def test_file_mapped buffer = File.open(__FILE__) {|file| IO::Buffer.map(file, nil, 0, IO::Buffer::READONLY)} - contents = buffer.get_string + assert_equal File.size(__FILE__), buffer.size + contents = buffer.get_string assert_include contents, "Hello World" assert_equal Encoding::BINARY, contents.encoding end + def test_file_mapped_with_size + buffer = File.open(__FILE__) {|file| IO::Buffer.map(file, 30, 0, IO::Buffer::READONLY)} + assert_equal 30, buffer.size + + contents = buffer.get_string + assert_equal "# frozen_string_literal: false", contents + assert_equal Encoding::BINARY, contents.encoding + end + + def test_file_mapped_size_too_large + assert_raise ArgumentError do + File.open(__FILE__) {|file| IO::Buffer.map(file, 200_000, 0, IO::Buffer::READONLY)} + end + assert_raise ArgumentError do + File.open(__FILE__) {|file| IO::Buffer.map(file, File.size(__FILE__) + 1, 0, IO::Buffer::READONLY)} + end + end + + def test_file_mapped_size_just_enough + File.open(__FILE__) {|file| + assert_equal File.size(__FILE__), IO::Buffer.map(file, File.size(__FILE__), 0, IO::Buffer::READONLY).size + } + end + + def test_file_mapped_offset_too_large + assert_raise ArgumentError do + File.open(__FILE__) {|file| IO::Buffer.map(file, nil, IO::Buffer::PAGE_SIZE * 100, IO::Buffer::READONLY)} + end + assert_raise ArgumentError do + File.open(__FILE__) {|file| IO::Buffer.map(file, 20, IO::Buffer::PAGE_SIZE * 100, IO::Buffer::READONLY)} + end + end + + def test_file_mapped_zero_size + assert_raise ArgumentError do + File.open(__FILE__) {|file| IO::Buffer.map(file, 0, 0, IO::Buffer::READONLY)} + end + end + + def test_file_mapped_negative_size + assert_raise ArgumentError do + File.open(__FILE__) {|file| IO::Buffer.map(file, -10, 0, IO::Buffer::READONLY)} + end + end + + def test_file_mapped_negative_offset + assert_raise ArgumentError do + File.open(__FILE__) {|file| IO::Buffer.map(file, 20, -1, IO::Buffer::READONLY)} + end + end + def test_file_mapped_invalid assert_raise TypeError do IO::Buffer.map("foobar")