module os import strings pub struct File { cfile voidptr // Using void* instead of FILE* pub: fd int pub mut: is_opened bool } struct FileInfo { name string size int } [deprecated] pub fn (f File) is_opened() bool { eprintln('warning: `file.is_opened()` has been deprecated, use `file.is_opened` instead') return f.is_opened } // **************************** Write ops *************************** pub fn (mut f File) write(s string) ?int { if !f.is_opened { return error('file is not opened') } /* $if linux { $if !android { C.syscall(sys_write, f.fd, s.str, s.len) return } } */ written := C.fwrite(s.str, s.len, 1, f.cfile) if written == 0 && s.len != 0 { return error('0 bytes written') } return written } pub fn (mut f File) writeln(s string) ?int { if !f.is_opened { return error('file is not opened') } /* $if linux { $if !android { snl := s + '\n' C.syscall(sys_write, f.fd, snl.str, snl.len) return } } */ // TODO perf written := C.fwrite(s.str, s.len, 1, f.cfile) if written == 0 && s.len != 0 { return error('0 bytes written') } x := C.fputs('\n', f.cfile) if x < 0 { return error('could not add newline') } return (written + 1) } pub fn (mut f File) write_bytes(data voidptr, size int) int { return C.fwrite(data, 1, size, f.cfile) } pub fn (mut f File) write_bytes_at(data voidptr, size, pos int) int { C.fseek(f.cfile, pos, C.SEEK_SET) res := C.fwrite(data, 1, size, f.cfile) C.fseek(f.cfile, 0, C.SEEK_END) return res } // **************************** Read ops *************************** // read_bytes reads bytes from the beginning of the file pub fn (f &File) read_bytes(size int) []byte { return f.read_bytes_at(size, 0) } // read_bytes_at reads bytes at the given position in the file pub fn (f &File) read_bytes_at(size, pos int) []byte { mut arr := []byte{len: size} nreadbytes := f.read_bytes_into(pos, mut arr) or { // return err return [] } return arr[0..nreadbytes] } // read_bytes_from fills `buf` with bytes at the given position in the file. // `buf` must have length greater than zero. // Returns number of bytes read or an error. pub fn (f &File) read_bytes_into(pos int, mut buf []byte) ?int { if buf.len == 0 { panic(@FN + ': `buf.len` == 0') } // Note: fseek errors if pos == os.file_size, which we accept C.fseek(f.cfile, pos, C.SEEK_SET) // errno is only set if fread fails, so clear it first to tell C.errno = 0 nbytes := C.fread(buf.data, 1, buf.len, f.cfile) if C.errno != 0 { return error(posix_get_error_msg(C.errno)) } $if debug { C.fseek(f.cfile, 0, C.SEEK_SET) } return nbytes } // **************************** Utility ops *********************** // write any unwritten data in stream's buffer pub fn (mut f File) flush() { if !f.is_opened { return } C.fflush(f.cfile) } // open_stdin - return an os.File for stdin, so that you can use .get_line on it too. pub fn open_stdin() File { return File{ fd: 0 cfile: C.stdin is_opened: true } } // File.get_line - get a single line from the file. NB: the ending newline is *included*. pub fn (mut f File) get_line() ?string { if !f.is_opened { return error('file is closed') } $if !windows { mut zbuf := byteptr(0) mut zblen := size_t(0) mut zx := 0 unsafe { zx = C.getline(&zbuf, &zblen, f.cfile) if zx == -1 { C.free(zbuf) if C.errno == 0 { return error('end of file') } return error(posix_get_error_msg(C.errno)) } return zbuf.vstring_with_len(zx) } } // // using C.fgets is less efficient than f.get_line_getline, // but is available everywhere, while C.getline does not work // on windows // buf := [4096]byte{} mut res := strings.new_builder(1024) mut x := 0 for { unsafe { x = C.fgets(charptr(buf), 4096, f.cfile) } if x == 0 { if res.len > 0 { break } return error('end of file') } bufbp := byteptr(buf) mut blen := vstrlen(bufbp) res.write_bytes(bufbp, blen) unsafe { if blen == 0 || bufbp[blen - 1] == `\n` || bufbp[blen - 1] == `\r` { break } } } return res.str() }