v/vlib/os/file.v

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module os
import strings
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pub struct File {
cfile voidptr // Using void* instead of FILE*
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pub:
fd int
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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 {
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if !f.is_opened {
return error('file is not opened')
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}
/*
$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
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}
pub fn (mut f File) writeln(s string) ?int {
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if !f.is_opened {
return error('file is not opened')
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}
/*
$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)
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}
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 an amount of 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 an amount of bytes at the given position in the file
pub fn (f &File) read_bytes_at(size, pos int) []byte {
// mut arr := [`0`].repeat(size)
mut arr := []byte{len: size}
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C.fseek(f.cfile, pos, C.SEEK_SET)
nreadbytes := C.fread(arr.data, 1, size, f.cfile)
C.fseek(f.cfile, 0, C.SEEK_SET)
return arr[0..nreadbytes]
}
// **************************** 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()
}