os: implement File.seek/2 and File.tell/0

pull/10890/head
Delyan Angelov 2021-07-22 07:46:21 +03:00
parent 054bd67490
commit d7dcb47db3
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GPG Key ID: 66886C0F12D595ED
4 changed files with 93 additions and 10 deletions

View File

@ -16,6 +16,7 @@ struct FileInfo {
fn C.fseeko(&C.FILE, u64, int) int fn C.fseeko(&C.FILE, u64, int) int
fn C._fseeki64(&C.FILE, u64, int) int fn C._fseeki64(&C.FILE, u64, int) int
fn C._ftelli64(&C.FILE) i64
fn C.getc(&C.FILE) int fn C.getc(&C.FILE) int
@ -727,3 +728,60 @@ pub fn (mut f File) write_raw_at<T>(t &T, pos u64) ? {
return error_with_code('incomplete struct write', nbytes) return error_with_code('incomplete struct write', nbytes)
} }
} }
pub enum SeekMode {
start
current
end
}
// seek moves the file cursor (if any) associated with a file
// to a new location, offset `pos` bytes from the origin. The origin
// is dependent on the `mode` and can be:
// .start -> the origin is the start of the file
// .current -> the current position/cursor in the file
// .end -> the end of the file
// If the file is not seek-able, or an error occures, the error will
// be returned to the caller.
// A successful call to the fseek() function clears the end-of-file
// indicator for the file.
pub fn (mut f File) seek(pos i64, mode SeekMode) ? {
if !f.is_opened {
return error_file_not_opened()
}
whence := int(mode)
mut res := 0
$if x64 {
$if windows {
res = C._fseeki64(f.cfile, pos, whence)
} $else {
res = C.fseeko(f.cfile, pos, whence)
}
}
$if x32 {
res = C.fseek(f.cfile, pos, whence)
}
if res == -1 {
return error(posix_get_error_msg(C.errno))
}
}
// tell will return the current offset of the file cursor measured from
// the start of the file, in bytes. It is complementary to seek, i.e.
// you can use the return value as the `pos` parameter to .seek( pos, .start ),
// so that your next read will happen from the same place.
pub fn (f &File) tell() ?i64 {
if !f.is_opened {
return error_file_not_opened()
}
mut pos := i64(0)
$if windows && x64 {
pos = C._ftelli64(f.cfile)
} $else {
pos = C.ftell(f.cfile)
}
if pos == -1 {
return error(posix_get_error_msg(C.errno))
}
return pos
}

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@ -331,3 +331,31 @@ fn test_read_raw_at_negative_pos() ? {
f.read_raw_at<Point>(-234) or { assert err.msg == 'Invalid argument' } f.read_raw_at<Point>(-234) or { assert err.msg == 'Invalid argument' }
f.close() f.close()
} }
fn test_seek() ? {
mut f := os.open_file(tfile, 'w') ?
f.write_raw(another_point) ?
f.write_raw(another_byte) ?
f.write_raw(another_color) ?
f.write_raw(another_permission) ?
f.close()
// println('> ${sizeof(Point)} ${sizeof(byte)} ${sizeof(Color)} ${sizeof(Permissions)}')
f = os.open_file(tfile, 'r') ?
defer {
f.close()
}
f.seek(i64(sizeof(Point)), .start) ?
assert f.tell() ? == sizeof(Point)
b := f.read_raw<byte>() ?
f.seek(i64(sizeof(Color)), .current) ?
x := f.read_raw<Permissions>() ?
f.seek(-i64(sizeof(Permissions) + sizeof(Color)), .end) ?
assert f.tell() ? == sizeof(Point) + sizeof(byte)
cc := f.read_raw<Color>() ?
assert b == another_byte
assert x == another_permission
assert cc == another_color
}

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@ -13,7 +13,7 @@ fn C.readlink(pathname &char, buf &char, bufsiz size_t) int
fn C.getline(voidptr, voidptr, voidptr) int fn C.getline(voidptr, voidptr, voidptr) int
fn C.ftell(fp voidptr) int fn C.ftell(fp voidptr) i64
fn C.sigaction(int, voidptr, int) int fn C.sigaction(int, voidptr, int) int
@ -83,12 +83,12 @@ pub fn read_bytes(path string) ?[]byte {
return error('ftell failed') return error('ftell failed')
} }
C.rewind(fp) C.rewind(fp)
mut res := []byte{len: fsize} mut res := []byte{len: int(fsize)}
nr_read_elements := int(C.fread(res.data, fsize, 1, fp)) nr_read_elements := int(C.fread(res.data, fsize, 1, fp))
if nr_read_elements == 0 && fsize > 0 { if nr_read_elements == 0 && fsize > 0 {
return error('fread failed') return error('fread failed')
} }
res.trim(nr_read_elements * fsize) res.trim(nr_read_elements * int(fsize))
return res return res
} }
@ -110,7 +110,7 @@ pub fn read_file(path string) ?string {
// C.fseek(fp, 0, SEEK_SET) // same as `C.rewind(fp)` below // C.fseek(fp, 0, SEEK_SET) // same as `C.rewind(fp)` below
C.rewind(fp) C.rewind(fp)
unsafe { unsafe {
mut str := malloc_noscan(fsize + 1) mut str := malloc_noscan(int(fsize) + 1)
nelements := int(C.fread(str, 1, fsize, fp)) nelements := int(C.fread(str, 1, fsize, fp))
is_eof := int(C.feof(fp)) is_eof := int(C.feof(fp))
is_error := int(C.ferror(fp)) is_error := int(C.ferror(fp))
@ -586,7 +586,7 @@ pub fn read_file_array<T>(path string) []T {
C.rewind(fp) C.rewind(fp)
// read the actual data from the file // read the actual data from the file
len := fsize / tsize len := fsize / tsize
buf := unsafe { malloc_noscan(fsize) } buf := unsafe { malloc_noscan(int(fsize)) }
nread := C.fread(buf, tsize, len, fp) nread := C.fread(buf, tsize, len, fp)
C.fclose(fp) C.fclose(fp)
return unsafe { return unsafe {
@ -594,7 +594,7 @@ pub fn read_file_array<T>(path string) []T {
element_size: tsize element_size: tsize
data: buf data: buf
len: int(nread) len: int(nread)
cap: len cap: int(len)
} }
} }
} }

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@ -304,10 +304,7 @@ pub fn is_dir(path string) bool {
return res return res
} }
*/ */
/*
pub fn (mut f File) fseek(pos, mode int) {
}
*/
// mkdir creates a new directory with the specified path. // mkdir creates a new directory with the specified path.
pub fn mkdir(path string) ?bool { pub fn mkdir(path string) ?bool {
if path == '.' { if path == '.' {