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Merge pull request #2516 from colrdavidson/read_at_fix

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Make read_at and write_at more consistent between platforms
This commit is contained in:
Jeroen van Rijn
2023-05-07 08:52:37 +02:00
committed by GitHub
parent 9f39209712 b0eda47b26
commit 2c01a4613c
1 changed files with 27 additions and 10 deletions
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37
core/os/file_windows.odin
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@@ -220,6 +220,7 @@ file_size :: proc(fd: Handle) -> (i64, Errno) {
@(private)
MAX_RW :: 1<<30
ERROR_EOF :: 38
@(private)
pread :: proc(fd: Handle, data: []byte, offset: i64) -> (int, Errno) {
@@ -228,11 +229,6 @@ pread :: proc(fd: Handle, data: []byte, offset: i64) -> (int, Errno) {
buf = buf[:MAX_RW]
}
curr_offset, e := seek(fd, offset, 1)
if e != 0 {
return 0, e
}
defer seek(fd, curr_offset, 0)
o := win32.OVERLAPPED{
OffsetHigh = u32(offset>>32),
@@ -243,6 +239,7 @@ pread :: proc(fd: Handle, data: []byte, offset: i64) -> (int, Errno) {
h := win32.HANDLE(fd)
done: win32.DWORD
e: Errno
if !win32.ReadFile(h, raw_data(buf), u32(len(buf)), &done, &o) {
e = Errno(win32.GetLastError())
done = 0
@@ -256,11 +253,6 @@ pwrite :: proc(fd: Handle, data: []byte, offset: i64) -> (int, Errno) {
buf = buf[:MAX_RW]
}
curr_offset, e := seek(fd, offset, 1)
if e != 0 {
return 0, e
}
defer seek(fd, curr_offset, 0)
o := win32.OVERLAPPED{
OffsetHigh = u32(offset>>32),
@@ -269,6 +261,7 @@ pwrite :: proc(fd: Handle, data: []byte, offset: i64) -> (int, Errno) {
h := win32.HANDLE(fd)
done: win32.DWORD
e: Errno
if !win32.WriteFile(h, raw_data(buf), u32(len(buf)), &done, &o) {
e = Errno(win32.GetLastError())
done = 0
@@ -276,6 +269,16 @@ pwrite :: proc(fd: Handle, data: []byte, offset: i64) -> (int, Errno) {
return int(done), e
}
/*
read_at returns n: 0, err: 0 on EOF
on Windows, read_at changes the position of the file cursor, on *nix, it does not.
bytes: [8]u8{}
read_at(fd, bytes, 0)
read(fd, bytes)
will read from the location twice on *nix, and from two different locations on Windows
*/
read_at :: proc(fd: Handle, data: []byte, offset: i64) -> (n: int, err: Errno) {
if offset < 0 {
return 0, ERROR_NEGATIVE_OFFSET
@@ -284,6 +287,10 @@ read_at :: proc(fd: Handle, data: []byte, offset: i64) -> (n: int, err: Errno) {
b, offset := data, offset
for len(b) > 0 {
m, e := pread(fd, b, offset)
if e == ERROR_EOF {
err = 0
break
}
if e != 0 {
err = e
break
@@ -294,6 +301,16 @@ read_at :: proc(fd: Handle, data: []byte, offset: i64) -> (n: int, err: Errno) {
}
return
}
/*
on Windows, write_at changes the position of the file cursor, on *nix, it does not.
bytes: [8]u8{}
write_at(fd, bytes, 0)
write(fd, bytes)
will write to the location twice on *nix, and to two different locations on Windows
*/
write_at :: proc(fd: Handle, data: []byte, offset: i64) -> (n: int, err: Errno) {
if offset < 0 {
return 0, ERROR_NEGATIVE_OFFSET