diff options
Diffstat (limited to 'win32/win32.c')
| -rw-r--r-- | win32/win32.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/win32/win32.c b/win32/win32.c index d84a913254..b23e9af24d 100644 --- a/win32/win32.c +++ b/win32/win32.c @@ -6469,12 +6469,16 @@ rb_w32_close(int fd) } static int -setup_overlapped(OVERLAPPED *ol, int fd) +setup_overlapped(OVERLAPPED *ol, int fd, int iswrite) { memset(ol, 0, sizeof(*ol)); if (!(_osfile(fd) & (FDEV | FPIPE))) { LONG high = 0; - DWORD method = _osfile(fd) & FAPPEND ? FILE_END : FILE_CURRENT; + /* On mode:a, it can write only FILE_END. + * On mode:a+, though it can write only FILE_END, + * it can read from everywhere. + */ + DWORD method = ((_osfile(fd) & FAPPEND) && iswrite) ? FILE_END : FILE_CURRENT; DWORD low = SetFilePointer((HANDLE)_osfhnd(fd), 0, &high, method); #ifndef INVALID_SET_FILE_POINTER #define INVALID_SET_FILE_POINTER ((DWORD)-1) @@ -6571,7 +6575,7 @@ rb_w32_read(int fd, void *buf, size_t size) /* if have cancel_io, use Overlapped I/O */ if (cancel_io) { - if (setup_overlapped(&ol, fd)) { + if (setup_overlapped(&ol, fd, FALSE)) { rb_acrt_lowio_unlock_fh(fd); return -1; } @@ -6701,7 +6705,7 @@ rb_w32_write(int fd, const void *buf, size_t size) /* if have cancel_io, use Overlapped I/O */ if (cancel_io) { - if (setup_overlapped(&ol, fd)) { + if (setup_overlapped(&ol, fd, TRUE)) { rb_acrt_lowio_unlock_fh(fd); return -1; } |