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Share file offset across execve() on Windows

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This is a breaking change. It defines the new environment variable named
_COSMO_FDS_V2 which is used for inheriting non-stdio file descriptors on
execve() or posix_spawn(). No effort has been spent thus far integrating
with the older variable. If a new binary launches the older ones or vice
versa they'll only be able to pass stdin / stdout / stderr to each other
therefore it's important that you upgrade all your cosmo binaries if you
depend on this functionality. You'll be glad you did because inheritance
of file descriptors is more aligned with the POSIX standard than before.
This commit is contained in:
Justine Tunney 2024-08-03 17:48:00 -07:00
parent 761c6ad615
commit 3f26dfbb31
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
29 changed files with 572 additions and 249 deletions
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28
libc/calls/readwrite-nt.c
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@ -61,29 +61,29 @@ sys_readwrite_nt(int fd, void *data, size_t size, ssize_t offset,
return espipe();
// determine if we need to lock a file descriptor across processes
bool locked = isdisk && !pwriting && f->shared;
bool locked = isdisk && !pwriting && f->cursor;
if (locked)
__fd_lock(f);
__cursor_lock(f->cursor);
RestartOperation:
// when a file is opened in overlapped mode win32 requires that we
// take over full responsibility for managing our own file pointer
// which is fine, because the one win32 has was never very good in
// the sense that it behaves so differently from linux, that using
// win32 i/o required more compatibilty toil than doing it by hand
if (!pwriting) {
if (seekable && f->shared) {
offset = f->shared->pointer;
if (seekable && f->cursor) {
offset = f->cursor->shared->pointer;
} else {
offset = 0;
}
}
RestartOperation:
bool eagained = false;
// check for signals and cancelation
if (_check_cancel() == -1) {
if (locked)
__fd_unlock(f);
__cursor_unlock(f->cursor);
return -1; // ECANCELED
}
if (_weaken(__sig_get) && (sig = _weaken(__sig_get)(waitmask))) {
@ -122,10 +122,10 @@ RestartOperation:
// if i/o succeeded then return its result
if (ok) {
if (!pwriting && seekable && f->shared)
f->shared->pointer = offset + exchanged;
if (!pwriting && seekable && f->cursor)
f->cursor->shared->pointer = offset + exchanged;
if (locked)
__fd_unlock(f);
__cursor_unlock(f->cursor);
return exchanged;
}
@ -134,31 +134,31 @@ RestartOperation:
// raise EAGAIN if it's due to O_NONBLOCK mmode
if (eagained) {
if (locked)
__fd_unlock(f);
__cursor_unlock(f->cursor);
return eagain();
}
// otherwise it must be due to a kill() via __sig_cancel()
if (_weaken(__sig_relay) && (sig = _weaken(__sig_get)(waitmask))) {
HandleInterrupt:
if (locked)
__fd_unlock(f);
__cursor_unlock(f->cursor);
int handler_was_called = _weaken(__sig_relay)(sig, SI_KERNEL, waitmask);
if (_check_cancel() == -1)
return -1; // possible if we SIGTHR'd
if (locked)
__fd_lock(f);
__cursor_lock(f->cursor);
// read() is @restartable unless non-SA_RESTART hands were called
if (!(handler_was_called & SIG_HANDLED_NO_RESTART))
goto RestartOperation;
}
if (locked)
__fd_unlock(f);
__cursor_unlock(f->cursor);
return eintr();
}
// read() and write() have generally different error-handling paths
if (locked)
__fd_unlock(f);
__cursor_unlock(f->cursor);
return -2;
}