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Implement __zipos_dup (#972)

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* Implement __zipos_dup

Makes ZiposHandle reference-counted by an `rc` field in a union with its
freelist `next` pointer. The functions `__zipos_free` and `__zipos_keep`
function as incref/decref for it. Adds `__zipos_postdup` to fix metadata
on file descriptors after dup-like operations, and adds zipos support to
`sys_dup_nt` + `sys_close_nt`.

* Remove noop __zipos_postdup

rc is never a zipos file because it is always a previously unused file
descriptor. fd is never a zipos file because that case has been handled
above by __zipos_fcntl.
This commit is contained in:
Jōshin 2023-12-01 03:08:30 -05:00 • committed by GitHub
parent 6556dd2673
commit d1a745c17c
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11 changed files with 138 additions and 39 deletions
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22
libc/calls/dup2.c
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@ -67,20 +67,24 @@ int dup2(int oldfd, int newfd) {
int rc;
// helps guarantee stderr log gets duplicated before user closes
if (_weaken(kloghandle)) _weaken(kloghandle)();
if (__isfdkind(oldfd, kFdZip)) {
rc = enotsup();
#ifdef __aarch64__
} else if (oldfd == newfd) {
if (oldfd == newfd) {
// linux aarch64 defines dup3() but not dup2(), which wasn't such a
// great decision, since the two syscalls don't behave the same way
if (!(rc = read(oldfd, 0, 0))) rc = oldfd;
} else
#endif
} else if (!IsWindows()) {
rc = sys_dup2(oldfd, newfd, 0);
if (rc != -1 && oldfd != newfd && __isfdkind(newfd, kFdZip) && !__vforked) {
_weaken(__zipos_free)(
(struct ZiposHandle *)(intptr_t)g_fds.p[newfd].handle);
bzero(g_fds.p + newfd, sizeof(*g_fds.p));
if (!IsWindows()) {
if (__isfdkind(oldfd, kFdZip) || __isfdkind(newfd, kFdZip)) {
if (__vforked) {
return enotsup();
}
rc = sys_dup2(oldfd, newfd, 0);
if (rc != -1) {
_weaken(__zipos_postdup)(oldfd, newfd);
}
} else {
rc = sys_dup2(oldfd, newfd, 0);
}
} else if (newfd < 0) {
rc = ebadf();