491d647a3b
This change effectively adds the VFS side of support for the SO_LINGER socket option, by allowing file descriptor close operations to be suspended (and later resumed) by socket drivers. Currently, support is limited to the close(2) system call--in all other cases where file descriptors are closed (dup2, close-on-exec, process exit..), the close operation still completes instantly. As a general policy, the close(2) return value will always indicate that the file descriptor has been closed: either 0, or -1 with errno set to EINPROGRESS. The latter error may be thrown only when a suspended close is interrupted by a signal. As necessary for UDS, this change also introduces a closenb(2) system call extension, allowing the caller to bypass blocking SO_LINGER close behavior. This extension allows UDS to avoid blocking on closing the last reference to an in-flight file descriptor, in an atomic fashion. The extension is currently part of libsys, but there is no reason why userland would not be allowed to make this call, so it is deliberately not protected from use by userland. Change-Id: Iec77d6665232110346180017fc1300b1614910b7
19 lines
271 B
C
19 lines
271 B
C
#include <sys/cdefs.h>
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#include "namespace.h"
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#include <lib.h>
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#include <string.h>
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#include <unistd.h>
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int
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close(int fd)
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{
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message m;
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memset(&m, 0, sizeof(m));
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m.m_lc_vfs_close.fd = fd;
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m.m_lc_vfs_close.nblock = 0;
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return _syscall(VFS_PROC_NR, VFS_CLOSE, &m);
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}
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