83 lines
2.1 KiB
C++
83 lines
2.1 KiB
C++
/* fcntl.cc: fcntl syscall
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This file is part of Cygwin.
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This software is a copyrighted work licensed under the terms of the
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Cygwin license. Please consult the file "CYGWIN_LICENSE" for
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details. */
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#include "winsup.h"
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#include <unistd.h>
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#include "cygerrno.h"
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#include "security.h"
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#include "path.h"
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#include "fhandler.h"
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#include "dtable.h"
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#include "cygheap.h"
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#include "cygtls.h"
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extern "C" int
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fcntl (int fd, int cmd, ...)
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{
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int res = -1;
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intptr_t arg = 0;
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va_list args;
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pthread_testcancel ();
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__try
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{
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debug_printf ("fcntl(%d, %d, ...)", fd, cmd);
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/* Don't lock the fd table when performing locking calls. */
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cygheap_fdget cfd (fd, cmd < F_GETLK || cmd > F_SETLKW);
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if (cfd < 0)
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__leave;
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/* FIXME? All numerical args to fcntl are defined as long on Linux.
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This relies on a really dirty trick on x86_64: A 32 bit mov to
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a register (e.g. mov $1, %edx) always sets the high 32 bit to 0.
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We're following the Linux lead here since the third arg to any
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function is in a register anyway (%r8 in MS ABI). That's the easy
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case which is covered here by always reading the arg with
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sizeof (intptr_t) == sizeof (long) == sizeof (void*) which matches
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all targets.
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However, the POSIX standard defines all numerical args as type int.
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If we take that literally, we had a (small) problem on 64 bit, since
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sizeof (void*) != sizeof (int). If we would like to follow POSIX more
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closely than Linux, we'd have to call va_arg on a per cmd basis. */
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va_start (args, cmd);
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arg = va_arg (args, intptr_t);
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va_end (args);
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switch (cmd)
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{
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case F_DUPFD:
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case F_DUPFD_CLOEXEC:
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if (arg >= 0 && arg < OPEN_MAX)
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{
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int flags = cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0;
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res = cygheap->fdtab.dup3 (fd, cygheap_fdnew ((arg) - 1), flags);
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}
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else
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{
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set_errno (EINVAL);
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res = -1;
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}
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break;
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default:
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res = cfd->fcntl (cmd, arg);
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break;
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}
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}
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__except (EFAULT) {}
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__endtry
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syscall_printf ("%R = fcntl(%d, %d, %ly)", res, fd, cmd, arg);
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return res;
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}
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EXPORT_ALIAS (fcntl, _fcntl)
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