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9e5c991106
readlink() opens the target with O_READ to be able to read the symlink content. When the target is actually a fifo, that would hang waiting for a writer (caught in the coreutils testsuite). We thus have to first lookup the target without O_READ to perform io_stat and lookout for fifos, and only after checking the symlink type, we can re-lookup with O_READ.
63 lines
1.9 KiB
C
63 lines
1.9 KiB
C
/* Copyright (C) 1991-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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#include <unistd.h>
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#include <hurd.h>
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#include <hurd/paths.h>
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#include <hurd/fd.h>
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#include <fcntl.h>
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#include <string.h>
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/* Read the contents of the symbolic link FILE_NAME relative to FD into no more
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than LEN bytes of BUF. The contents are not null-terminated.
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Returns the number of characters read, or -1 for errors. */
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ssize_t
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readlinkat (int fd, const char *file_name, char *buf, size_t len)
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{
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error_t err;
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file_t file;
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struct stat64 st;
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file = __file_name_lookup_at (fd, 0, file_name, O_NOLINK, 0);
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if (file == MACH_PORT_NULL)
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return -1;
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err = __io_stat (file, &st);
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if (! err)
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if (S_ISLNK (st.st_mode))
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{
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char *rbuf = buf;
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__mach_port_deallocate (__mach_task_self (), file);
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file = __file_name_lookup_at (fd, 0, file_name, O_READ | O_NOLINK, 0);
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err = __io_read (file, &rbuf, &len, 0, len);
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if (!err && rbuf != buf)
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{
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memcpy (buf, rbuf, len);
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__vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len);
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}
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}
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else
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err = EINVAL;
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__mach_port_deallocate (__mach_task_self (), file);
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return err ? __hurd_fail (err) : len;
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}
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libc_hidden_def (readlinkat)
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