68 lines
2.5 KiB
C
68 lines
2.5 KiB
C
/* Read symbolic links into a buffer without size limitation, relative to fd.
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Copyright (C) 2011-2022 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file 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
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Paul Eggert, Bruno Haible, and Jim Meyering. */
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#ifndef _GL_CAREADLINKAT_H
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#define _GL_CAREADLINKAT_H
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#include <fcntl.h>
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#include <unistd.h>
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struct allocator;
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/* Assuming the current directory is FD, get the symbolic link value
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of FILENAME as a null-terminated string and put it into a buffer.
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If FD is AT_FDCWD, FILENAME is interpreted relative to the current
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working directory, as in openat.
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If the link is small enough to fit into BUFFER put it there.
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BUFFER's size is BUFFER_SIZE, and BUFFER can be null
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if BUFFER_SIZE is zero.
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If the link is not small, put it into a dynamically allocated
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buffer managed by ALLOC. It is the caller's responsibility to free
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the returned value if it is nonnull and is not BUFFER.
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The PREADLINKAT function specifies how to read links. It operates
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like POSIX readlinkat()
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<https://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html>
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but can assume that its first argument is the same as FD.
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If successful, return the buffer address; otherwise return NULL and
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set errno. */
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char *careadlinkat (int fd, char const *filename,
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char *restrict buffer, size_t buffer_size,
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struct allocator const *alloc,
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ssize_t (*preadlinkat) (int, char const *,
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char *, size_t));
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/* Suitable value for careadlinkat's FD argument. */
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#if HAVE_READLINKAT
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/* AT_FDCWD is declared in <fcntl.h>. */
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#else
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/* Define AT_FDCWD independently, so that the careadlinkat module does
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not depend on the fcntl-h module. We might as well use the same value
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as fcntl-h. */
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# ifndef AT_FDCWD
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# define AT_FDCWD (-3041965)
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# endif
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#endif
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#endif /* _GL_CAREADLINKAT_H */
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