1 /* Read symbolic links into a buffer without size limitation, relative to fd. 2 3 Copyright (C) 2011-2021 Free Software Foundation, Inc. 4 5 This file is free software: you can redistribute it and/or modify 6 it under the terms of the GNU Lesser General Public License as 7 published by the Free Software Foundation; either version 2.1 of the 8 License, or (at your option) any later version. 9 10 This file is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public License 16 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 17 18 /* Written by Paul Eggert, Bruno Haible, and Jim Meyering. */ 19 20 #ifndef _GL_CAREADLINKAT_H 21 #define _GL_CAREADLINKAT_H 22 23 #include <fcntl.h> 24 #include <unistd.h> 25 26 struct allocator; 27 28 /* Assuming the current directory is FD, get the symbolic link value 29 of FILENAME as a null-terminated string and put it into a buffer. 30 If FD is AT_FDCWD, FILENAME is interpreted relative to the current 31 working directory, as in openat. 32 33 If the link is small enough to fit into BUFFER put it there. 34 BUFFER's size is BUFFER_SIZE, and BUFFER can be null 35 if BUFFER_SIZE is zero. 36 37 If the link is not small, put it into a dynamically allocated 38 buffer managed by ALLOC. It is the caller's responsibility to free 39 the returned value if it is nonnull and is not BUFFER. 40 41 The PREADLINKAT function specifies how to read links. It operates 42 like POSIX readlinkat() 43 <https://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html> 44 but can assume that its first argument is the same as FD. 45 46 If successful, return the buffer address; otherwise return NULL and 47 set errno. */ 48 49 char *careadlinkat (int fd, char const *filename, 50 char *restrict buffer, size_t buffer_size, 51 struct allocator const *alloc, 52 ssize_t (*preadlinkat) (int, char const *, 53 char *, size_t)); 54 55 /* Suitable value for careadlinkat's FD argument. */ 56 #if HAVE_READLINKAT 57 /* AT_FDCWD is declared in <fcntl.h>. */ 58 #else 59 /* Define AT_FDCWD independently, so that the careadlinkat module does 60 not depend on the fcntl-h module. We might as well use the same value 61 as fcntl-h. */ 62 # ifndef AT_FDCWD 63 # define AT_FDCWD (-3041965) 64 # endif 65 #endif 66 67 #endif /* _GL_CAREADLINKAT_H */