1 | /* Read symbolic links into a buffer without size limitation, relative to fd. |
2 | |
3 | Copyright (C) 2011-2019 Free Software Foundation, Inc. |
4 | |
5 | This program is free software: you can redistribute it and/or modify |
6 | it under the terms of the GNU General Public License as published by |
7 | the Free Software Foundation; either version 3 of the License, or |
8 | (at your option) any later version. |
9 | |
10 | This program 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 General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU 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 | <http://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 *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 */ |
68 | |