2 * This file is part of DisOrder
3 * Copyright (C) 2010 Richard Kettlewell
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.
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.
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 /** @file lib/hreader.h
19 * @brief Hands-off reader - read files without keeping them open
26 /** @brief A hands-off reader
28 * Allows files to be read without holding them open.
31 char *path
; /* file to read */
32 off_t size
; /* file size */
33 off_t read_offset
; /* for next hreader_read() */
34 off_t buf_offset
; /* offset of start of buffer */
35 char *buffer
; /* input buffer */
36 size_t bufsize
; /* buffer size */
37 size_t bytes
; /* size of last read */
40 /** @brief Initialize a hands-off reader
41 * @param path File to read
42 * @param h Reader to initialize
43 * @return 0 on success, -1 on error
45 int hreader_init(const char *path
, struct hreader
*h
);
47 /** @brief Close a hands-off reader
48 * @param h Reader to close
50 void hreader_close(struct hreader
*h
);
52 /** @brief Read some bytes
53 * @param h Reader to read from
54 * @param buffer Where to store bytes
55 * @param n Maximum bytes to read
56 * @return Bytes read, or 0 at EOF, or -1 on error
58 int hreader_read(struct hreader
*h
, void *buffer
, size_t n
);
60 /** @brief Read some bytes at a given offset
61 * @param h Reader to read from
62 * @param offset Offset to read at
63 * @param buffer Where to store bytes
64 * @param n Maximum bytes to read
65 * @return Bytes read, or 0 at EOF, or -1 on error
67 int hreader_pread(struct hreader
*h
, void *buffer
, size_t n
, off_t offset
);
69 /** @brief Seek within a file
70 * @param h Reader to seek
71 * @param offset Offset
72 * @param whence SEEK_*
73 * @return Result offset
75 off_t
hreader_seek(struct hreader
*h
, off_t offset
, int whence
);
77 /** @brief Return file size
78 * @param h Reader to find size of
79 * @return Size in bytes
81 static inline off_t
hreader_size(const struct hreader
*h
) {
85 /** @brief Test for end of file
86 * @param h Reader to test
87 * @return 1 at eof, 0 otherwise
89 * This tells you whether the next read will return 0 bytes, rather than
90 * whether the last read reached end of file. So it is slightly different to
93 static inline int hreader_eof(const struct hreader
*h
) {
94 return h
->read_offset
== h
->size
;
97 #endif /* HREADER_H */