chiark / gitweb /
Eliminate string_login().
[disorder] / lib / hreader.h
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1/*
2 * This file is part of DisOrder
3 * Copyright (C) 2010 Richard Kettlewell
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 <http://www.gnu.org/licenses/>.
17 */
18/** @file lib/hreader.h
19 * @brief Hands-off reader - read files without keeping them open
20 */
21#ifndef HREADER_H
22#define HREADER_H
23
24#include <unistd.h>
25
26/** @brief A hands-off reader
27 *
28 * Allows files to be read without holding them open.
29 */
30struct hreader {
6ebc4527 31 char *path; /* file to read */
21237d05 32 off_t size; /* file size */
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33 off_t read_offset; /* for next hreader_read() */
34 off_t buf_offset; /* offset of start of buffer */
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35 char *buffer; /* input buffer */
36 size_t bufsize; /* buffer size */
37 size_t bytes; /* size of last read */
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38};
39
40/** @brief Initialize a hands-off reader
41 * @param path File to read
42 * @param h Reader to initialize
21237d05 43 * @return 0 on success, -1 on error
5e57438c 44 */
21237d05 45int hreader_init(const char *path, struct hreader *h);
5e57438c 46
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47/** @brief Close a hands-off reader
48 * @param h Reader to close
49 */
50void hreader_close(struct hreader *h);
51
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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
57 */
58int hreader_read(struct hreader *h, void *buffer, size_t n);
59
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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
5e57438c 66 */
281d0fd4 67int hreader_pread(struct hreader *h, void *buffer, size_t n, off_t offset);
5e57438c 68
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69/** @brief Seek within a file
70 * @param h Reader to seek
71 * @param offset Offset
72 * @param whence SEEK_*
73 * @return Result offset
74 */
75off_t hreader_seek(struct hreader *h, off_t offset, int whence);
76
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77/** @brief Return file size
78 * @param h Reader to find size of
79 * @return Size in bytes
80 */
81static inline off_t hreader_size(const struct hreader *h) {
82 return h->size;
83}
84
85/** @brief Test for end of file
86 * @param h Reader to test
87 * @return 1 at eof, 0 otherwise
88 *
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
91 * feof().
92 */
93static inline int hreader_eof(const struct hreader *h) {
94 return h->read_offset == h->size;
95}
96
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97#endif /* HREADER_H */
98
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99/*
100Local Variables:
101c-basic-offset:2
102comment-column:40
103fill-column:79
104indent-tabs-mode:nil
105End:
106*/