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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 | */ | |
30 | struct hreader { | |
6ebc4527 | 31 | char *path; /* file to read */ |
21237d05 | 32 | off_t size; /* file size */ |
281d0fd4 RK |
33 | off_t read_offset; /* for next hreader_read() */ |
34 | off_t buf_offset; /* offset of start of buffer */ | |
5e57438c RK |
35 | char *buffer; /* input buffer */ |
36 | size_t bufsize; /* buffer size */ | |
37 | size_t bytes; /* size of last read */ | |
5e57438c RK |
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 | 45 | int hreader_init(const char *path, struct hreader *h); |
5e57438c | 46 | |
6ebc4527 RK |
47 | /** @brief Close a hands-off reader |
48 | * @param h Reader to close | |
49 | */ | |
50 | void hreader_close(struct hreader *h); | |
51 | ||
5e57438c RK |
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 | */ | |
58 | int hreader_read(struct hreader *h, void *buffer, size_t n); | |
59 | ||
281d0fd4 RK |
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 | 67 | int hreader_pread(struct hreader *h, void *buffer, size_t n, off_t offset); |
5e57438c | 68 | |
21237d05 RK |
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 | */ | |
75 | off_t hreader_seek(struct hreader *h, off_t offset, int whence); | |
76 | ||
d868c56e RK |
77 | /** @brief Return file size |
78 | * @param h Reader to find size of | |
79 | * @return Size in bytes | |
80 | */ | |
81 | static 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 | */ | |
93 | static 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 | ||
5e57438c RK |
99 | /* |
100 | Local Variables: | |
101 | c-basic-offset:2 | |
102 | comment-column:40 | |
103 | fill-column:79 | |
104 | indent-tabs-mode:nil | |
105 | End: | |
106 | */ |