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31bfa062 CF |
1 | /* |
2 | * Simple string buffer | |
3 | * | |
4 | * Copyright (C) 2017 Christian Franke | |
5 | * | |
6 | * This file is part of FRR. | |
7 | * | |
8 | * FRR is free software; you can redistribute it and/or modify it | |
9 | * under the terms of the GNU General Public License as published by the | |
10 | * Free Software Foundation; either version 2, or (at your option) any | |
11 | * later version. | |
12 | * | |
13 | * FRR is distributed in the hope that it will be useful, but | |
14 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with FRR; see the file COPYING. If not, write to the Free | |
20 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA | |
21 | * 02111-1307, USA. | |
22 | */ | |
23 | #ifndef SBUF_H | |
24 | #define SBUF_H | |
25 | ||
26 | /* | |
27 | * sbuf provides a simple string buffer. One application where this comes | |
28 | * in handy is the parsing of binary data: If there is an error in the parsing | |
29 | * process due to invalid input data, printing an error message explaining what | |
30 | * went wrong is definitely useful. However, just printing the actual error, | |
31 | * without any information about the previous parsing steps, is usually not very | |
32 | * helpful. | |
33 | * Using sbuf, the parser can log the whole parsing process into a buffer using | |
34 | * a printf like API. When an error ocurrs, all the information about previous | |
35 | * parsing steps is there in the log, without any need for backtracking, and can | |
36 | * be used to give a detailed and useful error description. | |
37 | * When parsing completes successfully without any error, the log can just be | |
38 | * discarded unless debugging is turned on, to not spam the log. | |
39 | * | |
40 | * For the described usecase, the code would look something like this: | |
41 | * | |
42 | * int sbuf_example(..., char **parser_log) | |
43 | * { | |
44 | * struct sbuf logbuf; | |
45 | * | |
46 | * sbuf_init(&logbuf, NULL, 0); | |
47 | * sbuf_push(&logbuf, 0, "Starting parser\n"); | |
48 | * | |
49 | * int rv = do_parse(&logbuf, ...); | |
50 | * | |
51 | * *parser_log = sbuf_buf(&logbuf); | |
52 | * | |
53 | * return 1; | |
54 | * } | |
55 | * | |
996c9314 LB |
56 | * In this case, sbuf_example uses a string buffer with undefined size, which |
57 | * will | |
58 | * be allocated on the heap by sbuf. The caller of sbuf_example is expected to | |
59 | * free | |
31bfa062 CF |
60 | * the string returned in parser_log. |
61 | */ | |
62 | ||
63 | struct sbuf { | |
64 | bool fixed; | |
65 | char *buf; | |
66 | size_t size; | |
67 | size_t pos; | |
68 | int indent; | |
69 | }; | |
70 | ||
71 | void sbuf_init(struct sbuf *dest, char *buf, size_t size); | |
72 | void sbuf_reset(struct sbuf *buf); | |
73 | const char *sbuf_buf(struct sbuf *buf); | |
74 | void sbuf_free(struct sbuf *buf); | |
75 | #include "lib/log.h" | |
76 | void sbuf_push(struct sbuf *buf, int indent, const char *format, ...) | |
77 | PRINTF_ATTRIBUTE(3, 4); | |
78 | ||
79 | #endif |