1 #pragma once
2 
3 // This module implements a configuration parser. Clients can query the
4 // contents of a configuration file through the interface provided here.
5 // The current implementation is read-only; mutations are only kept in
6 // memory. This parser supports the INI file format.
7 
8 // Implementation notes:
9 // - Key/value pairs that are not within a section are assumed to be under
10 //   the |CONFIG_DEFAULT_SECTION| section.
11 // - Multiple sections with the same name will be merged as if they were in
12 //   a single section.
13 // - Empty sections with no key/value pairs will be treated as if they do
14 //   not exist. In other words, |config_has_section| will return false for
15 //   empty sections.
16 // - Duplicate keys in a section will overwrite previous values.
17 // - All strings are case sensitive.
18 
19 #include <stdbool.h>
20 
21 // The default section name to use if a key/value pair is not defined within
22 // a section.
23 #define CONFIG_DEFAULT_SECTION "Global"
24 
25 typedef struct config_t config_t;
26 typedef struct config_section_node_t config_section_node_t;
27 
28 // Creates a new config object with no entries (i.e. not backed by a file).
29 // This function returns a config object or NULL on error. Clients must call
30 // |config_free| on the returned handle when it is no longer required.
31 config_t *config_new_empty(void);
32 
33 // Loads the specified file and returns a handle to the config file. If there
34 // was a problem loading the file or allocating memory, this function returns
35 // NULL. Clients must call |config_free| on the returned handle when it is no
36 // longer required. |filename| must not be NULL and must point to a readable
37 // file on the filesystem.
38 config_t *config_new(const char *filename);
39 
40 // Frees resources associated with the config file. No further operations may
41 // be performed on the |config| object after calling this function. |config|
42 // may be NULL.
43 void config_free(config_t *config);
44 
45 // Returns true if the config file contains a section named |section|. If
46 // the section has no key/value pairs in it, this function will return false.
47 // |config| and |section| must not be NULL.
48 bool config_has_section(const config_t *config, const char *section);
49 
50 // Returns true if the config file has a key named |key| under |section|.
51 // Returns false otherwise. |config|, |section|, and |key| must not be NULL.
52 bool config_has_key(const config_t *config, const char *section, const char *key);
53 
54 // Returns the integral value for a given |key| in |section|. If |section|
55 // or |key| do not exist, or the value cannot be fully converted to an integer,
56 // this function returns |def_value|. |config|, |section|, and |key| must not
57 // be NULL.
58 int config_get_int(const config_t *config, const char *section, const char *key, int def_value);
59 
60 // Returns the boolean value for a given |key| in |section|. If |section|
61 // or |key| do not exist, or the value cannot be converted to a boolean, this
62 // function returns |def_value|. |config|, |section|, and |key| must not be NULL.
63 bool config_get_bool(const config_t *config, const char *section, const char *key, bool def_value);
64 
65 // Returns the string value for a given |key| in |section|. If |section| or
66 // |key| do not exist, this function returns |def_value|. The returned string
67 // is owned by the config module and must not be freed. |config|, |section|,
68 // and |key| must not be NULL. |def_value| may be NULL.
69 const char *config_get_string(const config_t *config, const char *section, const char *key, const char *def_value);
70 
71 // Sets an integral value for the |key| in |section|. If |key| or |section| do
72 // not already exist, this function creates them. |config|, |section|, and |key|
73 // must not be NULL.
74 void config_set_int(config_t *config, const char *section, const char *key, int value);
75 
76 // Sets a boolean value for the |key| in |section|. If |key| or |section| do
77 // not already exist, this function creates them. |config|, |section|, and |key|
78 // must not be NULL.
79 void config_set_bool(config_t *config, const char *section, const char *key, bool value);
80 
81 // Sets a string value for the |key| in |section|. If |key| or |section| do
82 // not already exist, this function creates them. |config|, |section|, |key|, and
83 // |value| must not be NULL.
84 void config_set_string(config_t *config, const char *section, const char *key, const char *value);
85 
86 // Removes |section| from the |config| (and, as a result, all keys in the section).
87 // Returns true if |section| was found and removed from |config|, false otherwise.
88 // Neither |config| nor |section| may be NULL.
89 bool config_remove_section(config_t *config, const char *section);
90 
91 // Removes one specific |key| residing in |section| of the |config|. Returns true
92 // if the section and key were found and the key was removed, false otherwise.
93 // None of |config|, |section|, or |key| may be NULL.
94 bool config_remove_key(config_t *config, const char *section, const char *key);
95 
96 // Returns an iterator to the first section in the config file. If there are no
97 // sections, the iterator will equal the return value of |config_section_end|.
98 // The returned pointer must be treated as an opaque handle and must not be freed.
99 // The iterator is invalidated on any config mutating operation. |config| may not
100 // be NULL.
101 const config_section_node_t *config_section_begin(const config_t *config);
102 
103 // Returns an iterator to one past the last section in the config file. It does not
104 // represent a valid section, but can be used to determine if all sections have been
105 // iterated over. The returned pointer must be treated as an opaque handle and must
106 // not be freed and must not be iterated on (must not call |config_section_next| on
107 // it). |config| may not be NULL.
108 const config_section_node_t *config_section_end(const config_t *config);
109 
110 // Moves |iter| to the next section. If there are no more sections, |iter| will
111 // equal the value of |config_section_end|. |iter| may not be NULL and must be
112 // a pointer returned by either |config_section_begin| or |config_section_next|.
113 const config_section_node_t *config_section_next(const config_section_node_t *iter);
114 
115 // Returns the name of the section referred to by |iter|. The returned pointer is
116 // owned by the config module and must not be freed by the caller. The pointer will
117 // remain valid until |config_free| is called. |iter| may not be NULL and must not
118 // equal the value returned by |config_section_end|.
119 const char *config_section_name(const config_section_node_t *iter);
120 
121 // Saves |config| to a file given by |filename|. Note that this could be a destructive
122 // operation: if |filename| already exists, it will be overwritten. The config
123 // module does not preserve comments or formatting so if a config file was opened
124 // with |config_new| and subsequently overwritten with |config_save|, all comments
125 // and special formatting in the original file will be lost. Neither |config| nor
126 // |filename| may be NULL.
127 bool config_save(const config_t *config, const char *filename);
128