1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Filesystem parameter description and parser
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #ifndef _LINUX_FS_PARSER_H
9 #define _LINUX_FS_PARSER_H
10
11 #include <linux/fs_context.h>
12
13 struct path;
14
15 struct constant_table {
16 const char *name;
17 int value;
18 };
19
20 struct fs_parameter_spec;
21 struct fs_parse_result;
22 typedef int fs_param_type(struct p_log *,
23 const struct fs_parameter_spec *,
24 struct fs_parameter *,
25 struct fs_parse_result *);
26 /*
27 * The type of parameter expected.
28 */
29 fs_param_type fs_param_is_bool, fs_param_is_u32, fs_param_is_s32, fs_param_is_u64,
30 fs_param_is_enum, fs_param_is_string, fs_param_is_blob, fs_param_is_blockdev,
31 fs_param_is_path, fs_param_is_fd;
32
33 /*
34 * Specification of the type of value a parameter wants.
35 *
36 * Note that the fsparam_flag(), fsparam_string(), fsparam_u32(), ... macros
37 * should be used to generate elements of this type.
38 */
39 struct fs_parameter_spec {
40 const char *name;
41 fs_param_type *type; /* The desired parameter type */
42 u8 opt; /* Option number (returned by fs_parse()) */
43 unsigned short flags;
44 #define fs_param_neg_with_no 0x0002 /* "noxxx" is negative param */
45 #define fs_param_can_be_empty 0x0004 /* "xxx=" is allowed */
46 #define fs_param_deprecated 0x0008 /* The param is deprecated */
47 const void *data;
48 };
49
50 /*
51 * Result of parse.
52 */
53 struct fs_parse_result {
54 bool negated; /* T if param was "noxxx" */
55 union {
56 bool boolean; /* For spec_bool */
57 int int_32; /* For spec_s32/spec_enum */
58 unsigned int uint_32; /* For spec_u32{,_octal,_hex}/spec_enum */
59 u64 uint_64; /* For spec_u64 */
60 };
61 };
62
63 extern int __fs_parse(struct p_log *log,
64 const struct fs_parameter_spec *desc,
65 struct fs_parameter *value,
66 struct fs_parse_result *result);
67
fs_parse(struct fs_context * fc,const struct fs_parameter_spec * desc,struct fs_parameter * param,struct fs_parse_result * result)68 static inline int fs_parse(struct fs_context *fc,
69 const struct fs_parameter_spec *desc,
70 struct fs_parameter *param,
71 struct fs_parse_result *result)
72 {
73 return __fs_parse(&fc->log, desc, param, result);
74 }
75
76 extern int fs_lookup_param(struct fs_context *fc,
77 struct fs_parameter *param,
78 bool want_bdev,
79 unsigned int flags,
80 struct path *_path);
81
82 extern int lookup_constant(const struct constant_table tbl[], const char *name, int not_found);
83
84 #ifdef CONFIG_VALIDATE_FS_PARSER
85 extern bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
86 int low, int high, int special);
87 extern bool fs_validate_description(const char *name,
88 const struct fs_parameter_spec *desc);
89 #else
validate_constant_table(const struct constant_table * tbl,size_t tbl_size,int low,int high,int special)90 static inline bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
91 int low, int high, int special)
92 { return true; }
fs_validate_description(const char * name,const struct fs_parameter_spec * desc)93 static inline bool fs_validate_description(const char *name,
94 const struct fs_parameter_spec *desc)
95 { return true; }
96 #endif
97
98 /*
99 * Parameter type, name, index and flags element constructors. Use as:
100 *
101 * fsparam_xxxx("foo", Opt_foo)
102 *
103 * If existing helpers are not enough, direct use of __fsparam() would
104 * work, but any such case is probably a sign that new helper is needed.
105 * Helpers will remain stable; low-level implementation may change.
106 */
107 #define __fsparam(TYPE, NAME, OPT, FLAGS, DATA) \
108 { \
109 .name = NAME, \
110 .opt = OPT, \
111 .type = TYPE, \
112 .flags = FLAGS, \
113 .data = DATA \
114 }
115
116 #define fsparam_flag(NAME, OPT) __fsparam(NULL, NAME, OPT, 0, NULL)
117 #define fsparam_flag_no(NAME, OPT) \
118 __fsparam(NULL, NAME, OPT, fs_param_neg_with_no, NULL)
119 #define fsparam_bool(NAME, OPT) __fsparam(fs_param_is_bool, NAME, OPT, 0, NULL)
120 #define fsparam_u32(NAME, OPT) __fsparam(fs_param_is_u32, NAME, OPT, 0, NULL)
121 #define fsparam_u32oct(NAME, OPT) \
122 __fsparam(fs_param_is_u32, NAME, OPT, 0, (void *)8)
123 #define fsparam_u32hex(NAME, OPT) \
124 __fsparam(fs_param_is_u32_hex, NAME, OPT, 0, (void *)16)
125 #define fsparam_s32(NAME, OPT) __fsparam(fs_param_is_s32, NAME, OPT, 0, NULL)
126 #define fsparam_u64(NAME, OPT) __fsparam(fs_param_is_u64, NAME, OPT, 0, NULL)
127 #define fsparam_enum(NAME, OPT, array) __fsparam(fs_param_is_enum, NAME, OPT, 0, array)
128 #define fsparam_string(NAME, OPT) \
129 __fsparam(fs_param_is_string, NAME, OPT, 0, NULL)
130 #define fsparam_blob(NAME, OPT) __fsparam(fs_param_is_blob, NAME, OPT, 0, NULL)
131 #define fsparam_bdev(NAME, OPT) __fsparam(fs_param_is_blockdev, NAME, OPT, 0, NULL)
132 #define fsparam_path(NAME, OPT) __fsparam(fs_param_is_path, NAME, OPT, 0, NULL)
133 #define fsparam_fd(NAME, OPT) __fsparam(fs_param_is_fd, NAME, OPT, 0, NULL)
134
135 #endif /* _LINUX_FS_PARSER_H */
136