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 /*
21 * The type of parameter expected.
22 */
23 enum fs_parameter_type {
24 __fs_param_wasnt_defined,
25 fs_param_is_flag,
26 fs_param_is_bool,
27 fs_param_is_u32,
28 fs_param_is_u32_octal,
29 fs_param_is_u32_hex,
30 fs_param_is_s32,
31 fs_param_is_u64,
32 fs_param_is_enum,
33 fs_param_is_string,
34 fs_param_is_blob,
35 fs_param_is_blockdev,
36 fs_param_is_path,
37 fs_param_is_fd,
38 nr__fs_parameter_type,
39 };
40
41 /*
42 * Specification of the type of value a parameter wants.
43 *
44 * Note that the fsparam_flag(), fsparam_string(), fsparam_u32(), ... macros
45 * should be used to generate elements of this type.
46 */
47 struct fs_parameter_spec {
48 const char *name;
49 u8 opt; /* Option number (returned by fs_parse()) */
50 enum fs_parameter_type type:8; /* The desired parameter type */
51 unsigned short flags;
52 #define fs_param_v_optional 0x0001 /* The value is optional */
53 #define fs_param_neg_with_no 0x0002 /* "noxxx" is negative param */
54 #define fs_param_neg_with_empty 0x0004 /* "xxx=" is negative param */
55 #define fs_param_deprecated 0x0008 /* The param is deprecated */
56 };
57
58 struct fs_parameter_enum {
59 u8 opt; /* Option number (as fs_parameter_spec::opt) */
60 char name[14];
61 u8 value;
62 };
63
64 struct fs_parameter_description {
65 const char name[16]; /* Name for logging purposes */
66 const struct fs_parameter_spec *specs; /* List of param specifications */
67 const struct fs_parameter_enum *enums; /* Enum values */
68 };
69
70 /*
71 * Result of parse.
72 */
73 struct fs_parse_result {
74 bool negated; /* T if param was "noxxx" */
75 bool has_value; /* T if value supplied to param */
76 union {
77 bool boolean; /* For spec_bool */
78 int int_32; /* For spec_s32/spec_enum */
79 unsigned int uint_32; /* For spec_u32{,_octal,_hex}/spec_enum */
80 u64 uint_64; /* For spec_u64 */
81 };
82 };
83
84 extern int fs_parse(struct fs_context *fc,
85 const struct fs_parameter_description *desc,
86 struct fs_parameter *value,
87 struct fs_parse_result *result);
88 extern int fs_lookup_param(struct fs_context *fc,
89 struct fs_parameter *param,
90 bool want_bdev,
91 struct path *_path);
92
93 extern int __lookup_constant(const struct constant_table tbl[], size_t tbl_size,
94 const char *name, int not_found);
95 #define lookup_constant(t, n, nf) __lookup_constant(t, ARRAY_SIZE(t), (n), (nf))
96
97 #ifdef CONFIG_VALIDATE_FS_PARSER
98 extern bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
99 int low, int high, int special);
100 extern bool fs_validate_description(const struct fs_parameter_description *desc);
101 #else
validate_constant_table(const struct constant_table * tbl,size_t tbl_size,int low,int high,int special)102 static inline bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
103 int low, int high, int special)
104 { return true; }
fs_validate_description(const struct fs_parameter_description * desc)105 static inline bool fs_validate_description(const struct fs_parameter_description *desc)
106 { return true; }
107 #endif
108
109 /*
110 * Parameter type, name, index and flags element constructors. Use as:
111 *
112 * fsparam_xxxx("foo", Opt_foo)
113 *
114 * If existing helpers are not enough, direct use of __fsparam() would
115 * work, but any such case is probably a sign that new helper is needed.
116 * Helpers will remain stable; low-level implementation may change.
117 */
118 #define __fsparam(TYPE, NAME, OPT, FLAGS) \
119 { \
120 .name = NAME, \
121 .opt = OPT, \
122 .type = TYPE, \
123 .flags = FLAGS \
124 }
125
126 #define fsparam_flag(NAME, OPT) __fsparam(fs_param_is_flag, NAME, OPT, 0)
127 #define fsparam_flag_no(NAME, OPT) \
128 __fsparam(fs_param_is_flag, NAME, OPT, \
129 fs_param_neg_with_no)
130 #define fsparam_bool(NAME, OPT) __fsparam(fs_param_is_bool, NAME, OPT, 0)
131 #define fsparam_u32(NAME, OPT) __fsparam(fs_param_is_u32, NAME, OPT, 0)
132 #define fsparam_u32oct(NAME, OPT) \
133 __fsparam(fs_param_is_u32_octal, NAME, OPT, 0)
134 #define fsparam_u32hex(NAME, OPT) \
135 __fsparam(fs_param_is_u32_hex, NAME, OPT, 0)
136 #define fsparam_s32(NAME, OPT) __fsparam(fs_param_is_s32, NAME, OPT, 0)
137 #define fsparam_u64(NAME, OPT) __fsparam(fs_param_is_u64, NAME, OPT, 0)
138 #define fsparam_enum(NAME, OPT) __fsparam(fs_param_is_enum, NAME, OPT, 0)
139 #define fsparam_string(NAME, OPT) \
140 __fsparam(fs_param_is_string, NAME, OPT, 0)
141 #define fsparam_blob(NAME, OPT) __fsparam(fs_param_is_blob, NAME, OPT, 0)
142 #define fsparam_bdev(NAME, OPT) __fsparam(fs_param_is_blockdev, NAME, OPT, 0)
143 #define fsparam_path(NAME, OPT) __fsparam(fs_param_is_path, NAME, OPT, 0)
144 #define fsparam_fd(NAME, OPT) __fsparam(fs_param_is_fd, NAME, OPT, 0)
145
146
147 #endif /* _LINUX_FS_PARSER_H */
148
