1/* Filesystem parameter description and parser
2 *
3 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#ifndef _LINUX_FS_PARSER_H
13#define _LINUX_FS_PARSER_H
14
15#include <linux/fs_context.h>
16
17struct path;
18
19struct constant_table {
20 const char *name;
21 int value;
22};
23
24/*
25 * The type of parameter expected.
26 */
27enum fs_parameter_type {
28 __fs_param_wasnt_defined,
29 fs_param_is_flag,
30 fs_param_is_bool,
31 fs_param_is_u32,
32 fs_param_is_u32_octal,
33 fs_param_is_u32_hex,
34 fs_param_is_s32,
35 fs_param_is_u64,
36 fs_param_is_enum,
37 fs_param_is_string,
38 fs_param_is_blob,
39 fs_param_is_blockdev,
40 fs_param_is_path,
41 fs_param_is_fd,
42 nr__fs_parameter_type,
43};
44
45/*
46 * Specification of the type of value a parameter wants.
47 *
48 * Note that the fsparam_flag(), fsparam_string(), fsparam_u32(), ... macros
49 * should be used to generate elements of this type.
50 */
51struct fs_parameter_spec {
52 const char *name;
53 u8 opt; /* Option number (returned by fs_parse()) */
54 enum fs_parameter_type type:8; /* The desired parameter type */
55 unsigned short flags;
56#define fs_param_v_optional 0x0001 /* The value is optional */
57#define fs_param_neg_with_no 0x0002 /* "noxxx" is negative param */
58#define fs_param_neg_with_empty 0x0004 /* "xxx=" is negative param */
59#define fs_param_deprecated 0x0008 /* The param is deprecated */
60};
61
62struct fs_parameter_enum {
63 u8 opt; /* Option number (as fs_parameter_spec::opt) */
64 char name[14];
65 u8 value;
66};
67
68struct fs_parameter_description {
69 const char name[16]; /* Name for logging purposes */
70 const struct fs_parameter_spec *specs; /* List of param specifications */
71 const struct fs_parameter_enum *enums; /* Enum values */
72};
73
74/*
75 * Result of parse.
76 */
77struct fs_parse_result {
78 bool negated; /* T if param was "noxxx" */
79 bool has_value; /* T if value supplied to param */
80 union {
81 bool boolean; /* For spec_bool */
82 int int_32; /* For spec_s32/spec_enum */
83 unsigned int uint_32; /* For spec_u32{,_octal,_hex}/spec_enum */
84 u64 uint_64; /* For spec_u64 */
85 };
86};
87
88extern int fs_parse(struct fs_context *fc,
89 const struct fs_parameter_description *desc,
90 struct fs_parameter *value,
91 struct fs_parse_result *result);
92extern int fs_lookup_param(struct fs_context *fc,
93 struct fs_parameter *param,
94 bool want_bdev,
95 struct path *_path);
96
97extern int __lookup_constant(const struct constant_table tbl[], size_t tbl_size,
98 const char *name, int not_found);
99#define lookup_constant(t, n, nf) __lookup_constant(t, ARRAY_SIZE(t), (n), (nf))
100
101#ifdef CONFIG_VALIDATE_FS_PARSER
102extern bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
103 int low, int high, int special);
104extern bool fs_validate_description(const struct fs_parameter_description *desc);
105#else
106static inline bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
107 int low, int high, int special)
108{ return true; }
109static inline bool fs_validate_description(const struct fs_parameter_description *desc)
110{ return true; }
111#endif
112
113/*
114 * Parameter type, name, index and flags element constructors. Use as:
115 *
116 * fsparam_xxxx("foo", Opt_foo)
117 *
118 * If existing helpers are not enough, direct use of __fsparam() would
119 * work, but any such case is probably a sign that new helper is needed.
120 * Helpers will remain stable; low-level implementation may change.
121 */
122#define __fsparam(TYPE, NAME, OPT, FLAGS) \
123 { \
124 .name = NAME, \
125 .opt = OPT, \
126 .type = TYPE, \
127 .flags = FLAGS \
128 }
129
130#define fsparam_flag(NAME, OPT) __fsparam(fs_param_is_flag, NAME, OPT, 0)
131#define fsparam_flag_no(NAME, OPT) \
132 __fsparam(fs_param_is_flag, NAME, OPT, \
133 fs_param_neg_with_no)
134#define fsparam_bool(NAME, OPT) __fsparam(fs_param_is_bool, NAME, OPT, 0)
135#define fsparam_u32(NAME, OPT) __fsparam(fs_param_is_u32, NAME, OPT, 0)
136#define fsparam_u32oct(NAME, OPT) \
137 __fsparam(fs_param_is_u32_octal, NAME, OPT, 0)
138#define fsparam_u32hex(NAME, OPT) \
139 __fsparam(fs_param_is_u32_hex, NAME, OPT, 0)
140#define fsparam_s32(NAME, OPT) __fsparam(fs_param_is_s32, NAME, OPT, 0)
141#define fsparam_u64(NAME, OPT) __fsparam(fs_param_is_u64, NAME, OPT, 0)
142#define fsparam_enum(NAME, OPT) __fsparam(fs_param_is_enum, NAME, OPT, 0)
143#define fsparam_string(NAME, OPT) \
144 __fsparam(fs_param_is_string, NAME, OPT, 0)
145#define fsparam_blob(NAME, OPT) __fsparam(fs_param_is_blob, NAME, OPT, 0)
146#define fsparam_bdev(NAME, OPT) __fsparam(fs_param_is_blockdev, NAME, OPT, 0)
147#define fsparam_path(NAME, OPT) __fsparam(fs_param_is_path, NAME, OPT, 0)
148#define fsparam_fd(NAME, OPT) __fsparam(fs_param_is_fd, NAME, OPT, 0)
149
150
151#endif /* _LINUX_FS_PARSER_H */
152