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 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; } 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