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 17 struct path; 18 19 struct constant_table { 20 const char *name; 21 int value; 22 }; 23 24 /* 25 * The type of parameter expected. 26 */ 27 enum 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 */ 51 struct 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 62 struct fs_parameter_enum { 63 u8 opt; /* Option number (as fs_parameter_spec::opt) */ 64 char name[14]; 65 u8 value; 66 }; 67 68 struct 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 */ 77 struct 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 88 extern 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); 92 extern int fs_lookup_param(struct fs_context *fc, 93 struct fs_parameter *param, 94 bool want_bdev, 95 struct path *_path); 96 97 extern 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 102 extern bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size, 103 int low, int high, int special); 104 extern bool fs_validate_description(const struct fs_parameter_description *desc); 105 #else 106 static inline bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size, 107 int low, int high, int special) 108 { return true; } 109 static 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