include/linux/fs_parser.h

   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 */