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