LXR linux/include/linux/fs

   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
  13struct path;
  14
  15struct constant_table {
  16        const char      *name;
  17        int             value;
  18};
  19
  20struct fs_parameter_spec;
  21struct fs_parse_result;
  22typedef 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 */
  29fs_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 */
  39struct 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 */
  53struct 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
  63extern 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
  68static 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
  76extern int fs_lookup_param(struct fs_context *fc,
  77                           struct fs_parameter *param,
  78                           bool want_bdev,
  79                           struct path *_path);
  80
  81extern int lookup_constant(const struct constant_table tbl[], const char *name, int not_found);
  82
  83#ifdef CONFIG_VALIDATE_FS_PARSER
  84extern bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
  85                                    int low, int high, int special);
  86extern bool fs_validate_description(const char *name,
  87                                    const struct fs_parameter_spec *desc);
  88#else
  89static inline bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
  90                                           int low, int high, int special)
  91{ return true; }
  92static 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 */
 135