/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Filesystem parameter description and parser
 *
 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#ifndef _LINUX_FS_PARSER_H
#define _LINUX_FS_PARSER_H

#include <linux/fs_context.h>

struct path;

struct constant_table {
        const char      *name;
        int             value;
};

struct fs_parameter_spec;
struct fs_parse_result;
typedef int fs_param_type(struct p_log *,
                          const struct fs_parameter_spec *,
                          struct fs_parameter *,
                          struct fs_parse_result *);
/*
 * The type of parameter expected.
 */
fs_param_type fs_param_is_bool, fs_param_is_u32, fs_param_is_s32, fs_param_is_u64,
        fs_param_is_enum, fs_param_is_string, fs_param_is_blob, fs_param_is_blockdev,
        fs_param_is_path, fs_param_is_fd, fs_param_is_uid, fs_param_is_gid,
        fs_param_is_file_or_string;

/*
 * Specification of the type of value a parameter wants.
 *
 * Note that the fsparam_flag(), fsparam_string(), fsparam_u32(), ... macros
 * should be used to generate elements of this type.
 */
struct fs_parameter_spec {
        const char              *name;
        fs_param_type           *type;  /* The desired parameter type */
        u8                      opt;    /* Option number (returned by fs_parse()) */
        unsigned short          flags;
#define fs_param_neg_with_no    0x0002  /* "noxxx" is negative param */
#define fs_param_can_be_empty   0x0004  /* "xxx=" is allowed */
#define fs_param_deprecated     0x0008  /* The param is deprecated */
        const void              *data;
};

/*
 * Result of parse.
 */
struct fs_parse_result {
        bool                    negated;        /* T if param was "noxxx" */
        union {
                bool            boolean;        /* For spec_bool */
                int             int_32;         /* For spec_s32/spec_enum */
                unsigned int    uint_32;        /* For spec_u32{,_octal,_hex}/spec_enum */
                u64             uint_64;        /* For spec_u64 */
                kuid_t          uid;
                kgid_t          gid;
        };
};

extern int __fs_parse(struct p_log *log,
                    const struct fs_parameter_spec *desc,
                    struct fs_parameter *value,
                    struct fs_parse_result *result);

static inline int fs_parse(struct fs_context *fc,
             const struct fs_parameter_spec *desc,
             struct fs_parameter *param,
             struct fs_parse_result *result)
{
        return __fs_parse(&fc->log, desc, param, result);
}

extern int fs_lookup_param(struct fs_context *fc,
                           struct fs_parameter *param,
                           bool want_bdev,
                           unsigned int flags,
                           struct path *_path);

extern int lookup_constant(const struct constant_table tbl[], const char *name, int not_found);

extern const struct constant_table bool_names[];

#ifdef CONFIG_VALIDATE_FS_PARSER
extern bool fs_validate_description(const char *name,
                                    const struct fs_parameter_spec *desc);
#else
static inline bool fs_validate_description(const char *name,
                                           const struct fs_parameter_spec *desc)
{ return true; }
#endif

/*
 * Parameter type, name, index and flags element constructors.  Use as:
 *
 *  fsparam_xxxx("foo", Opt_foo)
 *
 * If existing helpers are not enough, direct use of __fsparam() would
 * work, but any such case is probably a sign that new helper is needed.
 * Helpers will remain stable; low-level implementation may change.
 */
#define __fsparam(TYPE, NAME, OPT, FLAGS, DATA) \
        { \
                .name = NAME, \
                .opt = OPT, \
                .type = TYPE, \
                .flags = FLAGS, \
                .data = DATA \
        }

#define fsparam_flag(NAME, OPT) __fsparam(NULL, NAME, OPT, 0, NULL)
#define fsparam_flag_no(NAME, OPT) \
                        __fsparam(NULL, NAME, OPT, fs_param_neg_with_no, NULL)
#define fsparam_bool(NAME, OPT) __fsparam(fs_param_is_bool, NAME, OPT, 0, NULL)
#define fsparam_u32(NAME, OPT)  __fsparam(fs_param_is_u32, NAME, OPT, 0, NULL)
#define fsparam_u32oct(NAME, OPT) \
                        __fsparam(fs_param_is_u32, NAME, OPT, 0, (void *)8)
#define fsparam_u32hex(NAME, OPT) \
                        __fsparam(fs_param_is_u32, NAME, OPT, 0, (void *)16)
#define fsparam_s32(NAME, OPT)  __fsparam(fs_param_is_s32, NAME, OPT, 0, NULL)
#define fsparam_u64(NAME, OPT)  __fsparam(fs_param_is_u64, NAME, OPT, 0, NULL)
#define fsparam_enum(NAME, OPT, array)  __fsparam(fs_param_is_enum, NAME, OPT, 0, array)
#define fsparam_string(NAME, OPT) \
                                __fsparam(fs_param_is_string, NAME, OPT, 0, NULL)
#define fsparam_blob(NAME, OPT) __fsparam(fs_param_is_blob, NAME, OPT, 0, NULL)
#define fsparam_bdev(NAME, OPT) __fsparam(fs_param_is_blockdev, NAME, OPT, 0, NULL)
#define fsparam_path(NAME, OPT) __fsparam(fs_param_is_path, NAME, OPT, 0, NULL)
#define fsparam_fd(NAME, OPT)   __fsparam(fs_param_is_fd, NAME, OPT, 0, NULL)
#define fsparam_file_or_string(NAME, OPT) \
                                __fsparam(fs_param_is_file_or_string, NAME, OPT, 0, NULL)
#define fsparam_uid(NAME, OPT) __fsparam(fs_param_is_uid, NAME, OPT, 0, NULL)
#define fsparam_gid(NAME, OPT) __fsparam(fs_param_is_gid, NAME, OPT, 0, NULL)

/* String parameter that allows empty argument */
#define fsparam_string_empty(NAME, OPT) \
        __fsparam(fs_param_is_string, NAME, OPT, fs_param_can_be_empty, NULL)

#endif /* _LINUX_FS_PARSER_H */