qemu/hw/9pfs/9p.h

#ifndef QEMU_9P_H
#define QEMU_9P_H

#include <dirent.h>
#include <utime.h>
#include <sys/resource.h>
#include "fsdev/file-op-9p.h"
#include "fsdev/9p-iov-marshal.h"
#include "qemu/thread.h"
#include "qemu/coroutine.h"
#include "qemu/qht.h"

enum {
    P9_TLERROR = 6,
    P9_RLERROR,
    P9_TSTATFS = 8,
    P9_RSTATFS,
    P9_TLOPEN = 12,
    P9_RLOPEN,
    P9_TLCREATE = 14,
    P9_RLCREATE,
    P9_TSYMLINK = 16,
    P9_RSYMLINK,
    P9_TMKNOD = 18,
    P9_RMKNOD,
    P9_TRENAME = 20,
    P9_RRENAME,
    P9_TREADLINK = 22,
    P9_RREADLINK,
    P9_TGETATTR = 24,
    P9_RGETATTR,
    P9_TSETATTR = 26,
    P9_RSETATTR,
    P9_TXATTRWALK = 30,
    P9_RXATTRWALK,
    P9_TXATTRCREATE = 32,
    P9_RXATTRCREATE,
    P9_TREADDIR = 40,
    P9_RREADDIR,
    P9_TFSYNC = 50,
    P9_RFSYNC,
    P9_TLOCK = 52,
    P9_RLOCK,
    P9_TGETLOCK = 54,
    P9_RGETLOCK,
    P9_TLINK = 70,
    P9_RLINK,
    P9_TMKDIR = 72,
    P9_RMKDIR,
    P9_TRENAMEAT = 74,
    P9_RRENAMEAT,
    P9_TUNLINKAT = 76,
    P9_RUNLINKAT,
    P9_TVERSION = 100,
    P9_RVERSION,
    P9_TAUTH = 102,
    P9_RAUTH,
    P9_TATTACH = 104,
    P9_RATTACH,
    P9_TERROR = 106,
    P9_RERROR,
    P9_TFLUSH = 108,
    P9_RFLUSH,
    P9_TWALK = 110,
    P9_RWALK,
    P9_TOPEN = 112,
    P9_ROPEN,
    P9_TCREATE = 114,
    P9_RCREATE,
    P9_TREAD = 116,
    P9_RREAD,
    P9_TWRITE = 118,
    P9_RWRITE,
    P9_TCLUNK = 120,
    P9_RCLUNK,
    P9_TREMOVE = 122,
    P9_RREMOVE,
    P9_TSTAT = 124,
    P9_RSTAT,
    P9_TWSTAT = 126,
    P9_RWSTAT,
};


/* qid.types */
enum {
    P9_QTDIR = 0x80,
    P9_QTAPPEND = 0x40,
    P9_QTEXCL = 0x20,
    P9_QTMOUNT = 0x10,
    P9_QTAUTH = 0x08,
    P9_QTTMP = 0x04,
    P9_QTSYMLINK = 0x02,
    P9_QTLINK = 0x01,
    P9_QTFILE = 0x00,
};

typedef enum P9ProtoVersion {
    V9FS_PROTO_2000U = 0x01,
    V9FS_PROTO_2000L = 0x02,
} P9ProtoVersion;

/**
 * @brief Minimum message size supported by this 9pfs server.
 *
 * A client establishes a session by sending a Tversion request along with a
 * 'msize' parameter which suggests the server a maximum message size ever to be
 * used for communication (for both requests and replies) between client and
 * server during that session. If client suggests a 'msize' smaller than this
 * value then session is denied by server with an error response.
 */
#define P9_MIN_MSIZE    4096

#define P9_NOTAG    UINT16_MAX
#define P9_NOFID    UINT32_MAX
#define P9_MAXWELEM 16

#define FID_REFERENCED          0x1
#define FID_NON_RECLAIMABLE     0x2
static inline char *rpath(FsContext *ctx, const char *path)
{
    return g_strdup_printf("%s/%s", ctx->fs_root, path);
}

/*
 * ample room for Twrite/Rread header
 * size[4] Tread/Twrite tag[2] fid[4] offset[8] count[4]
 */
#define P9_IOHDRSZ 24

typedef struct V9fsPDU V9fsPDU;
typedef struct V9fsState V9fsState;
typedef struct V9fsTransport V9fsTransport;

typedef struct {
    uint32_t size_le;
    uint8_t id;
    uint16_t tag_le;
} QEMU_PACKED P9MsgHeader;
/* According to the specification, 9p messages start with a 7-byte header.
 * Since most of the code uses this header size in literal form, we must be
 * sure this is indeed the case.
 */
QEMU_BUILD_BUG_ON(sizeof(P9MsgHeader) != 7);

struct V9fsPDU {
    uint32_t size;
    uint16_t tag;
    uint8_t id;
    uint8_t cancelled;
    CoQueue complete;
    V9fsState *s;
    QLIST_ENTRY(V9fsPDU) next;
    uint32_t idx;
};


/* FIXME
 * 1) change user needs to set groups and stuff
 */

#define MAX_REQ         128
#define MAX_TAG_LEN     32

#define BUG_ON(cond) assert(!(cond))

typedef struct V9fsFidState V9fsFidState;

enum {
    P9_FID_NONE = 0,
    P9_FID_FILE,
    P9_FID_DIR,
    P9_FID_XATTR,
};

typedef struct V9fsConf
{
    /* tag name for the device */
    char *tag;
    char *fsdev_id;
} V9fsConf;

/* 9p2000.L xattr flags (matches Linux values) */
#define P9_XATTR_CREATE 1
#define P9_XATTR_REPLACE 2

typedef struct V9fsXattr
{
    uint64_t copied_len;
    uint64_t len;
    void *value;
    V9fsString name;
    int flags;
    bool xattrwalk_fid;
} V9fsXattr;

typedef struct V9fsDir {
    DIR *stream;
    P9ProtoVersion proto_version;
    /* readdir mutex type used for 9P2000.u protocol variant */
    CoMutex readdir_mutex_u;
    /* readdir mutex type used for 9P2000.L protocol variant */
    QemuMutex readdir_mutex_L;
} V9fsDir;

static inline void v9fs_readdir_lock(V9fsDir *dir)
{
    if (dir->proto_version == V9FS_PROTO_2000U) {
        qemu_co_mutex_lock(&dir->readdir_mutex_u);
    } else {
        qemu_mutex_lock(&dir->readdir_mutex_L);
    }
}

static inline void v9fs_readdir_unlock(V9fsDir *dir)
{
    if (dir->proto_version == V9FS_PROTO_2000U) {
        qemu_co_mutex_unlock(&dir->readdir_mutex_u);
    } else {
        qemu_mutex_unlock(&dir->readdir_mutex_L);
    }
}

static inline void v9fs_readdir_init(P9ProtoVersion proto_version, V9fsDir *dir)
{
    dir->proto_version = proto_version;
    if (proto_version == V9FS_PROTO_2000U) {
        qemu_co_mutex_init(&dir->readdir_mutex_u);
    } else {
        qemu_mutex_init(&dir->readdir_mutex_L);
    }
}

/**
 * Type for 9p fs drivers' (a.k.a. 9p backends) result of readdir requests,
 * which is a chained list of directory entries.
 */
typedef struct V9fsDirEnt {
    /* mandatory (must not be NULL) information for all readdir requests */
    struct dirent *dent;
    /*
     * optional (may be NULL): A full stat of each directory entry is just
     * done if explicitly told to fs driver.
     */
    struct stat *st;
    /*
     * instead of an array, directory entries are always returned as
     * chained list, that's because the amount of entries retrieved by fs
     * drivers is dependent on the individual entries' name (since response
     * messages are size limited), so the final amount cannot be estimated
     * before hand
     */
    struct V9fsDirEnt *next;
} V9fsDirEnt;

/*
 * Filled by fs driver on open and other
 * calls.
 */
union V9fsFidOpenState {
    int fd;
    V9fsDir dir;
    V9fsXattr xattr;
    /*
     * private pointer for fs drivers, that
     * have its own internal representation of
     * open files.
     */
    void *private;
};

struct V9fsFidState {
    int fid_type;
    int32_t fid;
    V9fsPath path;
    V9fsFidOpenState fs;
    V9fsFidOpenState fs_reclaim;
    int flags;
    int open_flags;
    uid_t uid;
    int ref;
    bool clunked;
    QSIMPLEQ_ENTRY(V9fsFidState) next;
    QSLIST_ENTRY(V9fsFidState) reclaim_next;
};

typedef enum AffixType_t {
    AffixType_Prefix,
    AffixType_Suffix, /* A.k.a. postfix. */
} AffixType_t;

/**
 * @brief Unique affix of variable length.
 *
 * An affix is (currently) either a suffix or a prefix, which is either
 * going to be prepended (prefix) or appended (suffix) with some other
 * number for the goal to generate unique numbers. Accordingly the
 * suffixes (or prefixes) we generate @b must all have the mathematical
 * property of being suffix-free (or prefix-free in case of prefixes)
 * so that no matter what number we concatenate the affix with, that we
 * always reliably get unique numbers as result after concatenation.
 */
typedef struct VariLenAffix {
    AffixType_t type; /* Whether this affix is a suffix or a prefix. */
    uint64_t value; /* Actual numerical value of this affix. */
    /*
     * Lenght of the affix, that is how many (of the lowest) bits of @c value
     * must be used for appending/prepending this affix to its final resulting,
     * unique number.
     */
    int bits;
} VariLenAffix;

/* See qid_inode_prefix_hash_bits(). */
typedef struct {
    dev_t dev; /* FS device on host. */
    /*
     * How many (high) bits of the original inode number shall be used for
     * hashing.
     */
    int prefix_bits;
} QpdEntry;

/* QID path prefix entry, see stat_to_qid */
typedef struct {
    dev_t dev;
    uint16_t ino_prefix;
    uint32_t qp_affix_index;
    VariLenAffix qp_affix;
} QppEntry;

/* QID path full entry, as above */
typedef struct {
    dev_t dev;
    ino_t ino;
    uint64_t path;
} QpfEntry;

struct V9fsState {
    QLIST_HEAD(, V9fsPDU) free_list;
    QLIST_HEAD(, V9fsPDU) active_list;
    QSIMPLEQ_HEAD(, V9fsFidState) fid_list;
    FileOperations *ops;
    FsContext ctx;
    char *tag;
    P9ProtoVersion proto_version;
    int32_t msize;
    V9fsPDU pdus[MAX_REQ];
    const V9fsTransport *transport;
    /*
     * lock ensuring atomic path update
     * on rename.
     */
    CoRwlock rename_lock;
    int32_t root_fid;
    Error *migration_blocker;
    V9fsConf fsconf;
    struct stat root_st;
    dev_t dev_id;
    struct qht qpd_table;
    struct qht qpp_table;
    struct qht qpf_table;
    uint64_t qp_ndevices; /* Amount of entries in qpd_table. */
    uint16_t qp_affix_next;
    uint64_t qp_fullpath_next;
};

/* 9p2000.L open flags */
#define P9_DOTL_RDONLY        00000000
#define P9_DOTL_WRONLY        00000001
#define P9_DOTL_RDWR          00000002
#define P9_DOTL_NOACCESS      00000003
#define P9_DOTL_CREATE        00000100
#define P9_DOTL_EXCL          00000200
#define P9_DOTL_NOCTTY        00000400
#define P9_DOTL_TRUNC         00001000
#define P9_DOTL_APPEND        00002000
#define P9_DOTL_NONBLOCK      00004000
#define P9_DOTL_DSYNC         00010000
#define P9_DOTL_FASYNC        00020000
#define P9_DOTL_DIRECT        00040000
#define P9_DOTL_LARGEFILE     00100000
#define P9_DOTL_DIRECTORY     00200000
#define P9_DOTL_NOFOLLOW      00400000
#define P9_DOTL_NOATIME       01000000
#define P9_DOTL_CLOEXEC       02000000
#define P9_DOTL_SYNC          04000000

/* 9p2000.L at flags */
#define P9_DOTL_AT_REMOVEDIR         0x200

/* 9P2000.L lock type */
#define P9_LOCK_TYPE_RDLCK 0
#define P9_LOCK_TYPE_WRLCK 1
#define P9_LOCK_TYPE_UNLCK 2

#define P9_LOCK_SUCCESS 0
#define P9_LOCK_BLOCKED 1
#define P9_LOCK_ERROR 2
#define P9_LOCK_GRACE 3

#define P9_LOCK_FLAGS_BLOCK 1
#define P9_LOCK_FLAGS_RECLAIM 2

typedef struct V9fsFlock
{
    uint8_t type;
    uint32_t flags;
    uint64_t start; /* absolute offset */
    uint64_t length;
    uint32_t proc_id;
    V9fsString client_id;
} V9fsFlock;

typedef struct V9fsGetlock
{
    uint8_t type;
    uint64_t start; /* absolute offset */
    uint64_t length;
    uint32_t proc_id;
    V9fsString client_id;
} V9fsGetlock;

extern int open_fd_hw;
extern int total_open_fd;

static inline void v9fs_path_write_lock(V9fsState *s)
{
    if (s->ctx.export_flags & V9FS_PATHNAME_FSCONTEXT) {
        qemu_co_rwlock_wrlock(&s->rename_lock);
    }
}

static inline void v9fs_path_read_lock(V9fsState *s)
{
    if (s->ctx.export_flags & V9FS_PATHNAME_FSCONTEXT) {
        qemu_co_rwlock_rdlock(&s->rename_lock);
    }
}

static inline void v9fs_path_unlock(V9fsState *s)
{
    if (s->ctx.export_flags & V9FS_PATHNAME_FSCONTEXT) {
        qemu_co_rwlock_unlock(&s->rename_lock);
    }
}

static inline uint8_t v9fs_request_cancelled(V9fsPDU *pdu)
{
    return pdu->cancelled;
}

void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu);
void v9fs_path_init(V9fsPath *path);
void v9fs_path_free(V9fsPath *path);
void v9fs_path_sprintf(V9fsPath *path, const char *fmt, ...);
void v9fs_path_copy(V9fsPath *dst, const V9fsPath *src);
size_t v9fs_readdir_response_size(V9fsString *name);
int v9fs_name_to_path(V9fsState *s, V9fsPath *dirpath,
                      const char *name, V9fsPath *path);
int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t,
                               Error **errp);
void v9fs_device_unrealize_common(V9fsState *s);

V9fsPDU *pdu_alloc(V9fsState *s);
void pdu_free(V9fsPDU *pdu);
void pdu_submit(V9fsPDU *pdu, P9MsgHeader *hdr);
void v9fs_reset(V9fsState *s);

struct V9fsTransport {
    ssize_t     (*pdu_vmarshal)(V9fsPDU *pdu, size_t offset, const char *fmt,
                                va_list ap);
    ssize_t     (*pdu_vunmarshal)(V9fsPDU *pdu, size_t offset, const char *fmt,
                                  va_list ap);
    void        (*init_in_iov_from_pdu)(V9fsPDU *pdu, struct iovec **piov,
                                        unsigned int *pniov, size_t size);
    void        (*init_out_iov_from_pdu)(V9fsPDU *pdu, struct iovec **piov,
                                         unsigned int *pniov, size_t size);
    void        (*push_and_notify)(V9fsPDU *pdu);
};

#if defined(XATTR_SIZE_MAX)
/* Linux */
#define P9_XATTR_SIZE_MAX XATTR_SIZE_MAX
#elif defined(CONFIG_DARWIN)
/*
 * Darwin doesn't seem to define a maximum xattr size in its user
 * space header, so manually configure it across platforms as 64k.
 *
 * Having no limit at all can lead to QEMU crashing during large g_malloc()
 * calls. Because QEMU does not currently support macOS guests, the below
 * preliminary solution only works due to its being a reflection of the limit of
 * Linux guests.
 */
#define P9_XATTR_SIZE_MAX 65536
#else
#error Missing definition for P9_XATTR_SIZE_MAX for this host system
#endif

#endif