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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3 6/7] Mini-OS: add open and close handling to the 9pfs frontend
Juergen Gross, le lun. 13 févr. 2023 09:44:11 +0100, a ecrit:
> Add the open() and close() support to the 9pfs frontend. This requires
> to split the path name and to walk to the desired directory level.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
> ---
> V2:
> - check path to be canonical
> - avoid short read when walking the path
> - fix get_fid() (Samuel Thibault)
> - return EAGAIN if no free request got (Samuel Thibault)
> V3:
> - add check for "//" in path_canonical() (Samuel Thibault)
> ---
> 9pfront.c | 324 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 322 insertions(+), 2 deletions(-)
>
> diff --git a/9pfront.c b/9pfront.c
> index 0b8d5461..fb2e5669 100644
> --- a/9pfront.c
> +++ b/9pfront.c
> @@ -6,6 +6,7 @@
> #include <mini-os/os.h>
> #include <mini-os/lib.h>
> #include <mini-os/events.h>
> +#include <mini-os/fcntl.h>
> #include <mini-os/gnttab.h>
> #include <mini-os/semaphore.h>
> #include <mini-os/wait.h>
> @@ -52,13 +53,32 @@ struct dev_9pfs {
> struct wait_queue_head waitq;
> struct semaphore ring_out_sem;
> struct semaphore ring_in_sem;
> +
> + unsigned long long fid_mask; /* Bit mask for free fids. */
> +};
> +
> +struct file_9pfs {
> + uint32_t fid;
> + struct dev_9pfs *dev;
> + bool append;
> };
>
> #define DEFAULT_9PFS_RING_ORDER 4
>
> +/* P9 protocol commands (response is either cmd+1 or P9_CMD_ERROR). */
> #define P9_CMD_VERSION 100
> #define P9_CMD_ATTACH 104
> #define P9_CMD_ERROR 107
> +#define P9_CMD_WALK 110
> +#define P9_CMD_OPEN 112
> +#define P9_CMD_CREATE 114
> +#define P9_CMD_CLUNK 120
> +
> +/* P9 protocol open flags. */
> +#define P9_OREAD 0 /* read */
> +#define P9_OWRITE 1 /* write */
> +#define P9_ORDWR 2 /* read and write */
> +#define P9_OTRUNC 16 /* or'ed in, truncate file first */
>
> #define P9_QID_SIZE 13
>
> @@ -69,10 +89,27 @@ struct p9_header {
> } __attribute__((packed));
>
> #define P9_VERSION "9P2000.u"
> -#define P9_ROOT_FID ~0
> +#define P9_ROOT_FID 0
>
> static unsigned int ftype_9pfs;
>
> +static unsigned int get_fid(struct dev_9pfs *dev)
> +{
> + unsigned int fid;
> +
> + fid = ffs(dev->fid_mask);
> + if ( fid )
> + dev->fid_mask &= ~(1ULL << (fid - 1));
> +
> + return fid;
> +}
> +
> +static void put_fid(struct dev_9pfs *dev, unsigned int fid)
> +{
> + if ( fid )
> + dev->fid_mask |= 1ULL << (fid - 1);
> +}
> +
> static struct req *get_free_req(struct dev_9pfs *dev)
> {
> struct req *req;
> @@ -140,6 +177,9 @@ static void copy_from_ring(struct dev_9pfs *dev, void
> *data, unsigned int len)
> * send_9p() and rcv_9p() are using a special format string for specifying
> * the kind of data sent/expected. Each data item is represented by a single
> * character:
> + * b: 1 byte unsigned integer (uint8_t)
> + * Only valid for sending.
> + * u: 2 byte unsigned integer (uint16_t)
> * U: 4 byte unsigned integer (uint32_t)
> * S: String (2 byte length + <length> characters)
> * in the rcv_9p() case the data for string is allocated (length omitted,
> @@ -153,7 +193,9 @@ static void send_9p(struct dev_9pfs *dev, struct req
> *req, const char *fmt, ...)
> va_list ap, aq;
> const char *f;
> uint32_t intval;
> + uint16_t shortval;
> uint16_t len;
> + uint8_t byte;
> char *strval;
>
> hdr.size = sizeof(hdr);
> @@ -167,6 +209,14 @@ static void send_9p(struct dev_9pfs *dev, struct req
> *req, const char *fmt, ...)
> {
> switch ( *f )
> {
> + case 'b':
> + hdr.size += 1;
> + byte = va_arg(aq, unsigned int);
> + break;
> + case 'u':
> + hdr.size += 2;
> + shortval = va_arg(aq, unsigned int);
> + break;
> case 'U':
> hdr.size += 4;
> intval = va_arg(aq, unsigned int);
> @@ -196,6 +246,14 @@ static void send_9p(struct dev_9pfs *dev, struct req
> *req, const char *fmt, ...)
> {
> switch ( *f )
> {
> + case 'b':
> + byte = va_arg(ap, unsigned int);
> + copy_to_ring(dev, &byte, sizeof(byte));
> + break;
> + case 'u':
> + shortval = va_arg(ap, unsigned int);
> + copy_to_ring(dev, &shortval, sizeof(shortval));
> + break;
> case 'U':
> intval = va_arg(ap, unsigned int);
> copy_to_ring(dev, &intval, sizeof(intval));
> @@ -288,6 +346,7 @@ static void rcv_9p_copy(struct dev_9pfs *dev, struct req
> *req,
> char *str;
> uint16_t len;
> uint32_t err;
> + uint16_t *shortval;
> uint32_t *val;
> char **strval;
> uint8_t *qval;
> @@ -345,6 +404,10 @@ static void rcv_9p_copy(struct dev_9pfs *dev, struct req
> *req,
> {
> switch ( *f )
> {
> + case 'u':
> + shortval = va_arg(ap, uint16_t *);
> + copy_bufs(&buf1, &buf2, &len1, &len2, shortval,
> sizeof(*shortval));
> + break;
> case 'U':
> val = va_arg(ap, uint32_t *);
> copy_bufs(&buf1, &buf2, &len1, &len2, val, sizeof(*val));
> @@ -486,6 +549,170 @@ static int p9_attach(struct dev_9pfs *dev)
> return ret;
> }
>
> +static int p9_clunk(struct dev_9pfs *dev, uint32_t fid)
> +{
> + struct req *req = get_free_req(dev);
> + int ret;
> +
> + if ( !req )
> + return EAGAIN;
> +
> + req->cmd = P9_CMD_CLUNK;
> + send_9p(dev, req, "U", fid);
> + rcv_9p(dev, req, "");
> + ret = req->result;
> +
> + put_free_req(dev, req);
> +
> + return ret;
> +}
> +
> +static int p9_walk(struct dev_9pfs *dev, uint32_t fid, uint32_t newfid,
> + char *name)
> +{
> + struct req *req = get_free_req(dev);
> + int ret;
> + uint16_t nqid;
> + uint8_t qid[P9_QID_SIZE];
> +
> + if ( !req )
> + return EAGAIN;
> +
> + req->cmd = P9_CMD_WALK;
> + if ( name[0] )
> + {
> + send_9p(dev, req, "UUuS", fid, newfid, 1, name);
> + rcv_9p(dev, req, "uQ", &nqid, qid);
> + }
> + else
> + {
> + send_9p(dev, req, "UUu", fid, newfid, 0);
> + rcv_9p(dev, req, "u", &nqid);
> + }
> +
> + ret = req->result;
> +
> + put_free_req(dev, req);
> +
> + return ret;
> +}
> +
> +static int p9_open(struct dev_9pfs *dev, uint32_t fid, uint8_t omode)
> +{
> + struct req *req = get_free_req(dev);
> + int ret;
> + uint8_t qid[P9_QID_SIZE];
> + uint32_t iounit;
> +
> + if ( !req )
> + return EAGAIN;
> +
> + req->cmd = P9_CMD_OPEN;
> + send_9p(dev, req, "Ub", fid, omode);
> + rcv_9p(dev, req, "QU", qid, &iounit);
> +
> + ret = req->result;
> +
> + put_free_req(dev, req);
> +
> + return ret;
> +}
> +
> +static int p9_create(struct dev_9pfs *dev, uint32_t fid, char *path,
> + uint32_t mode, uint8_t omode)
> +{
> + struct req *req = get_free_req(dev);
> + int ret;
> + uint8_t qid[P9_QID_SIZE];
> + uint32_t iounit;
> +
> + if ( !req )
> + return EAGAIN;
> +
> + req->cmd = P9_CMD_CREATE;
> + send_9p(dev, req, "USUbS", fid, path, mode, omode, "");
> + rcv_9p(dev, req, "QU", qid, &iounit);
> +
> + ret = req->result;
> +
> + put_free_req(dev, req);
> +
> + return ret;
> +}
> +
> +/*
> + * Walk from root <steps> levels with the levels listed in <*paths> as a
> + * sequence of names. Returns the number of steps not having been able to
> + * walk, with <*paths> pointing at the name of the failing walk step.
> + * <fid> will be associated with the last successful walk step. Note that
> + * the first step should always succeed, as it is an empty walk in order
> + * to start at the root (needed for creating new files in root).
> + */
> +static unsigned int walk_9pfs(struct dev_9pfs *dev, uint32_t fid,
> + unsigned int steps, char **paths)
> +{
> + uint32_t curr_fid = P9_ROOT_FID;
> + int ret;
> +
> + while ( steps-- )
> + {
> + ret = p9_walk(dev, curr_fid, fid, *paths);
> + if ( ret )
> + return steps + 1;
> + curr_fid = fid;
> + *paths += strlen(*paths) + 1;
> + }
> +
> + return 0;
> +}
> +
> +static unsigned int split_path(const char *pathname, char **split_ptr)
> +{
> + unsigned int parts = 1;
> + char *p;
> +
> + *split_ptr = strdup(pathname);
> +
> + for ( p = strchr(*split_ptr, '/'); p; p = strchr(p + 1, '/') )
> + {
> + *p = 0;
> + parts++;
> + }
> +
> + return parts;
> +}
> +
> +static bool path_canonical(const char *pathname)
> +{
> + unsigned int len = strlen(pathname);
> + const char *c;
> +
> + /* Empty path is allowed. */
> + if ( !len )
> + return true;
> +
> + /* No trailing '/'. */
> + if ( pathname[len - 1] == '/' )
> + return false;
> +
> + /* No self or parent references. */
> + c = pathname;
> + while ( (c = strstr(c, "/.")) != NULL )
> + {
> + if ( c[2] == '.' )
> + c++;
> + if ( c[2] == 0 || c[2] == '/' )
> + return false;
> + c += 2;
> + }
> +
> + /* No "//". */
> + if ( strstr(pathname, "//") )
> + return false;
> +
> + return true;
> +}
> +
> static int connect_9pfs(struct dev_9pfs *dev)
> {
> int ret;
> @@ -504,10 +731,101 @@ static void intr_9pfs(evtchn_port_t port, struct
> pt_regs *regs, void *data)
> wake_up(&dev->waitq);
> }
>
> +static int close_9pfs(struct file *file)
> +{
> + struct file_9pfs *f9pfs = file->filedata;
> +
> + if ( f9pfs->fid != P9_ROOT_FID )
> + {
> + p9_clunk(f9pfs->dev, f9pfs->fid);
> + put_fid(f9pfs->dev, f9pfs->fid);
> + }
> +
> + free(f9pfs);
> +
> + return 0;
> +}
> +
> static int open_9pfs(struct mount_point *mnt, const char *pathname, int
> flags,
> mode_t mode)
> {
> - errno = ENOSYS;
> + int fd;
> + char *path = NULL;
> + char *p;
> + struct file *file;
> + struct file_9pfs *f9pfs;
> + uint16_t nwalk;
> + uint8_t omode;
> + int ret;
> +
> + if ( !path_canonical(pathname) )
> + return EINVAL;
> +
> + f9pfs = calloc(1, sizeof(*f9pfs));
> + f9pfs->dev = mnt->dev;
> + f9pfs->fid = P9_ROOT_FID;
> +
> + fd = alloc_fd(ftype_9pfs);
> + file = get_file_from_fd(fd);
> + file->filedata = f9pfs;
> +
> + switch ( flags & O_ACCMODE )
> + {
> + case O_RDONLY:
> + omode = P9_OREAD;
> + break;
> + case O_WRONLY:
> + omode = P9_OWRITE;
> + break;
> + case O_RDWR:
> + omode = P9_ORDWR;
> + break;
> + default:
> + ret = EINVAL;
> + goto err;
> + }
> +
> + if ( flags & O_TRUNC )
> + omode |= P9_OTRUNC;
> + f9pfs->append = flags & O_APPEND;
> +
> + nwalk = split_path(pathname, &path);
> +
> + f9pfs->fid = get_fid(mnt->dev);
> + if ( !f9pfs->fid )
> + {
> + ret = ENFILE;
> + goto err;
> + }
> + p = path;
> + nwalk = walk_9pfs(mnt->dev, f9pfs->fid, nwalk, &p);
> + if ( nwalk )
> + {
> + if ( nwalk > 1 || !(flags & O_CREAT) )
> + {
> + ret = ENOENT;
> + goto err;
> + }
> +
> + ret = p9_create(mnt->dev, f9pfs->fid, p, mode, omode);
> + if ( ret )
> + goto err;
> + goto out;
> + }
> +
> + ret = p9_open(mnt->dev, f9pfs->fid, omode);
> + if ( ret )
> + goto err;
> +
> + out:
> + free(path);
> +
> + return fd;
> +
> + err:
> + free(path);
> + close(fd);
> + errno = ret;
>
> return -1;
> }
> @@ -552,6 +870,7 @@ void *init_9pfront(unsigned int id, const char *mnt)
> init_waitqueue_head(&dev->waitq);
> init_SEMAPHORE(&dev->ring_out_sem, 1);
> init_SEMAPHORE(&dev->ring_in_sem, 1);
> + dev->fid_mask = ~0ULL;
>
> for ( i = 0; i < N_REQS; i++ )
> {
> @@ -753,6 +1072,7 @@ void shutdown_9pfront(void *dev)
>
> static const struct file_ops ops_9pfs = {
> .name = "9pfs",
> + .close = close_9pfs,
> };
>
> __attribute__((constructor))
> --
> 2.35.3
>
--
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.
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