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@suse.com>
---
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)
---
9pfront.c | 320 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 318 insertions(+), 2 deletions(-)
diff --git a/9pfront.c b/9pfront.c
index 0b8d5461..b4c54535 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 +549,166 @@ 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;
+ }
+
+ return true;
+}
+
static int connect_9pfs(struct dev_9pfs *dev)
{
int ret;
@@ -504,10 +727,101 @@ 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 +866,7 @@ 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 +1068,7 @@ void shutdown_9pfront(void *dev)
static const struct file_ops ops_9pfs = {
.name = "9pfs",
+ .close = close_9pfs,
};
__attribute__((constructor))
--
2.35.3Juergen Gross, le ven. 10 févr. 2023 11:46:27 +0100, a ecrit:
> +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;
> + }
> +
> + return true;
> +}
This doesn't seem to be catching "//"?
Samuel
On 10.02.23 19:53, Samuel Thibault wrote:
> Juergen Gross, le ven. 10 févr. 2023 11:46:27 +0100, a ecrit:
>> +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;
>> + }
>> +
>> + return true;
>> +}
>
> This doesn't seem to be catching "//"?
Oh, silly me!
Juergen
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