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NAME
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CFid, CFsys, fsinit, fsmount, fsroot, fssetroot, fsunmount, nsinit,
nsmount, fsversion, fsauth, fsattach, fsclose, fscreate, fsfcreate,
fsremove, fsfremove, fsaccess, fsdirread, fsdirreadall, fsdirstat,
fsdirfstat, fsdirwstat, fsdirfwstat, fsopen, fsfopen, nsopen,
fsopenfd, fspread, fspwrite, fsread, fsreadn, fsseek, fswrite,
fsprint, fsvprint – 9P client library
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SYNOPSIS
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#include <u.h>
#include <libc.h>
#include <fcall.h>
#include <thread.h>
#include <9pclient.h>
CFsys* fsmount(int fd, char *aname)
CFsys* nsmount(char *name, char *aname)
CFid* fsroot(CFsys *fsys)
void fsunmount(CFsys *fsys)
CFsys* fsinit(int fd)
CFsys* nsinit(char *name)
int fsversion(CFsys *fsys, int msize, char *version, int nversion)
CFid* fsauth(CFsys *fsys, char *uname, char *aname)
CFid* fsattach(CFsys *fsys, CFid *afid, char *uname, char *aname)
void fssetroot(CFsys *fsys, CFid *fid)
void fsclose(CFid *fid)
CFid* fscreate(CFsys *fs, char *path, int mode, ulong perm)
int fsfcreate(CFid *fid, char *path, int mode, ulong perm)
int fsremove(CFSys *fs, char *path)
int fsfremove(CFid *fid)
int fsaccess(CFsys *fs, char *path, int amode)
CFid* fsopen(CFsys *fs, char *path, int mode)
int fsfopen(CFid *fid, char *path, int mode)
long fspread(CFid *fid, void *buf, long n, vlong offset)
long fspwrite(CFid *fid, void *buf, long n, vlong offset)
long fsread(CFid *fid, void *buf, long n)
long fsreadn(CFid *fid, void *buf, long n)
long fswrite(CFid *fid, void *buf, long n)
int fsprint(CFid *fid, char *fmt, ...)
int fsvprint(CFid *fid, char *fmt, ...)
vlong fsseek(CFid *Fid, vlong n, int type)
Qid fsqid(CFid *fid)
long fsdirread(CFid *fid, Dir **d)
long fsdirreadall(CFid *fid, Dir **d)
Dir* fsdirstat(CFsys *fs, char *path)
Dir* fsdirfstat(CFid *fid)
int fsdirwstat(CFsys *fs, char *path, Dir *d)
int fsdirfwstat(CFid *fid, Dir *d)
int fsopenfd(CFsys *fs, char *path, int mode)
CFsys* nsopen(char *name, char *aname, char *path, int mode)
extern int chatty9pclient;
extern int eofkill9pclient;
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DESCRIPTION
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The 9pclient library helps client programs interact with 9P servers.
A CFsys* represents a connection to a 9P server. A CFid* represents
an active fid on some connection; see intro(9p).
A new connection to a 9P server is typically established by fsmount
or nsmount. Fsmount initializes a new 9P conversation on the open
file descriptor fd; nsmount connects to a service named name in
the current name space directory (see intro(4)). Both attach to
the root of the file system using the attach name aname. Fsroot
returns the CFid*
corresponding to this root.
Fsinit, nsinit, fsversion, fsauth, fsattach, and fssetroot provide
more detailed control over the file system connection than fsmount
and nsmount. Fsinit allocates a new CFsys* corresponding to a
9P conversation on the file descriptor fd and then calls fsversion
to initialize the connection. Nsinit does the same for name space
services. Fsversion
executes a version(9p) transaction to establish maximum message
size and 9P version. Fsauth executes an auth(9p) transaction,
returning the new auth fid. (Fsread and fswrite can then be used
to run the authentication protocol over the fid.) Fsattach executes
an attach(9p) transaction to connect to the root of a file tree
served by the server. It
presents afid (which may be nil) to establish identity. Fssetroot
sets the root fid used by fsopen, fsopenfd, fsdirstat, and fsdirwstat,
which evaluate rooted path names.
When a fid is no longer needed, it should be clunked by calling
fsclose and then considered freed. Similarly, when the connection
to the server is no longer needed, it should be closed by calling
fsunmount, which will take care of calling fsclose on the current
root fid. Once all fids have been clunked and the connection has
been closed (the order is not
important), the allocated structures will be freed and the file
descriptor corresponding to the connection will be closed (see
close(2)). Fids are not reference counted: when fsclose is called,
the clunk transaction and freeing of storage happen immediately.
Despite its name, fsclose can be used to clunk fids that are not
open for I/O.
Fscreate and fsopen establish new fids using the walk, create
and open transactions (see walk(9p) and open(9p)). The path argument
is evaluated relative to the CFsys root (see fsroot and fssetroot
above). The path is parsed as a slash-separated sequence of path
elements, as on Unix and Plan 9. Elements that are empty or dot
(.) are ignored.
Alternately, fswalk walks from a fid to a given name to create
a new fid. The name may be nil, corresponding to a walk with no
names. Otherwise the name is taken as a slash-separated sequence
of path elements. Fsfcreate and fsfopen issue create and open
transactions using the passed fid argument, which should have
been obtained by calling
fswalk.
Once opened, fids can be read and written using fspread and fspwrite,
which execute read and write transactions (see read(9p)). The
library maintains an offset for each fid, analagous to the offset
maintained by the kernel for each open file descriptor. Fsread
and fswrite read and write from this offset, and update it after
successful calls. Fsseek sets
the offset; the n and type arguments are used as in seek(3). Calling
fspread or fspwrite with an offset of –1 is identical to calling
fsread or fswrite. Fsreadn calls fsread repeatedly to obtain exactly
n bytes of data, unless it encounters end-of-file or an error.
Attach, walk, create, and open transactions include in their replies
an updated qid for the fid being manipulated. Fsqid returns the
most recent qid returned by one of these transactions for the
given fid.
Fsaccess behaves like Unix’s access(2). Fsremove removes the named
path. Fsfremove removes the path corresponding to an open CFid*.
Reading an open a directory returns directory entries encoded
as described in stat(9p).
Fsprint and fsvprint are like fprint and vfprint (see print(3))
but write to CFid*s.
Fsdirread calls fsread and then parses the encoded entries into
an array of Dir* data structures, storing a pointer to the array
in *d and returning the number of entries. Fsdirreadall is similar
but reads the entire directory. The returned pointer should be
freed with free (see malloc(3)) when no longer needed.
Fsdirfstat and fsdirfwstat execute stat and wstat (see stat(9p))
transactions. The Dir structure returned by fsdirfstat should
be freed with free (see malloc(3)) when no longer needed.
Fsdirstat and fsdirwstat are similar to fsdirfstat and fsdirfwstat
but operate on paths relative to the file system root (see fsopen
and fscreate above).
Fsopenfd opens a file on the 9P server for reading or writing
but returns a Unix file descriptor instead of a fid structure.
The file descriptor is actually one end of a pipe(2). A proxy
process on the other end is ferrying data between the pipe and
the 9P fid. Because of the implementation as a pipe, the only
signal of a read or write error is the closing of the
pipe. The file descriptor remains valid even after the CFsys is
unmounted.
Nsopen opens a single file on a name space server: it runs nsmount,
fsopen, and then fsunmount.
If the chatty9pclient flag is set, the library prints all 9P messages
to standard error. If the eofkill9pclient flag is set, the library
calls threadexitsall (see thread(3)) when it detects EOF on a
9P connection.
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SOURCE
SEE ALSO
BUGS
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The implementation should use a special version string to distinguish
between servers that support openfd(9p) and servers that do not.
The interface does not provide access to the walk(9p) transaction,
or to open and create on already-established fids.
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