PLUMB(3) PLUMB(3)
NAME
eplumb, plumbfree, plumbopen, plumbunmount, plumbopenfid,
plumbsend, plumbsendtofid, plumbsendtext, plumblookup,
plumbpack, plumbpackattr, plumbaddattr, plumbdelattr,
plumbrecv, plumbrecvfid, plumbunpack, plumbunpackpartial,
plumbunpackattr, Plumbmsg - plumb messages
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <plumb.h>
int plumbopen(char *port, int omode)
int plumbunmount(void)
int plumbsend(int fd, Plumbmsg *m)
int plumbsendtext(int fd, char *src, char *dst, char
*wdir, char *data)
void plumbfree(Plumbmsg *m)
Plumbmsg* plumbrecv(int fd)
char* plumbpack(Plumbmsg *m, int *np)
Plumbmsg* plumbunpack(char *buf, int n)
Plumbmsg* plumbunpackpartial(char *buf, int n, int *morep)
char* plumbpackattr(Plumbattr *a)
Plumbattr* plumbunpackattr(char *a)
char* plumblookup(Plumbattr *a, char *name)
Plumbattr* plumbaddattr(Plumbattr *a, Plumbattr *new)
Plumbattr* plumbdelattr(Plumbattra *a, char *name)
int eplumb(int key, char *port)
#include <9pclient.h>
CFid *plumbopenfid(char *port, int omode)
Plumbmsg* plumbrecvfid(CFid *fid)
int plumbsendtofid(CFid *fid, Plumbmsg *m)
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PLUMB(3) PLUMB(3)
DESCRIPTION
These routines manipulate plumb(7) messages, transmitting
them, receiving them, and converting them between text and
these data structures:
typedef
struct Plumbmsg
{
char *src;
char *dst;
char *wdir;
char *type;
Plumbattr *attr;
int ndata;
char *data;
} Plumbmsg;
typedef
struct Plumbattr
{
char *name;
char *value;
Plumbattr *next;
} Plumbattr;
Plumbopen opens the named plumb port, using open(3) mode
omode. If port begins with a slash, it is taken as a literal
file name; otherwise plumbopen searches for the location of
the plumber(4) service and opens the port there.
For programs using the event(3) interface, eplumb registers,
using the given key, receipt of messages from the named
port.
The library mounts the plumber(4) service on demand (using
the 9pclient(3)) library and reuses the mount instance for
future calls to plumbopen. Plumbunmount causes the library
to discard its cached mount. This can be useful if the
plumber service itself has been restarted and a client
wishes to reconnect.
Plumbsend formats and writes message m to the file descrip-
tor fd, which will usually be the result of
plumbopen("send", OWRITE). Plumbsendtext is a simplified
version for text-only messages; it assumes type is text,
sets attr to nil, and sets ndata to strlen(data).
Plumbfree frees all the data associated with the message m,
all the components of which must therefore have been allo-
cated with malloc(3).
Plumbrecv returns the next message available on the file
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PLUMB(3) PLUMB(3)
descriptor fd, or nil for error.
Plumbpack encodes message m as a character string in the
format of plumb(7), setting *np to the length in bytes of
the string. Plumbunpack does the inverse, translating the n
bytes of buf into a Plumbmsg.
Plumbunpackpartial enables unpacking of messages that arrive
in pieces. The first call to plumbunpackpartial for a given
message must be sufficient to unpack the header; subsequent
calls permit unpacking messages with long data sections.
For each call, buf points to the beginning of the complete
message received so far, and n reports the total number of
bytes received for that message. If the message is com-
plete, the return value will be as in plumbunpack. If not,
and morep is not null, the return value will be nil and
*morep will be set to the number of bytes remaining to be
read for this message to be complete (recall that the byte
count is in the header). Those bytes should be read by the
caller, placed at location buf+n, and the message unpacked
again. If an error is encountered, the return value will be
nil and *morep will be zero.
Plumbpackattr converts the list a of Plumbattr structures
into a null-terminated string. If an attribute value con-
tains white space, quote characters, or equal signs, the
value will be quoted appropriately. A newline character
will terminate processing. Plumbunpackattr converts the
null-terminated string a back into a list of Plumbattr
structures.
Plumblookup searches the Plumbattr list a for an attribute
with the given name and returns the associated value. The
returned string is the original value, not a copy. If the
attribute has no value, the returned value will be the empty
string; if the attribute does not occur in the list at all,
the value will be nil.
Plumbaddattr appends the new Plumbattr (which may be a list)
to the attribute list a and returns the new list. Plumbattr
searches the list a for the first attribute with name name
and deletes it from the list, returning the resulting list.
Plumbdelattr is a no-op if no such attribute exists.
The file descriptor returned by plumbopen is created with
fsopenfd (see 9pclient(3)), which masks information about
read and write errors. This is acceptable for use in
plumbrecv but not for plumbsend, which depends on seeing
details of write errors. Plumbopenfid, plumbrecvfid, and
plumbsendtofid provide an explicit interface to lib9pclient
that preserves the exact error details.
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PLUMB(3) PLUMB(3)
SOURCE
/usr/local/plan9/src/libplumb
SEE ALSO
plumb(1), event(3), plumber(4), plumb(7)
DIAGNOSTICS
When appropriate, including when a plumbsend fails, these
routine set errstr.
BUGS
To avoid rewriting clients that use plumbsend, the call
plumbopen("send", OWRITE) returns a useless file descriptor
(it is opened to /dev/null). Plumbsend looks for this par-
ticular file descriptor and uses a static copy of the CFid
instead.
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