Schily's LIBRARY FUNCTIONS RMTGETCONN(3L)
NAME
rmtinit, rmtdebug, rmthostname, rmtfilename, rmtgetconn -
initiate a connection to a remote tape server
SYNOPSIS
cc [ flag ... ] file ... -lrmt -lsocket -lnsl [ library ...
]
#include <schily/librmt.h>
void rmtinit(errmsgn, eexit)
int (*errmsgn) (int, const char *, ...);
void (*eexit) (int);
int rmtdebug(dlevel)
int dlevel;
const char *rmtrmt(rmtname)
const char *rmtname;
const char *rmtrsh(rshname)
const char *rshname;
char *rmtfilename(name)
char *name;
char *rmthostname(hostname, hnsize, rmtspec)
char *hostname;
int hnsize;
char *rmtspec;
int rmtgetconn(host, trsize, excode)
char *host;
int trsize;
int excode;
DESCRIPTION
rmtinit()
Is an optional function that allows to set up a func-
tion for error printing and a function to be called to
exit the program. If rmtinit(3) is not called or any
of the function pointers is NULL, the appropriate
default function is used instead. The supplied error
printing function needs to implement the same interface
as errmsgno(3) and the supplied exit function needs to
implement the same interface as exit(3).
rmtdebug()
allows to set the debug level for the library code. The
default debug level is 0 and does not print debug mes-
sages.
Joerg Schilling Last change: 2020/09/04 1
Schily's LIBRARY FUNCTIONS RMTGETCONN(3L)
rmtrmt()
allows to set up a different default path to the remote
rmt server program. The default is otherwise /etc/rmt.
The RMT environment still overwrites the default set up
by rmtrmt(3).
rmtrsh()
allows to set up a different remote login program to
the remote rmt server program. The default is otherwise
to use rcmd(3). The RSH environment still overwrites
the default set up by rmtrsh(3).
rmtfilename()
is given a filename that may be either in remote file
syntax ( hostname:filename or user@hostname:filename )
or specified as a hierarchical file path. If the argu-
ment turns out to be in remote file syntax, a pointer
to the filename part is returned.
rmthostname()
This function copies the user/host part of rmtspec
which should be in remote file syntax. The first argu-
ment is a character array that should be large enough
to hold the user/host part of rmtspec. The second
argument is the size of the character array. The third
argument is a string in remote file syntax.
rmtgetconn()
This function establishes a connection to the remote
tape server process. The first parameter is the
usr/host part of a string in remote file syntax and
should be created via rmthostname(3). The second
parameter is the expected maximum transfer size. It is
used to set up kernel buffering via setsockopt(3) to
increase performance. The third parameter is an alter-
nate exit code to be used instead of the library
default if rmtgetconn(3) decides to call exit(3). This
allows commands like ufsdump to use the documented exit
codes for startup errors.
RETURNS
rmtdebug()
returns the old debug level.
rmtrmt()
returns the old default remote rmt server program path
or NULL in case that the default was not overwritten.
rmtrsh()
returns the old default rmt remote login program or
NULL in case that the default was not overwritten.
Joerg Schilling Last change: 2020/09/04 2
Schily's LIBRARY FUNCTIONS RMTGETCONN(3L)
rmtfilename()
returns the filename part of the argument string or
NULL in case the argument turns out to be not in remote
file syntax.
rmthostname()
returns a pointer to the first argument or NULL in case
the rmtspec argument turns out to be not in remote file
syntax.
rmtgetconn()
return a file descriptor which is suitable to be used
as first argument for functions like rmtopen(3) or
rmtwrite(3). If rmtgetconn(3) fails to set up a con-
nection, -1 is returned. If rmtgetconn(3) is unable to
find the port number for shell/tcp, the current uid has
no entry in the passwd file or the user name includes
illegal characters, exit() is called. If you do not
like rmtgetconn(3) to exit in this case, call
rmtinit(3) before and install a non exiting function as
exit(3) handler; rmtgetconn(3) then will return -2
after this function did return.
EXAMPLES
int remfd;
char *remfn;
char host[256];
int iosize = 10240; /* socket send/receive size to set up */
if ((remfn = rmtfilename(filename)) != NULL) {
rmthostname(host, sizeof (host), filename);
if ((remfd = rmtgetconn(host, iosize, 0)) < 0)
comerrno(EX_BAD, "Cannot get connection to '%s'.\n",
/* errno not valid !! */ host);
}
if (rmtopen(remfd, remfn, mode) < 0)
comerr("Cannot open '%s'.\n", remfn);
if (rmtread(remfd, buf, sizeof(buf) < 0)
comerr("Read error on '%s'.\n", remfn);
rmtclose(remfd);
ENVIRONMENT
RSH If the RSH environment is present, the remote connec-
tion will not be created via rcmd(3) but by calling the
program pointed to by RSH. Use e.g. RSH=/usr/bin/ssh
to create a secure shell connection.
Joerg Schilling Last change: 2020/09/04 3
Schily's LIBRARY FUNCTIONS RMTGETCONN(3L)
If the environment RSH is empty, then the default
rcmd(3) is used even in case rmtrsh(3) has been called.
RMT If the RMT environment is present, the remote tape
server will not be the program /etc/rmt but the program
pointed to by RMT.
If the environment RMT is empty, then the default
/etc/rmt is used even in case rmtrmt(3) has been
called.
Note that the remote tape server program name will be
ignored if you log in using an account that has been
created with a remote tape server program as login
shell.
SEE ALSO
rmt(1), rsh(1), ssh(1), rcmd(3), rmtinit(3), rmtdebug(3),
rmtrmt(3), rmtrsh(3), rmthostname(3), rmtfilename(3),
rmtgetconn(3), rmtopen(3), rmtioctl(3), rmtclose(3),
rmtread(3), rmtwrite(3), rmtseek(3), rmtxstatus(3),
rmtstatus(3), _mtg2rmtg(3), _rmtg2mtg(3), errmsgno(3)
DIAGNOSTICS
NOTES
BUGS
For now (late 2002), we know that the following programs are
broken and do not implement signal handling correctly:
rsh on SunOS-5.0...SunOS-5.9
ssh from ssh.com
ssh from openssh.org
Sun already did accept a bug report for rsh(1). Openssh.org
accepted a bug for their implementation of ssh(1).
If you use rmtgetconn(3) to create a remote connection via
an unfixed rsh(1) or ssh(1), be prepared that terminal gen-
erated signals may interrupt the remote connection.
AUTHOR
librmt has been written in 1990 by Joerg Schilling. In
1995, support for RMT VERSION 1 has been added. librmt is
still maintained by Joerg Schilling.
Joerg Schilling
D-13353 Berlin
Germany
Joerg Schilling Last change: 2020/09/04 4
Schily's LIBRARY FUNCTIONS RMTGETCONN(3L)
Mail bugs and suggestions to:
joerg@schily.net
Joerg Schilling Last change: 2020/09/04 5
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