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RMTGETCONN(3L) Schily's LIBRARY FUNCTIONS RMTGETCONN(3L)
NAME
rmtinit, rmtdebug, rmthostname, rmtfilename, rmtgetconn - initiate a
connection to a remote tape server (-lrmt)
SYNOPSIS
#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 one to set up a function 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 one to set the debug level for the library code. The
default debug level is 0 and does not print debug messages.
rmtrmt()
allows one 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 one 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).
rmthostname()
This function copies the user/host part of rmtspec which should
be in remote file syntax. The first argument 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 alternate 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.
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 connection, -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);
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 connection 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.
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)
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 generated signals may
interrupt the remote connection.
Mail other bugs and suggestions to schilytools@mlists.in-berlin.de or
open a ticket at https://codeberg.org/schilytools/schilytools/issues.
The mailing list archive may be found at:
https://mlists.in-berlin.de/mailman/listinfo/schilytools-mlists.in-berlin.de.
AUTHORS
may be retrieved from the schilytools project at Codeberg at
https://codeberg.org/schilytools/schilytools.
The download directory is
https://codeberg.org/schilytools/schilytools/releases.
Joerg Schilling 2022/08/21 RMTGETCONN(3L)