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/*
* openpty - open a pseudo-terminal
*
* The first time that the routine is called, the device directory is
* searched and a list of all candidate pseudo-terminals is compiled.
* Candidates are defined to be those entries in "/dev" whose names
* (1) are the same length as PTY_PROTO and (2) start with the
* initial string PTY_PREFIX. Further, the master and slave sides
* must both exist.
*
* openpty() attempts to find an unused pseudo-terminal from the list
* of candidates. If one is found, the master and slave sides are
* opened and the file descriptors and names of these two devices are
* returned in a "ptydesc" structure. (The address of this structure
* is supplied by the caller. Zero is returned if openpty() was
* successful, -1 is returned if no pty could be found.
*/
#include <sys/types.h>
#include <sys/dir.h>
#include <fcntl.h>
#include <strings.h>
#include "openpty.h"
#define DEV_DIR "/dev" /* directory where devices live */
#define PT_INDEX (sizeof DEV_DIR) /* location of 'p' in "pty" */
#define PTY_PROTO "ptyp0" /* prototype for pty names */
#define PTY_PREFIX "pty" /* prefix required for name of pty */
struct ptyinfo {
struct ptyinfo *pi_next;
char *pi_pty;
char *pi_tty;
};
static struct ptyinfo *ptylist;
extern char *malloc();
static
char *
devname(name)
char *name;
{
register char *fullname;
/*
* Construct the full name of a device in DEV_DIR. Returns
* NULL if it failed (because malloc() failed).
*/
fullname = malloc((unsigned)(sizeof DEV_DIR + 1 + strlen(name)));
if (fullname != NULL) {
(void)strcpy(fullname, DEV_DIR);
(void)strcat(fullname, "/");
(void)strcat(fullname, name);
}
return(fullname);
}
static
isapty(dp)
struct direct *dp;
{
static struct ptyinfo *pi;
/*
* We don't care about the gory details of the directory entry.
* Instead, what we really want is an array of pointers to
* device names (with DEV_DIR prepended). Therefore, we create
* this array ourselves and tell scandir() to ignore every
* directory entry.
*
* If malloc() fails, the current directory entry is ignored.
*/
if (pi == NULL) {
pi = (struct ptyinfo *)malloc((unsigned)sizeof *pi);
if (pi == NULL)
return(0);
}
if (strlen(dp->d_name) == sizeof PTY_PROTO - 1 &&
strncmp(dp->d_name, PTY_PREFIX, sizeof PTY_PREFIX - 1) == 0) {
pi->pi_pty = devname(dp->d_name);
if (pi->pi_pty == NULL)
return(0);
pi->pi_tty = malloc((unsigned)(strlen(pi->pi_pty) + 1));
if (pi->pi_tty == NULL) {
free(pi->pi_pty);
return(0);
}
(void)strcpy(pi->pi_tty, pi->pi_pty);
pi->pi_tty[PT_INDEX] = 't';
if (access(pi->pi_pty, 0) == 0 && access(pi->pi_tty, 0) == 0) {
pi->pi_next = ptylist;
ptylist = pi;
pi = NULL;
} else {
free(pi->pi_pty);
free(pi->pi_tty);
}
}
return(0);
}
openpty(pt)
struct ptydesc *pt;
{
register struct ptyinfo *pi;
static int fail;
auto struct direct **dirlist;
extern char *re_comp();
extern int alphasort();
/*
* If scandir() fails or no possible pty's are found, then "fail"
* is set non-zero. If "fail" is non-zero then the routine bombs
* out immediately. Otherwise, the list of candidates is examined
* starting with the entry following the last one chosen.
*/
if (fail)
return(-1);
if (!ptylist) { /* first time */
if (scandir(DEV_DIR, &dirlist, isapty, alphasort) < 0 ||
ptylist == NULL) {
fail = 1;
return(-1);
}
for (pi=ptylist; pi->pi_next; pi=pi->pi_next)
;
pi->pi_next = ptylist; /* make the list circular */
}
pi = ptylist;
do {
if ((pt->pt_pfd = open(pi->pi_pty, O_RDWR)) >= 0) {
if ((pt->pt_tfd = open(pi->pi_tty, O_RDWR)) >= 0) {
ptylist = pi->pi_next;
pt->pt_pname = pi->pi_pty;
pt->pt_tname = pi->pi_tty;
return(0);
} else
(void)close(pt->pt_pfd);
}
pi = pi->pi_next;
} while (pi != ptylist);
return(-1);
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.