busybox/libbb/getpty.c

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/* vi: set sw=4 ts=4: */
/*
* Mini getpty implementation for busybox
* Bjorn Wesen, Axis Communications AB (bjornw@axis.com)
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
#define DEBUG 0
int FAST_FUNC xgetpty(char *line)
{
int p;
#if ENABLE_FEATURE_DEVPTS
p = open("/dev/ptmx", O_RDWR);
if (p >= 0) {
grantpt(p); /* chmod+chown corresponding slave pty */
unlockpt(p); /* (what does this do?) */
# ifndef HAVE_PTSNAME_R
{
const char *name;
name = ptsname(p); /* find out the name of slave pty */
if (!name) {
bb_perror_msg_and_die("ptsname error (is /dev/pts mounted?)");
}
safe_strncpy(line, name, GETPTY_BUFSIZE);
}
# else
/* find out the name of slave pty */
if (ptsname_r(p, line, GETPTY_BUFSIZE-1) != 0) {
bb_perror_msg_and_die("ptsname error (is /dev/pts mounted?)");
}
line[GETPTY_BUFSIZE-1] = '\0';
# endif
return p;
}
#else
struct stat stb;
int i;
int j;
strcpy(line, "/dev/ptyXX");
for (i = 0; i < 16; i++) {
line[8] = "pqrstuvwxyzabcde"[i];
line[9] = '0';
if (stat(line, &stb) < 0) {
continue;
}
for (j = 0; j < 16; j++) {
line[9] = j < 10 ? j + '0' : j - 10 + 'a';
if (DEBUG)
fprintf(stderr, "Trying to open device: %s\n", line);
p = open(line, O_RDWR | O_NOCTTY);
if (p >= 0) {
line[5] = 't';
return p;
}
}
}
#endif /* FEATURE_DEVPTS */
bb_error_msg_and_die("can't find free pty");
}