minix/lib/libc/other/getttyent.c

153 lines
3.5 KiB
C

/* getttyent(3) - get a ttytab entry Author: Kees J. Bot
* 28 Oct 1995
*/
#define nil 0
#define open _open
#define close _close
#define fcntl _fcntl
#define read _read
#include <string.h>
#include <sys/types.h>
#include <ttyent.h>
#include <unistd.h>
#include <fcntl.h>
#define arraysize(a) (sizeof(a) / sizeof((a)[0]))
#define arraylimit(a) ((a) + arraysize(a))
static char TTYTAB[]= "/etc/ttytab"; /* The table of terminal devices. */
static char buf[512]; /* Read buffer. */
static char ttline[256]; /* One line from the ttytab file. */
static char *ttargv[32]; /* Compound arguments. */
static struct ttyent entry; /* Entry to fill and return. */
static int ttfd= -1; /* Filedescriptor to the file. */
static char *bufptr; /* Place in buf. */
static ssize_t buflen= 0; /* Remaining characters in buf. */
static char *lineptr; /* Place in the line. */
static char **argvptr; /* Place in word lists. */
void endttyent(void)
/* Close the ttytab file. */
{
if (ttfd >= 0) {
(void) close(ttfd);
ttfd= -1;
buflen= 0;
}
}
int setttyent(void)
/* Open the ttytab file. */
{
if (ttfd >= 0) endttyent();
if ((ttfd= open(TTYTAB, O_RDONLY)) < 0) return -1;
(void) fcntl(ttfd, F_SETFD, fcntl(ttfd, F_GETFD) | FD_CLOEXEC);
return 0;
}
static int getline(void)
/* Get one line from the ttytab file, return 0 if bad or EOF. */
{
lineptr= ttline;
argvptr= ttargv;
do {
if (buflen == 0) {
if ((buflen= read(ttfd, buf, sizeof(buf))) <= 0)
return 0;
bufptr= buf;
}
if (lineptr == arraylimit(ttline)) return 0;
buflen--;
} while ((*lineptr++ = *bufptr++) != '\n');
lineptr= ttline;
return 1;
}
static int white(int c)
/* Whitespace? */
{
return c == ' ' || c == '\t';
}
static char *scan_white(int quoted)
/* Scan for a field separator in a line, return the start of the field.
* "quoted" is set if we have to watch out for double quotes.
*/
{
char *field, *last;
while (white(*lineptr)) lineptr++;
if (!quoted && *lineptr == '#') return nil;
field= lineptr;
for (;;) {
last= lineptr;
if (*lineptr == 0) return nil;
if (*lineptr == '\n') break;
if (quoted && *lineptr == '"') return field;
if (white(*lineptr++)) break;
}
*last= 0;
return *field == 0 ? nil : field;
}
static char **scan_quoted(void)
/* Read a field that may be a quoted list of words. */
{
char *p, **field= argvptr;
while (white(*lineptr)) lineptr++;
if (*lineptr == '"') {
/* Quoted list of words. */
lineptr++;
while ((p= scan_white(1)) != nil && *p != '"') {
if (argvptr == arraylimit(ttargv)) return nil;
*argvptr++= p;
}
if (*lineptr == '"') *lineptr++= 0;
} else {
/* Just one word. */
if ((p= scan_white(0)) == nil) return nil;
if (argvptr == arraylimit(ttargv)) return nil;
*argvptr++= p;
}
if (argvptr == arraylimit(ttargv)) return nil;
*argvptr++= nil;
return field;
}
struct ttyent *getttyent(void)
/* Read one entry from the ttytab file. */
{
/* Open the file if not yet open. */
if (ttfd < 0 && setttyent() < 0) return nil;
/* Look for a line with something on it. */
for (;;) {
if (!getline()) return nil; /* EOF or corrupt. */
if ((entry.ty_name= scan_white(0)) == nil) continue;
entry.ty_type= scan_white(0);
entry.ty_getty= scan_quoted();
entry.ty_init= scan_quoted();
return &entry;
}
}
struct ttyent *getttynam(const char *name)
/* Return the ttytab file entry for a given tty. */
{
struct ttyent *tty;
endttyent();
while ((tty= getttyent()) != nil && strcmp(tty->ty_name, name) != 0) {}
endttyent();
return tty;
}