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