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Annotation of 40BSD/libc/gen/ttyname.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * ttyname(f): return "/dev/ttyXX" which the the name of the
                      3:  * tty belonging to file f.
                      4:  *  NULL if it is not a tty
                      5:  */
                      6: 
                      7: #define        NULL    0
                      8: #include <sys/types.h>
                      9: #include <sys/dir.h>
                     10: #include <sys/stat.h>
                     11: 
                     12: static char    dev[]   = "/dev/";
                     13: char   *strcpy();
                     14: char   *strcat();
                     15: 
                     16: char *
                     17: ttyname(f)
                     18: {
                     19:        struct stat fsb;
                     20:        struct stat tsb;
                     21:        struct direct db;
                     22:        static char rbuf[32];
                     23:        register df;
                     24: 
                     25:        if (isatty(f)==0)
                     26:                return(NULL);
                     27:        if (fstat(f, &fsb) < 0)
                     28:                return(NULL);
                     29:        if ((fsb.st_mode&S_IFMT) != S_IFCHR)
                     30:                return(NULL);
                     31:        if ((df = open(dev, 0)) < 0)
                     32:                return(NULL);
                     33:        while (read(df, (char *)&db, sizeof(db)) == sizeof(db)) {
                     34:                if (db.d_ino == 0)
                     35:                        continue;
                     36:                if (db.d_ino != fsb.st_ino)
                     37:                        continue;
                     38:                strcpy(rbuf, dev);
                     39:                strcat(rbuf, db.d_name);
                     40:                if (stat(rbuf, &tsb) < 0)
                     41:                        continue;
                     42:                if (tsb.st_dev==fsb.st_dev && tsb.st_ino==fsb.st_ino) {
                     43:                        close(df);
                     44:                        return(rbuf);
                     45:                }
                     46:        }
                     47:        close(df);
                     48:        return(NULL);
                     49: }

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