71 lines
1.6 KiB
C
71 lines
1.6 KiB
C
#if !defined(lint) && defined(SCCSIDS)
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static char sccsid[] = "@(#)ttyname.c 1.1 92/07/30 SMI"; /* from S5R2 1.2 */
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#endif
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/*LINTLIBRARY*/
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/*
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* ttyname(f): return "/dev/ttyXX" which the the name of the
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* tty belonging to file f.
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*
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* This program works in two passes: the first pass tries to
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* find the device by matching device and inode numbers; if
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* that doesn't work, it tries a second time, this time doing a
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* stat on every file in /dev and trying to match device numbers
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* only. If that fails too, NULL is returned.
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*/
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#define NULL 0
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#include <sys/types.h>
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#include <sys/dir.h>
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#include <sys/stat.h>
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extern int stat(), fstat(), isatty();
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extern char *strcpy(), *strcat();
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/* should be malloc()'d, but not until vi, etc fixed. */
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static char rbuf[6+64], *dev="/dev/";
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char *
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ttyname(f)
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int f;
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{
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struct stat fsb, tsb;
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register struct direct *db;
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register DIR *df;
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register int pass1;
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if(isatty(f) == 0)
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return(NULL);
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if(fstat(f, &fsb) < 0)
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return(NULL);
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if((fsb.st_mode & S_IFMT) != S_IFCHR)
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return(NULL);
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if((df = opendir(dev)) == NULL)
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return(NULL);
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pass1 = 1;
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do {
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while((db = readdir(df)) != NULL) {
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if(pass1 && db->d_ino != fsb.st_ino)
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continue;
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if (strlen(dev)+strlen(db->d_name) > sizeof (rbuf)) {
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closedir(df);
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return (0);
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}
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(void) strcpy(rbuf, dev);
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(void) strcat(rbuf, db->d_name);
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if(stat(rbuf, &tsb) < 0)
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continue;
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if(tsb.st_rdev == fsb.st_rdev &&
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(tsb.st_mode&S_IFMT) == S_IFCHR &&
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(!pass1 || (tsb.st_dev == fsb.st_dev &&
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tsb.st_ino == fsb.st_ino))) {
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closedir(df);
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return(rbuf);
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}
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}
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rewinddir(df);
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} while(pass1--);
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closedir(df);
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return(NULL);
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}
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