ttyname.c

UNIX编程高级环境（第二版）的终端IO部分的程序源码

#include    <sys/types.h>
#include    <sys/stat.h>
#include    <dirent.h>
#include    <limits.h>
#include    <string.h>
#include    <termios.h>
#include    <unistd.h>

#define    DEV        "/dev/"            /* device directory */
#define    DEVLEN    sizeof(DEV)-1    /* sizeof includes null at end */

char *
ttyname(int fd)
{
    struct stat        fdstat, devstat;
    DIR                *dp;
    struct dirent    *dirp;
    static char        pathname[_POSIX_PATH_MAX + 1];
    char            *rval;

    if (isatty(fd) == 0)
        return(NULL);
    if (fstat(fd, &fdstat) < 0)
        return(NULL);
    if (S_ISCHR(fdstat.st_mode) == 0)
        return(NULL);

    strcpy(pathname, DEV);
    if ( (dp = opendir(DEV)) == NULL)
        return(NULL);
    rval = NULL;
    while ( (dirp = readdir(dp)) != NULL) {
        if (dirp->d_ino != fdstat.st_ino)
            continue;        /* fast test to skip most entries */

        strncpy(pathname + DEVLEN, dirp->d_name, _POSIX_PATH_MAX - DEVLEN);
        if (stat(pathname, &devstat) < 0)
            continue;
        if (devstat.st_ino == fdstat.st_ino &&
            devstat.st_dev == fdstat.st_dev) {    /* found a match */
                rval = pathname;
                break;
        }
    }
    closedir(dp);
    return(rval);
}