2.9BSD - /usr/src/lib/c/gen/getwd.c

   1: /*	@(#)getwd.c	4.8	(Berkeley)	3/2/83	*/
   2: 
   3: /*
   4:  * getwd() returns the pathname of the current working directory. On error
   5:  * an error message is copied to pathname and null pointer is returned.
   6:  */
   7: #include <sys/param.h>
   8: #include <sys/stat.h>
   9: #include <sys/dir.h>
  10: #include <sys/file.h>
  11: 
  12: #ifndef MAXPATHLEN
  13: #define MAXPATHLEN  128
  14: #endif
  15: 
  16: #define CURDIR      "."
  17: #define GETWDERR(s) strcpy(pathname, (s));
  18: #define PARENTDIR   ".."
  19: #define PATHSEP     "/"
  20: #define ROOTDIR     "/"
  21: 
  22: char *strcpy();
  23: static int pathsize;            /* pathname length */
  24: 
  25: char *
  26: getwd(pathname)
  27:     char *pathname;
  28: {
  29:     char pathbuf[MAXPATHLEN];       /* temporary pathname buffer */
  30:     char *pnptr = &pathbuf[(sizeof pathbuf)-1]; /* pathname pointer */
  31:     char *prepend();        /* prepend dirname to pathname */
  32:     dev_t rdev;         /* root device number */
  33:     int file;           /* directory file descriptor */
  34:     ino_t rino;         /* root inode number */
  35:     struct direct dir;      /* directory entry struct */
  36:     struct stat d ,dd;      /* file status struct */
  37: 
  38:     pathsize = 0;
  39:     *pnptr = '\0';
  40:     stat(ROOTDIR, &d);
  41:     rdev = d.st_dev;
  42:     rino = d.st_ino;
  43:     for (;;) {
  44:         stat(CURDIR, &d);
  45:         if (d.st_ino == rino && d.st_dev == rdev)
  46:             break;      /* reached root directory */
  47:         if ((file = open(PARENTDIR, FATT_RDONLY)) < 0) {
  48:             GETWDERR("getwd: can't open ..");
  49:             goto fail;
  50:         }
  51:         if (chdir(PARENTDIR) < 0) {
  52:             GETWDERR("getwd: can't chdir to ..");
  53:             goto fail;
  54:         }
  55:         fstat(file, &dd);
  56:         if (d.st_dev == dd.st_dev) {
  57:             if (d.st_ino == dd.st_ino) {
  58:                 /* reached root directory */
  59:                 close(file);
  60:                 break;
  61:             }
  62:             do {
  63:                 if (read(file, (char *) &dir, sizeof(dir)) < sizeof(dir)) {
  64:                     close(file);
  65:                     GETWDERR("getwd: read error in ..");
  66:                     goto fail;
  67:                 }
  68:             } while (dir.d_ino != d.st_ino);
  69:         } else
  70:             do {
  71:                 if (read(file, (char *) &dir, sizeof(dir)) < sizeof(dir)) {
  72:                     close(file);
  73:                     GETWDERR("getwd: read error in ..");
  74:                     goto fail;
  75:                 }
  76:                 stat(dir.d_name, &dd);
  77:             } while(dd.st_ino != d.st_ino || dd.st_dev != d.st_dev);
  78:         close(file);
  79:         pnptr = prepend(PATHSEP, prepend(dir.d_name, pnptr));
  80:     }
  81:     if (*pnptr == '\0')     /* current dir == root dir */
  82:         strcpy(pathname, ROOTDIR);
  83:     else {
  84:         strcpy(pathname, pnptr);
  85:         if (chdir(pnptr) < 0) {
  86:             GETWDERR("getwd: can't change back to .");
  87:             return (NULL);
  88:         }
  89:     }
  90:     return (pathname);
  91: 
  92: fail:
  93:     chdir(prepend(CURDIR, pnptr));
  94:     return (NULL);
  95: }
  96: 
  97: /*
  98:  * prepend() tacks a directory name onto the front of a pathname.
  99:  */
 100: static char *
 101: prepend(dirname, pathname)
 102:     register char *dirname;
 103:     register char *pathname;
 104: {
 105:     register int i;         /* directory name size counter */
 106: 
 107:     for (i = 0; *dirname != '\0'; i++, dirname++)
 108:         continue;
 109:     if ((pathsize += i) < MAXPATHLEN)
 110:         while (i-- > 0)
 111:             *--pathname = *--dirname;
 112:     return (pathname);
 113: }

Defined functions

Defined variables

Defined macros