diplodocus.org Git - nmh/blob - docs/historical/mh-jun-1982/Extras/libh/gwd.c

   1 #ifdef COMMENT
   2         Proprietary Rand Corporation, 1981.
   3         Further distribution of this software
   4         subject to the terms of the Rand
   5         license agreement.
   6 #endif
   7
   8 #include "../h/stat.h"
   9 #include "../h/dirent.h"
  10
  11 struct dirinfo {
  12         struct dirent dir;
  13         char null;
  14         int dotino;
  15         int dotdotino;
  16 };
  17
  18 char *rootlist[] {
  19         "/",
  20         "/rnd/",
  21         "/mnt/",
  22         "/sys/",
  23         "/bak/",
  24         "/fsd/",
  25         0
  26 };
  27 gwd()
  28 {
  29         return(fullpath(0));
  30 }
  31
  32 fullpath(str)
  33 char *str;
  34 {
  35         static char wdbuf[128];
  36         struct dirinfo d;
  37         register char *wp, *cp, **cpp;
  38         int fino;
  39         char *savewp, *markwp;
  40         int dotdev;
  41         struct inode statb;
  42
  43         wp = &wdbuf + 1;
  44         *--wp = 0;
  45         markwp = 0;
  46         if (str) {
  47                 wp = prepend(str, wp);
  48                 if (*wp == '/') return(wp);
  49                 *--wp = 0;
  50                 markwp = wp;
  51         }
  52         fino = 0;
  53
  54         for (;;) {
  55                 wp = scandir(&d, fino, wp);
  56                 if (d.dotino != d.dotdotino) {
  57                         fino = d.dotino;
  58                         chdir("..");
  59                         continue;
  60                 }
  61                 savewp = wp;
  62                 if (d.dotino != ROOTINO) break; /* error */
  63                 stat(".", &statb);
  64                 dotdev = statb.i_dev;
  65                 for (cpp = rootlist; cp = *cpp++; ) {
  66                         if (stat(cp, &statb) < 0) continue;
  67                         if (statb.i_dev == dotdev) {
  68                                 wp = prepend(cp, wp);
  69                                 break;
  70                         }
  71                 }
  72                 break;
  73         }
  74         chdir(savewp);
  75         if (markwp) *markwp = '/';
  76         return(wp);
  77 }
  78
  79 scandir(dp, fileino, endwhere)
  80 struct dirinfo *dp;
  81 char *endwhere;
  82 {
  83         register struct dirinfo *d;
  84         register char *cp, *wp;
  85         int fh;
  86
  87         d = dp;
  88         d->dotino = 0;
  89         d->dotdotino = 0;
  90         if (fileino == 0) wp = endwhere;
  91         else wp = 0;
  92         fh = open(".", 0);
  93         if (fh < 0) return(wp);
  94         while ((!d->dotino || !d->dotdotino || !wp) &&
  95             read(fh, &d->dir, sizeof d->dir) == sizeof d->dir) {
  96                 if (d->dir.d_ino == NULLINO) continue;
  97                 if (!d->dotino && equal(d->dir.d_name, "."))
  98                         d->dotino = d->dir.d_ino;
  99                 else if (!d->dotdotino && equal(d->dir.d_name, ".."))
 100                         d->dotdotino = d->dir.d_ino;
 101                 else if (!wp && d->dir.d_ino == fileino) {
 102                         /* ensure name is null term'd */
 103                         d->null = 0;
 104                         wp = endwhere;
 105                         /* separate with '/' */
 106                         if (*wp) *--wp = '/';
 107                         wp = prepend(d->dir.d_name, wp);
 108                 }
 109         }
 110         close(fh);
 111         return(wp);
 112 }
 113
 114 prepend(prefix, endwhere)
 115 char *prefix, *endwhere;
 116 {
 117         register char *cp, *wp;
 118
 119         for (cp = prefix; *cp++; );
 120         --cp;
 121         for (wp = endwhere; cp > prefix; *--wp = *--cp);
 122         return(wp);
 123 }