gcc/getpwd.c

   1 /* getpwd.c - get the working directory */
   2
   3 #include "config.h"
   4 #include "system.h"
   5 #include <sys/stat.h>
   6
   7 /* Virtually every UN*X system now in common use (except for pre-4.3-tahoe
   8    BSD systems) now provides getcwd as called for by POSIX.  Allow for
   9    the few exceptions to the general rule here.  */
  10
  11 #if !(defined (POSIX) || defined (USG) || defined (VMS)) || defined (HAVE_GETWD)
  12 #define getcwd(buf,len) getwd(buf)
  13 #ifdef MAXPATHLEN
  14 #define GUESSPATHLEN (MAXPATHLEN + 1)
  15 #else
  16 #define GUESSPATHLEN 100
  17 #endif
  18 #else /* (defined (USG) || defined (VMS)) */
  19 /* We actually use this as a starting point, not a limit.  */
  20 #define GUESSPATHLEN 100
  21 #endif /* (defined (USG) || defined (VMS)) */
  22
  23 char *xmalloc ();
  24
  25 #if !(defined (VMS) || (defined(_WIN32) && !defined(__CYGWIN32__)))
  26
  27 /* Get the working directory.  Use the PWD environment variable if it's
  28    set correctly, since this is faster and gives more uniform answers
  29    to the user.  Yield the working directory if successful; otherwise,
  30    yield 0 and set errno.  */
  31
  32 char *
  33 getpwd ()
  34 {
  35   static char *pwd;
  36   static int failure_errno;
  37
  38   char *p = pwd;
  39   size_t s;
  40   struct stat dotstat, pwdstat;
  41
  42   if (!p && !(errno = failure_errno))
  43     {
  44       if (! ((p = getenv ("PWD")) != 0
  45              && *p == '/'
  46              && stat (p, &pwdstat) == 0
  47              && stat (".", &dotstat) == 0
  48              && dotstat.st_ino == pwdstat.st_ino
  49              && dotstat.st_dev == pwdstat.st_dev))
  50
  51         /* The shortcut didn't work.  Try the slow, ``sure'' way.  */
  52         for (s = GUESSPATHLEN;  ! getcwd (p = xmalloc (s), s);  s *= 2)
  53           {
  54             int e = errno;
  55             free (p);
  56 #ifdef ERANGE
  57             if (e != ERANGE)
  58 #endif
  59               {
  60                 errno = failure_errno = e;
  61                 p = 0;
  62                 break;
  63               }
  64           }
  65
  66       /* Cache the result.  This assumes that the program does
  67          not invoke chdir between calls to getpwd.  */
  68       pwd = p;
  69     }
  70   return p;
  71 }
  72
  73 #else   /* VMS || _WIN32 && !__CYGWIN32__ */
  74
  75 #ifndef MAXPATHLEN
  76 #define MAXPATHLEN 255
  77 #endif
  78
  79 char *
  80 getpwd ()
  81 {
  82   static char *pwd = 0;
  83
  84   if (!pwd)
  85     pwd = getcwd (xmalloc (MAXPATHLEN + 1), MAXPATHLEN + 1
  86 #ifdef VMS
  87                   , 0
  88 #endif
  89                   );
  90   return pwd;
  91 }
  92
  93 #endif  /* VMS || _WIN32 && !__CYGWIN32__ */