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 #if !(defined (VMS) || (defined(_WIN32) && !defined(__CYGWIN__)))
  24
  25 /* Get the working directory.  Use the PWD environment variable if it's
  26    set correctly, since this is faster and gives more uniform answers
  27    to the user.  Yield the working directory if successful; otherwise,
  28    yield 0 and set errno.  */
  29
  30 char *
  31 getpwd ()
  32 {
  33   static char *pwd;
  34   static int failure_errno;
  35
  36   char *p = pwd;
  37   size_t s;
  38   struct stat dotstat, pwdstat;
  39
  40   if (!p && !(errno = failure_errno))
  41     {
  42       if (! ((p = getenv ("PWD")) != 0
  43              && *p == '/'
  44              && stat (p, &pwdstat) == 0
  45              && stat (".", &dotstat) == 0
  46              && dotstat.st_ino == pwdstat.st_ino
  47              && dotstat.st_dev == pwdstat.st_dev))
  48
  49         /* The shortcut didn't work.  Try the slow, ``sure'' way.  */
  50         for (s = GUESSPATHLEN;  ! getcwd (p = xmalloc (s), s);  s *= 2)
  51           {
  52             int e = errno;
  53             free (p);
  54 #ifdef ERANGE
  55             if (e != ERANGE)
  56 #endif
  57               {
  58                 errno = failure_errno = e;
  59                 p = 0;
  60                 break;
  61               }
  62           }
  63
  64       /* Cache the result.  This assumes that the program does
  65          not invoke chdir between calls to getpwd.  */
  66       pwd = p;
  67     }
  68   return p;
  69 }
  70
  71 #else   /* VMS || _WIN32 && !__CYGWIN__ */
  72
  73 #ifndef MAXPATHLEN
  74 #define MAXPATHLEN 255
  75 #endif
  76
  77 char *
  78 getpwd ()
  79 {
  80   static char *pwd = 0;
  81
  82   if (!pwd)
  83     pwd = getcwd (xmalloc (MAXPATHLEN + 1), MAXPATHLEN + 1
  84 #ifdef VMS
  85                   , 0
  86 #endif
  87                   );
  88   return pwd;
  89 }
  90
  91 #endif  /* VMS || _WIN32 && !__CYGWIN__ */