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 extern char *getwd ();
  13 #define getcwd(buf,len) getwd(buf)
  14 #ifdef MAXPATHLEN
  15 #define GUESSPATHLEN (MAXPATHLEN + 1)
  16 #else
  17 #define GUESSPATHLEN 100
  18 #endif
  19 #else /* (defined (USG) || defined (VMS)) */
  20 extern char *getcwd ();
  21 /* We actually use this as a starting point, not a limit.  */
  22 #define GUESSPATHLEN 100
  23 #endif /* (defined (USG) || defined (VMS)) */
  24
  25 char *xmalloc ();
  26
  27 #if !(defined (VMS) || (defined(_WIN32) && !defined(__CYGWIN32__)))
  28
  29 /* Get the working directory.  Use the PWD environment variable if it's
  30    set correctly, since this is faster and gives more uniform answers
  31    to the user.  Yield the working directory if successful; otherwise,
  32    yield 0 and set errno.  */
  33
  34 char *
  35 getpwd ()
  36 {
  37   static char *pwd;
  38   static int failure_errno;
  39
  40   char *p = pwd;
  41   size_t s;
  42   struct stat dotstat, pwdstat;
  43
  44   if (!p && !(errno = failure_errno))
  45     {
  46       if (! ((p = getenv ("PWD")) != 0
  47              && *p == '/'
  48              && stat (p, &pwdstat) == 0
  49              && stat (".", &dotstat) == 0
  50              && dotstat.st_ino == pwdstat.st_ino
  51              && dotstat.st_dev == pwdstat.st_dev))
  52
  53         /* The shortcut didn't work.  Try the slow, ``sure'' way.  */
  54         for (s = GUESSPATHLEN;  ! getcwd (p = xmalloc (s), s);  s *= 2)
  55           {
  56             int e = errno;
  57             free (p);
  58 #ifdef ERANGE
  59             if (e != ERANGE)
  60 #endif
  61               {
  62                 errno = failure_errno = e;
  63                 p = 0;
  64                 break;
  65               }
  66           }
  67
  68       /* Cache the result.  This assumes that the program does
  69          not invoke chdir between calls to getpwd.  */
  70       pwd = p;
  71     }
  72   return p;
  73 }
  74
  75 #else   /* VMS || _WIN32 && !__CYGWIN32__ */
  76
  77 #ifndef MAXPATHLEN
  78 #define MAXPATHLEN 255
  79 #endif
  80
  81 char *
  82 getpwd ()
  83 {
  84   static char *pwd = 0;
  85
  86   if (!pwd)
  87     pwd = getcwd (xmalloc (MAXPATHLEN + 1), MAXPATHLEN + 1
  88 #ifdef VMS
  89                   , 0
  90 #endif
  91                   );
  92   return pwd;
  93 }
  94
  95 #endif  /* VMS || _WIN32 && !__CYGWIN32__ */