gcc/getpwd.c

   1 /* getpwd.c - get the working directory */
   2
   3 #include "config.h"
   4
   5 #include <errno.h>
   6 #include <sys/types.h>
   7 #include <sys/stat.h>
   8
   9 #ifndef errno
  10 extern int errno;
  11 #endif
  12
  13 /* Virtually every UN*X system now in common use (except for pre-4.3-tahoe
  14    BSD systems) now provides getcwd as called for by POSIX.  Allow for
  15    the few exceptions to the general rule here.  */
  16
  17 #if !(defined (POSIX) || defined (USG) || defined (VMS)) || defined (HAVE_GETWD)
  18 #include <sys/param.h>
  19 extern char *getwd ();
  20 #define getcwd(buf,len) getwd(buf)
  21 #ifdef MAXPATHLEN
  22 #define GUESSPATHLEN (MAXPATHLEN + 1)
  23 #else
  24 #define GUESSPATHLEN 100
  25 #endif
  26 #else /* (defined (USG) || defined (VMS)) */
  27 extern char *getcwd ();
  28 /* We actually use this as a starting point, not a limit.  */
  29 #define GUESSPATHLEN 100
  30 #endif /* (defined (USG) || defined (VMS)) */
  31
  32 char *getenv ();
  33 char *xmalloc ();
  34
  35 #if !(defined (VMS) || (defined(_WIN32) && !defined(__CYGWIN32__)))
  36
  37 /* Get the working directory.  Use the PWD environment variable if it's
  38    set correctly, since this is faster and gives more uniform answers
  39    to the user.  Yield the working directory if successful; otherwise,
  40    yield 0 and set errno.  */
  41
  42 char *
  43 getpwd ()
  44 {
  45   static char *pwd;
  46   static int failure_errno;
  47
  48   char *p = pwd;
  49   size_t s;
  50   struct stat dotstat, pwdstat;
  51
  52   if (!p && !(errno = failure_errno))
  53     {
  54       if (! ((p = getenv ("PWD")) != 0
  55              && *p == '/'
  56              && stat (p, &pwdstat) == 0
  57              && stat (".", &dotstat) == 0
  58              && dotstat.st_ino == pwdstat.st_ino
  59              && dotstat.st_dev == pwdstat.st_dev))
  60
  61         /* The shortcut didn't work.  Try the slow, ``sure'' way.  */
  62         for (s = GUESSPATHLEN;  ! getcwd (p = xmalloc (s), s);  s *= 2)
  63           {
  64             int e = errno;
  65             free (p);
  66 #ifdef ERANGE
  67             if (e != ERANGE)
  68 #endif
  69               {
  70                 errno = failure_errno = e;
  71                 p = 0;
  72                 break;
  73               }
  74           }
  75
  76       /* Cache the result.  This assumes that the program does
  77          not invoke chdir between calls to getpwd.  */
  78       pwd = p;
  79     }
  80   return p;
  81 }
  82
  83 #else   /* VMS || _WIN32 && !__CYGWIN32__ */
  84
  85 #ifndef MAXPATHLEN
  86 #define MAXPATHLEN 255
  87 #endif
  88
  89 char *
  90 getpwd ()
  91 {
  92   static char *pwd = 0;
  93
  94   if (!pwd)
  95     pwd = getcwd (xmalloc (MAXPATHLEN + 1), MAXPATHLEN + 1
  96 #ifdef VMS
  97                   , 0
  98 #endif
  99                   );
 100   return pwd;
 101 }
 102
 103 #endif  /* VMS || _WIN32 && !__CYGWIN32__ */