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      1 /* getpwd.c - get the working directory */
      2 
      3 /*
      4 
      5 @deftypefn Supplemental char* getpwd (void)
      6 
      7 Returns the current working directory.  This implementation caches the
      8 result on the assumption that the process will not call @code{chdir}
      9 between calls to @code{getpwd}.
     10 
     11 @end deftypefn
     12 
     13 */
     14 
     15 #ifdef HAVE_CONFIG_H
     16 #include "config.h"
     17 #endif
     18 
     19 #include <sys/types.h>
     20 
     21 #include <errno.h>
     22 #ifndef errno
     23 extern int errno;
     24 #endif
     25 
     26 #ifdef HAVE_STDLIB_H
     27 #include <stdlib.h>
     28 #endif
     29 #ifdef HAVE_UNISTD_H
     30 #include <unistd.h>
     31 #endif
     32 #ifdef HAVE_SYS_PARAM_H
     33 #include <sys/param.h>
     34 #endif
     35 #if HAVE_SYS_STAT_H
     36 #include <sys/stat.h>
     37 #endif
     38 #if HAVE_LIMITS_H
     39 #include <limits.h>
     40 #endif
     41 
     42 #include "libiberty.h"
     43 
     44 /* Virtually every UN*X system now in common use (except for pre-4.3-tahoe
     45    BSD systems) now provides getcwd as called for by POSIX.  Allow for
     46    the few exceptions to the general rule here.  */
     47 
     48 #if !defined(HAVE_GETCWD) && defined(HAVE_GETWD)
     49 /* Prototype in case the system headers doesn't provide it. */
     50 extern char *getwd ();
     51 #define getcwd(buf,len) getwd(buf)
     52 #endif
     53 
     54 #ifdef MAXPATHLEN
     55 #define GUESSPATHLEN (MAXPATHLEN + 1)
     56 #else
     57 #define GUESSPATHLEN 100
     58 #endif
     59 
     60 #if !(defined (VMS) || (defined(_WIN32) && !defined(__CYGWIN__)))
     61 
     62 /* Get the working directory.  Use the PWD environment variable if it's
     63    set correctly, since this is faster and gives more uniform answers
     64    to the user.  Yield the working directory if successful; otherwise,
     65    yield 0 and set errno.  */
     66 
     67 char *
     68 getpwd (void)
     69 {
     70   static char *pwd;
     71   static int failure_errno;
     72 
     73   char *p = pwd;
     74   size_t s;
     75   struct stat dotstat, pwdstat;
     76 
     77   if (!p && !(errno = failure_errno))
     78     {
     79       if (! ((p = getenv ("PWD")) != 0
     80 	     && *p == '/'
     81 	     && stat (p, &pwdstat) == 0
     82 	     && stat (".", &dotstat) == 0
     83 	     && dotstat.st_ino == pwdstat.st_ino
     84 	     && dotstat.st_dev == pwdstat.st_dev))
     85 
     86 	/* The shortcut didn't work.  Try the slow, ``sure'' way.  */
     87 	for (s = GUESSPATHLEN;  !getcwd (p = XNEWVEC (char, s), s);  s *= 2)
     88 	  {
     89 	    int e = errno;
     90 	    free (p);
     91 #ifdef ERANGE
     92 	    if (e != ERANGE)
     93 #endif
     94 	      {
     95 		errno = failure_errno = e;
     96 		p = 0;
     97 		break;
     98 	      }
     99 	  }
    100 
    101       /* Cache the result.  This assumes that the program does
    102 	 not invoke chdir between calls to getpwd.  */
    103       pwd = p;
    104     }
    105   return p;
    106 }
    107 
    108 #else	/* VMS || _WIN32 && !__CYGWIN__ */
    109 
    110 #ifndef MAXPATHLEN
    111 #define MAXPATHLEN 255
    112 #endif
    113 
    114 char *
    115 getpwd (void)
    116 {
    117   static char *pwd = 0;
    118 
    119   if (!pwd)
    120     pwd = getcwd (XNEWVEC (char, MAXPATHLEN + 1), MAXPATHLEN + 1
    121 #ifdef VMS
    122 		  , 0
    123 #endif
    124 		  );
    125   return pwd;
    126 }
    127 
    128 #endif	/* VMS || _WIN32 && !__CYGWIN__ */
    129