libiberty/getpwd.c

   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
  39 /* Prototype these in case the system headers don't provide them. */
  40 extern char *getpwd ();
  41 extern char *getwd ();
  42
  43 #include "libiberty.h"
  44
  45 /* Virtually every UN*X system now in common use (except for pre-4.3-tahoe
  46    BSD systems) now provides getcwd as called for by POSIX.  Allow for
  47    the few exceptions to the general rule here.  */
  48
  49 #if !defined(HAVE_GETCWD) && defined(HAVE_GETWD)
  50 #define getcwd(buf,len) getwd(buf)
  51 #endif
  52
  53 #ifdef MAXPATHLEN
  54 #define GUESSPATHLEN (MAXPATHLEN + 1)
  55 #else
  56 #define GUESSPATHLEN 100
  57 #endif
  58
  59 #if !(defined (VMS) || (defined(_WIN32) && !defined(__CYGWIN__)))
  60
  61 /* Get the working directory.  Use the PWD environment variable if it's
  62    set correctly, since this is faster and gives more uniform answers
  63    to the user.  Yield the working directory if successful; otherwise,
  64    yield 0 and set errno.  */
  65
  66 char *
  67 getpwd ()
  68 {
  69   static char *pwd;
  70   static int failure_errno;
  71
  72   char *p = pwd;
  73   size_t s;
  74   struct stat dotstat, pwdstat;
  75
  76   if (!p && !(errno = failure_errno))
  77     {
  78       if (! ((p = getenv ("PWD")) != 0
  79              && *p == '/'
  80              && stat (p, &pwdstat) == 0
  81              && stat (".", &dotstat) == 0
  82              && dotstat.st_ino == pwdstat.st_ino
  83              && dotstat.st_dev == pwdstat.st_dev))
  84
  85         /* The shortcut didn't work.  Try the slow, ``sure'' way.  */
  86         for (s = GUESSPATHLEN;  ! getcwd (p = xmalloc (s), s);  s *= 2)
  87           {
  88             int e = errno;
  89             free (p);
  90 #ifdef ERANGE
  91             if (e != ERANGE)
  92 #endif
  93               {
  94                 errno = failure_errno = e;
  95                 p = 0;
  96                 break;
  97               }
  98           }
  99
 100       /* Cache the result.  This assumes that the program does
 101          not invoke chdir between calls to getpwd.  */
 102       pwd = p;
 103     }
 104   return p;
 105 }
 106
 107 #else   /* VMS || _WIN32 && !__CYGWIN__ */
 108
 109 #ifndef MAXPATHLEN
 110 #define MAXPATHLEN 255
 111 #endif
 112
 113 char *
 114 getpwd ()
 115 {
 116   static char *pwd = 0;
 117
 118   if (!pwd)
 119     pwd = getcwd (xmalloc (MAXPATHLEN + 1), MAXPATHLEN + 1
 120 #ifdef VMS
 121                   , 0
 122 #endif
 123                   );
 124   return pwd;
 125 }
 126
 127 #endif  /* VMS || _WIN32 && !__CYGWIN__ */