libiberty/getpwd.c

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