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 #if HAVE_LIMITS_H
  39 #include <limits.h>
  40 #endif
  41
  42 /* Prototype these in case the system headers don't provide them. */
  43 extern char *getpwd ();
  44 extern char *getwd ();
  45
  46 #include "libiberty.h"
  47
  48 /* Virtually every UN*X system now in common use (except for pre-4.3-tahoe
  49    BSD systems) now provides getcwd as called for by POSIX.  Allow for
  50    the few exceptions to the general rule here.  */
  51
  52 #if !defined(HAVE_GETCWD) && defined(HAVE_GETWD)
  53 #define getcwd(buf,len) getwd(buf)
  54 #endif
  55
  56 #ifdef MAXPATHLEN
  57 #define GUESSPATHLEN (MAXPATHLEN + 1)
  58 #else
  59 #define GUESSPATHLEN 100
  60 #endif
  61
  62 #if !(defined (VMS) || (defined(_WIN32) && !defined(__CYGWIN__)))
  63
  64 /* Get the working directory.  Use the PWD environment variable if it's
  65    set correctly, since this is faster and gives more uniform answers
  66    to the user.  Yield the working directory if successful; otherwise,
  67    yield 0 and set errno.  */
  68
  69 char *
  70 getpwd (void)
  71 {
  72   static char *pwd;
  73   static int failure_errno;
  74
  75   char *p = pwd;
  76   size_t s;
  77   struct stat dotstat, pwdstat;
  78
  79   if (!p && !(errno = failure_errno))
  80     {
  81       if (! ((p = getenv ("PWD")) != 0
  82              && *p == '/'
  83              && stat (p, &pwdstat) == 0
  84              && stat (".", &dotstat) == 0
  85              && dotstat.st_ino == pwdstat.st_ino
  86              && dotstat.st_dev == pwdstat.st_dev))
  87
  88         /* The shortcut didn't work.  Try the slow, ``sure'' way.  */
  89         for (s = GUESSPATHLEN;  ! getcwd (p = xmalloc (s), s);  s *= 2)
  90           {
  91             int e = errno;
  92             free (p);
  93 #ifdef ERANGE
  94             if (e != ERANGE)
  95 #endif
  96               {
  97                 errno = failure_errno = e;
  98                 p = 0;
  99                 break;
 100               }
 101           }
 102
 103       /* Cache the result.  This assumes that the program does
 104          not invoke chdir between calls to getpwd.  */
 105       pwd = p;
 106     }
 107   return p;
 108 }
 109
 110 #else   /* VMS || _WIN32 && !__CYGWIN__ */
 111
 112 #ifndef MAXPATHLEN
 113 #define MAXPATHLEN 255
 114 #endif
 115
 116 char *
 117 getpwd (void)
 118 {
 119   static char *pwd = 0;
 120
 121   if (!pwd)
 122     pwd = getcwd (xmalloc (MAXPATHLEN + 1), MAXPATHLEN + 1
 123 #ifdef VMS
 124                   , 0
 125 #endif
 126                   );
 127   return pwd;
 128 }
 129
 130 #endif  /* VMS || _WIN32 && !__CYGWIN__ */