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 #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__ */