getpwd.c revision 218822 
1/* getpwd.c - get the working directory */
2
3/*
4
5@deftypefn Supplemental char* getpwd (void)
6
7Returns the current working directory.  This implementation caches the
8result on the assumption that the process will not call @code{chdir}
9between 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
23extern 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. */
50extern 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
67char *
68getpwd (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
114char *
115getpwd (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