getpwd.c revision 130561
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/* Prototype these in case the system headers don't provide them. */
43extern char *getpwd ();
44extern 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
69char *
70getpwd ()
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
116char *
117getpwd ()
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__ */
131