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__ */
129