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[dragonfly.git] / lib / libc / gen / getcwd.3
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1.\" Copyright (c) 1991, 1993
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32.\" @(#)getcwd.3 8.2 (Berkeley) 12/11/93
33.\" $FreeBSD: src/lib/libc/gen/getcwd.3,v 1.7.2.6 2001/12/14 18:33:51 ru Exp $
44cb301e 34.\" $DragonFly: src/lib/libc/gen/getcwd.3,v 1.3 2006/05/26 19:39:36 swildner Exp $
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35.\"
36.Dd November 24, 1997
37.Dt GETCWD 3
38.Os
39.Sh NAME
40.Nm getcwd ,
41.Nm getwd
42.Nd get working directory pathname
43.Sh LIBRARY
44.Lb libc
45.Sh SYNOPSIS
46.In unistd.h
47.Ft char *
48.Fn getcwd "char *buf" "size_t size"
49.Ft char *
50.Fn getwd "char *buf"
51.Sh DESCRIPTION
52The
53.Fn getcwd
54function copies the absolute pathname of the current working directory
55into the memory referenced by
56.Fa buf
57and returns a pointer to
58.Fa buf .
59The
60.Fa size
61argument is the size, in bytes, of the array referenced by
62.Fa buf .
63.Pp
64If
65.Fa buf
66is
67.Dv NULL ,
68space is allocated as necessary to store the pathname.
69This space may later be
70.Xr free 3 Ns 'd .
71.Pp
72The function
73.Fn getwd
74is a compatibility routine which calls
75.Fn getcwd
76with its
77.Fa buf
78argument and a size of
79.Dv MAXPATHLEN
80(as defined in the include
81file
44cb301e 82.In sys/param.h ) .
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83Obviously,
84.Fa buf
85should be at least
86.Dv MAXPATHLEN
87bytes in length.
88.Pp
89These routines have traditionally been used by programs to save the
90name of a working directory for the purpose of returning to it.
91A much faster and less error-prone method of accomplishing this is to
92open the current directory
93.Pq Ql .\&
94and use the
95.Xr fchdir 2
96function to return.
97.Sh RETURN VALUES
98Upon successful completion, a pointer to the pathname is returned.
99Otherwise a
100.Dv NULL
101pointer is returned and the global variable
102.Va errno
103is set to indicate the error.
104In addition,
105.Fn getwd
106copies the error message associated with
107.Va errno
108into the memory referenced by
109.Fa buf .
110.Sh ERRORS
111The
112.Fn getcwd
113function
114will fail if:
115.Bl -tag -width Er
116.It Bq Er EACCES
117Read or search permission was denied for a component of the pathname.
118.It Bq Er EINVAL
119The
120.Fa size
121argument is zero.
122.It Bq Er ENOENT
123A component of the pathname no longer exists.
124.It Bq Er ENOMEM
125Insufficient memory is available.
126.It Bq Er ERANGE
127The
128.Fa size
129argument is greater than zero but smaller than the length of the pathname
130plus 1.
131.El
132.Sh SEE ALSO
133.Xr chdir 2 ,
134.Xr fchdir 2 ,
135.Xr malloc 3 ,
136.Xr strerror 3
137.Sh STANDARDS
138The
139.Fn getcwd
140function
141conforms to
142.St -p1003.1-90 .
143The ability to specify a
144.Dv NULL
145pointer and have
146.Fn getcwd
147allocate memory as necessary is an extension.
148.Sh HISTORY
149The
150.Fn getwd
151function appeared in
152.Bx 4.0 .
153.Sh BUGS
154The
155.Fn getwd
156function
157does not do sufficient error checking and is not able to return very
158long, but valid, paths.
159It is provided for compatibility.