xref: /freebsd/lib/libc/stdio/getline.3 (revision 2008043f386721d58158e37e0d7e50df8095942d)
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25.Dd July 30, 2016
26.Dt GETLINE 3
27.Os
28.Sh NAME
29.Nm getdelim ,
30.Nm getline
31.Nd get a line from a stream
32.Sh LIBRARY
33.Lb libc
34.Sh SYNOPSIS
35.In stdio.h
36.Ft ssize_t
37.Fn getdelim "char ** restrict linep" "size_t * restrict linecapp" "int delimiter" " FILE * restrict stream"
38.Ft ssize_t
39.Fn getline "char ** restrict linep" "size_t * restrict linecapp" " FILE * restrict stream"
40.Sh DESCRIPTION
41The
42.Fn getdelim
43function reads a line from
44.Fa stream ,
45delimited by the character
46.Fa delimiter .
47The
48.Fn getline
49function is equivalent to
50.Fn getdelim
51with the newline character as the delimiter.
52The delimiter character is included as part of the line, unless
53the end of the file is reached.
54.Pp
55The caller may provide a pointer to a malloced buffer for the line in
56.Fa *linep ,
57and the capacity of that buffer in
58.Fa *linecapp .
59These functions expand the buffer as needed, as if via
60.Fn realloc .
61If
62.Fa linep
63points to a
64.Dv NULL
65pointer, a new buffer will be allocated.
66In either case,
67.Fa *linep
68and
69.Fa *linecapp
70will be updated accordingly.
71.Sh RETURN VALUES
72The
73.Fn getdelim
74and
75.Fn getline
76functions return the number of characters stored in the buffer, excluding the
77terminating
78.Dv NUL
79character.
80The value \-1 is returned if an error occurs, or if end-of-file is reached.
81.Sh EXAMPLES
82The following code fragment reads lines from a file and
83writes them to standard output.
84The
85.Fn fwrite
86function is used in case the line contains embedded
87.Dv NUL
88characters.
89.Bd -literal -offset indent
90char *line = NULL;
91size_t linecap = 0;
92ssize_t linelen;
93while ((linelen = getline(&line, &linecap, fp)) > 0)
94	fwrite(line, linelen, 1, stdout);
95free(line);
96.Ed
97.Sh ERRORS
98These functions may fail if:
99.Bl -tag -width Er
100.It Bq Er EINVAL
101Either
102.Fa linep
103or
104.Fa linecapp
105is
106.Dv NULL .
107.It Bq Er EOVERFLOW
108No delimiter was found in the first
109.Dv SSIZE_MAX
110characters.
111.El
112.Pp
113These functions may also fail due to any of the errors specified for
114.Fn fgets
115and
116.Fn malloc .
117.Sh SEE ALSO
118.Xr fgetln 3 ,
119.Xr fgets 3 ,
120.Xr malloc 3
121.Sh STANDARDS
122The
123.Fn getdelim
124and
125.Fn getline
126functions conform to
127.St -p1003.1-2008 .
128.Sh HISTORY
129These routines first appeared in
130.Fx 8.0 .
131.Sh BUGS
132There are no wide character versions of
133.Fn getdelim
134or
135.Fn getline .
136