blob: f7dbcc9bfe937204801492dfbcba55131eabc380 [file] [log] [blame]
Mike Frysinger64b15022010-01-08 02:48:03 -05001/* getline.c -- Replacement for GNU C library function getline
Wolfgang Denk1a459662013-07-08 09:37:19 +02002 *
3 * Copyright (C) 1993, 1996, 2001, 2002 Free Software Foundation, Inc.
4 *
5 * SPDX-License-Identifier: GPL-2.0+
6 */
Mike Frysinger64b15022010-01-08 02:48:03 -05007
8/* Written by Jan Brittenson, bson@gnu.ai.mit.edu. */
9
10#include <assert.h>
11#include <stdio.h>
12
13/* Always add at least this many bytes when extending the buffer. */
14#define MIN_CHUNK 64
15
16/* Read up to (and including) a TERMINATOR from STREAM into *LINEPTR
17 + OFFSET (and null-terminate it). *LINEPTR is a pointer returned from
18 malloc (or NULL), pointing to *N characters of space. It is realloc'd
19 as necessary. Return the number of characters read (not including the
20 null terminator), or -1 on error or EOF.
21 NOTE: There is another getstr() function declared in <curses.h>. */
22static int getstr(char **lineptr, size_t *n, FILE *stream,
23 char terminator, size_t offset)
24{
25 int nchars_avail; /* Allocated but unused chars in *LINEPTR. */
26 char *read_pos; /* Where we're reading into *LINEPTR. */
27 int ret;
28
29 if (!lineptr || !n || !stream)
30 return -1;
31
32 if (!*lineptr) {
33 *n = MIN_CHUNK;
34 *lineptr = malloc(*n);
35 if (!*lineptr)
36 return -1;
37 }
38
39 nchars_avail = *n - offset;
40 read_pos = *lineptr + offset;
41
42 for (;;) {
43 register int c = getc(stream);
44
45 /* We always want at least one char left in the buffer, since we
46 always (unless we get an error while reading the first char)
47 NUL-terminate the line buffer. */
48
49 assert(*n - nchars_avail == read_pos - *lineptr);
50 if (nchars_avail < 2) {
51 if (*n > MIN_CHUNK)
52 *n *= 2;
53 else
54 *n += MIN_CHUNK;
55
56 nchars_avail = *n + *lineptr - read_pos;
57 *lineptr = realloc(*lineptr, *n);
58 if (!*lineptr)
59 return -1;
60 read_pos = *n - nchars_avail + *lineptr;
61 assert(*n - nchars_avail == read_pos - *lineptr);
62 }
63
64 if (c == EOF || ferror (stream)) {
65 /* Return partial line, if any. */
66 if (read_pos == *lineptr)
67 return -1;
68 else
69 break;
70 }
71
72 *read_pos++ = c;
73 nchars_avail--;
74
75 if (c == terminator)
76 /* Return the line. */
77 break;
78 }
79
80 /* Done - NUL terminate and return the number of chars read. */
81 *read_pos = '\0';
82
83 ret = read_pos - (*lineptr + offset);
84 return ret;
85}
86
87int getline (char **lineptr, size_t *n, FILE *stream)
88{
89 return getstr(lineptr, n, stream, '\n', 0);
90}