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