getline.c
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/* getline.c -- Replacement for GNU C library function getline
*
* Copyright (C) 1993, 1996, 2001, 2002 Free Software Foundation, Inc.
*
* SPDX-License-Identifier: GPL-2.0+
*/
/* Written by Jan Brittenson, bson@gnu.ai.mit.edu. */
#include <assert.h>
#include <stdio.h>
/* Always add at least this many bytes when extending the buffer. */
#define MIN_CHUNK 64
/* Read up to (and including) a TERMINATOR from STREAM into *LINEPTR
+ OFFSET (and null-terminate it). *LINEPTR is a pointer returned from
malloc (or NULL), pointing to *N characters of space. It is realloc'd
as necessary. Return the number of characters read (not including the
null terminator), or -1 on error or EOF.
NOTE: There is another getstr() function declared in <curses.h>. */
static int getstr(char **lineptr, size_t *n, FILE *stream,
char terminator, size_t offset)
{
int nchars_avail; /* Allocated but unused chars in *LINEPTR. */
char *read_pos; /* Where we're reading into *LINEPTR. */
int ret;
if (!lineptr || !n || !stream)
return -1;
if (!*lineptr) {
*n = MIN_CHUNK;
*lineptr = malloc(*n);
if (!*lineptr)
return -1;
}
nchars_avail = *n - offset;
read_pos = *lineptr + offset;
for (;;) {
register int c = getc(stream);
/* We always want at least one char left in the buffer, since we
always (unless we get an error while reading the first char)
NUL-terminate the line buffer. */
assert(*n - nchars_avail == read_pos - *lineptr);
if (nchars_avail < 2) {
if (*n > MIN_CHUNK)
*n *= 2;
else
*n += MIN_CHUNK;
nchars_avail = *n + *lineptr - read_pos;
*lineptr = realloc(*lineptr, *n);
if (!*lineptr)
return -1;
read_pos = *n - nchars_avail + *lineptr;
assert(*n - nchars_avail == read_pos - *lineptr);
}
if (c == EOF || ferror (stream)) {
/* Return partial line, if any. */
if (read_pos == *lineptr)
return -1;
else
break;
}
*read_pos++ = c;
nchars_avail--;
if (c == terminator)
/* Return the line. */
break;
}
/* Done - NUL terminate and return the number of chars read. */
*read_pos = '\0';
ret = read_pos - (*lineptr + offset);
return ret;
}
int getline (char **lineptr, size_t *n, FILE *stream)
{
return getstr(lineptr, n, stream, '\n', 0);
}