LXR uboot/tools/getline.c

   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>.  */
  21static 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
  86int getline (char **lineptr, size_t *n, FILE *stream)
  87{
  88        return getstr(lineptr, n, stream, '\n', 0);
  89}
  90