LXR uboot/tools/getline.c

   1/* getline.c -- Replacement for GNU C library function getline
   2 *
   3 * Copyright (C) 1993, 1996, 2001, 2002 Free Software Foundation, Inc.
   4 *
   5 * SPDX-License-Identifier:     GPL-2.0+
   6 */
   7
   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}
  91