libio/iogetline.c

   1 /* Copyright (C) 1993-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.
  17
  18    As a special exception, if you link the code in this file with
  19    files compiled with a GNU compiler to produce an executable,
  20    that does not cause the resulting executable to be covered by
  21    the GNU Lesser General Public License.  This exception does not
  22    however invalidate any other reasons why the executable file
  23    might be covered by the GNU Lesser General Public License.
  24    This exception applies to code released by its copyright holders
  25    in files containing the exception.  */
  26
  27 #include "libioP.h"
  28 #include <string.h>
  29
  30 size_t
  31 _IO_getline (FILE *fp, char *buf, size_t n, int delim,
  32              int extract_delim)
  33 {
  34   return _IO_getline_info (fp, buf, n, delim, extract_delim, (int *) 0);
  35 }
  36 libc_hidden_def (_IO_getline)
  37
  38 /* Algorithm based on that used by Berkeley pre-4.4 fgets implementation.
  39
  40    Read chars into buf (of size n), until delim is seen.
  41    Return number of chars read (at most n).
  42    Does not put a terminating '\0' in buf.
  43    If extract_delim < 0, leave delimiter unread.
  44    If extract_delim > 0, insert delim in output. */
  45
  46 size_t
  47 _IO_getline_info (FILE *fp, char *buf, size_t n, int delim,
  48                   int extract_delim, int *eof)
  49 {
  50   char *ptr = buf;
  51   if (eof != NULL)
  52     *eof = 0;
  53   if (__builtin_expect (fp->_mode, -1) == 0)
  54     _IO_fwide (fp, -1);
  55   while (n != 0)
  56     {
  57       ssize_t len = fp->_IO_read_end - fp->_IO_read_ptr;
  58       if (len <= 0)
  59         {
  60           int c = __uflow (fp);
  61           if (c == EOF)
  62             {
  63               if (eof)
  64                 *eof = c;
  65               break;
  66             }
  67           if (c == delim)
  68             {
  69               if (extract_delim > 0)
  70                 *ptr++ = c;
  71               else if (extract_delim < 0)
  72                 _IO_sputbackc (fp, c);
  73               if (extract_delim > 0)
  74                 ++len;
  75               return ptr - buf;
  76             }
  77           *ptr++ = c;
  78           n--;
  79         }
  80       else
  81         {
  82           char *t;
  83           if ((size_t) len >= n)
  84             len = n;
  85           t = (char *) memchr ((void *) fp->_IO_read_ptr, delim, len);
  86           if (t != NULL)
  87             {
  88               size_t old_len = ptr-buf;
  89               len = t - fp->_IO_read_ptr;
  90               if (extract_delim >= 0)
  91                 {
  92                   ++t;
  93                   if (extract_delim > 0)
  94                     ++len;
  95                 }
  96               memcpy ((void *) ptr, (void *) fp->_IO_read_ptr, len);
  97               fp->_IO_read_ptr = t;
  98               return old_len + len;
  99             }
 100           memcpy ((void *) ptr, (void *) fp->_IO_read_ptr, len);
 101           fp->_IO_read_ptr += len;
 102           ptr += len;
 103           n -= len;
 104         }
 105     }
 106   return ptr - buf;
 107 }
 108 libc_hidden_def (_IO_getline_info)