lib/getdelim.c

   1 /* getdelim.c --- Implementation of replacement getdelim function.
   2    Copyright (C) 1994, 1996-1998, 2001, 2003, 2005-2024 Free Software
   3    Foundation, Inc.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Ported from glibc by Simon Josefsson. */
  19
  20 /* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
  21    optimizes away the lineptr == NULL || n == NULL || fp == NULL tests below.  */
  22 #define _GL_ARG_NONNULL(params)
  23
  24 #include <config.h>
  25
  26 #include <stdio.h>
  27
  28 #include <limits.h>
  29 #include <stdint.h>
  30 #include <stdlib.h>
  31 #include <errno.h>
  32
  33 #if USE_UNLOCKED_IO
  34 # include "unlocked-io.h"
  35 # define getc_maybe_unlocked(fp)        getc(fp)
  36 #elif !HAVE_FLOCKFILE || !HAVE_FUNLOCKFILE || !HAVE_DECL_GETC_UNLOCKED
  37 # undef flockfile
  38 # undef funlockfile
  39 # define flockfile(x) ((void) 0)
  40 # define funlockfile(x) ((void) 0)
  41 # define getc_maybe_unlocked(fp)        getc(fp)
  42 #else
  43 # define getc_maybe_unlocked(fp)        getc_unlocked(fp)
  44 #endif
  45
  46 static void
  47 alloc_failed (void)
  48 {
  49 #if defined _WIN32 && ! defined __CYGWIN__
  50   /* Avoid errno problem without using the realloc module; see:
  51      https://lists.gnu.org/r/bug-gnulib/2016-08/msg00025.html  */
  52   errno = ENOMEM;
  53 #endif
  54 }
  55
  56 /* Read up to (and including) a DELIMITER from FP into *LINEPTR (and
  57    NUL-terminate it).  *LINEPTR is a pointer returned from malloc (or
  58    NULL), pointing to *N characters of space.  It is realloc'ed as
  59    necessary.  Returns the number of characters read (not including
  60    the null terminator), or -1 on error or EOF.  */
  61
  62 ssize_t
  63 getdelim (char **lineptr, size_t *n, int delimiter, FILE *fp)
  64 {
  65   ssize_t result;
  66   size_t cur_len = 0;
  67
  68   if (lineptr == NULL || n == NULL || fp == NULL)
  69     {
  70       errno = EINVAL;
  71       return -1;
  72     }
  73
  74   flockfile (fp);
  75
  76   if (*lineptr == NULL || *n == 0)
  77     {
  78       char *new_lineptr;
  79       *n = 120;
  80       new_lineptr = (char *) realloc (*lineptr, *n);
  81       if (new_lineptr == NULL)
  82         {
  83           alloc_failed ();
  84           result = -1;
  85           goto unlock_return;
  86         }
  87       *lineptr = new_lineptr;
  88     }
  89
  90   for (;;)
  91     {
  92       int i;
  93
  94       i = getc_maybe_unlocked (fp);
  95       if (i == EOF)
  96         {
  97           result = -1;
  98           break;
  99         }
 100
 101       /* Make enough space for len+1 (for final NUL) bytes.  */
 102       if (cur_len + 1 >= *n)
 103         {
 104           size_t needed_max =
 105             SSIZE_MAX < SIZE_MAX ? (size_t) SSIZE_MAX + 1 : SIZE_MAX;
 106           size_t needed = 2 * *n + 1;   /* Be generous. */
 107           char *new_lineptr;
 108
 109           if (needed_max < needed)
 110             needed = needed_max;
 111           if (cur_len + 1 >= needed)
 112             {
 113               result = -1;
 114               errno = EOVERFLOW;
 115               goto unlock_return;
 116             }
 117
 118           new_lineptr = (char *) realloc (*lineptr, needed);
 119           if (new_lineptr == NULL)
 120             {
 121               alloc_failed ();
 122               result = -1;
 123               goto unlock_return;
 124             }
 125
 126           *lineptr = new_lineptr;
 127           *n = needed;
 128         }
 129
 130       (*lineptr)[cur_len] = i;
 131       cur_len++;
 132
 133       if (i == delimiter)
 134         break;
 135     }
 136   (*lineptr)[cur_len] = '\0';
 137   result = cur_len ? cur_len : result;
 138
 139  unlock_return:
 140   funlockfile (fp); /* doesn't set errno */
 141
 142   return result;
 143 }