lib/getdelim.c

   1 /* getdelim.c --- Implementation of replacement getdelim function.
   2    Copyright (C) 1994, 1996-1998, 2001, 2003, 2005-2020 Free Software
   3    Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU General Public License as
   7    published by the Free Software Foundation; either version 2, or (at
   8    your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful, but
  11    WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    General Public License for more details.
  14
  15    You should have received a copy of the GNU 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 #ifndef SSIZE_MAX
  34 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
  35 #endif
  36
  37 #if USE_UNLOCKED_IO
  38 # include "unlocked-io.h"
  39 # define getc_maybe_unlocked(fp)        getc(fp)
  40 #elif !HAVE_FLOCKFILE || !HAVE_FUNLOCKFILE || !HAVE_DECL_GETC_UNLOCKED
  41 # undef flockfile
  42 # undef funlockfile
  43 # define flockfile(x) ((void) 0)
  44 # define funlockfile(x) ((void) 0)
  45 # define getc_maybe_unlocked(fp)        getc(fp)
  46 #else
  47 # define getc_maybe_unlocked(fp)        getc_unlocked(fp)
  48 #endif
  49
  50 static void
  51 alloc_failed (void)
  52 {
  53 #if defined _WIN32 && ! defined __CYGWIN__
  54   /* Avoid errno problem without using the realloc module; see:
  55      https://lists.gnu.org/r/bug-gnulib/2016-08/msg00025.html  */
  56   errno = ENOMEM;
  57 #endif
  58 }
  59
  60 /* Read up to (and including) a DELIMITER from FP into *LINEPTR (and
  61    NUL-terminate it).  *LINEPTR is a pointer returned from malloc (or
  62    NULL), pointing to *N characters of space.  It is realloc'ed as
  63    necessary.  Returns the number of characters read (not including
  64    the null terminator), or -1 on error or EOF.  */
  65
  66 ssize_t
  67 getdelim (char **lineptr, size_t *n, int delimiter, FILE *fp)
  68 {
  69   ssize_t result;
  70   size_t cur_len = 0;
  71
  72   if (lineptr == NULL || n == NULL || fp == NULL)
  73     {
  74       errno = EINVAL;
  75       return -1;
  76     }
  77
  78   flockfile (fp);
  79
  80   if (*lineptr == NULL || *n == 0)
  81     {
  82       char *new_lineptr;
  83       *n = 120;
  84       new_lineptr = (char *) realloc (*lineptr, *n);
  85       if (new_lineptr == NULL)
  86         {
  87           alloc_failed ();
  88           result = -1;
  89           goto unlock_return;
  90         }
  91       *lineptr = new_lineptr;
  92     }
  93
  94   for (;;)
  95     {
  96       int i;
  97
  98       i = getc_maybe_unlocked (fp);
  99       if (i == EOF)
 100         {
 101           result = -1;
 102           break;
 103         }
 104
 105       /* Make enough space for len+1 (for final NUL) bytes.  */
 106       if (cur_len + 1 >= *n)
 107         {
 108           size_t needed_max =
 109             SSIZE_MAX < SIZE_MAX ? (size_t) SSIZE_MAX + 1 : SIZE_MAX;
 110           size_t needed = 2 * *n + 1;   /* Be generous. */
 111           char *new_lineptr;
 112
 113           if (needed_max < needed)
 114             needed = needed_max;
 115           if (cur_len + 1 >= needed)
 116             {
 117               result = -1;
 118               errno = EOVERFLOW;
 119               goto unlock_return;
 120             }
 121
 122           new_lineptr = (char *) realloc (*lineptr, needed);
 123           if (new_lineptr == NULL)
 124             {
 125               alloc_failed ();
 126               result = -1;
 127               goto unlock_return;
 128             }
 129
 130           *lineptr = new_lineptr;
 131           *n = needed;
 132         }
 133
 134       (*lineptr)[cur_len] = i;
 135       cur_len++;
 136
 137       if (i == delimiter)
 138         break;
 139     }
 140   (*lineptr)[cur_len] = '\0';
 141   result = cur_len ? cur_len : result;
 142
 143  unlock_return:
 144   funlockfile (fp); /* doesn't set errno */
 145
 146   return result;
 147 }