newlib/libc/stdio/getdelim.c

   1 /* Copyright 2002, Red Hat Inc. - all rights reserved */
   2 /*
   3 FUNCTION
   4 <<getdelim>>---read a line up to a specified line delimiter
   5
   6 INDEX
   7         getdelim
   8
   9 SYNOPSIS
  10         #include <stdio.h>
  11         int getdelim(char **<[bufptr]>, size_t *<[n]>,
  12                      int <[delim]>, FILE *<[fp]>);
  13
  14 DESCRIPTION
  15 <<getdelim>> reads a file <[fp]> up to and possibly including a specified
  16 delimiter <[delim]>.  The line is read into a buffer pointed to
  17 by <[bufptr]> and designated with size *<[n]>.  If the buffer is
  18 not large enough, it will be dynamically grown by <<getdelim>>.
  19 As the buffer is grown, the pointer to the size <[n]> will be
  20 updated.
  21
  22 RETURNS
  23 <<getdelim>> returns <<-1>> if no characters were successfully read;
  24 otherwise, it returns the number of bytes successfully read.
  25 At end of file, the result is nonzero.
  26
  27 PORTABILITY
  28 <<getdelim>> is a glibc extension.
  29
  30 No supporting OS subroutines are directly required.
  31 */
  32
  33 #include <_ansi.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <errno.h>
  37 #include "local.h"
  38
  39 #define MIN_LINE_SIZE 4
  40 #define DEFAULT_LINE_SIZE 128
  41
  42 ssize_t
  43 __getdelim (char **bufptr,
  44        size_t *n,
  45        int delim,
  46        FILE *fp)
  47 {
  48   char *buf;
  49   char *ptr;
  50   size_t newsize, numbytes;
  51   int pos;
  52   int ch;
  53   int cont;
  54
  55   if (fp == NULL || bufptr == NULL || n == NULL)
  56     {
  57       errno = EINVAL;
  58       return -1;
  59     }
  60
  61   buf = *bufptr;
  62   if (buf == NULL || *n < MIN_LINE_SIZE)
  63     {
  64       buf = (char *)realloc (*bufptr, DEFAULT_LINE_SIZE);
  65       if (buf == NULL)
  66         {
  67           return -1;
  68         }
  69       *bufptr = buf;
  70       *n = DEFAULT_LINE_SIZE;
  71     }
  72
  73   CHECK_INIT (_REENT, fp);
  74
  75   _newlib_flockfile_start (fp);
  76
  77   numbytes = *n;
  78   ptr = buf;
  79
  80   cont = 1;
  81
  82   while (cont)
  83     {
  84       /* fill buffer - leaving room for nul-terminator */
  85       while (--numbytes > 0)
  86         {
  87           if ((ch = getc_unlocked (fp)) == EOF)
  88             {
  89               cont = 0;
  90               break;
  91             }
  92           else
  93             {
  94               *ptr++ = ch;
  95               if (ch == delim)
  96                 {
  97                   cont = 0;
  98                   break;
  99                 }
 100             }
 101         }
 102
 103       if (cont)
 104         {
 105           /* Buffer is too small so reallocate a larger buffer.  */
 106           pos = ptr - buf;
 107           newsize = (*n << 1);
 108           buf = realloc (buf, newsize);
 109           if (buf == NULL)
 110             {
 111               cont = 0;
 112               break;
 113             }
 114
 115           /* After reallocating, continue in new buffer */
 116           *bufptr = buf;
 117           *n = newsize;
 118           ptr = buf + pos;
 119           numbytes = newsize - pos;
 120         }
 121     }
 122
 123   _newlib_flockfile_end (fp);
 124
 125   /* if no input data, return failure */
 126   if (ptr == buf)
 127     return -1;
 128
 129   /* otherwise, nul-terminate and return number of bytes read */
 130   *ptr = '\0';
 131   return (ssize_t)(ptr - buf);
 132 }
 133