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3rdparty/c-ares-1.18.1/src/lib/ares__read_line.c 2.14 KB
73ef4ff3   Hu Chunming   提交三方库
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  /* Copyright 1998 by the Massachusetts Institute of Technology.
   *
   * Permission to use, copy, modify, and distribute this
   * software and its documentation for any purpose and without
   * fee is hereby granted, provided that the above copyright
   * notice appear in all copies and that both that copyright
   * notice and this permission notice appear in supporting
   * documentation, and that the name of M.I.T. not be used in
   * advertising or publicity pertaining to distribution of the
   * software without specific, written prior permission.
   * M.I.T. makes no representations about the suitability of
   * this software for any purpose.  It is provided "as is"
   * without express or implied warranty.
   */
  
  #include "ares_setup.h"
  
  #include "ares.h"
  #include "ares_nowarn.h"
  #include "ares_private.h"
  
  /* This is an internal function.  Its contract is to read a line from
   * a file into a dynamically allocated buffer, zeroing the trailing
   * newline if there is one.  The calling routine may call
   * ares__read_line multiple times with the same buf and bufsize
   * pointers; *buf will be reallocated and *bufsize adjusted as
   * appropriate.  The initial value of *buf should be NULL.  After the
   * calling routine is done reading lines, it should free *buf.
   */
  int ares__read_line(FILE *fp, char **buf, size_t *bufsize)
  {
    char *newbuf;
    size_t offset = 0;
    size_t len;
  
    if (*buf == NULL)
      {
        *buf = ares_malloc(128);
        if (!*buf)
          return ARES_ENOMEM;
        *bufsize = 128;
      }
  
    for (;;)
      {
        int bytestoread = aresx_uztosi(*bufsize - offset);
  
        if (!fgets(*buf + offset, bytestoread, fp))
          return (offset != 0) ? 0 : (ferror(fp)) ? ARES_EFILE : ARES_EOF;
        len = offset + strlen(*buf + offset);
        if ((*buf)[len - 1] == '\n')
          {
            (*buf)[len - 1] = 0;
            break;
          }
        offset = len;
        if(len < *bufsize - 1)
          continue;
  
        /* Allocate more space. */
        newbuf = ares_realloc(*buf, *bufsize * 2);
        if (!newbuf)
          {
            ares_free(*buf);
            *buf = NULL;
            return ARES_ENOMEM;
          }
        *buf = newbuf;
        *bufsize *= 2;
      }
    return ARES_SUCCESS;
  }