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From:	"Brebner, Gavin" <gavin DOT brebner AT hp DOT com>
To:	"cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Date:	Thu, 1 Apr 2010 09:06:30 +0000
Subject:	fopen with "a+" does not respect setting file read position to start of file
Message-ID:	<B0E0B6C348D8AB4BAD6290DC0BDE99D47427D7442A@GVW1115EXC.americas.hpqcorp.net>
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We hit a problem in a code, and narrowed it down to a test case that does :

  while (cnt) {
    f=3Dfopen(host_file, "a+");
    if (!f)
      perror("dup_host_file: Could not open hostfile");
    /* rewind(f); */
    while (cnt) {
      int ret=3Dfscanf(f, "%s", line);
      if (ret !=3D EOF) {
	  fprintf(f, "%s\n", line);
	  cnt--;
	  dup++;
	}
    }
    fclose(f);

In earlier versions of cygwin we have, this works fine, however in the rece=
ntly installed=20
versions, it no longer works. It seems that fopen(host_file, "a+") is NOT p=
ositioning the
read position at the start of the file as it should. Adding an explicit rew=
ind(f) is a=20
work around.

Gavin

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