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From bugzi...@apache.org
Subject DO NOT REPLY [Bug 12615] New: - Incorrect comparison in misc/unix/rand.c
Date Fri, 13 Sep 2002 14:54:59 GMT
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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=12615

Incorrect comparison in misc/unix/rand.c

           Summary: Incorrect comparison in misc/unix/rand.c
           Product: APR
           Version: HEAD
          Platform: Other
        OS/Version: Other
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: APR
        AssignedTo: bugs@httpd.apache.org
        ReportedBy: tenthumbs@cybernex.net


I found this while building apache 2.0.40 but it's in the current APR as well.

In apr/misc/unix/rand.c, Linux gcc 3.1.1 says

 rand.c:95: warning: comparison of unsigned expression < 0 is always false

and the code is

    89      apr_size_t got, tot;
    90
    91      if ((rnd = open(STR(DEV_RANDOM), O_RDONLY)) == -1)
    92          return errno;
    93
    94      for (tot=0; tot<length; tot += got)
    95          if ((got = read(rnd, buf+tot, length-tot)) < 0)
    96              return errno;

While read may return a signed value, got is unsigned so the error return 
becomes unreachable and gcc optimizes it away. That's not what's intended.

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