[Bug libc/11595] New: sprintf %% format error resulting in output corruption

[Bug libc/11595] New: sprintf %% format error resulting in output corruption

[michael dot yacc at blueyonder dot co dot uk]

The following program produces different output for printf and sprintf. It 
appears the sprintf is being corrupted by the %% in the format string


#include <cstdio>

int main(int ac, char **av)
    {
    char buf[1024];

    printf("%8.4f%%  AAAA\n", 98.3450);
    sprintf(buf, "%8.4f%%  AAAA\n", 98.3450); 
    printf(buf);
    return (0);
    }

The output on my server (Linux analysis-043 2.6.18-92.el5 #1 SMP Tue Jun 10 
18:51:06 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux) is

 98.3450%  AAAA
 98.3450 0X1.896147AE147AEP+6AAA

I think the output should be identical. When %% is present in the sprintf 
format string the output is being corrupted.

-- 
           Summary: sprintf %% format error resulting in output corruption
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: michael dot yacc at blueyonder dot co dot uk
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=11595

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[Bug libc/11595] sprintf %% format error resulting in output corruption

[jakub at redhat dot com]

------- Additional Comments From jakub at redhat dot com  2010-05-13 11:46 -------
No, the testcase is invalid.  In the second printf you pass in %  AAAA
in the format string, which means that a double argument of that printf (none
was provided) is printed in hexadecimal notation, followed by AAA.
You should use printf ("%s", buf); or fputs etc.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


http://sourceware.org/bugzilla/show_bug.cgi?id=11595

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