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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Dear Mr. Supnik:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I stumbled across a small problem in the scp.c module for SIMH. I entered the command “help get”. The <i>help_cmd()</i> function did a lookup for the “GET” command in <i>cmd_table[], </i>which it found, but the structure member <i>help</i> (a char pointer) for the “GET” command was a NULL pointer, which was in turn passed into <i>fputs(),</i> which tried to dereference the NULL pointer and caused an exception.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I took the liberty of patching <i>help_cmd()</i> to supply a default string if help text is unavailable in <i>cmd_table[].</i> My version of <i>help_cmd() </i>now reads as follows:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>t_stat help_cmd <span style='color:purple'>(</span>int32 flag<span style='color:purple'>,</span> <span style='color:blue'>char</span> <span style='color:purple'>*</span>cptr<span style='color:purple'>)</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas;color:purple'>{</span><span style='font-size:9.5pt;font-family:Consolas'><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas;color:blue'>char</span><span style='font-size:9.5pt;font-family:Consolas'> gbuf<span style='color:purple'>[</span>CBUFSIZE<span style='color:purple'>];</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>CTAB <span style='color:purple'>*</span>cmdp<span style='color:purple'>;</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'><o:p> </o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'>GET_SWITCHES <span style='color:purple'>(</span>cptr<span style='color:purple'>);</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas;color:blue'>if</span><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:purple'>(*</span>cptr<span style='color:purple'>)</span> <span style='color:purple'>{</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> cptr <span style='color:purple'>=</span> get_glyph <span style='color:purple'>(</span>cptr<span style='color:purple'>,</span> gbuf<span style='color:purple'>,</span> 0<span style='color:purple'>);</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:blue'>if</span> <span style='color:purple'>(*</span>cptr<span style='color:purple'>)</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:blue'>return</span> SCPE_2MARG<span style='color:purple'>;</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:blue'>if</span> <span style='color:purple'>(</span>cmdp <span style='color:purple'>=</span> find_cmd <span style='color:purple'>(</span>gbuf<span style='color:purple'>))</span> <span style='color:purple'>{</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:blue'>const char</span><span style='color:purple'>*</span> helptxt <span style='color:purple'>=</span> cmdp<span style='color:purple'>-></span>help <span style='color:purple'>?</span> cmdp<span style='color:purple'>-></span>help <span style='color:purple'>:</span> <span style='color:#A31515'>"No help available\n"</span><span style='color:purple'>; // </span></span><span style='font-size:9.5pt;font-family:Wingdings;color:purple'>ß</span><span style='font-size:9.5pt;font-family:Consolas;color:purple'> insert line</span><span style='font-size:9.5pt;font-family:Consolas'><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> fputs <span style='color:purple'>(</span>helptxt<span style='color:purple'>,</span> stdout<span style='color:purple'>); // </span></span><span style='font-size:9.5pt;font-family:Wingdings;color:purple'>ß</span><span style='font-size:9.5pt;font-family:Consolas;color:purple'> change line</span><span style='font-size:9.5pt;font-family:Consolas'><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:blue'>if</span> <span style='color:purple'>(</span>sim_log<span style='color:purple'>)</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> fputs <span style='color:purple'>(</span>helptxt<span style='color:purple'>,</span> sim_log<span style='color:purple'>); // </span></span><span style='font-size:9.5pt;font-family:Wingdings;color:purple'>ß</span><span style='font-size:9.5pt;font-family:Consolas;color:purple'> change line</span><span style='font-size:9.5pt;font-family:Consolas'><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:purple'>}</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:blue'>else</span> <span style='color:blue'>return</span> SCPE_ARG<span style='color:purple'>;</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:purple'>}</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas;color:blue'>else</span><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:purple'>{</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> fprint_help <span style='color:purple'>(</span>stdout<span style='color:purple'>);</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:blue'>if</span> <span style='color:purple'>(</span>sim_log<span style='color:purple'>)</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> fprint_help <span style='color:purple'>(</span>sim_log<span style='color:purple'>);</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas'> <span style='color:purple'>}</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas;color:blue'>return</span><span style='font-size:9.5pt;font-family:Consolas'> SCPE_OK<span style='color:purple'>;</span><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:9.5pt;font-family:Consolas;color:purple'>}<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thank you for this wonderful SIMH system!<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Best regards,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Darrell<o:p></o:p></p></div></body></html>