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Hi John,
Is the problem because the second message is too short and the function is
picking up garbage?
Theoretically, it shouldn't matter. QSH is calculating the length of
your string and passing that to the API. The API shouldn't care how
long/short the data is, as long as the length is reported correctly.
Or, guessing here, and just a guess, is the parameter
following '%s', which is x'%08x', the problem here? I thought that was the
length of the message.
the printf utility is supposed to format a message. When it sees %08x
it's supposed to output an 8-character hexadecimal number. For example,
if you did this:
> printf "%08x\n" 1024
00000400
$
So when I coded this: printf "x'%08x'" ${#doubledquotes} it should
output the length of the doubledquotes variable in an 8-character
hexadecimal string. If yours is 38 characters long, it should output
x'00000026' (since x'26' is decimal 38). That's how the appropriate
length is supposed to be passed to the API.
If you think that's not working correctly, you can debug it easily
enough by adding the following right before the system command:
echo "$cmd"
it should print the contents of the $cmd variable before running it, and
you'll be able to verify that it's building a valid command string to
call the API.
But, if that is the case, then shouldn't both invocations of the
function throw the message?
No... memory corruption is one of those things that's hard to predict.
Usually, you don't corrupt the actual statement you're on, you corrupt
something else. You're overwriting a space in memory, whatever data
happens (by some luck) to come immediately after the variable you were
using. It's hard to predict what will happen to be in that spot in
memory. It could be corrupting stuff you're already finished with, in
which case you may see no error at all. It could be corrupting
something that hasn't been used yet, in which case you'll see the error
later. It could be corrupting unused memory, in which case you might
never notice any problems. It could be corrupting a pointer that will
be used later, in which case you get the MCH3601. It could be running
past the end of the space object, in which case your program would crash
with a different MCH error. It's hard to predict, because you don't
know what will happen to be immediately after the temporary memory that
QSH uses to store the string...
I don't see anything in the code you posted that would corrupt memory,
and it's not causing any problems on my system. Of course, there's
always a chance that I'm overlooking something, and it's just by sheer
luck (or lack thereof) that it's working for me.
midrange.com
