What could possibly lead to the following assembly execution result - aix

I was debugging under IBM AIX with dbx. I was seeing the following:
(dbx) print $r4
0x00000001614aa050
(dbx) print *((int64*)0x00000001614aa050)
-1
(dbx) print $r3
0x0000000165e08468
Then I "stepi" my 64bit program which executed the following instruction:
std r3,0x0(r4)
I then immediately checked the content of that memory:
(dbx) print *((int64*)0x00000001614aa050)
-1
Still -1? I was expecting the content in $r3 should be saved to that
memory. I then manually assigned the value to that address using my
variables:
(dbx) print &bmc._pLong
0x00000001614aa050
(dbx) assign bmc._pLong=(int64 *)0x0000000165e08468
(dbx) print *((int64*)0x00000001614aa050)
6004180072 (which is 0x0000000165e08468)
How could that happen?

I assume, somehow, this is "pilot" error. e.g. you did stepi and then the std instruction was displayed? which means that that is the instruction it is about to execute -- not the instruction it executed -- at least I think that's right.
I would do some stepi's before and after and make sure I am understanding what stepi is doing. And, of course, print out the iar, and the instruction at the iar, to verify that dbx is not fibbing on you.

Related

Valgrind(memcheck) not showing all contexts

My last context/error I see in my valgrind output file is...
==3030== 1075 errors in context 61 of 540:
==3030== Syscall param ioctl(SIOCETHTOOL,ir) points to uninitialised byte(s)
==3030== at 0x7525248: ioctl (syscall-template.S:84)
==3030== by 0x686A2A7: ??? (in /lib/libpal.so)
==3030== Address 0x96cf958 is on thread 16's stack
==3030== Uninitialised value was created by a stack allocation
==3030== at 0x686A20C: ??? (in /lib/libpal.so)
...but I don't see error contexts 62 - 540. My first thought was maybe in closing the program, valgrind crashed, but after this context it printed the ERROR SUMMARY
ERROR SUMMARY: 9733 errors from 540 contexts (suppressed: 0 from 0)
I don't think it's because we came across a frame without debug info because I can see this exact same issue get hit the first time at the very beginning of my output file. Or maybe the printing of error contexts specifically, is halted when a stacktrace has missing debug info?
Any ideas? Need an additional command line argument for valgrind? I know in helgrind it'll quit after seeing 1000000 errors(something like that) but it explicitly tells you what it's doing.
So for my version of valgrind I also executed helgrind and saw all contexts(647) as expected. I think the problem above is simply a result of valgrind coming across a frame with no debug symbols and saying, "If there's no debug info, I'm moving on"
All of my logs I'm producing end with this same libpal frame at various context numbers 100-something, 200-something, etc.

Is it possible to enable exit on error behavior in an interactive Tcl shell?

I need to automate a huge interactive Tcl program using Tcl expect.
As I realized, this territory is really dangerous, as I need to extend the already existing mass of code, but I can't rely on errors actually causing the program to fail with a positive exit code as I could in a regular script.
This means I have to think about every possible thing that could go wrong and "expect" it.
What I currently do is use a "die" procedure instead of raising an error in my own code, that automatically exits. But this kind of error condition can not be catched, and makes it hard to detect errors especially in code not written by me, since ultimately, most library routines will be error-based.
Since I have access to the program's Tcl shell, is it possible to enable fail-on-error?
EDIT:
I am using Tcl 8.3, which is a severe limitation in terms of available tools.
Examples of errors I'd like to automatically exit on:
% puts $a(2)
can't read "a(2)": no such element in array
while evaluating {puts $a(2)}
%
% blublabla
invalid command name "blublabla"
while evaluating blublabla
%
As well as any other error that makes a normal script terminate.
These can bubble up from 10 levels deep within procedure calls.
I also tried redefining the global error command, but not all errors that can occur in Tcl use it. For instance, the above "command not found" error did not go through my custom error procedure.
Since I have access to the program's Tcl shell, is it possible to
enable fail-on-error?
Let me try to summarize in my words: You want to exit from an interactive Tcl shell upon error, rather than having the prompt offered again?
Update
I am using Tcl 8.3, which is a severe limitation in terms of available
tools [...] only source patches to the C code.
As you seem to be deep down in that rabbit hole, why not add another source patch?
--- tclMain.c 2002-03-26 03:26:58.000000000 +0100
+++ tclMain.c.mrcalvin 2019-10-23 22:49:14.000000000 +0200
## -328,6 +328,7 ##
Tcl_WriteObj(errChannel, Tcl_GetObjResult(interp));
Tcl_WriteChars(errChannel, "\n", 1);
}
+ Tcl_Exit(1);
} else if (tsdPtr->tty) {
resultPtr = Tcl_GetObjResult(interp);
Tcl_GetStringFromObj(resultPtr, &length);
This is untested, the Tcl 8.3.5 sources don't compile for me. But this section of Tcl's internal are comparable to current sources, tested using my Tcl 8.6 source installation.
For the records
With a stock shell (tclsh), this is a little fiddly, I am afraid. The following might work for you (though, I can imagine cases where this might fail you). The idea is
to intercept writes to stderr (this is to where an interactive shell redirects error messages, before returning to the prompt).
to discriminate between arbitrary writes to stderr and error cases, one can use the global variable ::errorInfo as a sentinel.
Step 1: Define a channel interceptor
oo::class create Bouncer {
method initialize {handle mode} {
if {$mode ne "write"} {error "can't handle reading"}
return {finalize initialize write}
}
method finalize {handle} {
# NOOP
}
method write {handle bytes} {
if {[info exists ::errorInfo]} {
# This is an actual error;
# 1) Print the message (as usual), but to stdout
fconfigure stdout -translation binary
puts stdout $bytes
# 2) Call on [exit] to quit the Tcl process
exit 1
} else {
# Non-error write to stderr, proceed as usual
return $bytes
}
}
}
Step 2: Register the interceptor for stderr in interactive shells
if {[info exists ::tcl_interactive]} {
chan push stderr [Bouncer new]
}
Once registered, this will make your interactive shell behave like so:
% puts stderr "Goes, as usual!"
Goes, as usual!
% error "Bye, bye"
Bye, bye
Some remarks
You need to be careful about the Bouncer's write method, the error message has already been massaged for the character encoding (therefore, the fconfigure call).
You might want to put this into a Tcl package or Tcl module, to load the bouncer using package req.
I could imagine that your program writes to stderr and the errorInfo variable happens to be set (as a left-over), this will trigger an unintended exit.

Ghostscript for PS integrity test: terminate at EOF, return error unless stack is empty

To test the integrity of PostScript files, I'd like to run Ghostscript in the following way:
Return 1 (or other error code) on error
Return 0 (success) at EOF if stack is empty
Return 1 (or other error code) otherwise
I could run gs in the background, and use a timeout to force termination if gs hangs with items left on the stack. Is there an easier solution?
Ghostscript won't hang if you send files as input (unless you write a program which enters an infinite loop or otherwise fails to reach a halting state). Having items on any of the stacks won't cause it to hang.
On the other hand, it won't give you an error if a PostScript program leaves operands on the operand stack (or dictionaries on the dictionary stack, clips on the clip stack or gstates on the graphics state stack). This is because that's not an error, and since PostScript interpreters normally run in a job server loop its not a problem either. Terminating the job returns control to the job server loop which does a save and restore round the total job, thereby clearing up anything left behind.
I'd suggest that if you really want to do this you need to adopt the same approach, you need to write a PostScript program which executes the PostScript program you want to 'test', then checks the operand stack (and other stacks if required) to see if anything is left. Note that you will want to execute the test program in a stopped context, as an error in the course of the program will clearly potentially leave stuff lying around.
Ghostscript returns 0 on a clean exit and a value less than 0 for errors, if I remember correctly. You would need to use signalerror in your test framework in order to raise an error if items are left at the end of a program.
[EDIT]
Anything supplied to Ghostscript on the command line by either -s or -d is defined in systemdict, so if we do -sInputFileName=/test.pdf then we will find in systemdict a key /InputFileName whose value is a string with the contents (/test.pdf). We can use that to pass the filename to our program.
The stopped operator takes an executable array as an argument, and returns either true or false depending on whether an error occurred while executing the array (3rd Edition PLRM, p 697).
So we need to run the program contained in the filename we've been given, and do it in a 'stopped' context. Something like this:
{InputFileName run} stopped
{
(Error occurred\n) print flush
%% Potentially check $error for more information.
}{
(program terminated normally\n) print flush
%% Here you could check the various stacks
} ifelse
The following, based 90% on KenS's answer, is 99% satisfactory:
Program checkIntegrity.ps:
{Script run} stopped
{
(\n===> Integrity test failed: ) print Script print ( has error\n\n) print
handleerror
(ignore this error which only serves to force a return value of 1) /syntaxerror signalerror
}{
% script passed, now check the stack
count dup 0 eq {
pop (\n===> Integrity test passed: ) print Script print ( terminated normally\n\n) print
} {
(\n===> Integrity test failed: ) print Script print ( left ) print
3 string cvs print ( item(s) on stack\n\n) print
Script /syntaxerror signalerror
} ifelse
} ifelse
quit
Execute with
gs -q -sScript=CodeToBeChecked.ps checkIntegrity.ps ; echo $?
For the last 1% of satisfaction I would need a replacement for
(blabla) /syntaxerror signalerror
It forces exit with return code 1, but is very verbous and distracts from the actual error in the checked script that is reported by handleerror. Therefore a cleaner way to exit(1) would be welcome.

tcl tcltest unknown option -run

When I run ANY test I get the same message. Here is an example test:
package require tcltest
namespace import -force ::tcltest::*
test foo-1.1 {save 1 in variable name foo} {} {
set foo 1
} {1}
I get the following output:
WARNING: unknown option -run: should be one of -asidefromdir, -constraints, -debug, -errfile, -file, -limitconstraints, -load, -loadfile, -match, -notfile, -outfile, -preservecore, -relateddir, -singleproc, -skip, -testdir, -tmpdir, or -verbose
I've tried multiple tests and nothing seems to work. Does anyone know how to get this working?
Update #1:
The above error was my fault, it was due to it being run in my script. However if I run the following at a command line I got no output:
[root#server1 ~]$ tcl
tcl>package require tcltest
2.3.3
tcl>namespace import -force ::tcltest::*
tcl>test foo-1.1 {save 1 in variable name foo} {expr 1+1} {2}
tcl>echo [test foo-1.1 {save 1 in variable name foo} {expr 1+1} {2}]
tcl>
How do I get it to output pass or fail?
You don't get any output from the test command itself (as long as the test passes, as in the example: if it fails, the command prints a "contents of test case" / "actual result" / "expected result" summary; see also the remark on configuration below). The test statistics are saved internally: you can use the cleanupTests command to print the Total/Passed/Skipped/Failed numbers (that command also resets the counters and does some cleanup).
(When you run runAllTests, it runs test files in child processes, intercepting the output from each file's cleanupTests and adding them up to a grand total.)
The internal statistics collected during testing is available in AFACT undocumented namespace variables like ::tcltest::numTests. If you want to work with the statistics yourself, you can access them before calling cleanupTests, e.g.
parray ::tcltest::numTests
array set myTestData [array get ::tcltest::numTests]
set passed $::tcltest::numTests(Passed)
Look at the source for tcltest in your library to see what variables are available.
The amount of output from the test command is configurable, and you can get output even when the test passes if you add p / pass to the -verbose option. This option can also let you have less output on failure, etc.
You can also create a command called ::tcltest::ReportToMaster which, if it exists, will be called by cleanupTests with the pertinent data as arguments. Doing so seems to suppress both output of statistics and at least most resetting and cleanup. (I didn't go very far in investigating that method.) Be aware that messing about with this is more likely to create trouble than solve problems, but if you are writing your own testing software based on tcltest you might still want to look at it.
Oh, and please use the newer syntax for the test command. It's more verbose, but you'll thank yourself later on if you get started with it.
Obligatory-but-fairly-useless (in this case) documentation link: tcltest

valgrind give error when printing the second line to file

I'm using valgrind to find faults in my code. The command I use is
valgrind --leak-check=yes ./a.out
and I compile the code with -g code alone. I get many errors pointing to a single write line (The three printed values are initialized and well defined).
write (22,*) avlength, stdlength, avenergy
All with the Conditional jump or move depends on uninitialised value(s) error. The said line is the second line from a bunch of lines printing to a single file. At the end of the errors, I get two more, one pointing to the line opening the file
resStep = int(conf*100/iterate)
if (resStep.lt.10) then
write (resFile, "(A5,I1)") "res00",resStep
elseif (ResStep.lt.100) then
write (resFile, "(A4,I2)") "res0",resStep
else
write (resFile, "(A3,I1)") "res",resStep
endif
open (unit=22,file=trim(resFile),status='replace',
c action='write')
resStep is integer. The error is Syscall param write(buf) points to uninitialised byte(s). Finally, I get an error Address 0x52d83f4 is 212 bytes inside a block of size 8,344 alloc'd when I flush the file (before closing it).
I can't find any logic here. If the problem is with opening the file in a faulty way, wouldn't I get the error at the first line?
I use f95 to compile this and my gcc version is 4.1.2. I can't upgrade any of it.
Wild guess: check the data type of resFile. Is it a string or a unit number?
My Fortran 95 is beyond rusty but try moving the call to open() before the calls to write() and pass an integer resUnit instead of resFile as the first argument to write():
CHARACTER(LEN=20):: resFile
INTEGER(KIND=2) :: resUnit, resStep
resStep = 1
resFile = 'MY-results'
resUnit = 22
open (unit=resUnit, file=trim(resFile), status='replace', action='write')
write(resUnit, "(A5,I1)") "res00", resStep
END