How to read a call stack? - winapi

We have a native C++ application running via COM+ on a windows 2003 server. I've recently noticed from the event viewer that its throwing exceptions, specifically the C0000005 exception, which, according to http://blogs.msdn.com/calvin_hsia/archive/2004/06/30/170344.aspx means that the process is trying to write to memory not within its address space, aka access violation.
The entry in event viewer provides a call stack:
LibFmwk!UTIL_GetDateFromLogByDayDirectory(char const *,class utilCDate &) + 0xa26c
LibFmwk!UTIL_GetDateFromLogByDayDirectory(char const *,class utilCDate &) + 0x8af4
LibFmwk!UTIL_GetDateFromLogByDayDirectory(char const *,class utilCDate &) + 0x13a1
LibFmwk!utilCLogController::GetFLFInfoLevel(void)const + 0x1070
LibFmwk!utilCLogController::GetFLFInfoLevel(void)const + 0x186
Now, I understand that its giving me method names to go look at but I get a feeling that the address at the end of each line (e.g. + 0xa26c) is trying to point me to a specific line or instruction within that method.
So my questions are:
Does anyone know how I might use this address or any other information in a call stack to determine which line within the code its falling over on?
Are there any resources out there that I could read to better understand call stacks,
Are there any freeware/opensource tools that could help in analysing a call stack, perhaps by attaching to a debug symbol file and/or binaries?
Edit:
As requested, here is the method that appears to be causing the problem:
BOOL UTIL_GetDateFromLogByDayDirectory(LPCSTR pszDir, utilCDate& oDate)
{
BOOL bRet = FALSE;
if ((pszDir[0] == '%') &&
::isdigit(pszDir[1]) && ::isdigit(pszDir[2]) &&
::isdigit(pszDir[3]) && ::isdigit(pszDir[4]) &&
::isdigit(pszDir[5]) && ::isdigit(pszDir[6]) &&
::isdigit(pszDir[7]) && ::isdigit(pszDir[8]) &&
!pszDir[9])
{
char acCopy[9];
::memcpy(acCopy, pszDir + 1, 8);
acCopy[8] = '\0';
int iDay = ::atoi(&acCopy[6]);
acCopy[6] = '\0';
int iMonth = ::atoi(&acCopy[4]);
acCopy[4] = '\0';
int iYear = ::atoi(&acCopy[0]);
oDate.Set(iDay, iMonth, iYear);
bRet = TRUE;
}
return (bRet);
}
This is code written over 10 years ago by a member of our company who has long since gone, so I don't presume to know exactly what this is doing but I do know its involved in the process of renaming a log directory from 'Today' to the specific date, e.g. %20090329. The array indexing, memcpy and address of operators do make it look rather suspicious.
Another problem we seem to have is that this only happens on the production system, we've never been able to reproduce it on our test systems or development systems here, which would allow us to attach a debugger.
Much appreciated!
Andy

Others have said this in-between the lines, but not explicitly. look at:
LibFmwk!UTIL_GetDateFromLogByDayDirectory(char const *,class utilCDate &) + 0xa26c
The 0xa26c offset is huge, way past the end of the function. the debugger obviously doesn't have the proper symbols for LibFmwk so instead it's relying on the DLL exports and showing the offset relative to the closest one it can find.
So, yeah, get proper symbols and then it should be a breeze. UTIL_GetDateFromLogByDayDirectory is not at fault here.

if you really need to map those addresses to your functions - you'll need to work with .MAP file and see where those addresses really point to.
But being in your situation I would rather investigate this problem under debugger (e.g. MSVS debugger or windbg); as alternative (if crash happens at customer's site) you can generate crash dump and study it locally - it can be done via Windows MiniDumpWriteDump API or SysInternals ProcDump utility (http://download.sysinternals.com/Files/procdump.zip).
Make sure that all required symbol files are generated and available (also setup microsoft symbol server path so that windows DLLs' entry points get resolved also).
IMHO this is just the web site you need: http://www.dumpanalysis.org - which is the best resource to cover all your questions.
Consider also taking a look at this PDF - http://windbg.info/download/doc/pdf/WinDbg_A_to_Z_color.pdf

Point 2 and 3 are easily answered:
3rd Point. Any debugger. That's what they are made for. Set your debugger to break on this special exception. You should be able to click yourself through the callstack and find the different calls on the stack (at least delphi can do this, so visual studio should be able as well). Compile without optimisations if possible. OllyDBG might work as well - perhaps in combination with its trace functionality.
2nd Point. Any information about x86 Assembler, Reverseengineering ... Try: OpenRCE, NASM Documentation, ASM Community.
1st Point. The callstack tells you the functions. I don't know if it is written in order or in opposite order - so it might be that the first line is the last called function or the first called function. Follow the calls with the help of the debugger. Sometimes you can change between asm and code (depending on the debugger, map files ...). If you don't have the source - learn assembler, read about reverse engineering. Read the documentation of the functions you call in third party components. Perhaps you do not satisfy a precondition.
If you can tell a bit more about the programm (which parts of the source code do you have, is a library call involved?, ...)
Now some code-reading:
The function accepts a pointer to a zero terminated string and a reference to a date object. The pointer is assumed to be valid!
The function checks wether the string is in a specific format (% followed by 8 digits followed by a \0). If this is not the case, it returns false. This check (the big if) accesses the pointer without any validity checks. The length is not checked and if the pointer is pointing somewhere in the wild, this space is accessed. I don't know if a shorter string will cause problems. It shouldn't because of the way && is evaluated.
Then some memory is allocated on the stack. The number-part of the string is copied into it (which is ok) and the buffer gets its \0 termination. The atois extract the numbers. This will work because of the different start-locations used and the \0-termination after each part. Somehow tricky but nice. Some comments would have made everything clear.
These numbers are then inserted into the object. It should be valid since it is passed into the function by reference. I don't know if you can pass a reference to a deleted object but if this is the case, this might be your problem as well.
Anyway - except the missing check for the string-pointer, this function is sound and not the cause of your problem. It's only the place that throws the exception. Search for arguments that are passed into this function. Are they always valid? Do some logging.
I hope I didn't do any major mistakes as I am a Delphi programmer. If I did - feel free to comment.

Related

Add new system call at FreeBSD

I wanna add custom helloworld syscall to FreeBSD. I used following link as my guide: http://members.tripod.com/s_mathur/bsdhowto.html In step 4 says: Modify the Make File to include sys_hello.c , etc and recompile the kernel! Which Make File? Where is it? and how to compile it and how call syscall hello?
The error that I faced with it, is:
init_sysent.o:(.data + 0x6638): undefined reference to 'sys_hello'
I think that it is because of my Make file, because I don't know I should modify which Make File.
I'm afraid you are not ready to do any kernel development and as such strongly suggest you refrain from it.
I don't know how you ended up on that guide, I have trouble finding it when I look for ways to add system calls to the FreeBSD kernel.
The guide has bits which are outdated and some which were always wrong.
You created a new file (sys_hello.c) but did not add it to the build process. Figuring out how to do that should be trivial.
1. pick a syscall which is always provided, like fork
2. find the file implementing it
3. grep the source tree for mentions of that file
4. profit
Performing the steps and getting the answer is left as an exercise for the reader.
int syshello(p, uap)
struct proc* p; struct syshello_args uap;
K&R C declaration? Just how old is this?
The first argument for several years now is struct thread *.
{
sprintf(uap->buf,"Hello"); /* fill the buffer with Hello */
Fundamentally wrong. Consider what happens if userspace passes a kernel address. Also this assumes shared address spaces to "work". The code should have used copyout. Except the code is additionally wrong by not having an argument allowing the userspace to say what the size is.
p->p_retval[0] = 0; /* set the return value of the system call*/
return 0;
}
As noted earlier, given your difficulty with figuring out what to do with the new file it is clear you are new to programming and as such you really should not touch the kernel until you grow.

VB6 random double overflow errors

does anyone know a cause for random overflow errors in vb6?
I have to customize a legacy application written in VB6 and lately overflow errors have started to occur all over the place. Sometimes in functions which have not been touched in years!
The error always happens when trying to assign something to a variable of type Double.
The reason for those errors is probably not the code that throws the error but something else. But I dont know what to look for. The most confusing example of a function failing with an overflow error was the following code:
Dim test As Double
test = 0#
How can that possibly throw an overflow error?
I tried enabling some compiler optimizations, like not checking for floating point calculation errors, and some more. This has "solved" some of the problems, but others remain.
VB6 will run things in such a way where if something external signals a floating-point error flag, it'll not be reported until the next floating-point operation is performed within your own code.
Under most circumstances, this is likely caused by some DLL that is performing floating-point operation. If you have any control over these external DLLs, then my suggestion is to put this line at the end of the functions called by your application:
_clearfp();
This function is documented here: http://msdn.microsoft.com/en-us/library/49bs2z07.aspx
If you do not have much control, you can get around this by making your own function called from a DLL that calls that function. Or a simple hack with only using VB6 is:
Public Sub ClearFP()
On Error Resume Next
Dim d as Double
d = 0#
End Sub
Which you can call after any DLL calls that you believe is the culprit.
A trick to isolating which function did it originally, is simply look at the calls before the error appears. Alternatively, a more complicated solution, is to compile your application and run it through a debugger that can break on floating-point exceptions.
In VB6 the hash (#) symbol can mean many things:
Used in file names
used with dates ususlly when applied to DBs
To treat Numbers as Doubles
To compile constants or sections of code if a condition is true
I'm sure there are more.
It may depend on the compiler.
My suggestion would be to try:
Dim test As Double
test = CDbl(0)
to see if that resolves the issue.

Cross version line matching

I'm considering how to do automatic bug tracking and as part of that I'm wondering what is available to match source code line numbers (or more accurate numbers mapped from instruction pointers via something like addr2line) in one version of a program to the same line in another. (Assume everything is in some kind of source control and is available to my code)
The simplest approach would be to use a diff tool/lib on the files and do some math on the line number spans, however this has some limitations:
It doesn't handle cross file motion.
It might not play well with lines that get changed
It doesn't look at the information available in the intermediate versions.
It provides no way to manually patch up lines when the diff tool gets things wrong.
It's kinda clunky
Before I start diving into developing something better:
What already exists to do this?
What features do similar system have that I've not thought of?
Why do you need to do this? If you use decent source version control, you should have access to old versions of the code, you can simply provide a link to that so people can see the bug in its original place. In fact the main problem I see with this system is that the bug may have already been fixed, but your automatic line tracking code will point to a line and say there's a bug there. Seems this system would be a pain to build, and not provide a whole lot of help in practice.
My suggestion is: instead of trying to track line numbers, which as you observed can quickly get out of sync as software changes, you should decorate each assertion (or other line of interest) with a unique identifier.
Assuming you're using C, in the case of assertions, this could be as simple as changing something like assert(x == 42); to assert(("check_x", x == 42)); -- this is functionally identical, due to the semantics of the comma operator in C and the fact that a string literal will always evaluate to true.
Of course this means that you need to identify a priori those items that you wish to track. But given that there's no generally reliable way to match up source line numbers across versions (by which I mean that for any mechanism you could propose, I believe I could propose a situation in which that mechanism does the wrong thing) I would argue that this is the best you can do.
Another idea: If you're using C++, you can make use of RAII to track dynamic scopes very elegantly. Basically, you have a Track class whose constructor takes a string describing the scope and adds this to a global stack of currently active scopes. The Track destructor pops the top element off the stack. The final ingredient is a static function Track::getState(), which simply returns a list of all currently active scopes -- this can be called from an exception handler or other error-handling mechanism.

What is the most obfuscated code you've had to fix?

Most programmers will have had the experience of debugging/fixing someone else's code. Sometimes that "someone else's code" is so obfuscated it's bad enough trying to understand what it's doing.
What's the worst (most obfuscated) code you've had to debug/fix?
If you didn't throw it away and recode it from scratch, well why didn't you?
PHP OSCommerce is enough to say, it is obfuscated code...
a Java class
only static methods that manipulates DOM
8000 LOCs
long chain of methods that return null on "error": a.b().c().d().e()
very long methods (400/500 LOC each)
nested if, while, like:
if (...) {
for (...) {
if (...) {
if (...) {
while (...) {
if (...) {
cut-and-paste oriented programming
no exceptions, all exceptions are catched and "handled" using printStackTrace()
no unit tests
no documentation
I was tempted to throw away and recode... but, after 3 days of hard debugging,
I've added the magic if :-)
Spaghetti code PHP CMS system.
by default, programmers think someone else's code is obfuscated.
The worse I probably had to do was interpreting what variables i1, i2 j, k, t were in a simple method and they were not counters in 'for' loops.
In all other circumstances I guess the problem area was difficult which made the code look difficult.
I found this line in our codebase today and thought it was a nice example of sneaky obfuscation:
if (MULTICLICK_ENABLED.equals(propService.getProperty(PropertyNames.MULTICLICK_ENABLED))) {} else {
return false;
}
Just making sure I read the whole line. NO SKIMREADING.
When working on a GWT project, I would reach parts of GWT-compiled obfuscated JS code which wasn't mine.
Now good luck debugging real obfuscated code.
I can't remember the full code, but a single part of it remains burned into my memory as something I spend hours trying to understand:
do{
$tmp = shift unless shift;
$tmp;
}while($tmp);
I couldn't understand it at first, it looks so useless, then I printed out #_ for a list of arguments, a series of alternating boolean and function names, the code was used in conjunction with a library detection module that changed behaviour if a function was broken, but the code was so badly documented and made of things like that which made no sense without a complete understanding of the full code I gave up and rewrote the whole thing.
UPDATE from DVK:
And, lest someone claims this was because Perl is unreadable as opposed to coder being a golf master instead of good software developer, here's the same code in a slightly less obfuscated form (the really correct code wouldn't even HAVE alternating sub names and booleans in the first place :)
# This subroutine take a list of alternating true/false flags
# and subroutine names; and executes the named subroutines for which flag is true.
# I am also weird, otherwise I'd have simply have passed list of subroutines to execute :)
my #flags_and_sub_names_list = #_;
while ( #flags_and_sub_names_list ) {
my $flag = shift #flags_and_sub_names_list;
my $subName = shift #flags_and_sub_names_list;
next unless $flag && $subName;
&{ $subName }; # Call the named subroutine
}
I've had a case of a 300lines function performing input sanitization which missed a certain corner case. It was parsing certain situations manually using IndexOf and Substring plus a lot of inlined variables and constants (looks like the original coder didn't know anything about good practices), and no comment was provided. Throwing it away wasn't feasible due to time constraints and the fact that I didn't have the specification required so rewriting it would've meant understanding the original, but after understanding it fixing it was just quicker. I also added lots of comments, so whoever shall come after me won't feel the same pain taking a look at it...
The Perl statement:
select((select(s),$|=1)[0])
which, at the suggestion of the original author (Randal Schwartz himself, who said he disliked it but nothing else was available at the time), was replaced with something a little more understandable:
IO::Handle->autoflush
Beyond that one-liner, some of the Java JDBC libraries from IBM are obfuscated and all variables and functions are either combinations of the letter 'l' and '1' or single/double characters - very hard to track anything down until you get them all renamed. Needed to do this to track down why they worked fine in IBM's JRE but not Sun's.
If you're talking about HLL codes, once I was updating project written by a chinese and all comments were chinese (stored in ansii) and it was a horror to understand some code fragments, if you're talking about low level code there were MANY of them (obfuscated, mutated, vm-ed...).
I once had to reverse engineer a Java 1.1 framework that:
Extended event-driven SAX parser classes for every class, even those that didn't parse XML (the overridden methods were simply invoked ad hoc by other code)
Custom runtime exceptions were thrown in lieu of method invocations wherever possible. As a result, most of the business logic landed in a nested series of catch blocks.
If I had to guess, it was probably someone's "smart" idea that method invocations were expensive in Java 1.1, so throwing exceptions for non-exceptional flow control was somehow considered an optimization.
Went through about three bottles of eye drops.
I once found a time bomb that had been intentionally obfuscated.
When I had finally decoded what it was doing I mentioned it to the manager who said they knew about the time bomb but had left it in place because it was so ineffective and was interwoven with other code.
The time bomb was (presumably) supposed to go off after a certain date.
Instead, it had a bug in it so it only activated if someone was working after lunchtime on Dec 31st.
It had taken three years for that circumstance to occur since the guy who wrote the time bomb left the company.

What was the strangest coding standard rule that you were forced to follow? [closed]

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When I asked this question I got almost always a definite yes you should have coding standards.
What was the strangest coding standard rule that you were ever forced to follow?
And by strangest I mean funniest, or worst, or just plain odd.
In each answer, please mention which language, what your team size was, and which ill effects it caused you and your team.
I hate it when the use of multiple returns is banned.
reverse indentation. For example:
for(int i = 0; i < 10; i++)
{
myFunc();
}
and:
if(something)
{
// do A
}
else
{
// do B
}
Maybe not the most outlandish one you'll get, but I really really hate when I have to preface database table names with 'tbl'
Almost any kind of hungarian notation.
The problem with hungarian notation is that it is very often misunderstood. The original idea was to prefix the variable so that the meaning was clear. For example:
int appCount = 0; // Number of apples.
int pearCount = 0; // Number of pears.
But most people use it to determine the type.
int iAppleCount = 0; // Number of apples.
int iPearCount = 0; // Number of pears.
This is confusing, because although both numbers are integers, everybody knows, you can't compare apples with pears.
No ternary operator allowed where I currently work:
int value = (a < b) ? a : b;
... because not everyone "gets it". If you told me, "Don't use it because we've had to rewrite them when the structures get too complicated" (nested ternary operators, anyone?), then I'd understand. But when you tell me that some developers don't understand them... um... Sure.
To NEVER remove any code when making changes. We were told to comment all changes. Bear in mind we use source control. This policy didn't last long because developers were in an uproar about it and how it would make the code unreadable.
I once worked under the tyranny of the Mighty VB King.
The VB King was the pure master of MS Excel and VBA, as well as databases (Hence his surname : He played with Excel while the developers worked with compilers, and challenging him on databases could have detrimental effects on your career...).
Of course, his immense skills gave him an unique vision of development problems and project management solutions: While not exactly coding standards in the strictest sense, the VB King regularly had new ideas about "coding standards" and "best practices" he tried (and oftentimes succeeded) to impose on us. For example:
All C/C++ arrays shall start at index 1, instead of 0. Indeed, the use of 0 as first index of an array is obsolete, and has been superseded by Visual Basic 6's insightful array index management.
All functions shall return an error code: There are no exceptions in VB6, so why would we need them at all? (i.e. in C++)
Since "All functions shall return an error code" is not practical for functions returning meaningful types, all functions shall have an error code as first [in/out] parameter.
All our code will check the error codes (this led to the worst case of VBScript if-indentation I ever saw in my career... Of course, as the "else" clauses were never handled, no error was actually found until too late).
Since we're working with C++/COM, starting this very day, we will code all our DOM utility functions in Visual Basic.
ASP 115 errors are evil. For this reason, we will use On Error Resume Next in our VBScript/ASP code to avoid them.
XSL-T is an object oriented language. Use inheritance to resolve your problems (dumb surprise almost broke my jaw open this one day).
Exceptions are not used, and thus should be removed. For this reason, we will uncheck the checkbox asking for destructor call in case of exception unwinding (it took days for an expert to find the cause of all those memory leaks, and he almost went berserk when he found out they had willingly ignored (and hidden) his technical note about checking the option again, sent handfuls of weeks before).
catch all exceptions in the COM interface of our COM modules, and dispose them silently (this way, instead of crashing, a module would only appear to be faster... Shiny!... As we used the über error handling described above, it even took us some time to understand what was really happening... You can't have both speed and correct results, can you?).
Starting today, our code base will split into four branches. We will manage their synchronization and integrate all bug corrections/evolutions by hand.
All but the C/C++ arrays, VB DOM utility functions and XSL-T as OOP language were implemented despite our protests. Of course, over the time, some were discovered, ahem, broken, and abandoned altogether.
Of course, the VB King credibility never suffered for that: Among the higher management, he remained a "top gun" technical expert...
This produced some amusing side effects, as you can see by following the link What is the best comment in source code you have ever encountered?
Back in the 80's/90's, I worked for an aircraft simulator company that used FORTRAN. Our FORTRAN compiler had a limit of 8 characters for variable names. The company's coding standards reserved the first three of them for Hungarian-notation style info. So we had to try and create meaningful variable names with just 5 characters!
I worked at a place that had a merger between 2 companies. The 'dominant' one had a major server written in K&R C (i.e. pre-ANSI). They forced the Java teams (from both offices -- probably 20 devs total) to use this format, which gleefully ignored the 2 pillars of the "brace debate" and goes straight to crazy:
if ( x == y )
{
System.out.println("this is painful");
x = 0;
y++;
}
Forbidden:
while (true) {
Allowed:
for (;;) {
a friend of mine - we'll call him CodeMonkey - got his first job out of college [many years ago] doing in-house development in COBOL. His first program was rejected as 'not complying with our standards' because it used... [shudder!] nested IF statements
the coding standards banned the use of nested IF statements
now, CodeMonkey was not shy and was certain of his abilities, so he persisted in asking everyone up the chain and down the aisle why this rule existed. Most claimed they did not know, some made up stuff about 'readability', and finally one person remembered the original reason: the first version of the COBOL compiler they used had a bug and didn't handle nested IF statements correctly.
This compiler bug, of course, had been fixed for at least a decade, but no one had challenged the standards. [baaa!]
CodeMonkey was successful in getting the standards changed - eventually!
Once worked on a project where underscores were banned. And I mean totally banned. So in a c# winforms app, whenever we added a new event handler (e.g. for a button) we'd have to rename the default method name from buttonName_Click() to something else, just to satisfy the ego of the guy that wrote the coding standards. To this day I don't know what he had against the humble underscore
Totally useless database naming conventions.
Every table name has to start with a number. The numbers show which kind of data is in the table.
0: data that is used everywhere
1: data that is used by a certain module only
2: lookup table
3: calendar, chat and mail
4: logging
This makes it hard to find a table if you only know the first letter of its name.
Also - as this is a mssql database - we have to surround tablenames with square brackets everywhere.
-- doesn't work
select * from 0examples;
-- does work
select * from [0examples];
We were doing a C++ project and the team lead was a Pascal guy.
So we had a coding standard include file to redefine all that pesky C and C++ syntax:
#define BEGIN {
#define END }
but wait there's more!
#define ENDIF }
#define CASE switch
etc. It's hard to remember after all this time.
This took what would have been perfectly readable C++ code and made it illegible to anyone except the team lead.
We also had to use reverse Hungarian notation, i.e.
MyClass *class_pt // pt = pointer to type
UINT32 maxHops_u // u = uint32
although oddly I grew to like this.
At a former job:
"Normal" tables begin with T_
"System" tables (usually lookups) begin with TS_ (except when they don't because somebody didn't feel like it that day)
Cross-reference tables begin with TSX_
All field names begin with F_
Yes, that's right. All of the fields, in every single table. So that we can tell it's a field.
A buddy of mine encountered this rule while working at a government job. The use of ++ (pre or post) was completely banned. The reason: Different compilers might interpret it differently.
Half of the team favored four-space indentation; the other half favored two-space indentation.
As you can guess, the coding standard mandated three, so as to "offend all equally" (a direct quote).
Not being able to use Reflection as the manager claimed it involved too much 'magic'.
The very strangest one I had, and one which took me quite some time to overthrow, was when the owner of our company demanded that our new product be IE only. If it could work on FireFox, that was OK, but it had to be IE only.
This might not sound too strange, except for one little flaw. All of the software was for a bespoke server software package, running on Linux, and all client boxes that our customer was buying were Linux. Short of trying to figure out how to get Wine (in those days, very unreliable) up and running on all of these boxes and seeing if we could get IE running and training their admins how to debug Wine problems, it simply wasn't possible to meet the owner's request. The problem was that he was doing the Web design and simply didn't know how to make Web sites compliant with FireFox.
It probably won't shock you to know that that our company went bankrupt.
Using generic numbered identifier names
At my current work we have two rules which are really mean:
Rule 1: Every time we create a new field in a database table we have to add additional reserve fields for future use. These reserve fields are numbered (because no one knows which data they will hold some day) The next time we need a new field we first look for an unused reserve field.
So we end up with with customer.reserve_field_14 containing the e-mail address of the customer.
At one day our boss thought about introducing reserve tables, but fortunatly we could convince him not to do it.
Rule 2: One of our products is written in VB6 and VB6 has a limit of the total count of different identifier names and since the code is very large, we constantly run into this limit. As a "solution" all local variable names are numbered:
Lvarlong1
Lvarlong2
Lvarstr1
...
Although that effectively circumvents the identifier limit, these two rules combined lead to beautiful code like this:
...
If Lvarbool1 Then
Lvarbool2 = True
End If
If Lvarbool2 Or Lvarstr1 <> Lvarstr5 Then
db.Execute("DELETE FROM customer WHERE " _
& "reserve_field_12 = '" & Lvarstr1 & "'")
End If
...
You can imagine how hard it is to fix old or someone else's code...
Latest update: Now we are also using "reserve procedures" for private members:
Private Sub LSub1(Lvarlong1 As Long, Lvarstr1 As String)
If Lvarlong1 >= 0 Then
Lvarbool1 = LFunc1(Lvarstr1)
Else
Lvarbool1 = LFunc6()
End If
If Lvarbool1 Then
LSub4 Lvarstr1
End If
End Sub
EDIT: It seems that this code pattern is becoming more and more popular. See this The Daily WTF post to learn more: Astigmatism :)
Back in my C++ days we were not allowed to use ==,>=, <=,&&, etc. there were macros for this ...
if (bob EQ 7 AND alice LEQ 10)
{
// blah
}
this was obviously to deal with the "old accidental assignment in conditional bug", however we also had the rule "put constants before variables", so
if (NULL EQ ptr); //ok
if (ptr EQ NULL); //not ok
Just remembered, the simplest coding standard I ever heard was "Write code as if the next maintainer is a vicious psychopath who knows where you live."
Hungarian notation in general.
I've had a lot of stupid rules, but not a lot that I considered downright strange.
The sillyiest was on a NASA job I worked back in the early 90's. This was a huge job, with well over 100 developers on it. The experienced developers who wrote the coding standards decided that every source file should begin with a four letter acronym, and the first letter had to stand for the group that was responsible for the file. This was probably a great idea for the old FORTRAN 77 projects they were used to.
However, this was an Ada project, with a nice hierarchal library structure, so it made no sense at all. Every directory was full of files starting with the same letter, followed by 3 more nonsense leters, an underscore, and then part of the file name that mattered. All the Ada packages had to start with this same five-character wart. Ada "use" clauses were not allowed either (arguably a good thing under normal circumstances), so that meant any reference to any identifier that wasn't local to that source file also had to include this useless wart. There probably should have been an insurrection over this, but the entire project was staffed by junior programmers and fresh from college new hires (myself being the latter).
A typical assignment statement (already verbose in Ada) would end up looking something like this:
NABC_The_Package_Name.X := NABC_The_Package_Name.X +
CXYZ_Some_Other_Package_Name.Delta_X;
Fortunately they were at least enlightened enough to allow us more than 80 columns! Still, the facility wart was hated enough that it became boilerplate code at the top of everyone's source files to use Ada "renames" to get rid of the wart. There'd be one rename for each imported ("withed") package. Like this:
package Package_Name renames NABC_Package_Name;
package Some_Other_Package_Name renames CXYZ_Some_Other_Package_Name;
--// Repeated in this vein for an average of 10 lines or so
What the more creative among us took to doing was trying to use the wart to make an acutally sensible (or silly) package name. (I know what you are thinking, but explitives were not allowed and shame on you! That's disgusting). For example, I was in the Common code group, and I needed to make a package to interface with the Workstation group. After a brainstorming session with the Workstation guy, we decided to name our packages so that someone needing both would have to write:
with CANT_Interface_Package;
with WONT_Interface_Package;
When I started working at one place, and started entering my code into the source control, my boss suddenly came up to me, and asked me to stop committing so much. He told me it is discouraged to do more than 1 commit per-day for a developer because it litters the source control. I simply gaped at him...
Later I understood that the reason he even came up to me about it is because the SVN server would send him (and 10 more high executives) a mail for each commit someone makes. And by littering the source control I guessed he ment his mailbox.
Doing all database queries via stored procedures in Sql Server 2000. From complex multi-table queries to simple ones like:
select id, name from people
The arguments in favor of procedures were:
Performance
Security
Maintainability
I know that the procedure topic is quite controversial, so feel free to score my answer negatively ;)
There must be 165 unit tests (not necessarily automated) per 1000 lines of code. That works out at one test for roughly every 8 lines.
Needless to say, some of the lines of code are quite long, and functions return this pointers to allow chaining.
We had to sort all the functions in classes alphabetically, to make them "easier to find".
Never mind the ide had a drop down. That was too many clicks.
(same tech lead wrote an app to remove all comments from our source code).
In 1987 or so, I took a job with a company that hired me because I was one of a small handful of people who knew how to use Revelation. Revelation, if you've never heard of it, was essentially a PC-based implementation of the Pick operating system - which, if you've never heard of it, got its name from its inventor, the fabulously-named Dick Pick. Much can be said about the Pick OS, most of it good. A number of supermini vendors (Prime and MIPS, at least) used Pick, or their own custom implementations of it.
This company was a Prime shop, and for their in-house systems they used Information. (No, that was really its name: it was Prime's implementation of Pick.) They had a contract with the state to build a PC-based system, and had put about a year into their Revelation project before the guy doing all the work, who was also their MIS director, decided he couldn't do both jobs anymore and hired me.
At any rate, he'd established a number of coding standards for their Prime-based software, many of which derived from two basic conditions: 1) the use of 80-column dumb terminals, and 2) the fact that since Prime didn't have a visual editor, he'd written his own. Because of the magic portability of Pick code, he'd brought his editor down into Revelation, and had built the entire project on the PC using it.
Revelation, of course, being PC-based, had a perfectly good full-screen editor, and didn't object when you went past column 80. However, for the first several months I was there, he insisted that I use his editor and his standards.
So, the first standard was that every line of code had to be commented. Every line. No exceptions. His rationale for that was that even if your comment said exactly what you had just written in the code, having to comment it meant you at least thought about the line twice. Also, as he cheerfully pointed out, he'd added a command to the editor that formatted each line of code so that you could put an end-of-line comment.
Oh, yes. When you commented every line of code, it was with end-of-line comments. In short, the first 64 characters of each line were for code, then there was a semicolon, and then you had 15 characters to describe what your 64 characters did. In short, we were using an assembly language convention to format our Pick/Basic code. This led to things that looked like this:
EVENT.LIST[DATE.INDEX][-1] = _ ;ADD THE MOST RECENT EVENT
EVENTS[LEN(EVENTS)] ;TO THE END OF EVENT LIST
(Actually, after 20 years I have finally forgotten R/Basic's line-continuation syntax, so it may have looked different. But you get the idea.)
Additionally, whenever you had to insert multiline comments, the rule was that you use a flower box:
************************************************************************
** IN CASE YOU NEVER HEARD OF ONE, OR COULDN'T GUESS FROM ITS NAME, **
** THIS IS A FLOWER BOX. **
************************************************************************
Yes, those closing asterisks on each line were required. After all, if you used his editor, it was just a simple editor command to insert a flower box.
Getting him to relent and let me use Revelation's built-in editor was quite a battle. At first he was insistent, simply because those were the rules. When I objected that a) I already knew the Revelation editor b) it was substantially more functional than his editor, c) other Revelation developers would have the same perspective, he retorted that if I didn't train on his editor I wouldn't ever be able to work on the Prime codebase, which, as we both knew, was not going to happen as long as hell remained unfrozen over. Finally he gave in.
But the coding standards were the last to go. The flower-box comments in particular were a stupid waste of time, and he fought me tooth and nail on them, saying that if I'd just use the right editor maintaining them would be perfectly easy. (The whole thing got pretty passive-aggressive.) Finally I quietly gave in, and from then on all of the code I brought to code reviews had his precious flower-box comments.
One day, several months into the job, when I'd pretty much proven myself more than competent (especially in comparison with the remarkable parade of other coders that passed through that office while I worked there), he was looking over my shoulder as I worked, and he noticed I wasn't using flower-box comments. Oh, I said, I wrote a source-code formatter that converts my comments into your style when I print them out. It's easier than maintaining them in the editor. He opened his mouth, thought for a moment, closed it, went away, and we never talked about coding standards again. Both of our jobs got easier after that.
At my first job, all C programs, no matter how simple or complex, had only four functions. You had the main, which called the other three functions in turn. I can't remember their names, but they were something along the lines of begin(), middle(), and end(). begin() opened files and database connections, end() closed them, and middle() did everything else. Needless to say, middle() was a very long function.
And just to make things even better, all variables had to be global.
One of my proudest memories of that job is having been part of the general revolt that led to the destruction of those standards.
An externally-written C coding standard that had the rule 'don't rely on built in operator precedence, always use brackets'
Fair enough, the obvious intent was to ban:
a = 3 + 6 * 2;
in favour of:
a = 3 + (6 * 2);
Thing was, this was enforced by a tool that followed the C syntax rules that '=', '==', '.' and array access are operators. So code like:
a[i].x += b[i].y + d - 7;
had to be written as:
((a[i]).x) += (((b[i]).y + d) - 7);

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