Parsing pem certificates with OpenSSL can fail for various reasons after calling SSL_CTX_use_certificate(), listed as constants in openssl/x509_vfy.h, for instance X509_V_ERR_CA_MD_TOO_WEAK. In this case however, ERR_get_error() only returns 0x0A00018E, and SSL_get_error() doesn't apply to error handling of SSL_CTX_use_certificate() according to the documentation.
Calling ERR_print_error_fp(stderr) however prints X509_V_ERR_CA_MD_TOO_WEAK as the main problem in this case.
How can I catch individual errors as listed in openssl/err_vfy.h without parsing the text returned by ERR_print_error_fp() (which I consider inelegant and non portable)?
Related
When using Mockito with Kotlin, if I try to verify Mock calls, it work fine like (this is in a Spring test):
#MockBean
lateinit var fragmentProcessor: FragmentProcessor
verify(fragmentProcessor, timeout(20000)).processFragment(expectedFragment)
that gives the expected behaviour... but just doing something like:
verify(fragmentProcessor, timeout(20000)).processFragment(Mockito.eq(expectedFragment))
will give the following error:
Missing method call for verify(mock) here:
-> at uk.co.argos.productapi.services.kafka.KafkaConsumerServiceTest.testFragmentProcessorReceivesMessages(KafkaConsumerServiceTest.kt:47)
Example of correct verification:
verify(mock).doSomething()
Also, this error might show up because you verify either of: final/private/equals()/hashCode() methods.
Those methods *cannot* be stubbed/verified.
Mocking methods declared on non-public parent classes is not supported.
the same happens with ArgumentCaptor or other matchers
Are you sure that you call fragmentProcessor.processFragment(expectedFragment) somewhere in your code before verify times out?
Error message says that you don't, so verify throws an exception (as it should do).
In this line:
verify(fragmentProcessor, timeout(20000)).processFragment(expectedFragment)
You don't use verify correctly (you have to use Mockito.eq): it doesn't verify anything so doesn't throw, but it doesn't mean that it works as you suppose.
I've made a large program that opens and closes files and databases, perform writes and reads on them etc among other things. Since there no such thing as "exception handling in go", and since I didn't really know about "defer" statement and "recover()" function, I applied error checking after every file-open, read-write, database entry etc. E.g.
_,insert_err := stmt.Run(query)
if insert_err != nil{
mylogs.Error(insert_err.Error())
return db_updation_status
}
For this, I define db_updation_status at the beginning as "false" and do not make it "true" until everything in the program goes right.
I've done this in every function, after every operation which I believe could go wrong.
Do you think there's a better way to do this using defer-panic-recover? I read about these here http://golang.org/doc/articles/defer_panic_recover.html, but can't clearly get how to use them. Do these constructs offer something similar to exception-handling? Am I better off without these constructs?
I would really appreciate if someone could explain this to me in a simple language, and/or provide a use case for these constructs and compare them to the type of error handling I've used above.
It's more handy to return error values - they can carry more information (advantage to the client/user) than a two valued bool.
What concerns panic/recover: There are scenarios where their use is completely sane. For example, in a hand written recursive descent parser, it's quite a PITA to "bubble" up an error condition through all the invocation levels. In this example, it's a welcome simplification if there's a deferred recover at the top most (API) level and one can report any kind of error at any invocation level using, for example
panic(fmt.Errorf("Cannot %v in %v", foo, bar))
If an operation can fail and returns an error, than checking this error immediately and handling it properly is idiomatic in go, simple and nice to check if anything gets handled properly.
Don't use defer/recover for such things: Needed cleanup actions are hard to code, especially if stuff gets nested.
The usual way to report an error to a caller is to return an error as an extra return value. The canonical Read method is a well-known instance; it returns a byte count and an error.
But what if the error is unrecoverable? Sometimes the program simply cannot continue.
For this purpose, there is a built-in function panic that in effect creates a run-time error that will stop the program (but see the next section). The function takes a single argument of arbitrary type—often a string—to be printed as the program dies. It's also a way to indicate that something impossible has happened, such as exiting an infinite loop.
http://golang.org/doc/effective_go.html#errors
I have a set of classes to which I am trying to apply unit tests, to maintain their current utility through future revisions.
My problem is that within CPPUNIT, to which I am new, where-ever I call CPPUNIT_ASSERT ( [condition] ), I am met with Error Unhandled Exception...: Access Violation at 0xffffffffffffffff.
This happens even I write the simplest test case
int main(){
CPPUNIT_ASSERT ( true );
}
I have tried calling my testing functions with manual calls, as well as adding them to a registry, as is done in the Money example. The problem reportedly arises within the constructor for SourceLine, as the filename string it expects is a bad pointer.
After a bit of a search I've found that this is called within the CPPUNIT_ASSERT, as it's a macro with the following definition
#define CPPUNIT_ASSERT(condition) \
( CPPUNIT_NS::Asserter::failIf( !(condition), \
CPPUNIT_NS::Message( "assertion failed", \
"Expression: " #condition), \
CPPUNIT_SOURCELINE() ) )
I've searched the tutorials on CppUnit's site, and scrutinised stackoverflow, but I have not found anything that addresses this in particular. I do find it strange that what is, in every example I've seen, a single-parameter function (assert), will call another function with no arguments (sourceline) that is actually another macro that is assuming it receives a string, but can receive no such thing. I found that SourceLine is a class that still has a default constructor, but above is called a macro, which really refers to the 2-parameter constructor, but is passed no arguments that I can see. I am at a loss.
I am using a 64 bit compilation of CppUnit, verified with a dumpbin, and Visual Studio 2008.
Cppunit's assertion system uses macros so it is expected that your simple example complains about unhandled exception.
Normally you don't use an assertion outside of a test method. I suggest you have a look at the Cppunit Cookbook which provides some information and examples how to effectively use cppunit.
I have an antlr generated Java parser that uses the C target and it works quite well. The problem is I also want it to parse erroneous code and produce a meaningful AST. If I feed it a minimal Java class with one import after which a semicolon is missing it produces two "Tree Error Node" objects where the "import" token and the tokens for the imported class should be.
But since it parses the following code correctly and produces the correct nodes for this code it must recover from the error by adding the semicolon or by resyncing. Is there a way to make antlr reflect this fixed input it produces internally in the AST? Or can I at least get the tokens/text that produced the "Tree Node Errors" somehow?
In the C targets
antlr3commontreeadaptor.c around line 200 the following fragment indicates that the C target only creates dummy error nodes so far:
static pANTLR3_BASE_TREE
errorNode (pANTLR3_BASE_TREE_ADAPTOR adaptor, pANTLR3_TOKEN_STREAM ctnstream, pANTLR3_COMMON_TOKEN startToken, pANTLR3_COMMON_TOKEN stopToken, pANTLR3_EXCEPTION e)
{
// Use the supplied common tree node stream to get another tree from the factory
// TODO: Look at creating the erronode as in Java, but this is complicated by the
// need to track and free the memory allocated to it, so for now, we just
// want something in the tree that isn't a NULL pointer.
//
return adaptor->createTypeText(adaptor, ANTLR3_TOKEN_INVALID, (pANTLR3_UINT8)"Tree Error Node");
}
Am I out of luck here and only the error nodes the Java target produces would allow me to retrieve the text of the erroneous nodes?
I haven't used antlr much, but typically the way you handle this type of error is to add rules for matching wrong syntax, make them produce error nodes, and try to fix up after errors so that you can keep parsing. Fixing up afterwards is the problem because you don't want one error to trigger more and more errors for each new token until the end.
I solved the problem by adding new alternate rules to the grammer for all possible erroneous statements.
Each Java import statement gets translated to an AST subtree with the artificial symbol IMPORT as the root for example. To make sure that I can differentiate between ASTs from correct and erroneous code the rules for the erroneous statements rewrite them to an AST with a root symbol with the prefix ERR_, so in the example of the import statement the artifical root symbol would be ERR_IMPORT.
More different root symbols could be used to encode more detailed information about the parse error.
My parser is now as error tolerant as I need it to be and it's very easy to add rules for new kinds of erroneous input whenever I need to do so. You have to watch out to not introduce any ambiguities into your grammar, though.
In my language I can use a class variable in my method when the definition appears below the method. It can also call methods below my method and etc. There are no 'headers'. Take this C# example.
class A
{
public void callMethods() { print(); B b; b.notYetSeen();
public void print() { Console.Write("v = {0}", v); }
int v=9;
}
class B
{
public void notYetSeen() { Console.Write("notYetSeen()\n"); }
}
How should I compile that? what i was thinking is:
pass1: convert everything to an AST
pass2: go through all classes and build a list of define classes/variable/etc
pass3: go through code and check if there's any errors such as undefined variable, wrong use etc and create my output
But it seems like for this to work I have to do pass 1 and 2 for ALL files before doing pass3. Also it feels like a lot of work to do until I find a syntax error (other than the obvious that can be done at parse time such as forgetting to close a brace or writing 0xLETTERS instead of a hex value). My gut says there is some other way.
Note: I am using bison/flex to generate my compiler.
My understanding of languages that handle forward references is that they typically just use the first pass to build a list of valid names. Something along the lines of just putting an entry in a table (without filling out the definition) so you have something to point to later when you do your real pass to generate the definitions.
If you try to actually build full definitions as you go, you would end up having to rescan repatedly, each time saving any references to undefined things until the next pass. Even that would fail if there are circular references.
I would go through on pass one and collect all of your class/method/field names and types, ignoring the method bodies. Then in pass two check the method bodies only.
I don't know that there can be any other way than traversing all the files in the source.
I think that you can get it down to two passes - on the first pass, build the AST and whenever you find a variable name, add it to a list that contains that blocks' symbols (it would probably be useful to add that list to the corresponding scope in the tree). Step two is to linearly traverse the tree and make sure that each symbol used references a symbol in that scope or a scope above it.
My description is oversimplified but the basic answer is -- lookahead requires at least two passes.
The usual approach is to save B as "unknown". It's probably some kind of type (because of the place where you encountered it). So you can just reserve the memory (a pointer) for it even though you have no idea what it really is.
For the method call, you can't do much. In a dynamic language, you'd just save the name of the method somewhere and check whether it exists at runtime. In a static language, you can save it in under "unknown methods" somewhere in your compiler along with the unknown type B. Since method calls eventually translate to a memory address, you can again reserve the memory.
Then, when you encounter B and the method, you can clear up your unknowns. Since you know a bit about them, you can say whether they behave like they should or if the first usage is now a syntax error.
So you don't have to read all files twice but it surely makes things more simple.
Alternatively, you can generate these header files as you encounter the sources and save them somewhere where you can find them again. This way, you can speed up the compilation (since you won't have to consider unchanged files in the next compilation run).
Lastly, if you write a new language, you shouldn't use bison and flex anymore. There are much better tools by now. ANTLR, for example, can produce a parser that can recover after an error, so you can still parse the whole file. Or check this Wikipedia article for more options.