libcsdbg
Contents
1. e UNIX standard tools such as rm mkdir cp In ldconfig Unpack the archive unless you already have done that tar xjpf x86_64 linux dbg libcsdbg 1 15 tar bz2 or tar xjpf x86_64 linux libcsdbg 1 15 tar bz2 Then install it cd x86_64 linux dbg libcsdbg 1 15 sudo sh install or cd x86_64 linux libcsdbg 1 15 sudo sh install If you install as a simple user not root use of sudo is essential if you want to keep the default prefix usr local Installing in another prefix doesn t need root privilege but the dynamic loader configuration file Id so conf will not be updated Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 1 3 Installation 7 The install script should flawlessly install libcsdbg library headers and other project files examples e t c using usr local as the prefix If you want to alter the installation prefix edit the Makefile and change PREFIX to a path of your choice For an overview of other install script options and modes of operation use sh install h Project libcsdbg installer Usage install u h install will install its target by default The following options change the default behaviour u Uninstall the package make uninstall h Show this message 1 3 3 Verify installation If all project components are correctly built and installed the directory used as prefix usr local by default will have something like the following layout2. usr local bin r rWXr xr x root root 50851 Jan 5 15 36 csdbg_stepl r rWXr xr x root root 56811 Jan 5 15 36 csdbg_step2 rwxr Xr X root root 57151 Jan 5 15 36 csdbg_step3 r rWXr xr x root root 67683 Jan 5 15 36 csdbg_step4 rWXr xr x root root 35929 Jan 5 15 36 csdbg_tutl r rWXr xr x root root 36191 Jan 5 15 36 csdbg_tut2 r rWXr xr x root root 36311 Jan 5 15 36 csdbg_tut3 rwxr Xr xX root root 39343 Jan 5 15 36 csdbg_tut4 rwxr Xr xX root root 38057 Jan 5 15 36 csdbg_tut5 usr local include drwxr xr x 2 root root 4096 Jan 5 15 36 csdbg rw r r root root 853 Jan 5 15 36 csdbg hpp usr local include csdbg rw r r root root 700 Jan 5 15 36 call hpp rw r r 1 root root 7251 Jan 5 15 36 chain hpp rw r r 1 root root 5321 Jan 5 15 36 config App rw r r root root 1591 Jan 5 15 36 exception hpp rw r r root root 1291 Jan 5 15 36 filebuf hpp rw Yr r root root 1900 Jan 5 15 36 name_space hpp rw Yr r root root 3343 Jan 5 15 36 node hpp rw r r root root 504 Jan 5 15 36 object hpp Siweresre root root 2277 Jan 5 15 36 plugin hpp rw r r root root 5822 Jan 5 15 36 stack hpp rw r r root root 2020 Jan 5 15 36 streambuf hpp rw r r root root 2214 Jan 5 15 36 string hpp rw r r root root 793 Jan 5 15 36 symbol hpp rw r r root root 1908 Jan 5 15 36 symbol_table hpp rw r r root root 2211 Jan 5 15 36 tcpsockbuf hpp rw r r 1 root root 1474 Jan 5 15 36 thread hpp
3. path usr local bin csdbg_step4 pid 7064 tid 7 85dc174700 tstamp 4ee23066d8960 at thread 0x7f 85dc174700 at csdbg_extra pthread_main void at csdbg_extra start char const unsigned char csdbg_step4 cpp 139 at csdbg_extra add_one_level char const unsigned short csdbg_step4 cpp 158 at void csdbg_extra middle lt csdbg string gt csdbg string amp unsigned int amp csdbg_step4 cpp 165 at csdbg_extra bottom char const unsigned long long volatile void double csdbg_step4 cpp 176 Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 14 CONTENTS Project j Tracer is a libcsdbg sister project a portable LDP server implemented with Java Each application that uses the libcsdbg LDP API can implement a jTracer client This can be essential for cross platform development with embedded devices and development boards Most often target platforms such as these don t have a screen or other resources to visualize output and data collection during the development and debugging cycles is controlled at a workstation through ethernet or serial ports Instead of cluttering the IDE console or debugger with trace data LDP is designed to isolate these generated data collect them with jTracer even from multiple target hosts with diverse architectures and provide an easy way to navigate through them 1 5 5 5 5 Buffered output streams Subclassing the abstract class csdbg streambuf is the standard way
4. 14 you can patch it to upgrade it to the latest release libesdbg 1 14 tar bz2 upgrade 1 15 patch If you have both these files in the same directory to apply the patch execute tar xjpf libcsdbg 1 14 tar bz2 cd libcsdbg 1 14 patch pl lt upgrade 1 15 patch There are also binary distributions for 64 bit Linux debug and release versions compiled on Ubuntu 13 04 TLS libbfd 2 22 X36 64 lLinuxs lt lLipescbog 1 sis tar bz 286 64 Linux dbq libesdbg 1 1s tar bz2 The project documentation exists in the binary distributions and can be recreated with doxygen in the source code distributions It can also be separately downloaded in HTML or as a single hyperlinked PDF document apl ret libesdbgq 1 15 tar be2 user manual libcsdbg 1 15 pdf Finally if you want an overview of all project files check the libcsdbg repository at sourceforge net Click on any file s info icon and obtain its SHA1 or MD5 checksum to verify the file you ve downloaded After you download any project file remember to subscribe follow libcsdbg in order to receive notification about new releases updates news announcements and other libcsdbg related material in your mailbox The easiest way to do so is to visitthe Libcsdbg project page at freecode comand click on follow 1 3 Installation 1 3 1 Compile the sources Unix Linux If you downloaded the source distribution you need at least the following to build the library
5. can select which DSO symbol tables to load and which to discard by declaring the CSDBG_LIBS shell variable as a delimited list of POSIX extended regular expressions The absolute path of each DSO is matched against each regexp If one matches then the symbol table of the DSO is loaded to the libcsdbg namespace and the DSO functions are instrumented throughout execution If CSDBG_LIBS is not set all linked DSO symbol tables will be loaded If it is set with a void value all DSO are filtered out from instrumentation You should only load DSO that are compiled with libcsdbg support Loading non instrumented DSO is not a problem apart from additional overhead For example to run the example programs you must execute export CSDBG_LIBS csdbg_test Another shell variable you may care to set is CSDBG_PEER In case you utilize any csdbg tcpsockbuf object to implement an LDP j Tracer client this variable tells these objects the default server IP address and TCP port if not set programmatically as the constructor arguments It must be formatted as IPaddress TCPport If the port is omitted the default LDP port 4242 is assumed Generally to get the value of such shell variables parsed to their components you need to use the csdbg tracer getenv method instead of the equivalent libe function Libcsdbg can also accept command line arguments To avoid conflicts with the application and its command line arguments the ones for libcsdbg are prefix
6. errors to the user Users may use it or even subclass it for their own needs An exception object can be constructed using printf style formatting and a variable argument list for its error message Inside the constructor copy constructor and assignment operator other formatting or allocation exceptions may be recursively thrown but they are internally caught and silently ignored In these cases the object is still safe to use by ignoring its error message The std ostream insertion operator implementation and all exception methods take this into account Although an exception object is not thread safe by itself all overloaded std ostream insertion operator implementations that output exceptions synchronize thread access Class csdbg string A string object is mainly used to create trace text Text is easily appended using printf style format strings ex panded with variable argument lists Memory is allocated in blocks aligning to reduce overhead when appending multiple small strings It is comparable against POSIX extended regular expressions By creating traces in string buffers it is easy to direct library output to any kind of stream console file serial network plugin device e t c Apart from traces a string can be used for generic dynamic text manipulation This class is not thread safe the caller must implement thread sychronization Data structure classes csdbg node csdbg chain and csdbg stack A node can be instantiated only
7. interfaces to output traces to files and to sockets connected to LDP servers Fourth step example csdbg_step4 cpp This is the final all inclusive example It builds on all previous examples and demonstrates all libcsdbg tricks and features from working with multithreaded programs and DSO to doing output to files and LDP servers The tutorial are the simplest possible programs showing how to perform a simple single task using one of the libcsdbg interfaces First tutorial example csdbg_tut1 cpp Simple exception stack trace output to console Second tutorial example csdbg_tut2 cpp Simple thread stack trace output to console Third tutorial example csdbg_tut3 cpp Simple thread stack trace output to a file Fourth tutorial example csdbg_tut4 cpp Simple thread stack trace output to a client socket connected to an LDP server Fifth tutorial example csdbg_tut5 cpp This tutorial demonstrates the use of instrumentation plugins and plugin modules DSO The example plugin module PREFIX lib modules libcsdbg mod_null so must be visible from the dynamic linker so its path must be declared in Id so conf or in the LD_LIBRARY_PATH shell variable Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen
8. n fout open fout flush fout close 1 5 5 2 5 5 2 Using csdbg tcpsockbuf A csdbg tcpsockbuf object is a buffered output stream than can be used to implement the client side of the LDP Libcsdbg Debug Protocol or a generic TCP IP client socket Nevertheless this class is optimized for LDP and generally for unidirectional protocols If you need to implement a bidirectional protocol you must subclass tcpsockbuf This class is not thread safe the caller must implement thread synchronization A tcpsockbuf object inherits all the csdbg string methods designed for text manipulation append clear set e t c You use these methods to process the buffer data or the csdbg tracer methods to store traces to the buffer Then you may connect the socket to its peer and flush clear the buffer You can re fill and re flush as many times as you wish before you close disconnect the tcpsockbuf Disconnecting closing or shutting down the socket is just the opposite of open connect it doesn t release the object and its buffer so you may re connect it The steps to use a tcpsockbuf object are 1 Create a tcpsockbuf object for a peer IP address and TCP port 2 Connect to the peer 3 Append set text data in the buffer 4 Flush the buffer 5 Repeat steps 3 4 until completion 6 Disconnect 7 Repeat steps 2 6 until completion 8 Release the object Step 2 in this list can be inserted anywhere within steps 2 4 you don t nee
9. t c LDP is a unidirectional client server protocol Unidirectional because only the client sends trace data to the server the server need not aknowledge or reply in any way The only role that the server plays in LDP is to collect these data from multiple and possibly of variant architecture and OS client peers and store them or let a user collectively navigate through them and process them LDP is designed as a message oriented protocol like HTTP A single connection kept alive can be used to send multiple messages but this is not mandatory it is up to the implementation Nevertheless two LDP messages are not connected in any way and can be thought as two separate LDP sessions This is a pseudo BNF description of a message e The message consists of a head and a body separated by an empty line r n The head consists of a number of headers Each header is formatted as key value r n e Header numeric values are hexadecimal no Ox prefix e The message body is the whole trace e The message is terminated by an empty line This is the generic layout keyl valuel r n key2 value2 r n keyN valueN r n r n trace data r n r n The mandatory protocol headers are for executable absolute path process ID e thread ID e timestamp in microseconds The non mandatory protocol headers are for exception data other user and OEM headers The following is an LDP message created by example csdbg_step4 cpp
10. through the public methods of a chain or stack object When a node is released it also calls delete not delete on its data pointer unless it s previously detached Therefore each node must point to a single T and not a T allocated with operator new not newJ If a node is constructed with a pointer to a T memory leaks are bound to happen When a node is copied or assigned only its data are copied not the position in its container The data copy works for any type integral or user defined except arrays Data copying invokes T const T amp or T operator const T amp exceptions thrown from these methods are not handled by the node nor its container they are just propagated up the call stack The chain supports shared data multiple chains can point to the same data but it is not thread safe callers should synchronize thread access This implementation doesn t allow a node with a NULL or a duplicate data pointer A node can be detached dispose the node without deleting its data or removed dispose both node and data A chain can be traversed using simple callbacks and method csdbg chain foreach The stack supports shared data multiple stacks can point to the same data but it is not thread safe callers should synchronize thread access This implementation doesn t allow a node with a NULL or a duplicate data pointer A stack can be traversed using simple callbacks and method stack foreach Apart from the legacy push pop fu
11. RSE EE Oe ee ae Y 17 1 Overview 1 1 Introduction 1 1 1 Description Project libesdbg is mainly a C exception stack tracer When an exception is thrown caught and handled lipbcsdbg offers the tools to create and process the exception stack trace the path the exception has propagated up the call stack unwinding it up to the section were it was handled The traces are detailed with demangled function signatures and additional addr2line info the source code file and line that each function was called Libcsdbg will perform flawlessly with single and multithreaded or multiprocess programs with any dynamically linked shared object DSO Dynamic Shared Object and with any statically linked library Additionally libcsdbg helps the developer tester create sophisticated stack traces of any thread at any given moment during a process execution or create a dump of the call stacks of all threads as a snapshot of the runtime call graph This is very useful in cases of fatal errors reception of terminating signals or process abortion termination such as segmentation faults In an object oriented programming paradigm it s usually not enough to catch and handle an exception It s essential to know at runtime where in the code and under what circumstances the exception was thrown and also the path that the exception followed from the throw point up to the point where it was caught Although much of this information can be embedded inside the exc
12. ack Subminor releases are stable beta snapshots of the current code development status with the last additions since the last minor update The following are locations essential to the development of libcsdbg Website e libcsdbg sourceforge libcsdbg freecode Downloads e Release News Forum Support e jTracer website jJTracer freecode 1 2 Obtaining the sources The latest version of libcsdbg is 1 15 release date January 5th 2014 This version introduces the first implementation of the instrumentation plugins and the corresponding examples and tutorials It also introduces the first edition of the project user manual A plugin object is the way to declare a pair of instrumentation functions and register them with libcsdbg to be run upon function call and return A plugin can be created by passing it the addresses of the instrumentation functions or by loading a plugin module DSO that implements and exports these two functions Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 4 CONTENTS The names of the instrumentation functions __cyg_profile_func_enter and __cyg_profile_func_exit are hard coded into g so only a unique implementation of these can exist at linkage time therefore only one profiler can be used at a time The plugin class is the fix to this shortcoming The latest source distribution is Libcsdbg 1 15 tar bz2 Alternatively if you ve already got the previous version 1
13. bfd lpthread will print the flags you must pass to the linker You may need to add PREFIX lib pkgconfig to your pkg config path Stack traces created with libcsdbg can only contain calls to functions that are instrumented by libcsdbg For example if you write code for an application and instrument that code with libcsdbg only these functions you instrument will appear in traces If you link your application with third party DSO the DSO function calls will not appear in the trace by default You need to recompile those DSO to add libcsdbg support As a rule of thumb you should recompile code to add support for libcsdbg if that code throws exceptions and if it is essential to you to see how those exceptions propagated inside the module call graph Even if you don t call a single API method if liocsdbg is compiled with debug support it is easy to see if everything linked properly by just running your application libcsdbg will at least attempt to load its symbol table and it will print various debug messages 1 5 2 5 2 Configuring libcsdbg at runtime Before you run a program linked with libcsdbg there are some things you may want to configure apart from the dynamic linker path to help libcsdbg decide what to load and what to ignore as well as some other runtime config uration tokens Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 10 CONTENTS The symbol table of the program is always loaded by libcsdbg The user
14. d to connect the socket in order to process its buffer it must be connected before you flush the buffer The following is an example of using the tcpsockbuf class using namespace csdbg tracer iface tracer interface if unlikely iface NULL return tcpsockbuf client NULL chain lt string gt peer tracer getenv csdbg g_peer_env if peer NULL client new tcpsockbuf else client new tcpsockbuf peer gt at 0 gt cstr x Log a trace to a socket connected to an LDP server at port 4242 x client gt header client gt append r n iface gt trace xclient pthread_self Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 16 CONTENTS client gt append r n client gt open client gt flush client gt close 1 5 6 5 6 Using the internal libcsdbg API Although now you know everything you need to produce and process any kind of stack trace some libcsdbg types may still come in handy for other more generic purposes although these types are quite specific and optimized for the project This is why some of these classes have some rather tricky details so instead of getting lost in the code and comments to get an idea some of them are shortly described here with some of their most uncommon features Class csdbg exception This type is used internally by libcsdbg to propagate and process errors It is also used by the library to report internal
15. ed with csdbg To feed those arguments to libcsdbg you must call early in your code the csdbg tracer init method This method parses the command line argument vector identifies the arguments for libcsdbg canonicalizes removes the csdbg prefix stores them internally and removes them from the vector so the application never knows they were there These arguments may just be flags or pass values to the library Currently no such argument is utilized and the mechanism is there only for the users to use but in the future the runtime configuration of libcsdbg will be affected by them and or a configuration file 1 5 3 5 3 Using the csdbg tracer API To be able to do anything with libcsdbg even when you use its higher level objects csdbg filebuf csdbg tcpsockbuf e t c you first need to obtain a csdbg tracer object The word is obtain not create because the class constructors destructor and assignment operator are not public The class itself provides you with interfacing tracer objects You must call the csdbg tracer interface static method as seen in the following snippet to obtain a pointer to an interfacing tracer object using namespace csdbg tracer iface tracer interface if unlikely iface NULL ff abort If this call returns NULL that means that library initialization failed to load at least one symbol table You should check the debug and generic output to see why this occured For example this can happ
16. en if all modules and the executable itself are stripped of symbols You don t need to release or otherwise clear the obtained interface object after you are done The library will take care of it internally Read the code and comments of the Examples this will help you understand how to use libcsdbg how to interface with it with code and use its facilities The interface is really very simple and usually it takes one or two lines of code to produce a trace 1 5 3 1 5 3 1 Exception stack traces The best place to create and output or process an exception stack trace is in the catch section that is handling it There are two ways to output such a trace The first is to feed the tracer object to an STL output stream using the insertion operator for example using namespace csdbg tracer iface tracer interface if unlikely iface NULL return try Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 1 5 Usage 11 catch exception amp x std cout lt lt x lt lt r n lt lt xiface lt lt r n iface gt unwind This is the simplest way possible Although inside the tracer object lots of things are happening behind the scenes things that can throw exceptions you don t need to worry they are taken care of internally Moreover the output to an STL stream is atomic in the scope of the library no other library output method will interleave The other way to get the stack
17. entation translations or by answering questions on the mailing list We always welcome users whose only contribution is simply using libcsdbg giving us feedback on how to improve it and telling others about it Thank you for supporting lipcsdbg Donate money If you don t have time to help but do find libcsdbg useful then please consider making a financial donation This will help to pay the bills and motivate us to continue working on libcsdbg You can do so using the Paypal account indicated on the project page at sourcefore net or contact us for other payment methods 1 5 Usage 1 5 1 5 1 Compiling with libcsdbg support Integration with libcsdbg is transparent and simple just compile your code with some g mandatory flags and link with libcsdbg lcsdbg From these g flags the most prominent are finstrument functions and g format You may need to invoke pkg config cflags libcsdbg f PLe 9 finstrument functions finstrument functions exclude file list usr include finstrument functions exclude file list siostream finstrument functions exclude file list ios finstrument functions exclude file list sistream finstrument functions exclude file list sostream finstrument functions exclude file list usr local include csdbg I usr local include to see all the additional flags you must pass to the compiler Similarly pkg config libs libcsdbg L usr local lib L usr local lib modules libcsdbg lcsdbg ldl l
18. eption object this has several drawbacks namely e It s not a complete solution Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 2 CONTENTS e It needs lots of code to keep track the exception objects must have small footprint e It can t function with STL exceptions and integral types e It s difficult to make it generic and portable In Java method exception prinStackTrace can provide this additional exception information because the Java language is interpreted not native as C is To implement this with GNU g libcsdbg exploits the g capability to generate and inject code for function instrumentation Compiling code with the finstrument functions flag commands g to inject code to call the instrumentation functions csdbg instrument_enter csdbg instrument_ exit at the beginning and end of all the instrumented functions The compiled code is linked with libcsdbg that implements these two functions At runtime libcsdbg uses these functions to transparently simulate the call stack of each thread of execution within the debugged process adding only minimum overhead When an exception is thrown the actual thread stack is unwound until a catch section is found or until the process aborts because of the unhandled exception The stack simulator detects there is an exception being thrown and does not unwind so the libcsdbg user can print a stack trace at any place in the code usually in the catch sections
19. f libcsdbg VERSION directory The PDF manual refman pdf will be located in the LaTex directory of the distribution doc user manual libesdbg VERSION Just view and print it via the acrobat reader Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 6 CONTENTS make doc Finally if you need to uninstall all liocsdbg related files from your system make uninstall As said earlier no autotools support exists for the project but this is under way So currently all you can do is edit Makefile to change some options that may give you a headache The Makefile options you may want to alter are PREFIX Where to install libcsdbg PLATFORM The target prefix you need to cross compile the package for example mips linux It is used as the prefix for various binaries in the toolchain LPATHS Additional paths to search for DSO IPATHS Additional paths to search for header files DOPTS Define various preprocessor macros such as word size for the target machine achitecture the default is 64 bits the target machine endianity debug or release mode optimizations include or discard modules e t c GOPTS Various g options such as target machine architecture C standard used throughout compilation e t c 1 3 2 Install a binary distribution Unix Linux If you downloaded the binary distribution you need the following to install and use libcsdbg e GNU make e GNU binutils at least libbfd so v2 22 and addr2line
20. hread e csdbg tracer current_thread Get the current thread descriptor e csdbg tracer thread_by_id Get the thread descriptor for a specific ID e csdbg tracer thread_at Get the thread descriptor at an offset in the thread enumerator This is an example of creating a stack trace for the third thread in the list using namespace csdbg tracer iface tracer interface if unlikely iface NULL return thread thr iface gt thread_at 2 string buf iface gt trace buf thr gt handle Another version of thread stack tracing is to create a batch trace for all the threads within a process This feature is delivered by calling the method csdbg tracer dump This can prove extremely helpful when you want to debug an application that has totally crashed Instead of loading and debugging the core dump ifthe OS supports this you can solve the problem quicker by taking a look at the thread stack traces to see what each was doing and what the then executing thread was doing before the program crashed Here s an example scenario 1 The application setups and registers a handler for the SIGSEGV signal A thread execution creates a memory access violation The process receives a SIGSEGV because of the segmentation fault Pp ON The registered handler creates a stack trace dump for all the threads and stores it in a file using a csdbg filebuf object oa The process aborts There are additional methods i
21. libcsdbg 1 15 Generated by Doxygen 1 8 5 Sun Jan 5 2014 16 11 36 CONTENTS 1 Contents 1 Overview 1 A APUGEINCIOM i i SO a ee OR Ge Pe RS SR Se ee ok ry ee aes 1 LEIL DESCIPUDH cone a ak a ae ee ee Be me RO OE RR ee oe 8 1 Wale FORRES 4 4 2 45 8 6 Rdge i Phi 2d kee ee Se Pee ER PER EEA 8 4 2 TiS Lieenceand Geialls n 6s ka ee A wee ee PE ee eee a a a 3 1e Obtaining ihe SOUICES oe os we ee i a ce a he Ae a a aia 3 to IMStONeOM ke ot ba be eee eb PE ede he ee bh ee Ae a 4 1 3 1 Compile the sources Unix Linux aoaaa a 4 1 3 2 Install a binary distribution Unix Linux lt lt ss rae ee 6 133 veny msalah aos dc ee ak aw Ee ek ae eo a ee Be es a 7 14 Troubleshooting s sc eec ee be bebe dhe bbb GEG4 44 bbb AA eb ee bw hb es 8 Wel BUGTEPONS pora aLe hee Ea Be ee Re Rae Bee a ee hee eS 8 14 2 Howie conttibite 2 See ee eee Bw ee ee ee Sa oe e a 8 Eo USOE e oeda n el Be Re ee ee Ae ae are a ache mee ee A Re ee eee S 9 1 5 1 5 1 Compiling with libcsdbg support ss soos reca ee 9 15 2 2 Conilguring libesdbg at runtime lt s cemara ndia i a ee ee a a 9 153 3 Using the cedbgitracerAPl osos reco epo i eee a a G 10 15 4 54 The Libesaby Debug Protocol LDP o ss ea saa ctra ee dia 13 15 5 5 5 Buffered output streams 2 6 64 ecos saa ce toka ns ewe ir he ws 14 15 6 5 6 Using the internal libesdbg API co sacro aosa somas doraa a i e DnE A 16 18 6 Exampies and TONAS o s soo coe mordi a ve eee SOS Sa A
22. line support e Full support for Position Independent Code for DSO e Works with generic throwables and user defined exception types Support for most of the objective code formats elf a out coff ecoff e t c e Support for both 32 and 64 bit systems e Support for both big and little endian CPUs e Compiled tested for x86 x86_64 ARM AVR32 Leon Project libcsdbg exports an extended well documented and reusable library API to provide e Easy and minimal code interface transparent library integration e Easy library runtime configuration e Transparent but configurable loading of symbol tables of any executable DSO or other module Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 1 2 Obtaining the sources 3 e Instrumentation algorithms add only minimal overhead and memory footprint e The high level API provides thread safety e Smart API to output trace or generic data to files or to network peers with the use of Libesdbg Debug Protocol LDP e Library API can be used as the base for custom instrumentation code Libcsdbg is currently available for GNU Linux uClibc platforms There is development going on to provide a version for Windows 32 and 64 bit systems through MinGW and Unix FreeBSD OpenBSD NetBSD systems along with an GNU autotools based build system and plugins for various IDE Eclipse Code Blocks e t c Project j Tracer is a libcsdbg sister project a portable LDP server implemented with Ja
23. lly not very helpful and it will cost much more time to figure out what you mean In the worst case your bug report may even be completely ignored so always try to include the following information in your bug report The version of libcsdbg you are using use pkg config modversion libcsdbg if you are not sure The name and version number of your operating system uname a e The libcsdbg related shell and CLI variables All libcsdbg output to the console files network that is specific to the problematic scenario The easiest way for us to fix bugs is if you can attach a small example that demonstrates the problem you have to the bug report so we can reproduce it on our machines Please make sure the example is valid source code and that the problem is really captured by the example If you intend to send more than one file please zip or tar the files together into a single file for easier processing You can and are encouraged to add a patch for a bug If you do so please use PATCH as a keyword in the bug entry form or in the email subject If you have ideas how to fix existing bugs and limitations please discuss them on the users forums For patches please use diff uprN or include the files you modified 1 4 2 How to contribute Donate time Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 1 5 Usage 9 You can contribute your time by helping with programming testing and filing bug reports improving docum
24. me in a series of four programs of incremental complexity to cover as many of the features as possible Thats why the examples are treated as steps that the library user must follow to understand the various tricks needed to correctly integrate libcsdbg and exploit it to the maximum These programs will be dynamically linked with libcsdbg so and with the example DSO ibcsdbg_test so so their installation directories SPREFIX lib and PREFIX lib modules libcsdbg must be in the Id path or in the LD_LIBRARY_PATH shell variable You may need to invoke the following line before you run any of the examples export LD_LIBRARY_PATH usr local lib usr local lib modules libcsdbg or in generic export LD_LIBRARY_PATH PREFIX 1lib SPREFIX lib modules libcsdbg Example DSO example libcsdbg_test cpp This example is compiled into a DSO and linked with all of the example executables to demonstrate the flawless and easy integration of relocatable shared objects with libcsdbg with either singlethreaded or multithreaded programs First step example csdbg_step1 cpp Demonstrates the way to integrate and use libcsdbg with a sin glethreaded program a DSO and a user defined exception type Second step example csdbg_step2 cpp This example shows the way libcsdbg works with multithreaded programs and a signal handler for fatal signals that generates process stack trace dumps Third step example csdbg_step3 cpp Demonstrates the use of multiple output
25. n the csdbg tracer public API they are designed to be called by the instrumentation functions these functions are not part of the csdbg namespace so they too need to obtain a tracer interface and use its public methods These methods are used for thread management and symbol lookup and they may be called by the library user One of them csdbg tracer cleanup_thread is specifically for the library user This method should be called from thread cancellation handlers to release resources If you don t cleanup the thread descriptor though it becomes useless when the actual thread has exited it continues to occupy memory and will also inject junk empty traces in dumps or in explicit trace requests This method may also be called just before a thread exits If you don t call cleanup_thread it is not a bug it s just poor coding When you have called this method you should call no more methods for the deleted thread ID Again this will be handled by the library but again it is poor coding Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 1 5 Usage 13 1 5 4 5 4 The Libcsdbg Debug Protocol LDP Ok you have created some traces and learned how to output them to a console or store them in buffers LDP Libcsdbg Debug Protocol is an application level protocol designed to transmit trace data together with other process thread and exception descriptive data through any media and transport layer protocol TCP IP UDP IP e
26. nctions node data can be accessed using stack offsets Class csdbg symbol_table A symbol_table object can load code from executables or dynamic shared objects with absolute addressing or position independent It supports all the binary formats supported by the libbfd backends on the host or target machine elf coff ecoff e t c To optimize lookups the symbol table as structured in libbfd is parsed the non function symbols are discarded and function symbols are demangled once and stored in simpler data structures A symbol_table can be traversed using simple callbacks and method csdbg symbol_table foreach The access to a symbol_table is not thread safe the caller must implement thread synchronization Class csdbg name_space Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 1 6 6 Examples and tutorials 17 This class defines the way to group symbol tables of different objective code files executables and DSO libraries into a single object the namespace and perform batch symbol lookups on them Inverse lookups are also sup ported given a resolved symbol find the module that defines it A lookup cache is used internally to optimize symbol resolving A name_space can be traversed its symbol tables using simple callbacks and method csdbg iname_space foreach The access to a name_space is not thread safe the caller must implement thread synchro nization 1 6 6 Examples and tutorials The examples co
27. ocal lib usr local lib modules libcsdbg or in generic export LD_LIBRARY_PATH S PREFIX lib SPREFIX lib modules libcsdbg The symbol table of the program is always loaded by libcsdbg The user can select which DSO symbol tables to load and which to discard by declaring the CSDBG_LIBS shell variable as a delimited list of POSIX extended regular expressions The absolute path of each DSO is matched against each regexp If CSDBG_LIBS is not set all linked DSO symbol tables will be loaded If it is set with a void value all DSO are filtered out from instrumentation You should only load the DSO that are compiled with libcsdbg support see Usage Loading non instrumented DSO is not a problem except additional overhead For example to run the example programs you must execute something like export CSDBG_LIBS csdbg_test 1 4 Troubleshooting 1 4 1 Bug reports Bugs are tracked in the tickets section of the libcsdbg site at sourceforge net Before submitting a new bug first search through all the tickets open and closed if the same bug has already been submitted by others If you are unsure whether or not something is a bug you may ask help on the users forums first subscription is not required the forums are moderated So you think you found a bug You should report it either on the user forums or by sending an email to the project admin tasos42 users sourceforge net If you send only a vague description of a bug you are usua
28. or process the trace data any way seem fit Libcsdbg transparently loads the symbol tables of the executable and of any chosen dynamic shared objects demangles function symbols to complete signatures and binds function names to runtime addresses even for relocatable position independent DSO symbols Libcsdbg can use all the well known objective code file formats a out elf coff ecoff e t c works with 32 and 64 bit systems and with both big and little endian architectures The library API can easily be used as the base for your own instrumentation code The following is one of the traces produced when you execute example csdbg_step1 cpp at thread 0x7 5e38289740 at main at csdbg_extra start char const unsigned char csdbg_stepl cpp 151 at csdbg_extra add_one_level char const unsigned short csdbg_stepl cpp 90 at void csdbg_extra middle lt csdbg string gt csdbg string amp unsigned int amp csdbg_stepl cpp 97 at csdbg_extra bottom char const unsigned long long volatile void double csdbg_stepl cpp 107 at csdbg_extra dso_main char const csdbg_stepl cpp 126 at csdbg_extra dso_inner char constx libcsdbg_test cpp 55 1 1 2 Features This is a comprehensive albeit not complete list of libcsdbg features e Create sophisticated exception stack traces with addr2line support e Works with multithreaded processes and with multiprocess programs e Create detailed Posix thread stack traces with addr2
29. rface if unlikely iface NULL return try string buf iface gt trace buf Gaten fisat f try catch exception amp x foo x iface gt unwind Due to C polymorfism all subclasses of csdbg string including the buffered output stream types of the library like csdbg filebuf csdbg tcposockbuf and those to come work in the same way Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 12 CONTENTS 1 5 3 2 5 3 2 Thread stack traces You can create a thread stack trace anywhere in your code at any moment of execution You can create a stack trace for the currently running thread or for any process thread running stopped resumed or blocked with a call at the two argument variant of csdbg tracer trace as in the next example using namespace csdbg tracer iface tracer interface if unlikely iface NULL return string buf iface gt trace buf pthread_self In case you have stored the thread ID of any thread you then can obtain its stack trace from any other thread Although the libcdbg higher lever interface library calls are thread safe you should be vigilant for data races that you may create Another consideration is that the above code can throw some exceptions that of course you need to handle somewhere Libcsdbg maintains a list of all simulated threads There are three tracer methods to obtain the csdbg thread object descriptor for a t
30. rw r r 1 root root 3001 Jan 5 15 36 tracer hpp rw r r root root 1020 Jan 5 15 36 util hpp usr local lib drwxr xr x 3 root root 4096 Jan 5 15 36 modules drwxr xr x 2 root root 4096 Jan 5 15 36 pkgconfig lrwxrwxrwx 1 root root 31 Jan 5 15 36 libcsdbg so gt usr local lib libcsdbg so 1 15 rwxr xr x 1 root root 163360 Jan 5 15 36 libcsdbg so 1 15 usr local lib modules libcsdbg rwxr xr x 1 root root 32086 Jan 5 15 36 libcsdbg_test so rwxr xr x 1 root root 13610 Jan 5 15 36 mod_null so usr local lib pkgconfig rw r r 1 root root 671 Jan 5 15 36 libcsdbg pc To validate that lipcsdbg works correctly for your platform all you have to do is to execute the example executables csdbg_step or any of the tutorial executables csdbg_tut The examples utilize most of the library API so they Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 8 CONTENTS provide best coverage but the third and fourth examples are also j Tracer clients and you will need a running server to verify the API The installation directory SPREFIX bin of these executables must be in PATH These programs will be dynamically linked with ibcsdbg so and with the example DSO ibcsdbg_test so so their installation directories SPREFIX lib and PREFIX lib modules libcsdbg must be in the Id path or in the LD_LIBRARY_P ATH shell variable You may need to invoke the following line before you run any of the examples export LD_LIBRARY_PATH usr l
31. s d h build will compile and install its target by default The following options change the default behaviour c Clear the source tree make clean u Uninstall the package make uninstall m Compile but don t install s Don t parallelize compilation on multicore systems d Create update the documentation make doc h Show this message Although the build script can do all that you may need to compile and install or uninstall recreate the documentation or clear the source tree by calling the equivalent Makefile targets in the right order it is essential to describe these individual targets First of all clear the source tree from built binaries and documentation make clean Compile the sources the result binaries are stored in build make Install the library header files and pkg config file under usr local by default make install Then if you want to compile and install the example executables and DSO even in order to verify your installation this is done by default by build you must invoke make example dso make example Optionally generate the documentation This will create the API reference in HTML and the user manual in LaTex and in hyperlinked PDF all generated under doc To generate the PDF version of the manual you will need a running distribution of LaTex and pdflatex makeindex and egrep To see the HTML documentation just point a browser to index html in the doc api re
32. the example executables and the project documentation GNU g GNU make e GNU binutils atleast libbfd so strip and addr2line e UNIX standard tools such as rm echo touch mkdir cd cp In mv grep id tar ldconfig wc sudo You will need doxygen and graphviz to recreate the project documentation Unpack the archive unless you already have done that If you want to recreate the documentation you must unpack the tarball in devel or change the paths in the doxygen configuration files doc docgen_html and doc docgen_tex with a simple text editor or doxywizard Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 1 3 Installation 5 mkdir p devel mv libcsdbg 1 15 tar bz2 devel cd devel tar xjpf libcsdbg 1 15 tar bz2 Then compile and install it cd libcsdbg 1 15 sudo sh build If you install as a simple user not root use of sudo is essential if you want to keep the default prefix usr local Installing in another prefix doesn t need root privilege but the dynamic loader configuration file Id so conf will not be updated Currently GNU autotools are not supported but this is under development The build script should compile without problems and install libcsdbg library headers and other project files examples e t c with usr local as the prefix For an overview of all build script options and modes of operation use sh build H Project libcsdbg installer Usage build c u m
33. to create objects that output traces and other data to various media A streambuf derived object is both a string buffer an object of class csdbg string and an output stream The media that are supported are those that can be handled with an integer descriptor files character devices terminals sockets pipes e t c The libcsdbg project is currently shipped with two streambuf subclasses csdbg filebuf is used to output traces to files and csdbg tcpsockbuf is used to transmit traces through a TCP IP network Other classes to support serial terminals UDP IP and Unix sockets pipes FIFOs and other will be added in the future Class streambuf apart from providing the common base functionality it also implements a part of the LDP Libcsdbg Debug Protocol These classes are not thread safe the caller must implement thread synchronization 1 5 5 1 5 5 1 Using csdbg filebuf A csdbg filebuf object is a buffered output stream used to output LDP Libcsdbg Debug Protocol data protocol headers and traces or generic data to a file This class is not thread safe the caller must implement thread synchronization A filebuf object inherits all the csdbg string methods designed for text manipulation append clear set e t c You use these methods to process the buffer data or the csdbg tracer methods to store traces to the buffer Then you may open the underlaying file stream and flush clear the buffer You can re fill and re flush as many times as yo
34. trace of the currently handled exception is to call the interface tracer object to store it in a csdbg string buffer as in the following example using namespace csdbg tracer iface tracer interface if unlikely iface NULL return try catch exception amp x try string buf iface gt trace buf eCateh fsx iface gt unwind As you see in this last example creating a stack trace in this way may throw exceptions that are the caller s respon sibility to handle The call to csdbg tracer unwind is only mandatory when the exception stack trace is ignored in order to dispose that stored trace If you don t properly unwind the simulated stack the stored trace will mess with the next attempt to obtain a stack trace Nevertheless if the trace was actually created a call to unwind doesn t affect the tracer object state at all nothing to dispose so it is not an error to call it once or even more times even when the trace was produced Mind you all calls to csdbg tracer trace even from the sid ostream insertion operator unwind the stack on their own A final point is if you code a function to do the trace creation and output this function must not be instrumented otherwise it will corrupt the exception stack trace Here s an example using namespace csdbg void foo exception amp __attribute no_instrument_function void foo exception amp x tracer xiface tracer inte
35. u wish before you close the filebuf Closing is just the opposite of open it doesn t release the object and its buffer so you may re open it The steps to use a filebuf object are 1 Create a filebuf object for a path 2 Open the file 3 Append set text data in the buffer 4 Flush the buffer 5 Repeat steps 3 4 until completion 6 Close 7 Repeat steps 2 6 until completion 8 Release the object Step 2 in this list can be inserted anywhere within steps 2 4 you don t need to open the file in order to process its buffer it must be opened before you flush the buffer To name files in an unambiguous way method csdbg filebuf stunique_id can come in handy It takes a printf style format string the default format is e_ p_ t_ s and uses the following specifiers e executable name a executable absolute path p process ID t thread ID s timestamp in microseconds Generated on Sun Jan 5 2014 16 11 36 for libcsdbg by Doxygen 1 5 Usage 15 The following is an example of using the filebuf class using namespace csdbg tracer iface tracer interface if unlikely iface NULL return Log a trace to a file with a unique trace describing name string nm filebuf unique_id e_ s nm gt append trace filebuf fout nm gt cstr Add a header that describes the trace fout header fout append r n iface gt trace fout pthread_self fout append r
36. va Each application that uses the libcsdbg LDP API can implement a jTracer client This can be essential for cross platform development with embedded devices and development boards Most often target platforms such as these don t have a screen or other resources to visualize output and data collection during the development and debugging cycles is controlled at a workstation through ethernet or serial ports Instead of cluttering the IDE console or debugger with trace data LDP is designed to isolate these generated data collect them with jTracer even from multiple target hosts with diverse architectures and provide an easy way to navigate through them 1 1 3 Licence and details Libcsdbg is currently published as an Open Source project licenced under the GNU Library or Lesser General Public License version 3 0 LGPLv3 Tasos Parisinos develops and maintains libcsdbg and the project documentation while Antonis Kalamaras develops and maintains the build system Version numbering uses three numbers major minor and subminor The current library version is 1 15 Major library updates are related with multiple feature addition significant changes in the library interface major bug fixes or overall optimization Minor library updates usually add minor features or major features that were almost ready to be included in the major release but didn t minor bug fixes typos and documentation updates or entities that need to be tested to gather feedb
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