CSE 303 Homework 5 - Debugging memory leaks

Preface

I have written a small library to help you debugging memory leaks. When your program terminates, it will tell you about apparent memory leaks (memory allocated but not freed), with some detailed information like the location of allocation, size and content. It is small and fast, since it does nearly nothing compared to the other commercial quality debugging and profiling tools, so can be used even when running your program against the full data set. Even though it doesn't have the full functionality of production tools, I'm sure that this library will help give you some idea to how to debug your program.

Note: This program is segmentation fault prone. If you try to free memory that wasn't allocated, it will generate error message with specific location and exit gracefully. But if your program has a bug causing it to seg fault because of a corrupted heap, the library probably makes the situation worse. So if you are debugging a segmentation fault, I recommend that you not use this library and instead try the other way such as gdb with core dump.

How to install?

1. If you don't have hw#5 version 1.1, please download and install it first
2. You can download the library and header file from the following links:
   
   • Libdmem for attu: Download
     Or you can copy this library on attu using following command:
     

     $ cd <To your hw5 directory>
     $ cp /cse/courses/cse303/05au/hw5/dmem/dmem.h .
     $ cp /cse/courses/cse303/05au/hw5/dmem/libdmem.a .
     

   • Libdmem for cygwin: Download
     After download, copy the file into your homework 5 directory and unzip & untar using following command:
     

     $ tar zxvf dmem-cygwin-0.1.bin.tar.gz
     

   • Libdmem source: Download
     You need Austin library 0.2 to build this library. The source is provided only for your interest - you can use the precompiled libraries and .h file from the previous two links on their own.
3. Edit makefile in your homework5 directory and modify like this:
   
   • If you want to debug everything, download this and replace the original makefile in your hw5 directory.
   • If you want to debug dllistdriver, find
     

     $(CC) -o dllistdriver dllistdriver.o dllist/dllist.o

     line and append -L. -ldmem at the end of the line. The line will look like this:
     

     $(CC) -o dllistdriver dllistdriver.o dllist/dllist.o -L. -ldmem

   • If you want to debug hw5, find
     

     $(CC) -o hw5 $^ -lfl -L. -llexer

     line and append -ldmem at the end of the line. The line will look like this:
     

     $(CC) -o hw5 $^ -lfl -L. -llexer -ldmem

   • If you want to debug btdriver, find
     

     $(CC) -o btdriver btdriver.o bt/bt.o dllist/dllist.o

     line and append -L. -ldmem at the end of the line. The line will look like this:
     

     $(CC) -o btdriver btdriver.o bt/bt.o dllist/dllist.o -L. -ldmem

4. Set environment variable MOREFLAGS like this.
   

   $ cd <To your hw5 directory>
   $ export MOREFLAGS="-DDMEM -include `pwd`/dmem.h"
   

5. Now you are ready to use the library with your program. Rebuild your program to let the dmem library work.
   

   $ cd <To your hw5 directory>
   $ make clean
   $ make
   

6. If you want to build your program without the library, type following commands:
   

   $ unset MOREFLAGS
   $ cd <To your hw5 directory>
   $ make clean
   $ make
   

7. Enjoy debugging! :-)

$ ./hw5 ./data www.nytimes.com

Done: 0 pages, 0 words, 0 links total
memory leaks: 1 memory chunks have not been freed
0x004b0300(22 bytes): allocated at lexer.c(100)
    ./.c.y.g.d.r.i.v.e./.z./.h.w.5./.d.a.t.a./00
Total: 22 bytes memory leaks