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diff --git a/README.me b/README.me deleted file mode 100644 index f7122ca..0000000 --- a/README.me +++ /dev/null @@ -1,52 +0,0 @@ -# preload-libbt - -`preload-libbt` is a utility library for some very special occasions. - -It aims to extract a backtrace when a program *segfaults*, on machines where -[`ptrace(2)`][ptrace] syscalls are restricted, and hence launching the program -under *gdb* or attaching wth *gdb* is not possible. - -The library must be `LD_PRELOAD`ed, which then installs a signal handler that -dumps a stacktrace. For it to work the program must adhere to the following -rules: - -- The program must not override the installed signal handler. -- If the program overrides the signal handler, it properly needs to implement -signal handler chaining. - -The preload library `libbt.so` is build with the default make target. -``` -make -``` - -The library installs *alternative signal stacks* to be able to do its work even -when the program *segfaults* due to a *stackoverflow*. This is demonstrated by -the `example/recurse*.c` examples. - -## Examples - -The following gives an example and shows how a stacktrace dump looks like. -``` -cc -o libbt.so bt.c -shared -fPIC -ldl -cc -o raise1 example/raise1.c -rdynamic -LD_PRELOAD=./libbt.so ./raise1 - -[INFO:BT]: installed signal handler -[INFO:BT]: caught signal 11 -# 0 [ 0x7f53b9e203f4] /usr/lib/libc.so.6+0x963f4 -# 1 [ 0x7f53b9dc7120] gsignal+0x20 /usr/lib/libc.so.6+0x3d100 -# 2 [ 0x55748166c147] foo+0xe raise1+0x1139 -# 3 [ 0x55748166c158] bar+0xe raise1+0x114a -# 4 [ 0x55748166c169] qux+0xe raise1+0x115b -# 5 [ 0x55748166c17a] main+0xe raise1+0x116c -# 6 [ 0x7f53b9dafe08] /usr/lib/libc.so.6+0x25e08 -# 7 [ 0x7f53b9dafecc] __libc_start_main+0x8c /usr/lib/libc.so.6+0x25e40 -# 8 [ 0x55748166c065] _start+0x25 raise1+0x1040 -``` - -Alternatively one can run `make run`, to run all examples under `example/`. - -## License -This project is licensed under the MIT license. - -[https://www.man7.org/linux/man-pages/man2/ptrace.2.html] |