It is normally stored in the comment section strings -a <binary/library> |grep “GCC: (” returns GCC: (GNU) X.X.X strip -R .comment <binary> strings -a <binary/library> |grep “GCC: (” returns no output It is not uncommon to strip the .comment (as well as .note) section out to reduce size via strip –strip-all -R .note -R .comment … Read more
First of all, the original reason for this was largely political – the people who added DWARF-based unwinding (.eh_frame) wanted it to be a feature that’s always there so it could be used for implementing all kinds of stuff other than just C++ exceptions, including: backtrace() __attribute__((__cleanup__(f))) __builtin_return_address(n), for n>0 pthread_cleanup_push, implemented in terms of … Read more
I’ve found that bcrypt compiled on OSX will not quite work on Linux. In other words, if you check in the bcrypt compiled on your local OSX workstation, and try to run the node app on your linux servers, you will see the error above. Solution: npm install bcrypt on Linux, check that in, solved. … Read more
The problem is that replacing call printf@PLT with call [printf@GOTPLT] requires that the compiler knows that the function printf exists in a shared library and not a static library (or even in just a plain object file). The linker can change call printf into call printf@PLT, jmp printf into jmp printf@PLT or even mov eax, … Read more
Here is a simple example project to illustrate the use of -rdynamic. bar.c extern void foo(void); void bar(void) { foo(); } main.c #include <dlfcn.h> #include <stdio.h> #include <stdlib.h> void foo(void) { puts(“Hello world”); } int main(void) { void * dlh = dlopen(“./libbar.so”, RTLD_NOW); if (!dlh) { fprintf(stderr, “%s\n”, dlerror()); exit(EXIT_FAILURE); } void (*bar)(void) = dlsym(dlh,”bar”); … Read more
objdump -s -j .rodata exefile gives a side-by-side hex/printable ASCII dump of the contents of the rodata section like: Contents of section .rodata: 0000 67452301 efcdab89 67452301 efcdab89 gE#…..gE#….. 0010 64636261 68676665 64636261 68676665 dcbahgfedcbahgfe It doesn’t look like there’s anything in there to control formatting, but it’s a start. You could always undump the … Read more
As long as the section name results in a valid C variable name, gcc (ld, rather) generates two magic variables: __start_SECTION and __stop_SECTION. Those can be used to retrieve the start and end addresses of a section, like so: /** * Assuming you’ve tagged some stuff earlier with: * __attribute((__section__(“my_custom_section”))) */ struct thing *iter = … Read more
Use the -O binary output format: objcopy -O binary –only-section=.text foobar.elf foobar.text Just verified with avr-objcopy and an AVR ELF image’s .text section. Note that if, as Tim points out below, your section doesn’t have the ALLOC flag, you may have to add –set-section-flags .text=alloc to be able to extract it.