Re: C23 thoughts and opinions

On Thu, 30 May 2024 17:08:36 +0300
Michael S <already5chosen@yahoo.com> wrote:

On Thu, 30 May 2024 14:34:00 +0100
bart <bc@freeuk.com> wrote:
 

On 30/05/2024 03:32, Lawrence D'Oliveiro wrote: 

On Wed, 29 May 2024 13:58:20 +0200, Bonita Montero wrote:
   

I've got a small commandline-tool that makes a const'd char
-array from any binary file.   

 
It seems to me it would be more efficient to use objcopy to turn
that binary file directly into an object file with symbols
accessible from C code defining its beginning and ending points.
Then just link it into the executable.   

 
None of my compilers, whether for C or anything else, generate
object files.
 
However, suppose I wanted to link a file called 'logo.bmp' say, into
my program, which consisted of a file called main.c.
 
What is the entire process using your suggestion? What do I put
into main.c? Assume the data is represented by a char-array.
 

 
extern unsigned char _binary_logo_bmp_start[];
extern unsigned char _binary_logo_bmp_size[];
 
The first symbol is an array itself.
The seconded symbol contains the length of array. You use it in
somewhat non-intuitive way:
  size_t my_size = (size_t)_binary_logo_bmp_size;
 
Pay attention that I never used this method myself, just took a look
at the output of objcopy with 'objdump -t', so please don't take my
words as a sure thing.
 
BTW, options in this case are rather simple:
objcopy -I binary -O elf32-little logo.bmp logo_bmp.o
Replace elf32-little with relevant format for your software. However I
am not sure that it would work for none-elf output formats.
>

Tested it.
On msys2 it can produce correct pe-x86-64 format but does it in
counter-intuitive way: you have to ask for elf64-x86-64 instead of
pe-x86-64.
I don't know why it works like that.

The rest of what I wrote above was correct.