Openssl crate and linked code

help
1

When using vendored openssl crate, is the whole openssl library linked in the executable or only the relevant functionality ?

How could I have found out myself ?

(Coming from interpreted Python, my mental model of compile and link is very rough.)

2

Experimenting with using various parts of the openssl crate, I can see that the size of the linked executable changes. I am thus guessing that the vendored crate does dead code elimination.

I have tried to read openssl-src-rs/lib.rs at main · alexcrichton/openssl-src-rs · GitHub but did not convince myself that it asks for dead code elimination.

Any hint would be appreciated.

3

openssl-src-rs doesn't need to ask for dead code elimination. The linker just does it.

4

Compile with debug symbols (in release) and see if any function you expect to be missing is still there objdump -W

Hint, also be sure to run ldd to know what is dynamic.
Compile with RUSTFLAGS="-C linker-plugin-lto" for added optimization.

5

Thanks

6

Thanks for the suggestion. AFAICS, objdump is a Linux tool. otool seems to be the MacOS corresponding tool. I went through its man page. I guess I lack some concepts: I did not find how to get to debug symbols.

7

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