Compile Static Library

由 datahunter 在四, 20/02/2020 - 22:04 發表

最後更新: 2020-02-24

Check Static / Dynamic linking

ldd openssl

[]

not a dynamic executable

[]

linux-vdso.so.1 (0x00007ffe25989000)
libssl.so.1.1 => /usr/lib/x86_64-linux-gnu/libssl.so.1.1 (0x00007f3f53bd0000)
libcrypto.so.1.1 => /usr/lib/x86_64-linux-gnu/libcrypto.so.1.1 (0x00007f3f538e7000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f3f538e2000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f3f538c1000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3f53700000)
/lib64/ld-linux-x86-64.so.2 (0x00007f3f53d38000)

*.o *.a

object file (*.o)
static library (archiver, *.a 一個 object file 的集合)
.so 為動態函式庫

GCC

# foo.c -> foo.o

$ gcc -g -fPIC -c foo.c

-fPIC

PIC = position-independent code

# foo.o -> libfoo.so

$ gcc -shared foo.o -o libfoo.so

# Compile main link libfoo.so

gcc -g -o main main.c -lfoo -L.

-lfoo: 表示要連結 libfoo.so

-L.: 表示搜尋 libfoo.so 時, 除了預設目錄外, 也要找目前的位置 "./"

Test

# 因為 libfoo.so 不在 ld.so 搜尋的路徑裡

LD_LIBRARY_PATH=. ./main

call foo

nm

nm - list symbols from object files

nm -A libssl.a

libssl.a:bio_ssl.o:                 U BIO_callback_ctrl
...

Remark

"U" The symbol is undefined.
"T" The symbol is in the text (code) section.

Flag

CC # C compiler command
CFLAGS # C compiler flags
LDFLAGS # linker flags, e.g. -L<lib dir> if you have libraries in a nonstandard directory <lib dir>
LIBS # libraries to pass to the linker, e.g. -l<library>
CPPFLAGS # (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if you have headers in a nonstandard directory <include dir>
CPP # C preprocessor

i.e.

# "-I", "-L"

-I=/opt/openssl/include/openssl -L=/opt/openssl/lib

# pass linker flags in via LDFLAGS

./configure LDFLAGS=-static

randomize_va_space

此方法可以 Pack all so with binary

/proc/sys/kernel/randomize_va_space

Address space layout randomization

Static Linking Flag

Flag

# On systems that support dynamic linking, this overrides -pie and prevents linking with the shared libraries.

CFLAGS="-static"

LDFLAGS=-static

# 準備

yum install openssl-static uthash-devel

# "--disable-" 愈小 libray 依賴愈好

./configure \
--prefix=/opt/burp \
--disable-acl \
--disable-xattr \
--enable-static \
CFLAGS="-static"

error

configure: error: Unable to find librsync.h, please install librsync

# Centos7 Version: 2.0.2

rpm -ql librsync

/usr/bin/rdiff
/usr/lib64/librsync.so.2
...

Troubleshoot Static Linking

./configure 有 error error

./configure \
--prefix=/opt/burp \
--enable-static \
--disable-ipv6 \
--disable-acl \
--disable-xattr \
--with-openssl=/opt/openssl

config.log

configure:9811: gcc -o conftest -Wall -g -O2 -I/opt/openssl/include   -L/opt/openssl/lib conftest.c -lm  -lssl -lcrypto >&5
/usr/bin/ld: /opt/openssl/lib/libcrypto.a(threads_pthread.o): in function `CRYPTO_THREAD_lock_new':
threads_pthread.c:(.text+0x45): undefined reference to `pthread_rwlock_init'
...

Test

nm -A /opt/openssl/lib/libcrypto.a | grep pthread_rwlock_init

/opt/openssl/lib/libcrypto.a:threads_pthread.o:    U pthread_rwlock_init

nm -A /usr/lib/x86_64-linux-gnu/libssl.a | grep pthread

configure.ac

位置

/opt/openssl/lib
/opt/openssl/include/openssl

OPENSSL_LIB        "-lssl -lcrypto"
OPENSSL_LDFLAGS="-L${openssl_dir}/lib"
OPENSSL_INC="-I${openssl_dir}/include"

libdl

libdl - dynamic linking library

Historically, functions in libdl provided for dynamic linking support.

This functionality now resides in libc(ld.so).

This library is maintained to provide backward compatibility for both runtime and compilation environments.

The shared object is implemented as a filter on the runtime linker.

Static Link Openssl

-lssl -lcrypto -ldl -lpthread

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