What exactly happened behind gcc-static hello. C?

You may often use gcc-static ***. C. What commands and libraries are used for this static link?

First, let's analyze what libc. A is. We already know that XXX. So is a dynamic link library, XXX. O is a static link library or relocated file, And/bin/bash is an executable file.

Libc. A is actually a collection of many relocated files, and generally only one function is written in each relocated file. For example, printf. O only has one printf function to link less useless libraries during static connections.

 

First use the command locate libc. a, we will find libc. A is located in/usr/lib/x86_64-linux-gnu/libc. a, and then use the command ar-T libc. A to check the number of relocable files. You can give it a try. There are a lot of relocated files in it, and one screen won't be displayed. This includes printf. O.

Run the ar-x libc. a command to decompress the file and find the printf. o file. Run the NM printf. O command. The following result is displayed:

Once again, it is confirmed that printf. O only has one printf function. The purpose is to link less useless libraries during static connections.

Below we attach the source code hello. C:

#include <stdio.h>int main(){printf("HelloWorld\n");return 0;}

Run the GCC-static -- verbose-fno-builtin hello. C, -- verbose command to enter the compilation details.-fno-builtin prevents the compiler from converting printf to puts. The result is as follows:

Using built-in specs.
Collect_gcc = gcc
Collect_lto_wrapper =/usr/lib/GCC/x86_64-linux-gnu/4.6/Lto-wrapper
Target: x86_64-linux-gnu
Configured :.. /src/configure-V -- With-pkgversion = 'ubuntu/linaro 4.6.3-1ubuntu5' -- With-bugurl = file: // usr/share/doc/gcc-4.6/readme. bugs -- enable-languages ages = C, C ++, Fortran, objc, OBJ-C ++ -- prefix =/usr -- Program-suffix =-4.6 -- enable-shared -- enable-linker-Build-id -- With-system-zlib -- libexecdir =/usr /lib -- without-included-gettext -- enable-threads = POSIX -- With-gxx-include-Dir =/usr/include/C ++/4.6 -- libdir =/usr/lib -- enable-NLS -- With-sysroot =/-- enable-clocale = GNU -- enable-libstdcxx-Debug -- enable-libstdcxx-time = yes -- enable-GNU-unique-object -- enable -plugin -- enable-objc-GC -- disable-werror -- With-arch-32 = i686 -- With-tune = generic -- enable-checking = release -- Build = x86_64-linux-gnu -- Host = x86_64-linux-gnu -- target = x86_64-linux-gnu
Thread model: POSIX
GCC version 4.6.3 (Ubuntu/linaro 4.6.3-1ubuntu5)
Collect_gcc_options = '-static ''-v''-fno-builtin''-mtune = generic ''-March = x86-64'
/Usr/lib/GCC/x86_64-linux-gnu/4.6/PC3-quiet-v-imultilib. -imultiarch x86_64-linux-gnu hello. c-quiet-dumpbase hello. c-mtune = generic-March = x86-64-auxbase hello-version-fno-builtin-fstack-protector-o/tmp/ccrsgv2j. s
Gnu c (Ubuntu/linaro 4.6.3-1ubuntu5) version 4.6.3 (x86_64-linux-gnu)
Compiled by gnu c version 4.6.3, GMP version 5.0.2, mpfr version 3.1.0-P3, MCM version 0.9
GGC Heuristics: -- Param GGC-Min-expand = 100 -- Param GGC-Min-heapsize = 131072
Ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
Ignoring nonexistent directory "/usr/lib/GCC/x86_64-linux-gnu/4.6/.../x86_64-linux-gnu/include"
# Include "..." search starts here:
# Include <...> search starts here:
/Usr/lib/GCC/x86_64-linux-gnu/4.6/include
/Usr/local/include
/Usr/lib/GCC/x86_64-linux-gnu/4.6/include-fixed
/Usr/include/x86_64-linux-gnu
/Usr/include
End of search list.
Gnu c (Ubuntu/linaro 4.6.3-1ubuntu5) version 4.6.3 (x86_64-linux-gnu)
Compiled by gnu c version 4.6.3, GMP version 5.0.2, mpfr version 3.1.0-P3, MCM version 0.9
GGC Heuristics: -- Param GGC-Min-expand = 100 -- Param GGC-Min-heapsize = 131072
Compiler executable checksum: 75e879ed14f91af504f4150eadeaa0e6
Collect_gcc_options = '-static ''-v''-fno-builtin''-mtune = generic ''-March = x86-64'
As -- 64-O/tmp/cc5x9ffe. O/tmp/ccrsgv2j. s
Compiler_path =/usr/lib/GCC/x86_64-linux-gnu/4.6/:/usr/lib/GCC/x86_64-linux-gnu/4.6/:/usr/lib/GCC/x86_64-linux-gnu /: /usr/lib/GCC/x86_64-linux-gnu/4.6/:/usr/lib/GCC/x86_64-linux-gnu/
LIBRARY_PATH =/usr/lib/GCC/x86_64-linux-gnu/4.6/:/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /x86_64-linux-gnu/:/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /.. /lib/:/lib/x86_64-linux-gnu //:/lib /.. /lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib /.. /lib/:/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /:/lib/:/usr/lib/
Collect_gcc_options = '-static ''-v''-fno-builtin''-mtune = generic ''-March = x86-64'
/Usr/lib/GCC/x86_64-linux-gnu/4.6/collect2 -- sysroot =/-- Build-id -- no-add-needed -- as-needed-M elf_x86_64 -- hash-style = GNU- static-Z relro/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /x86_64-linux-gnu/crt1.o/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /x86_64-linux-gnu/crti. o/usr/lib/GCC/x86_64-linux-gnu/4.6/crtbegint. o-L/usr/lib/GCC/x86_64-linux-gnu/4.6-L/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /x86_64-linux-gnu-L/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /.. /lib-L/lib/x86_64-linux-gnu-L/lib /.. /lib-L/usr/lib/x86_64-linux-gnu-L/usr/lib /.. /lib-L/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /tmp/cc5x9ffe. O -- start-group-lgcc-lgcc_eh-LC -- end-group/usr/lib/GCC/x86_64-linux-gnu/4.6/crtend. o/usr/lib/GCC/x86_64-linux-gnu/4.6 /.. /.. /.. /x86_64-linux-gnu/crtn. O

The red text above

Step 1: compile and use command to compile hello. c into/tmp/ccrsgv2j. S.

Step 2: Compile and run the as command to generate/tmp/cc5x9ffe. O from/tmp/ccrsgv2j. S.

Step 3: Link to the static Link Library of/tmp/cc5x9ffe. O with the command collect2 (which can be regarded as an upgraded LD.

So far, the story behind gcc-static hello. C has been analyzed. This article will refer to the self-cultivation of programmers.

What exactly happened behind gcc-static hello. C?