On Tue, Oct 25, 2011 at 3:57 PM, Jeremy Huntwork
<jhuntw...@lightcubesolutions.com> wrote:
> There appears to be a somewhat bogus statement in section 6.63
> "Stripping Again". It says there:
> "If disk space is very tight, the --strip-all option can be used on
> the binaries in /{,usr/}{bin,sbin} to gain several more megabytes. Do
> not use this option on libraries—they will be destroyed."
> The statement that libs will be destroyed by --strip-all may be
> correct for chapter 5 libs due to the adjustments we've made (and will
> yet make) in chapter 6, the nature of the varying environments.
> However, by the end of chapter 6 I don't believe that statement is
> true any more.
Looks like you are indeed right about shared libraries. strip removes
the regular symbol table, but doesn't touch the dynamic symbol table.
Here's an example.
# Create some separate directories
mkdir full stripped
# Make a simple shared and static library
cat > dragon.c << "EOF"
#include <stdio.h>
void dragons(void)
{
printf("Here be dragons!\n");
}
EOF
gcc -c -o dragon.o -fPIC dragon.c
gcc -o full/libdragon.so -shared dragon.o
ar r full/libdragon.a dragon.o
ranlib full/libdragon.a
# Make stripped copies of the libraries
cp full/* stripped/
strip --strip-all stripped/*
# Look at the symbol tables of the shared libraries
# Notice that the .symtab section of the stripped library
# is gone, but the .dynsym sections are identical
readelf -s */libdragon.so
# Look at the symbol tables of the static libraries
# Notice that the stripped library has no symbols left
readelf -s */libdragon.a
# Make a test app
cat > test.c << "EOF"
extern void dragons(void);
int main(void)
{
dragons();
return 0;
}
EOF
# Build and run against stripped shared library
# Notice that it runs fine
gcc -o test test.c -Lstripped -ldragon
LD_LIBRARY_PATH=stripped ./test
# Now try again with the stripped static library
# Notice that it fails to build
gcc -o test test.c stripped/libdragon.a
So, it seems that --strip-all will only destroy your static libraries.
I couldn't find any way to strip the .dynsym section out of the
generated binaries. Then later I found this:
http://www.technovelty.org/linux/strip.html
Interesting stuff.
--
Dan
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