Re: port binary dumping core on recent head in poudriere [1500026 libsass.so.1.0.0 vs. 1500027 one]

Summary:

Turns out in my context: libsass.so <http://libsass.so/>.1.0.0 built for
1500026 fails and built for 1500027 works, at least
when used via a 1500027 world.

# file /usr/local/lib/libsass.so.1.0.0*
/usr/local/lib/libsass.so.1.0.0:               ELF 64-bit LSB shared object, x86-64, version 1 (FreeBSD), dynamically linked, for FreeBSD 15.0 (1500026), with debug_info, not stripped
/usr/local/lib/libsass.so.1.0.0.good-from-pkg: ELF 64-bit LSB shared object, x86-64, version 1 (FreeBSD), dynamically linked, for FreeBSD 15.0 (1500027), stripped
/usr/local/lib/libsass.so.1.0.0.orig-stripped: ELF 64-bit LSB shared object, x86-64, version 1 (FreeBSD), dynamically linked, for FreeBSD 15.0 (1500026), stripped

Use of the 1500026 ones fail; use of the 1500027 one works.

FYI:

# file /usr/local/bin/sassc /usr/obj/DESTDIRs/main-amd64-pbase/usr/local/bin/sassc 
/usr/local/bin/sassc:                                   ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), dynamically linked, interpreter /libexec/ld-elf.so.1, for FreeBSD 15.0 (1500026), FreeBSD-style, with debug_info, not stripped
/usr/obj/DESTDIRs/main-amd64-pbase/usr/local/bin/sassc: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), dynamically linked, interpreter /libexec/ld-elf.so.1, for FreeBSD 15.0 (1500027), FreeBSD-style, stripped


The details that lead to finding that out . . .

I've no got both a failing context (outside a chroot)
and a working one (inside a PkgBase based chroot that
got sassc and such via pkg install). So exploring . . .

Failing (the "Old value = 0x0" is odd):

Reading symbols from /usr/local/bin/sassc...
(gdb) set radix 16
Input and output radices now set to decimal 16, hex 10, octal 20.
(gdb) watch -l *(unsigned long*)0x800508108
Hardware watchpoint 1: -location *(unsigned long*)0x800508108
(gdb) watch -l *(unsigned long*)0x800671170
Hardware watchpoint 2: -location *(unsigned long*)0x800671170
(gdb) run
Starting program: /usr/local/bin/sassc  
Hardware watchpoint 1: -location *(unsigned long*)0x800508108

Old value = 0x0
New value = 0x800249000
reloc_plt (obj=obj@entry=0x80022a808, flags=flags@entry=0x4, lockstate=lockstate@entry=0x0) at /usr/main-src/libexec/rtld-elf/amd64/reloc.c:343
343   break;
(gdb) c
Continuing.

Hardware watchpoint 2: -location *(unsigned long*)0x800671170

Old value = 0x39696
New value = 0x80066e696
reloc_plt (obj=obj@entry=0x80022e408, flags=flags@entry=0x4, lockstate=lockstate@entry=0x0) at /usr/main-src/libexec/rtld-elf/amd64/reloc.c:343
343   break;
(gdb) c
Continuing.

Program received signal SIGSEGV, Segmentation fault.
Invalid permissions for mapped object.
0x0000000800249000 in ?? ()



Working (no odd "Old value" this time):
(The "watchpoint 2" address is somewhat different.)

Reading symbols from /usr/local/bin/sassc...
(No debugging symbols found in /usr/local/bin/sassc)
(gdb) set radix 16
Input and output radices now set to decimal 16, hex 10, octal 20.
(gdb) watch -l *(unsigned long*)0x800508108
Hardware watchpoint 1: -location *(unsigned long*)0x800508108
(gdb) watch -l *(unsigned long*)0x800670170
Hardware watchpoint 2: -location *(unsigned long*)0x800670170
(gdb) run
Starting program: /usr/local/bin/sassc  
Hardware watchpoint 1: -location *(unsigned long*)0x800508108

Old value = 0x2aada6
New value = 0x8004f3da6
reloc_plt (obj=obj@entry=0x80022a808, flags=flags@entry=0x4, lockstate=lockstate@entry=0x0) at /home/pkgbuild/worktrees/main/libexec/rtld-elf/amd64/reloc.c:343
343   break;
(gdb) c
Continuing.

Hardware watchpoint 2: -location *(unsigned long*)0x800670170

Old value = 0x39696
New value = 0x80066d696
reloc_plt (obj=obj@entry=0x80022e408, flags=flags@entry=0x4, lockstate=lockstate@entry=0x0) at /home/pkgbuild/worktrees/main/libexec/rtld-elf/amd64/reloc.c:343
343   break;
(gdb) c
Continuing.

Hardware watchpoint 1: -location *(unsigned long*)0x800508108

Old value = 0x8004f3da6
New value = 0x800648870
reloc_jmpslot (where=where@entry=0x800508108 <acos@got[plt]>, target=target@entry=0x800648870, obj=obj@entry=0x80022e408, refobj=refobj@entry=0x80022a808, rel=rel@entry=0x8002fcf10)
    at /home/pkgbuild/worktrees/main/libexec/rtld-elf/amd64/reloc.c:413
413 return (target);
(gdb) c
Continuing.
Usage: /usr/local/bin/sassc [options] [INPUT] [OUTPUT]

Options:
   -s, --stdin             Read input from standard input instead of an input file.
   -t, --style NAME        Output style. Can be: nested, expanded, compact, compressed.
   -l, --line-numbers      Emit comments showing original line numbers.
       --line-comments
   -I, --load-path PATH    Set Sass import path.
   -P, --plugin-path PATH  Set path to autoload plugins.
   -m, --sourcemap[=TYPE]  Emit source map (auto or inline).
   -M, --omit-map-comment  Omits the source map url comment.
   -p, --precision         Set the precision for numbers.
   -a, --sass              Treat input as indented syntax.
   -v, --version           Display compiled versions.
   -h, --help              Display this help message.

[Inferior 1 (process 87037) exited normally]



Turns out that copying the /usr/local/lib/libsass.so.1.0.0
from the working environment to the failing one makes the
failing one work. So something about the content of
/usr/local/lib/libsass.so.1.0.0 makes the difference.

Turns out it tracks the 1500026 vs. 1500027 distinctions
below:

# file /usr/local/lib/libsass.so.1.0.0*
/usr/local/lib/libsass.so.1.0.0:               ELF 64-bit LSB shared object, x86-64, version 1 (FreeBSD), dynamically linked, for FreeBSD 15.0 (1500026), with debug_info, not stripped
/usr/local/lib/libsass.so.1.0.0.good-from-pkg: ELF 64-bit LSB shared object, x86-64, version 1 (FreeBSD), dynamically linked, for FreeBSD 15.0 (1500027), stripped
/usr/local/lib/libsass.so.1.0.0.orig-stripped: ELF 64-bit LSB shared object, x86-64, version 1 (FreeBSD), dynamically linked, for FreeBSD 15.0 (1500026), stripped



===
Mark Millard
marklmi at yahoo.com