Почему я не могу найти таблицы символов в библиотеках C в MacOS?

Como se puede ver en MacOS High Sierra:

$ ls -la libc.dylib 
lrwxr-xr-x  1 root  wheel  15 25 Nov 01:32 libc.dylib -> libSystem.dylib

libc.dylibes un enlace simbólico a libSystem.dylib.

Al intentar mostrar el contenido de libSystem.dylib, no verá muchos caracteres, ya que dependiendo de si usa stringso cat, encontrará caracteres no imprimibles o el final -del archivo -personajes de forma prematura.

Para comprender esto, consulte el resultado destrings:

$ strings /usr/lib/libSystem.dylib 
executable_path=
@(#)PROGRAM:System.B  PROJECT:Libsystem-1252.50.4 

libSystem.dylibes, sin embargo, un caché de varias bibliotecas encadenadas.

Elegir libc.dyliben High Sierra:

$ otool -L /usr/lib/libSystem.dylib
libSystem.dylib:
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.50.4)
    /usr/lib/system/libcache.dylib (compatibility version 1.0.0, current version 80.0.0)
    /usr/lib/system/libcommonCrypto.dylib (compatibility version 1.0.0, current version 60118.50.1)
    /usr/lib/system/libcompiler_rt.dylib (compatibility version 1.0.0, current version 62.0.0)
    /usr/lib/system/libcopyfile.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/system/libcorecrypto.dylib (compatibility version 1.0.0, current version 562.50.17)
    /usr/lib/system/libdispatch.dylib (compatibility version 1.0.0, current version 913.50.12)
    /usr/lib/system/libdyld.dylib (compatibility version 1.0.0, current version 551.3.0)
    /usr/lib/system/libkeymgr.dylib (compatibility version 1.0.0, current version 28.0.0)
    /usr/lib/system/liblaunch.dylib (compatibility version 1.0.0, current version 1205.50.76)
    /usr/lib/system/libmacho.dylib (compatibility version 1.0.0, current version 906.0.0)
    /usr/lib/system/libquarantine.dylib (compatibility version 1.0.0, current version 86.0.0)
    /usr/lib/system/libremovefile.dylib (compatibility version 1.0.0, current version 45.0.0)
    /usr/lib/system/libsystem_asl.dylib (compatibility version 1.0.0, current version 356.50.1)
    /usr/lib/system/libsystem_blocks.dylib (compatibility version 1.0.0, current version 67.0.0)
    /usr/lib/system/libsystem_c.dylib (compatibility version 1.0.0, current version 1244.50.9)
    /usr/lib/system/libsystem_configuration.dylib (compatibility version 1.0.0, current version 963.50.8)
    /usr/lib/system/libsystem_coreservices.dylib (compatibility version 1.0.0, current version 51.0.0)
    /usr/lib/system/libsystem_darwin.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/system/libsystem_dnssd.dylib (compatibility version 1.0.0, current version 878.50.17)
    /usr/lib/system/libsystem_info.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/system/libsystem_m.dylib (compatibility version 1.0.0, current version 3147.50.1)
    /usr/lib/system/libsystem_malloc.dylib (compatibility version 1.0.0, current version 140.50.6)
    /usr/lib/system/libsystem_network.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/system/libsystem_networkextension.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/system/libsystem_notify.dylib (compatibility version 1.0.0, current version 172.0.0)
    /usr/lib/system/libsystem_sandbox.dylib (compatibility version 1.0.0, current version 765.50.51)
    /usr/lib/system/libsystem_secinit.dylib (compatibility version 1.0.0, current version 30.0.0)
    /usr/lib/system/libsystem_kernel.dylib (compatibility version 1.0.0, current version 4570.51.2)
    /usr/lib/system/libsystem_platform.dylib (compatibility version 1.0.0, current version 161.50.1)
    /usr/lib/system/libsystem_pthread.dylib (compatibility version 1.0.0, current version 301.50.1)
    /usr/lib/system/libsystem_symptoms.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/system/libsystem_trace.dylib (compatibility version 1.0.0, current version 829.50.17)
    /usr/lib/system/libunwind.dylib (compatibility version 1.0.0, current version 35.3.0)
    /usr/lib/system/libxpc.dylib (compatibility version 1.0.0, current version 1205.50.76)

También como correctamente @ajeh también sugiere:

$ nm /usr/lib/libSystem.dylib  
0000000000001a6a T R8289209$_close
0000000000001a6f T R8289209$_fork
0000000000001a74 T R8289209$_fsync
0000000000001a79 T R8289209$_getattrlist
0000000000001a7e T R8289209$_getrlimit
0000000000001a83 T R8289209$_getxattr
0000000000001a88 T R8289209$_open
0000000000001a8d T R8289209$_pthread_attr_destroy
0000000000001a92 T R8289209$_pthread_attr_init
0000000000001a97 T R8289209$_pthread_attr_setdetachstate
0000000000001a9c T R8289209$_pthread_create
0000000000001aa1 T R8289209$_pthread_mutex_lock
0000000000001aa6 T R8289209$_pthread_mutex_unlock
0000000000001aab T R8289209$_pthread_self
0000000000001ab0 T R8289209$_ptrace
0000000000001ab5 T R8289209$_read
0000000000001aba T R8289209$_setattrlist
0000000000001abf T R8289209$_setrlimit
0000000000001ac4 T R8289209$_sigaction
0000000000001ac9 T R8289209$_stat
0000000000001ace T R8289209$_sysctl
0000000000001ad3 T R8289209$_time
0000000000001ad8 T R8289209$_unlink
0000000000001add T R8289209$_write
0000000000001f98 S ___System_BVersionNumber
0000000000001f60 S ___System_BVersionString
00000000000022d0 S ___crashreporter_info__
                 U ___error
                 U ___keymgr_initializer
                 U ___libdarwin_init
                 U ___libkernel_init
                 U ___libplatform_init
                 U ___malloc_init
                 U ___pthread_init
                 U ___stack_logging_early_finished
                 U __asl_fork_child
                 U __dirhelper
                 U __dyld_fork_child
                 U __dyld_initializer
                 U __libSC_info_fork_child
                 U __libSC_info_fork_parent
                 U __libSC_info_fork_prepare
                 U __libc_fork_child
                 U __libc_initializer
                 U __libcoreservices_fork_child
                 U __libsecinit_initializer
                 U __libtrace_fork_child
                 U __libtrace_init
                 U __libxpc_initializer
                 U __mach_fork_child
                 U __malloc_fork_child
                 U __malloc_fork_parent
                 U __malloc_fork_prepare
                 U __notify_fork_child
                 U __pthread_atfork_child
                 U __pthread_atfork_child_handlers
                 U __pthread_atfork_parent
                 U __pthread_atfork_parent_handlers
                 U __pthread_atfork_prepare
                 U __pthread_atfork_prepare_handlers
                 U __pthread_clear_qos_tsd
                 U __pthread_exit_if_canceled
                 U _close
                 U _dispatch_atfork_child
                 U _dispatch_atfork_parent
                 U _dispatch_atfork_prepare
                 U _dlsym
                 U _dyld_get_program_sdk_version
                 U _exit
                 U _fork
                 U _free
                 U _fsync
                 U _getattrlist
                 U _getrlimit
                 U _getxattr
0000000000001ae2 T _libSystem_atfork_child
0000000000001a47 T _libSystem_atfork_parent
0000000000001a22 T _libSystem_atfork_prepare
000000000000194a t _libSystem_initializer
00000000000022a0 s _libSystem_initializer.libc_funcs
0000000000002220 s _libSystem_initializer.libkernel_funcs
0000000000002280 s _libSystem_initializer.libpthread_funcs
                 U _libdispatch_init
0000000000001b28 t _mach_init_old
00000000000022c8 D _mach_init_routine
                 U _malloc
                 U _open
                 U _pthread_attr_destroy
                 U _pthread_attr_init
                 U _pthread_attr_setdetachstate
                 U _pthread_create
                 U _pthread_mutex_lock
                 U _pthread_mutex_unlock
                 U _pthread_self
                 U _ptrace
                 U _read
                 U _realloc
                 U _setattrlist
                 U _setrlimit
                 U _sigaction
                 U _stat
                 U _strncmp
                 U _sysctl
                 U _time
                 U _unlink
                 U _write
                 U _xpc_atfork_child
                 U _xpc_atfork_parent
                 U _xpc_atfork_prepare
                 U dyld_stub_binder

Sin embargo, un nmpuro en libSystem.dylibmostrará los símbolos de todas las bibliotecas incluidas agrupadas.

Podría ser un poco más interesante hacerlo uno por uno como en este script bash:

#!/bin/bash
for i in `otool -L /usr/lib/libSystem.dylib | sed "1d" | awk ' { print $1 } '` 
do 
    echo $i
    echo "======="
    nm $i 
    echo
done

O como una sola línea:

for i in `otool -L /usr/lib/libSystem.dylib | sed "1d" | awk ' { print $1 } '`; do echo $i; echo "=======" ; nm $i ; echo ; done

En cuanto al volcado hexadecimal, como no nos lo ha mostrado, asumiré que está confundido por la salida de 16 -bits (Creo que ).

Para ver algunos volcados de cadenas, pruebe:

$ od -tc /usr/lib/libSystem.dylib  | tr -d " "  | grep -v "\\\\" | sed 's/^[0-9]*//g' | less
*
*
/usr/lib/libSyst
/system/libcache
/usr/lib/system/
libcommonCrypto.
/usr/lib/system/
libcompiler_rt.d
/usr/lib/system/
libcopyfile.dyli
/usr/lib/system/
libcorecrypto.dy
/usr/lib/system/
libdispatch.dyli
/usr/lib/system/
/system/libkeymg
/usr/lib/system/
/system/libmacho
/usr/lib/system/
libquarantine.dy
/usr/lib/system/
libremovefile.dy
/usr/lib/system/
libsystem_asl.dy
/usr/lib/system/
libsystem_blocks
/usr/lib/system/
libsystem_c.dyli
/usr/lib/system/
libsystem_config
/system/libsyste
m_coreservices.d
/usr/lib/system/
libsystem_darwin
/usr/lib/system/
libsystem_dnssd.
/usr/lib/system/
libsystem_info.d
/usr/lib/system/
libsystem_m.dyli
/usr/lib/system/
libsystem_malloc
/usr/lib/system/
libsystem_networ
/usr/lib/system/
libsystem_networ
kextension.dylib
/usr/lib/system/
libsystem_notify
/usr/lib/system/
libsystem_sandbo
/usr/lib/system/
libsystem_secini
/usr/lib/system/
libsystem_kernel
/usr/lib/system/
libsystem_platfo
/system/libsyste
/system/libsyste
m_symptoms.dylib
/usr/lib/system/
libsystem_trace.
/usr/lib/system/
/system/libxpc.d
*
AVSPM211306I211317H211323H215=
@(#)PROGRAM:Syst
em.BPROJECT:Li
bsystem-1252.50.
*
*
A__pthread_cl
@__pthre
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@__dyld_fork_chi
@__libSC_info_f
__libSC_info_for
_libSC_info_fork
__libc_fork_chil
@__libcoreserv
@__libtrace_i
__malloc_fork_ch
@__notify_for
_pthread_atfork_
thread_atfork_ch
@__pthread_at
@__pthread_atf
ork_parent_handl
read_atfork_prep
read_atfork_prep
@_dispatch_atfo
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dispatch_atfork_
dyld_get_program
read_attr_destro
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q2000040@_xpc_atfork
pc_atfork_parent
setdetachstate
%025226003006006006006006006006006006

*
%#005005005005005005005005005005
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*
/lib/libSystem.B
/usr/lib/system/
/system/libcommo
/system/libcompi
/system/libcopyf
tem/libcorecrypt
/usr/lib/system/
libdispatch.dyli
/lib/system/libd
tem/libkeymgr.dy
/lib/system/libl
tem/libmacho.dyl
/lib/system/libq
/system/libremov
tem/libsystem_as
/usr/lib/system/
libsystem_blocks
/usr/lib/system/
libsystem_c.dyli
/lib/system/libs
ystem_configurat
tem/libsystem_co
reservices.dylib
/lib/system/libs
ystem_darwin.dyl
/lib/system/libs
ystem_dnssd.dyli
/lib/system/libs
ystem_info.dylib
/lib/system/libs
/system/libsyste
/system/libsyste
/system/libsyste
m_networkextensi
tem/libsystem_no
tem/libsystem_sa
tem/libsystem_se
tem/libsystem_ke
tem/libsystem_pl
/system/libsyste
/system/libsyste
m_symptoms.dylib
/lib/system/libs
ystem_trace.dyli
/lib/system/libu
tem/libxpc.dylib
*
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*
*
hread_clear_qos_
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_pthread_attr_de
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$_pthread
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$_pthread_attr
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ad_atfork_prepar
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ializer.libkerne
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alizer.libc_func
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