svcadm(1M)을 검색하려면 섹션에서 1M 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
lari(1)
lari(1) User Commands lari(1)
NAME
lari - link analysis of runtime interfaces
SYNOPSIS
lari [-bCDsvV] [-a | -i | -o] file | directory...
lari [-CDosv] [-m [-d mapdir]] file
DESCRIPTION
The lari utility analyzes the interface requirements of dynamic ELF
objects. Two basic modes of operation are available. The first mode
displays runtime interface information. The second mode generates
interface definitions.
Dynamic objects offer symbolic definitions that represent the interface
that the object provides for external consumers. At runtime, bindings
are established from the symbolic references of one object to the sym‐
bolic definitions of another object. lari analyzes both the interface
definitions and runtime bindings of the specified objects.
When displaying runtime interface information, lari can analyze a num‐
ber of files and/or directories. lari analyzes each file that is speci‐
fied on the command line. lari recursively descends into each directory
that is specified on the command line, processing each file that is
found.
When generating interface definitions, lari can only process a single
file specified on the command line.
The lari utility can analyze userland and kernel objects:
Userland Dynamic executable and shared objects are used by user pro‐
cesses, and are managed at runtime by the runtime linker,
ld.so.1(1). The lari utility processes files as dynamic ELF
objects by using ldd(1).
The ldd utility provides information on all bindings that
are established as part of loading the object. Due to the
use of the ldd, the specified object is not executed, and
no user controlled loading of objects by dlopen(3C) occurs.
The -D option can be employed to analyze such cases. See
Analysis of User Controlled Object Loading under EXTENDED
DESCRIPTION.
Kernel Kernel modules are used by the unix kernel, and are managed
at runtime by the Kernel Runtime Linker (krtld). The lari
utility processes kernel modules by using kldd(1). This
processing uses the -r and -b kldd options to obtain
information on all bindings that are established as part of
loading the object. Due to the use of kldd, the specified
kernel module is not loaded or executed.
When displaying interface information, lari analyzes the interfaces of
the processed dynamic objects and, by default, displays any interesting
information. See Interesting Information under EXTENDED DESCRIPTION.
The information that is displayed is also suitable for piping to other
tools. This capability can aid developers in analyzing process bindings
or debugging complex binding scenarios.
The generation of interface definitions by lari can be used to refine
the interface requirements of the dynamic objects that are processed.
When creating a dynamic object, you should define an explicit, ver‐
sioned interface. This definition controls the symbol definitions that
are available to external users. In addition, this definition fre‐
quently reduces the overall runtime execution cost of the object.
Interface definitions can be assigned to an object during its creation
by the link-editor using the -M option and the associated mapfile
directives. See the Oracle Solaris 11.4 Linkers and Libraries Guide for
more details on using mapfiles to version objects. An initial version
of these mapfiles can be created by lari.
OPTIONS
The following options are supported.
-a Displays all interface information for the objects ana‐
lyzed. Note: The output from this option can be substan‐
tial, but is often useful for piping to other analysis
tools.
-b Limits the interface information to those symbols that
have been explicitly bound to. Note: Symbols defined as
protected might have been bound to from within the defin‐
ing object. This binding is satisfied at link-edit time
and is therefore not visible to the runtime environment.
Protected symbols are displayed with this option.
-C Demangles C++ symbol names. This option is useful for aug‐
menting runtime interface information. When generating
interface definitions, demangled names are added to the
mapfiles as comments.
-d mapdir Defines the directory, mapdir, in which mapfiles are cre‐
ated. By default, the current working directory is used.
-D Interprets any input files as debugging information rather
than as dynamic objects. See Analysis of User Controlled
Object Loading under EXTENDED DESCRIPTION.
-i Displays interesting interface binding information. This
mode is the default if no other output controlling option
is supplied. See Interesting Information under EXTENDED
DESCRIPTION.
-m Creates mapfiles for each dynamic object that is pro‐
cessed. These mapfiles reflect the interface requirements
of each object as required by the input file being pro‐
cessed.
-o Limits the interface information to those symbols that are
deemed an overhead. When creating mapfiles, any overhead
symbols are itemized as local symbols. See Overhead Infor‐
mation under EXTENDED DESCRIPTION.
-s Saves the bindings information produced from ldd(1), or
kldd(1), for further analysis. See FILES.
-v Ignores any objects that are already versioned. Versioned
objects have had their interfaces defined, but can con‐
tribute to the interface information displayed. For exam‐
ple, a versioned shared object might reveal overhead sym‐
bols for a particular process. Shared objects are fre‐
quently designed for use by multiple processes, and thus
the interfaces these objects provide can extend beyond the
requirements of any one process. The -v option therefore,
can reduce noise when displaying interface information.
-V Appends interesting symbol visibilities. Symbols that are
defined as singleton or are defined protected are identi‐
fied with this option.
--version Print version information and immediately exit.
-? Print usage message and immediately exit.
--help
The runtime interface information produced from lari has the following
format:
[information]: symbol-name [demangled-name]: object-name
Each line describes the interface symbol, symbol-name, together with
the object, object-name, in which the symbol is defined. If the symbol
represents a function, the symbol name is followed by (). If the symbol
represents a data object, the symbol name is followed by the symbol
size, enclosed within []. If the -C option is used, the symbol name is
accompanied by the demangled name, demangled-name. The information
field provides one or more of the following tokens that describe the
symbol's use:
cnt:bnd Two decimal values indicate the symbol count, cnt, and the
number of bindings to this object, bnd. The symbol count
is the number of occurrences of this symbol definition
that have been found in the objects that are analyzed. A
count that is greater than 1 indicates multiple instances
of a symbol definition. The number of bindings indicate
the number of objects that have been bound to this symbol
definition by the runtime linker.
E This symbol definition has been bound to from an external
object.
S This symbol definition has been bound to from the same
object.
The following tokens are specific to userland executables and shared
objects:
A This symbol definition is the address of a procedure link‐
age table entry within a dynamic executable.
C This symbol definition is the reference data of a copy-
relocation.
D This symbol definition has been directly bound to.
F This symbol definition resides in a filtee.
I This symbol definition provides for an interposer. An
object that explicitly identifies itself as an interposer
defines all global symbols as interposers. See the -z
interpose option of ld(1), and the LD_PRELOAD variable of
ld.so.1(1). Individual symbols within a dynamic executable
can be defined as interposers by using the INTERPOSE map‐
file directive.
N This symbol definition explicitly prohibits directly bind‐
ing to the definition.
P This symbol is defined as protected. This symbol might
have an internal binding from the object in which the sym‐
bol is declared. Any internal bindings with this attribute
can not be interposed upon by another symbol definition.
R This symbol definition is acting as a filter, and provides
for redirection to a filtee.
r A binding to this symbol was rejected at some point during
a symbol search. A rejection can occur when a direct bind‐
ing request finds a symbol that has been tagged to prevent
direct binding. In this scenario, the symbol search is
repeated using a default search model. The binding can
still resolve to the original, rejected symbol. A rejec‐
tion can also occur when a non-default symbol search finds
a symbol identified as a singleton. Again, the symbol
search is repeated using a default search model.
U This symbol lookup originated from a user request, for
example, dlsym(3C).
The following token is specific to kernel modules:
M This symbol definition is a module stub (modstub) provided
by the unix kernel.
See the Oracle Solaris 11.4 Linkers and Libraries Guide for more
details of these symbol classifications.
EXTENDED DESCRIPTION
Interesting Information
By default, or specifically using the -i option, lari filters any run‐
time interface information to present interesting events. This filter‐
ing is carried out mainly to reduce the amount of information that can
be generated from large applications. In addition, this information is
intended to be the focus in debugging complex binding scenarios, and
often highlights problem areas. However, classifying what information
is interesting for any particular application is an inexact science.
You are still free to use the -a option and to search the binding
information for events that are unique to the application being inves‐
tigated.
When an interesting symbol definition is discovered, all other defini‐
tions of the same symbol are output. The focus of interesting interface
information is the existence of multiple definitions of a symbol. How‐
ever, the userland and kernel runtime linking environments differ sub‐
stantially in the details of their operations, and so, the ways in
which multiple definitions become interesting differ.
Userland
The userland runtime linking environment provides the concept of
interposition, in which one symbol typically interposes on one or
more other symbol definitions. This interposition is seen when the
binding count, bnd, of one definition is non-zero, while the bind‐
ing count of all other definitions is zero. Interposition that
results from the compilation environment, or the linking environ‐
ment, is not characterized as interesting. Examples of these inter‐
position occurrences include copy relocations ([C]) and the binding
to procedure linkage addresses ([A]).
Interposition is often desirable. The intent is to overload, or
replace, the symbolic definition from a shared object. Interposi‐
tioning objects can be explicitly tagged ([I]), using the -z inter‐
pose option of ld(1). These objects can safely interpose on sym‐
bols, no matter what order the objects are loaded in a process.
However, be cautious when non-explicit interposition is employed,
as this interposition is a consequence of the load-order of the
objects that make up the process.
User-created, multiply-defined symbols are output from lari as
interesting. In this example, two definitions of interpose1()
exist, but only the definition in main is referenced:
[2:1E]: interpose1(): ./main
[2:0]: interpose1(): ./libA.so
Interposition can also be an undesirable and surprising event,
caused by an unexpected symbol name clash. A symptom of this inter‐
position might be that a function is never called although you know
a reference to the function exists. This scenario can be identified
as a multiply defined symbol, as covered in the previous example.
However, a more surprising scenario is often encountered when an
object both defines and references a specific symbol.
An example of this scenario is if two dynamic objects define and
reference the same function, interpose2(). Any reference to this
symbol binds to the first dynamic object loaded with the process.
In this case, the definition of interpose2() in object libA.so
interposes on, and hides, the definition of interpose2() in object
libB.so. The output from lari might be:
[2:2ES]: interpose2(): ./libA.so
[2:0]: interpose2(): ./libB.so
Multiply defined symbols can also be bound to separately. Separate
bindings can be the case when direct bindings are in effect ([D]),
or because a symbol has protected visibility ([P]). Although sepa‐
rate bindings can be explicitly established, instances can exist
that are unexpected and surprising. Directly bound symbols, and
symbols with protected visibility, are output as interesting infor‐
mation.
Kernel
The kernel runtime linking environment is more basic than the user‐
land environment, and does not support the full userland interposi‐
tion concept. However, multiple definitions can still cause a sim‐
ple form of interposition in which one definition hides the other.
A typical scenario is a module that defines a function that is also
defined by one of its dependencies, or by the kernel runtime sys‐
tem. This type of interposition is seen when there are multiple
definitions, each with a non-zero binding count.
This form of interposition might be useful. A module could provide
a variation of some other module, by redefining the functions that
differ, and allowing the older module to provide the remaining
functions that do not need to be changed. Such interface inheri‐
tance must be managed carefully. The use of a mapfile to define
explicit interfaces for such use is recommended.
Multiply-defined symbols are output from lari as interesting. In
this example, module kmod provides its own implementation of the
strlen() function. The module binds to its own version, while the
rest of the system binds to the version found in the unix kernel:
[2:1E]: strlen(): /platform/i86pc/kernel/amd64/unix
[2:1S]: strlen(): kmod
A scenario such as this is usually an undesirable and surprising
event, caused by an unexpected symbol name clash. It is rarely
desirable for parts of the system to use one implementation of a
function like strlen(), while other parts use another. More typi‐
cally, this output would suggest that a duplicate definition is
unnecessary, and could be removed.
Overhead Information
When using the -o option, lari displays symbol definitions that might
be considered overhead.
Global symbols that are not referenced are considered an overhead. The
symbol information that is provided within the object unnecessarily
adds to the size of the object's text segment. In addition, the symbol
information can increase the processing required to search for other
symbolic references within the object at runtime.
Global symbols that are only referenced from the same object have the
same characteristics. The runtime search for a symbolic reference, that
results in binding to the same object that made the reference, is an
additional overhead.
Both of these symbol definitions are candidates for reduction to local
scope by defining the object's interface. Interface definitions can be
assigned to a file during its creation by the link-editor using the -M
option and the associated mapfile directives. See the Oracle Solaris
11.4 Linkers and Libraries Guide for more details on mapfiles. Use lari
with the -m option to create initial versions of these mapfiles.
If lari is used to generate mapfiles, versioned shared objects will
have mapfiles created indicating that their overhead symbols should be
reduced to locals. This model allows lari to generate mapfiles for com‐
parison with existing interface definitions. Use the -v option to
ignore versioned shared objects when creating mapfiles.
Copy-relocations are also viewed as an overhead and generally should be
avoided. The size of the copied data is a definition of its interface.
This definition restricts the ability to change the data size in newer
versions of the shared object in which the data is defined. This
restriction, plus the cost of processing a copy relocation, can be
avoided by referencing data using a functional interface. The output
from lari for a copy relocation might be:
[2:1EC]: __iob[0x140]: ./main
[2:0]: __iob[0x140]: ./libA.so.1
Notice that a number of small copy relocations, such as __iob used in
the previous example, exist because of historic programming interac‐
tions with system libraries.
Another example of overhead information is the binding of a dynamic
object to the procedure linkage table entry of a dynamic executable. If
a dynamic executable references an external function, a procedure link‐
age table entry is created. This structure allows the reference binding
to be deferred until the function call is actually made. If a dynamic
object takes the address of the same referenced function, the dynamic
object binds to the dynamic executables procedure linkage table entry.
An example of this type of event reveals the following:
[2:1EA]: foo(): ./main
[2:1E]: foo(): ./libA.so
A small number of bindings of this type are typically not cause for
concern. However, a large number of these bindings, perhaps from a
jump-table programming technique, can contribute to start up overhead.
Address relocation bindings of this type require relocation processing
at application start up, rather than the deferred relocation processing
used when calling functions directly. Use of this address also requires
an indirection at runtime.
Analysis of User Controlled Object Loading
Without the -D option, lari uses ldd(1) to process userland executable
and shared object files. The following options are used:
-r and -e LD_DEBUG=files,bindings,detail
These options provide information on all bindings that are established
as part of loading the object. Due to the use of the ldd, the specified
object is not executed, and hence no user controlled loading of
objects, by dlopen(3C) occurs. To capture all binding information from
an executing process, the following environment variables can be passed
directly to the runtime linker, ld.so.1(1):
LD_DEBUG=files,bindings,detail LD_DEBUG_OUTPUT=lari.dbg \
LD_BIND_NOW=yes
The resulting debug output, lari.dbg.pid, can be processed by lari
using the -D option. Note: lari attempts to analyze each object that
has been processed using the path name defined in the debug output.
Each object must therefore be accessible to lari for a complete, accu‐
rate analysis to be provided. The debug output file must be generated
in the C locale.
EXAMPLES
Example 1 Analyzing a case of multiple bindings
The following example shows the analysis of a process in which multiple
symbol definitions exist. The shared objects libX.so and libY.so both
call the function interpose(). This function exists in both the appli‐
cation main, and the shared object libA.so. Because of interposition,
both references bind to the definition of interpose() in main.
The shared objects libX.so and libY.so also both call the function
foo(). This function exists in the application main, and the shared
objects libA.so, libX.so, and libY.so. Because both libX.so and libY.so
were built with direct bindings enabled, each object binds to its own
definition.
example% lari ./main
[3:0]: foo(): ./libA.so
[3:1SD]: foo(): ./libX.so
[3:1SD]: foo(): ./libY.so
[2:0]: interpose(): ./libA.so
[2:2EP]: interpose(): ./main
To analyze binding information more thoroughly, the bindings data can
be saved for further inspection. For example, the previous output indi‐
cates that the function interpose() was called from two objects exter‐
nal to main. Inspection of the binding output reveals where the refer‐
ences to this function originated.
example% lari -s ./main
lari: ./main: bindings information saved as: \
/usr/tmp/lari.dbg.main
.....
example% fgrep foo /usr/tmp/lari.dbg.main
binding file=./libX.so to file=./main: symbol `interpose'
binding file=./libY.so to file=./main: symbol `interpose'
Note: The bindings output is typically more extensive than shown here,
as the output is accompanied with process identifier, address and other
bindings information.
Example 2 Generating an interface definition
The following example creates interface definitions for an application
and its dependency, while ignoring any versioned system libraries. The
application main makes reference to the interfaces one(), two(), and
three() in foo.so:
example% lari -omv ./main
example% cat mapfile-foo.so
#
# Interface Definition mapfile for:
# Dynamic Object: ./foo.so
# Process: ./main
#
foo.so {
global:
one;
three;
two;
local:
_one;
_three;
_two;
*;
};
FILES
$TMPDIR/lari.dbg.file Binding output produced by ldd(1).
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
TRIBUTE VALUE _ Availabilitydeveloper/base-developer-utilities _ Inter‐
face StabilitySee below.
The human readable output is Uncommitted. The options are Committed.
SEE ALSO
kldd(1), ld(1), ld.so.1(1), ldd(1), dlopen(3C), dlsym(3C),
attributes(7)
Oracle Solaris 11.4 Linkers and Libraries Guide
Oracle Solaris 11.4 22 June 2021 lari(1)