Re: [IBMiOSS] Latest node installation woes -- OPENSOURCE

At program startup the linker/loader will analyze all the dependent
libraries of the program and load them in to the program's address space.
Any dependencies of those libraries will also be loaded as well (I don't
know if it's done depth-first or breadth-first). Then static
initialization occurs and finally the program entry point (main) is
called. These libraries are loaded in to your address space until program
termination or you call exec(). You can dynamically load at runtime
through dlopen() API set and in that case, libraries can become unloaded
(though it's not recommended as many libraries do not handle this
properly).

What you're asking about is completely different, though. Let's say you're
at a shell prompt and run some perzl application:

$ /opt/freeware/bin/curl http://google.com

- The shell will first fork a new child process
- In the child, it will pass the program and its arguments to exec() (or
some variant thereof).
- exec will overwrite the process's address space with the program binary
- the loader will load all the dependent libraries as detailed above,
including /opt/freeware/lib/libcurl.a which then causes
/opt/freeware/lib/libssl.a to be loaded
- curl downloads the url and echoes it to the screen
- the parent (shell) is waiting for the child to exit and finally gets
signalled that it has
- the parent reads the child's exit code and sets $?

Now you call node:

$ /QOpenSys/QIBM/ProdData/Node/bin/node -v

- The shell forks a new child process
- In the child, again passes node and the arguments to exec
- exec overwrites the child's address space with the node binary
- the loader will load all of node's dependent libraries, including
/QOpenSys/usr/lib/libssl.a
- node prints out its version and exits with a 0 return code
- the parent gets signalled that the child has exited
- the parent reads the child's exit code and sets $?

If you pay close enough attention above, you'll see that each of these
programs run in a new process (job), so there is no way a cached version
in the process could have affected it. When you do an exec, everything in
the process is replaced by a new program so you don't have to worry about
that.

Now, AIX does have the concept of a system-wide cache. Basically when a
library is first loaded, it will be loaded in to this system wide cache
and mapped in to memory. Then instead of having to load from disk for
every process that wants to use the library, the linker just has to map
those pages in to the process's address space. You can run slibclean to
clear this cache of any libraries that are not in use. This cache is
affected by loader domains as well as the permissions set on the library
itself. If a library is set executable only by the owner, it is loaded in
to a private mapping and is not cached.

The other thing to remember is that the library is really just an archive
of shared objects (.so or .o) or static objects (.o).

For instance, looking at libcurl.a, we see it depends on libssl.a, but
really the libssl.so.0.9.8 shared object inside the libssl.a archive:
/opt/freeware/lib/libcurl.a[libcurl.so.4]:

***Loader Section***
Loader Header Information
VERSION# #SYMtableENT #RELOCent LENidSTR
0x00000001 0x000002b9 0x00000aef 0x00000102

#IMPfilID OFFidSTR LENstrTBL OFFstrTBL
0x00000009 0x0000c4ac 0x00002f31 0x0000c5ae

***Import File Strings***
INDEX PATH BASE MEMBER
0 /opt/freeware/lib:/opt/freeware/lib:/usr/vac/lib:/usr/lib:/lib

1 libc.a shr.o
2 libidn.a libidn.so.11
3 libcrypto.a libcrypto.so.0.9.8
4 libssl.a libssl.so.0.9.8
5 libz.a libz.so.1
6 libldap.a libldap-2.4.so.2

7 liblber.a liblber-2.4.so.2

8 libssh2.a libssh2.so.1

Also looking at index 0 is where you find the compiled in LIBPATH for this
library. This is where the linker will look for these dependent libraries
when loading libcurl.a.

When looking at node, however, we see that it is dependent on libssl.so.1
shared object in libssl.a:

kadler@wernstrom:~>dump -H /QOpenSys/QIBM/ProdData/OPS/Node4/bin/node

/QOpenSys/QIBM/ProdData/OPS/Node4/bin/node:

***Loader Section***
Loader Header Information
VERSION# #SYMtableENT #RELOCent LENidSTR
0x00000001 0x00005904 0x00013a47 0x000001da

#IMPfilID OFFidSTR LENstrTBL OFFstrTBL
0x00000006 0x001713d4 0x00173f11 0x001715ae

***Import File Strings***
INDEX PATH BASE MEMBER
0
.:/QOpenSys/opt/freeware/bin/../lib/gcc/powerpc-ibm-aix6.1.0.0/4.8.4/pthread:/QOpenSys/opt/freeware/bin/../lib/gcc/powerpc-ibm-aix6.1.0.0/4.8.4/../../../pthread:/QOpenSys/opt/freeware/bin/../lib/gcc/powerpc-ibm-aix6.1.0.0/4.8.4:/QOpenSys/opt/freeware/bin/../lib/gcc:/QOpenSys/opt/freeware/bin/../lib/gcc/powerpc-ibm-aix6.1.0.0/4.8.4/../../..:/usr/lib:/lib

1 libc.a shr.o
2 libpthreads.a shr_xpg5.o
3 libcrypto.a libcrypto.so.1
4 libpthreads.a shr_comm.o
5 libssl.a libssl.so.1

It has quite a complicated LIBPATH set, since by default the linker will
add any path you specify with -L to this LIBPATH and GCC adds a bunch of
its own paths automatically. So the only time you would run in to a
problem is if you had a libssl.a that was in one of these common paths
between the two binaries that did not contain both dependent objects
(libssl.so.0.9.8 and libssl.so.1).

Anyway, quite a rambling knowledge dump. I should probably polish it a bit
and turn it in to an article or something...

"OpenSource" <opensource-bounces@xxxxxxxxxxxx> wrote on 10/03/2016
07:43:30 PM:

From: Aaron Bartell <aaronbartell@xxxxxxxxx>
To: IBMi Open Source Roundtable <opensource@xxxxxxxxxxxx>
Date: 10/03/2016 07:43 PM
Subject: Re: [IBMiOSS] Latest node installation woes
Sent by: "OpenSource" <opensource-bounces@xxxxxxxxxxxx>

Ignorance question: when libxxxxx.a resolution happens is there ever a
cached version in the job's memory based on it being previously loaded?
That's where my PATH comments are coming from. Specifically, if perzl

stuff

was run immediately previous to "node -v" could it effect it if both

were

going after libcrypto.a?

On Oct 3, 2016 5:49 PM, "Kevin Adler" <kadler@xxxxxxxxxx> wrote:

"OpenSource" <opensource-bounces@xxxxxxxxxxxx> wrote on 10/03/2016
07:02:06 AM:

From: Aaron Bartell <aaronbartell@xxxxxxxxx>
To: IBMi Open Source Roundtable <opensource@xxxxxxxxxxxx>
Date: 10/03/2016 07:02 AM
Subject: Re: [IBMiOSS] Latest node installation woes
Sent by: "OpenSource" <opensource-bounces@xxxxxxxxxxxx>

Further to Robert's comments, you should also run the
/QOpenSys/QIBM/ProdData/OPS/Node4/bin/nodeenv.sh(n1) shell script

which

will set the symlinks in /QOpenSys/usr/bin.

n1 - More info here: http://bit.ly/developerWorks-node-v4

Concerning why it bombs on libcrypto.a, that many times is because

of a

conflict with perzl stuff. Remove /opt/freeware/bin from PATH and

see

if

that allows it to continue. If you need perzl stuff in your path

then

that's a longer conversation to fix it.

PATH doesn't matter for finding libraries (only binaries). Only

LIBPATH

would matter in this case (don't set LIBPATH unless you know what

you're

doing).

Also, it appears you're using Node
v.0.12.x(/QOpenSys/QIBM/ProdData/Node/bin/node). IBM has alluded

giving

that an EndOfLife, time to move on to Node
v4.x(/QOpenSys/QIBM/ProdData/OPS/Node4/bin/node).

Aaron Bartell
litmis.com - Services for open source on IBM i

On Mon, Oct 3, 2016 at 5:11 AM, R Brown <rbpaservices@xxxxxxxxx>

wrote:

I had the same issue. Look inside the OPS for NODE4 and add that

the

path. It should find node then.

On Oct 3, 2016 4:40 AM, "Kevin Turner"

<kevin.turner@xxxxxxxxxxxxxxx>

wrote:

Hi

The guys managing our US IBMi servers are now trying to install

5770OPS.

They have installed the product and all PTFs, but it is still

foobar.

First and foremost no symbolic links have been created in

/usr/bin

for

the

“node” and “npm” commands.
Despite that, even if you navigate to

QOpenSys/QIBM/ProdData/Node/bin

and

execute the node command it fails:

node -v
exec(): 0509-036 Cannot load program node because of the

following

errors:

0509-150 Dependent module libcrypto.a(libcrypto.so.1)

could not

be loaded.
0509-022 Cannot load module libcrypto.a(libcrypto.so.1).
0509-026 System error: A file or directory in the path

name

does

not exist.

Sounds like something else needs to be there that 5770OPS does

not

install

(ssh perhaps)?

I am not sure how or why IBM are making such a pigs ear of this.

Anyone

seen this before?

Thanks
Kevin

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