#2 PARSE SOURCE not working under ANY Unix; WORKAROUND INSIDE

[cniggeler]

Hi,

I've built RexxWrapper 3.4 for use under SGI Irix 6.5 and have Regina 3.3. I'm linking statically (libregina.a). After wrapping this simple test program,
parse source mypath
say mypath

I get
UNIX COMMAND testparse

If I run the same test program through the Rexx interpreter (rexx testparse.rexx), I get
UNIX COMMAND /usr/people/chris/build/testparse.rexx

which is the correct output. I do not experience this problem under Linux, which is configured exactly the same (i.e., RW 2.4, Regina 3.3, static link). Does anyone know what is going on here?

Thanks,
Chris

[Mark Hessling]

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Hi Chris,

When the executable built by Rexx/Wrapper runs it attempts to find a fully qualified name for the current executable. Under Linux this is achieved by calling readlink( /proc/self/exe ) which will return the fully qualified (ie full path) of the executable that is currently running. Even on Linux it will only return /usr/people/chris/build/testparse (no .rexx).
See getargv0.c in the Rexx/Wrapper distro.

The readlink() doesn't work on Irix. It will return whatever is available to the executable based on how it was executed. Examples:
./testparse should result in "say mypath" returning "./testparse"
/usr/people/chris/build/testparse should result in "say mypath" returning "/usr/people/chris/build/testparse"

Cheers, Mark

[cniggeler]

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Hi Mark,

Thanks for the prompt reply. At least in Irix 6.5, the situation is much worse than that. For the RexxWrapped program mentioned before, the results are almost always only the name without path or extension! So the commands
./testparse
cd ..
build/testparse

ALWAYS return
UNIX COMMAND testparse

The one exception is if the fully qualified pathname is given:
/home/chris/build/testparse
returns
UNIX COMMAND /home/chris/build/testparse

I have a rather extensive workaround, and I'll put that in the next comment.

[cniggeler]

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WORKAROUND -
Assuming the program is named "testparse":

if uname('s') = "IRIX" then do
ls. = "<NIL>"
whoami = ''
prod="testparse"
address system 'ps -ef | grep "'||prod'||" | grep -v grep' with output stem ls.
do i=1 while ls.i <> "<NIL>"
do j=1 to words(ls.i)
if right(word(ls.i, j), length(prod)) = prod then do
whoami = word(ls.i, j)
signal gotit
end
end
end
end
else parse source . . whoami

gotit:
...

[cniggeler]

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The same stated (mis)behavior occurs in all the *nixes I've ported to: Irix 6.5, Solaris 8, HP-UX 11.1, and AIX 5.2. Only Linux and Windows(!) seem to behave like they're supposed to.

FULL WORKAROUND
Caveat - this workaround assumes you're inspecting "whoami" and the results of "ps" in an application started from the command line - it is not a daemon. I don't know what happens if you start it from a GUI.

mysys=translate(left(uname('S'), 3))
if mysys="WIN" then slash='\'
else slash='/'

if mysys<>"WIN" & mysys<>"LIN" then do
found=0 /* Flag to get us out of the loops */
ls. ="<NIL>"
prod ="testparse" /* <- Insert your program name */

address system 'ps -ef | grep "'prod'" | grep -v grep' with output stem ls.
do i=1 while ls.i <> "<NIL>" & \found
do j=1 to words(ls.i) while \found
if right(word(ls.i, j), length(prod)) = prod then do
whoami = word(ls.i, j)
if left(whoami, 1) <> slash then do
address system 'pwd' with output stem ls.
if ls.1 <> slash then whoami=ls.1||slash||whoami
else whoami=ls.1||whoami
end
found=1
end
end
end
end

else parse source . . whoami
mydir = left(whoami, lastpos(slash, whoami)-1)