Experimental Physics and
Industrial Control System

Dirk Zimoch via Core-talk <core-talk at aps.anl.gov> · Wed, 01 Feb 2023 09:27:00 -0000

The reason is in iocsh.cpp line 363:
        if (quote != EOF) {

Here, quote is 0xff but EOF is -1.

quote is initialized in line 265:
        char quote = EOF;

The problem is the usage of EOF in function split().

On any architecture, where char is unsigned  (e.g. VxWorks on PPC), the initialization 
        char quote = EOF;
sets quote to (char)-1 = 255.

Later, the comparison (quote != EOF) compares an unsigned char with the
signed int literal -1. Thus the unsigned char gets promoted to a signed
int with the same value 255 which is then then compared to -1. That is
of course not equal.

The possible fixes are:
1. use signed char quote
2. use int quote
3. use 0 instead of EOF

I prefer solution 3. The attached patch has been created with commit
60128ee but can be applied to the current HEAD (bc54524) as well.

** Patch added: "iocsh_fix_for_unsigned_char.patch"
   https://bugs.launchpad.net/epics-base/+bug/2004463/+attachment/5644257/+files/iocsh_fix_for_unsigned_char.patch

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https://bugs.launchpad.net/bugs/2004463

Title:
  iocsh on vxWorks broken

Status in EPICS Base:
  New

Bug description:
  Since commit 60128ee9 "Com: separate iocsh argument splitting", iocsh
  is broken on VxWorks (tested with version 6.9.4.12)

  Any command prints the error "Unbalanced quote."

  > iocsh
  epics> echo
  Unbalanced quote.
  epics> "echo"
  Unbalanced quote.
  epics> "echo
  Unbalanced quote.
  epics> echo bla
  Unbalanced quote.
  epics> echo 1 2 3
  Unbalanced quote.
  epics> exit
  Unbalanced quote.

  I have started investigating....

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System