Experimental Physics and
Industrial Control System

Dirk Zimoch via Core-talk <core-talk at aps.anl.gov> · Fri, 09 Feb 2024 15:07:36 -0000

Public bug reported:

A template file that only contains macros with default values can be
loaded with `dbLoadRecords("file.db","")` but not with
`dbLoadRecords("file.db",NULL)`. In particular, in the startup script,
it cannot be loaded with `dbLoadRecords "file.db"` but only with
`dbLoadRecords "file.db",""`. (VxWorks shell as well as iocsh.)

Using such a macro in a record name results in the error message:
ERROR: Bad character '$' in Record/Alias name "$(P=)Name"

Using macros with defaults in fields shows error messages like this:
ERRORName.PREC Has unexpanded macro
Can't set "Name.PREC" to "$(PREC=3)"  : Bad Field value
ERRORERROR failed to load 'file.db'

(Unrelated: Someone please fix the missing blanks after ERROR and the
ERRORERROR.)

The reason is that `dbReadCOM`, the function that does the real work,
only creates a `macHandle` when `substitutions` is not `NULL`. Not
having a `macHandle` prevents any macro substitution from working, even
those which provide a default value.

In the old times, when macros could not have defaults, this was fine,
but not any more. A macro handle should always be created, even if it
stays empty when `substitutions` is `NULL`.

** Affects: epics-base
     Importance: Undecided
         Status: New

** Description changed:

  A template file that only contains macros with default values can be
  loaded with `dbLoadRecords("file.db","")` but not with
  `dbLoadRecords("file.db",NULL)`. In particular, in the startup script,
  it cannot be loaded with `dbLoadRecords "file.db"` but only with
  `dbLoadRecords "file.db",""`. (VxWorks shell as well as iocsh.)

  Using such a macro in a record name results in the error message:
  ERROR: Bad character '$' in Record/Alias name "$(P=)Name"

  Using macros with defaults in fields shows error messages like this:
  ERRORName.PREC Has unexpanded macro
  Can't set "Name.PREC" to "$(PREC=3)"  : Bad Field value
  ERRORERROR failed to load 'file.db'

  (Unrelated: Someone please fix the missing blanks after ERROR and the
  ERRORERROR.)

  The reason is that `dbReadCOM`, the function that does the real work,
  only creates a `macHandle` when `substitutions` is not `NULL`. Not
  having a `macHandle` prevents any macro substitution from working, even
  those which provide a default value.

  In the old times, when macros could not have defaults, this was fine,
- but not any more. A macro handle should always be created, even it it
+ but not any more. A macro handle should always be created, even if it
  stays empty when `substitutions` is `NULL`.

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https://bugs.launchpad.net/bugs/2052814

Title:
  dbLoadRecords with subs=NULL fails to expand macros with defaults

Status in EPICS Base:
  New

Bug description:
  A template file that only contains macros with default values can be
  loaded with `dbLoadRecords("file.db","")` but not with
  `dbLoadRecords("file.db",NULL)`. In particular, in the startup script,
  it cannot be loaded with `dbLoadRecords "file.db"` but only with
  `dbLoadRecords "file.db",""`. (VxWorks shell as well as iocsh.)

  Using such a macro in a record name results in the error message:
  ERROR: Bad character '$' in Record/Alias name "$(P=)Name"

  Using macros with defaults in fields shows error messages like this:
  ERRORName.PREC Has unexpanded macro
  Can't set "Name.PREC" to "$(PREC=3)"  : Bad Field value
  ERRORERROR failed to load 'file.db'

  (Unrelated: Someone please fix the missing blanks after ERROR and the
  ERRORERROR.)

  The reason is that `dbReadCOM`, the function that does the real work,
  only creates a `macHandle` when `substitutions` is not `NULL`. Not
  having a `macHandle` prevents any macro substitution from working,
  even those which provide a default value.

  In the old times, when macros could not have defaults, this was fine,
  but not any more. A macro handle should always be created, even if it
  stays empty when `substitutions` is `NULL`.

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System