Experimental Physics and
Industrial Control System

mdavidsaver via Core-talk <core-talk at aps.anl.gov> · Fri, 27 Aug 2021 15:25:32 -0000

** Changed in: epics-base
       Status: New => Confirmed

** Changed in: epics-base
   Importance: Undecided => Low

** Changed in: epics-base
     Assignee: (unassigned) => mdavidsaver (mdavidsaver)

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https://bugs.launchpad.net/bugs/1941875

Title:
  Buggy warning message "Record/Alias name '...' should not contain non-
  printable ...

Status in EPICS Base:
  Confirmed

Bug description:
  There are multiple bugs in dbRecordNameValidate()
  (modules/database/src/ioc/dbStatic/dbLexRoutines.c).

  /* any character restrictions */
  char c = *pos;
  [...]
  if(c < ' ') {
    errlogPrintf("Warning: Record/Alias name '%s' should not contain non-printable 0x%02u\n",
                           name, (unsigned)c);
  }

  1. The check for non-printable characters: if(c < ' ') does not consider implementations where char is signed. Characters with the high bit set are considered negative and thus <' '.
  2. Printing the character with "0x%02u" prints a decimal number prefixed with 0x which is confusing (not to say wrong).
  3. Casting a signed char to unsigned effectively first sign extends the char to int, then re-interprets it as unsigned int, turning a char >0x80 into a number >4294967168.
  On an implementation where char is unsigned, the whole casting is pointless anyway.

  This results in confusing warnings like:
  Warning: Record/Alias name 'Ä' should not contain non-printable 0x4294967235

  The function should explicitly use unsigned char c to fix (c < ' '),
  use "0x%02x" to format c and not cast c.

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System