bin/50199: "awk: out of memory in strftime" when calling strftime() with empty format string

[juho.salminen%iki.fi@localhost]

>Number:         50199
>Category:       bin
>Synopsis:       "awk: out of memory in strftime" when calling strftime() with empty format string
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 03 18:15:00 +0000 2015
>Originator:     Juho Salminen
>Release:        NetBSD-6.1.5
>Organization:
>Environment:
NetBSD isokaijanen.jmos.iki.fi 6.1.5 NetBSD 6.1.5 (ISOKAIJANEN) #0: Thu Mar 19 11:59:14 EET 2015  jmosalmi%isokaijanen.jmos.iki.fi@localhost:/usr/netbsd-6.1.5/obj/sys/arch/amd64/compile/ISOKAIJANEN amd64
>Description:
awk fails with error message "out of memory in strftime" when calling strftime() function with an empty format string.

This occurs because it is assumed that return value 0 of strftime() means that the resulting string did not fit into the buffer, even though for an empty format string it really means the length of the resulting string. Thus a bigger and bigger buffer is reallocated until memory exhausts.

>How-To-Repeat:
[jmosalmi@isokaijanen ~]$ awk 'BEGIN {strftime("")}'
awk: out of memory in strftime
 source line number 1
[jmosalmi@isokaijanen ~]$ 
>Fix:
--- src/external/historical/nawk/dist/run.c.~1.4.2.1.~  2012-07-12 22:24:21.000000000 +0300
+++ src/external/historical/nawk/dist/run.c     2015-09-03 20:55:44.000000000 +0300
@@ -1650,7 +1650,7 @@
                do {
                        if ((buf = realloc(buf, (sz *= 2))) == NULL)
                                FATAL("out of memory in strftime");
-               } while(strftime(buf, sz, fmt, tm) == 0);
+               } while(strftime(buf, sz, fmt, tm) == 0 && fmt[0] != '\0');

                y = gettemp();
                setsval(y, buf);