cannot fully disable checking of mail

[eravin]

Configuration Information [Automatically generated, do not change]:
Machine: i386
OS: netbsdelf3.0
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i386' 
-DCONF_OSTYPE='netbsdelf3.0' -DCONF_MACHTYPE='i386-unknown-netbsdelf3.0' 
-DCONF_VENDOR='unknown' -DLOCALEDIR='/pkg/bash-3.2/share/locale' 
-DPACKAGE='bash' -DSHELL  -DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib 
-I./lib/intl -I/devel/build/NetBSD/bash/bash-3.2/lib/intl  
-Wl,-Map,/tmp/pipes/bash-3.2
uname output: NetBSD panix5.panix.com 3.1_RC3 NetBSD 3.1_RC3 (PANIX-35) #0: Wed 
Oct 18 22:28:22 EDT 2006  
root@juggler.panix.com:/devel/netbsd/3.1-RC3/src/sys/arch/i386/compile/PANIX-35 
i386
Machine Type: i386-unknown-netbsdelf3.0

Bash Version: 3.2
Patch Level: 0
Release Status: release

Description:

Some of our customers have large inboxes in maildir format
(thousands of messages).

bash is very inefficient when used to check mail files this
way, because it loops over the entire maildir/new and maildir/cur
directories whenever it checks mail.

We thus tried to turn off mail checking in /etc/profile. But
code like this in /etc/profile:

  unset MAILCHECK
  MAIL=$HOME/.maildir/

still provokes a complete walk of the maildir directory (observed via
ktrace).  The culprit appears to be the mailstat() function, which is
called whenever the value of MAIL is changed (from sv_mail):

#0  0x080b05e1 in mailstat ()
#1  0x0807ff46 in update_mail_file ()
#2  0x0808018d in add_mail_file ()
#3  0x0808065b in remember_mail_dates ()
#4  0x08066cae in sv_mail ()


Repeat-By:

  set /etc/profile to "unset MAILCHECK; MAIL=/large/user/.maildir"
  
  $ ktrace bash -l
  bash> exit
  # show how many times maildir was referenced:
  $ kdump | grep -c /large/user/.maildir


Fix:

Don't ever call mailstat() if MAILCHECK is not set?