CVS commit: src/usr.bin/ftp

["Luke Mewburn" <lukem%netbsd.org@localhost>]

Module Name:    src
Committed By:   lukem
Date:           Sat Jul 11 02:19:32 UTC 2020

Modified Files:
        src/usr.bin/ftp: ftp.c version.h

Log Message:
ftp.c: improve signal handler restoration

Only invoke the old signal handler if it's a real signal handler
and not SIG_IGN, SIG_DFL, SIG_HOLD, or SIG_ERR, using new static
function issighandler().
Avoids an intermittent race condition with a null pointer
dereference via (*SIG_DFL)().
Bug class reported by Joyu Liao from Juniper Networks.

Use SIG_ERR instead of NULL as the indicator that a signal handler
hasn't been changed, so that SIG_DFL (equivalent to NULL)
will be restored.


To generate a diff of this commit:
cvs rdiff -u -r1.169 -r1.170 src/usr.bin/ftp/ftp.c
cvs rdiff -u -r1.89 -r1.90 src/usr.bin/ftp/version.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.