Re: [libvirt] [PATCH] docs: ensure outputfile is deleted if rst2html/rst2man fail

On Wed, Dec 11, 2019 at 12:52:20PM -0600, Eric Blake wrote: > On 12/11/19 12:45 PM, Daniel P. Berrangé wrote: >> This avoids leaving a zero length or partially generated output >> file on errors. >> >> Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; >> --- >> docs/Makefile.am | 10 +++++----- >> 1 file changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/docs/Makefile.am b/docs/Makefile.am >> index eb8de80b9c..9a1f7a6117 100644 >> --- a/docs/Makefile.am >> +++ b/docs/Makefile.am >> @@ -259,21 +259,21 @@ man8_MANS = $(manpages8_rst:%.rst=%.8) >> grep -v '^\.\. contents::' < $< | \ >> sed -e 's|SYSCONFDIR|$(sysconfdir)|g' \ >> -e 's|RUNSTATEDIR|$(runstatedir)|g' | \ >> - $(RST2MAN) > $@ >> + $(RST2MAN) > $@ || { rm $@ && exit 1; } > > But still allows a truncated view of the file if another process accesses > the file while RST2MAN is still running. Even better is to generate output > to a temp file then atomically mv it into place, so that no concurrent > process can ever see an incomplete file. Is that a problem that actually impacts negatively in real world for builds? In various places in the make rules, we've either done the "|| rm" approach, or the temp file and rename approach. Personally I find the recipes using the "|| rm" approach are more maintainable/readable.