Automatically reload rpm configuration on mismatching BuildArch

When BuildArch is encountered during spec parse, rpm recurses the
parse, but this doesn't reset/reload the global configuration and macros
to match. So eg a "BuildArch: noarch" package gets built with a
dramatically different macros depending on whether "--target noarch"
was used or not, whereas people expect it to be the same - after all we
give zero indication that anything might be wrong when --target wasn't
specified.

Automatically detect and handle this condition in the rpmbuild tool:
if the spec parse architecture disagrees with our loaded configuration,
request a reparse with reloaded configuration for the matching target.
This ensures 'rpmbuild -bb noarch.spec' and 'rpmbuild -bb --target
noarch noarch.spec' run with the same exact configuration.
Doing this also fixes the situation where build-time macro expansion
of build scriptlets (for template bits and dynamically generated spec
parts) yields totally different (bogus) than in the initial spec parse.
This also goes for RPM_ARCH environment and similar.

Avoid --undefine for dependency generation test, it doesn't work.
--undefine with --target was always broken, now it's just more visible
since it automatically applies to BuildArch too. Fixing that is a
separate matter (#3070).

A more sophisticated fix could be having a stack of macro contexts that we
copy, push and pop as necessary. That ought to solve the undefine too.

Fixes: #3049

tests/data/SPECS/templ.spec

@@ -0,0 +1,12 @@
+Name: templ
+Version: 1
+Release: 1
+License: Public domain
+Summary: Spec template tests
+BuildArch: noarch
+
+%description
+%{summary}
+
+%build
+echo BUILD ${RPM_ARCH} %{_arch} %{_target_cpu} >> /tmp/build.out

tests/rpmbuild.at

@@ -1105,7 +1105,7 @@ RPMDB_INIT
 
 runroot rpmbuild -bb --quiet \
  --define '__script_mime text/plain' \
- --undefine '__script_magic' \
+ --define '__script_magic %{nil}' \
  /data/SPECS/shebang.spec
 runroot rpm -qp --requires /build/RPMS/noarch/shebang-0.1-1.noarch.rpm|grep -v ^rpmlib
 ],
@@ -3068,3 +3068,55 @@ hello-1.0-install.patch
 ],
 [])
 RPMTEST_CLEANUP
+
+AT_SETUP([rpmbuild target macro sanity])
+AT_KEYWORDS([build])
+RPMDB_INIT
+
+# This is surprisingly tricky - we need to place these macros in a place
+# that is after the platform stuff in macro path so we can't just drop
+# into macros.d, and then we need to take cmake prefix into account,
+# escape \'s and $'s and whatnot. Pff. Would be easier to place to
+# a macro file, but this is so tightly coupled that seems saner to
+# have it all here.
+etcdir=$(runroot rpm --eval "%_sysconfdir")
+mkdir -p ${RPMTEST}/${etcdir}/rpm/
+
+cat << EOF >> ${RPMTEST}/${etcdir}/rpm/macros.template
+%__spec_build_pre\\
+%{___build_pre_env}\\
+echo BUILD_PRE \${RPM_ARCH} %{_arch} %{_target_cpu} >> /tmp/build.out\\
+%{nil}
+
+%__spec_build_post\\
+echo BUILD_POST \${RPM_ARCH} %{_arch} %{_target_cpu} >> /tmp/build.out\\
+%{nil}
+EOF
+
+RPMTEST_CHECK([
+runroot_other rm -f /tmp/build.out
+runroot rpmbuild --quiet \
+ -bc /data/SPECS/templ.spec
+runroot_other cat /tmp/build.out
+],
+[0],
+[BUILD_PRE noarch noarch noarch
+BUILD noarch noarch noarch
+BUILD_POST noarch noarch noarch
+],
+[])
+
+RPMTEST_CHECK([
+runroot_other rm -f /tmp/build.out
+runroot rpmbuild --quiet \
+ --target noarch \
+ -bc /data/SPECS/templ.spec
+runroot_other cat /tmp/build.out
+],
+[0],
+[BUILD_PRE noarch noarch noarch
+BUILD noarch noarch noarch
+BUILD_POST noarch noarch noarch
+],
+[])
+RPMTEST_CLEANUP

tools/rpmbuild.c

@@ -422,7 +422,8 @@ static char * getTarSpec(const char *arg)
  return specFinal;
 }
 
-static int buildForTarget(rpmts ts, const char * arg, BTA_t ba)
+static int buildForTarget(rpmts ts, const char * arg, BTA_t ba,
+ ARGV_t *specarch)
 {
  int buildAmount = ba->buildAmount;
  char * buildRootURL = NULL;
@@ -512,6 +513,21 @@ static int buildForTarget(rpmts ts, const char * arg, BTA_t ba)
  goto exit;
  }
 
+ if (specarch) {
+ Header h = rpmSpecSourceHeader(spec);
+ const char *buildarch = headerGetString(h, RPMTAG_ARCH);
+ const char *arch = NULL;
+
+ rpmGetArchInfo(&arch, NULL);
+
+ /* if spec buildarch differs from current arch, request a reparse */
+ if (strcmp(arch, buildarch)) {
+ rc = -1;
+ argvAdd(specarch, buildarch);
+ goto exit;
+ }
+ }
+
  /* Create build tree if necessary */
  if (rpmMkdirs(root, "%{_topdir}:%{_builddir}:%{_rpmdir}:%{_srcrpmdir}"))
  goto exit;
@@ -520,11 +536,11 @@ static int buildForTarget(rpmts ts, const char * arg, BTA_t ba)
  goto exit;
  }
 
- if (buildMode == 't')
- (void) unlink(specFile);
  rc = 0;
 
 exit:
+ if (buildMode == 't')
+ (void) unlink(specFile);
  free(specFile);
  rpmSpecFree(spec);
  free(buildRootURL);
@@ -534,21 +550,23 @@ static int buildForTarget(rpmts ts, const char * arg, BTA_t ba)
 static int build(rpmts ts, const char * arg, BTA_t ba, const char * rcfile)
 {
  int rc = 0;
- char * targets = argvJoin(build_targets, ",");
 #define buildCleanMask (RPMBUILD_RMSOURCE|RPMBUILD_RMSPEC)
  int cleanFlags = ba->buildAmount & buildCleanMask;
  rpmVSFlags vsflags, ovsflags;
+ char *targets = NULL;
 
  vsflags = rpmExpandNumeric("%{_vsflags_build}");
  vsflags |= rpmcliVSFlags;
  ovsflags = rpmtsSetVSFlags(ts, vsflags);
 
  if (build_targets == NULL) {
- rc = buildForTarget(ts, arg, ba);
- goto exit;
+ rc = buildForTarget(ts, arg, ba, &build_targets);
+ if (rc >= 0)
+ goto exit;
  }
 
  /* parse up the build operators */
+ targets = argvJoin(build_targets, ",");
  if (!quiet)
  fprintf(stderr, _("Building target platforms: %s\n"), targets);
 
@@ -569,7 +587,7 @@ static int build(rpmts ts, const char * arg, BTA_t ba, const char * rcfile)
  }
  rpmFreeRpmrc();
  (void) rpmReadConfigFiles(rcfile, *target);
- rc = buildForTarget(ts, arg, ba);
+ rc = buildForTarget(ts, arg, ba, NULL);
  if (rc)
  break;
  }