vcs-svn: handle log message with embedded NUL

Pass the log message by strbuf instead of as a C-style string and use
fwrite instead of printf to write it to fast-import so embedded '\0'
bytes can be preserved.

Currently "git log" doesn't show the embedded NULs but "git cat-file
commit" can.

While at it, stop including system headers from repo_tree.h.  git
source files need to include git-compat-util.h (or cache.h or
builtin.h) sooner to ensure the appropriate feature test macros are
defined.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

t/t9010-svn-fe.sh

@@ -397,6 +397,83 @@ test_expect_success 'NUL in property value' '
 	test_cmp expect.message actual.message
 '
 
+test_expect_success 'NUL in log message, file content, and property name' '
+	# Caveat: svnadmin 1.6.16 (r1073529) truncates at \0 in the
+	# svn:specialQnotreally example.
+	reinit_git &&
+	cat >expect <<-\EOF &&
+	OBJID
+	:100644 100644 OBJID OBJID M	greeting
+	OBJID
+	:000000 100644 OBJID OBJID A	greeting
+	EOF
+	printf "\n%s" "something with an ASCII NUL (Q)" >expect.message &&
+	printf "%s\n" "helQo" >expect.hello1 &&
+	printf "%s\n" "link hello" >expect.hello2 &&
+	{
+		properties svn:log "something with an ASCII NUL (Q)" &&
+		echo PROPS-END
+	} |
+	q_to_nul >props &&
+	{
+		q_to_nul <<-\EOF &&
+		SVN-fs-dump-format-version: 3
+
+		Revision-number: 1
+		Prop-content-length: 10
+		Content-length: 10
+
+		PROPS-END
+
+		Node-path: greeting
+		Node-kind: file
+		Node-action: add
+		Prop-content-length: 10
+		Text-content-length: 6
+		Content-length: 16
+
+		PROPS-END
+		helQo
+
+		Revision-number: 2
+		EOF
+		echo Prop-content-length: $(wc -c <props) &&
+		echo Content-length: $(wc -c <props) &&
+		echo &&
+		cat props &&
+		q_to_nul <<-\EOF
+
+		Node-path: greeting
+		Node-kind: file
+		Node-action: change
+		Prop-content-length: 43
+		Text-content-length: 11
+		Content-length: 54
+
+		K 21
+		svn:specialQnotreally
+		V 1
+		*
+		PROPS-END
+		link hello
+		EOF
+	} >8bitclean.dump &&
+	test-svn-fe 8bitclean.dump >stream &&
+	git fast-import <stream &&
+	{
+		git rev-list HEAD |
+		git diff-tree --root --stdin |
+		sed "s/$_x40/OBJID/g"
+	} >actual &&
+	git cat-file commit HEAD | nul_to_q | sed -ne "/^\$/,\$ p" >actual.message &&
+	git cat-file blob HEAD^:greeting | nul_to_q >actual.hello1 &&
+	git cat-file blob HEAD:greeting | nul_to_q >actual.hello2 &&
+	test_cmp expect actual &&
+	test_cmp expect.message actual.message &&
+	test_cmp expect.hello1 actual.hello1 &&
+	test_cmp expect.hello2 actual.hello2
+'
+
 test_expect_success 'change file mode and reiterate content' '
 	reinit_git &&
 	cat >expect <<-\EOF &&