Don't use "<unknown>" for placeholders and suppress printing of empty…

… user formats.

This changes the interporate() to replace entries with NULL values
by the empty string, and uses it to interpolate missing fields in
custom format output used in git-log and friends.  It is most useful
to avoid <unknown> output from %b format for a commit log message
that lack any body text.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-rev-list.c

@@ -85,7 +85,8 @@ static void show_commit(struct commit *commit)
 		pretty_print_commit(revs.commit_format, commit, ~0,
 				    &buf, &buflen,
 				    revs.abbrev, NULL, NULL, revs.date_mode);
-		printf("%s%c", buf, hdr_termination);
+		if (*buf)
+			printf("%s%c", buf, hdr_termination);
 		free(buf);
 	}
 	maybe_flush_or_die(stdout, "stdout");

commit.c

@@ -917,9 +917,6 @@ long format_commit_message(const struct commit *commit, const void *format,
 	}
 	if (msg[i])
 		table[IBODY].value = xstrdup(msg + i);
-	for (i = 0; i < ARRAY_SIZE(table); i++)
-		if (!table[i].value)
-			interp_set_entry(table, i, "<unknown>");
 
 	do {
 		char *buf = *buf_p;

interpolate.c

@@ -76,8 +76,12 @@ unsigned long interpolate(char *result, unsigned long reslen,
 			/* Check for valid interpolation. */
 			if (i < ninterps) {
 				value = interps[i].value;
-				valuelen = strlen(value);
+				if (!value) {
+					src += namelen;
+					continue;
+				}
 
+				valuelen = strlen(value);
 				if (newlen + valuelen + 1 < reslen) {
 					/* Substitute. */
 					strncpy(dest, value, valuelen);

log-tree.c

@@ -298,7 +298,8 @@ void show_log(struct rev_info *opt, const char *sep)
 	if (opt->show_log_size)
 		printf("log size %i\n", len);
 
-	printf("%s%s%s", msgbuf, extra, sep);
+	if (*msgbuf)
+		printf("%s%s%s", msgbuf, extra, sep);
 	free(msgbuf);
 }
 

t/t6006-rev-list-format.sh

@@ -79,9 +79,7 @@ EOF
 
 test_format encoding %e <<'EOF'
 commit 131a310eb913d107dd3c09a65d1651175898735d
-<unknown>
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
-<unknown>
 EOF
 
 test_format subject %s <<'EOF'
@@ -93,9 +91,7 @@ EOF
 
 test_format body %b <<'EOF'
 commit 131a310eb913d107dd3c09a65d1651175898735d
-<unknown>
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
-<unknown>
 EOF
 
 test_format colors %Credfoo%Cgreenbar%Cbluebaz%Cresetxyzzy <<'EOF'
@@ -121,9 +117,7 @@ test_format complex-encoding %e <<'EOF'
 commit f58db70b055c5718631e5c61528b28b12090cdea
 iso8859-1
 commit 131a310eb913d107dd3c09a65d1651175898735d
-<unknown>
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
-<unknown>
 EOF
 
 test_format complex-subject %s <<'EOF'
@@ -142,9 +136,7 @@ and it will be encoded in iso8859-1. We should therefore
 include an iso8859 character: ¡bueno!
 
 commit 131a310eb913d107dd3c09a65d1651175898735d
-<unknown>
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
-<unknown>
 EOF
 
 test_done

t/t7500-commit.sh

@@ -81,7 +81,7 @@ test_expect_success 'explicit commit message should override template' '
 	git add foo &&
 	GIT_EDITOR=../t7500/add-content git commit --template "$TEMPLATE" \
 		-m "command line msg" &&
-	commit_msg_is "command line msg<unknown>"
+	commit_msg_is "command line msg"
 '
 
 test_expect_success 'commit message from file should override template' '
@@ -90,7 +90,7 @@ test_expect_success 'commit message from file should override template' '
 	echo "standard input msg" |
 		GIT_EDITOR=../t7500/add-content git commit \
 			--template "$TEMPLATE" --file - &&
-	commit_msg_is "standard input msg<unknown>"
+	commit_msg_is "standard input msg"
 '
 
 test_done