dtc: cpp co-existence: add support for #line directives

Line control directives of the following formats are supported:
    #line LINE "FILE"
    # LINE "FILE" [FLAGS]

This allows dtc to consume the output of pre-processors, and to provide
error messages that refer to the original filename, including taking
into account any #include directives that the pre-processor may have
performed.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

dtc-lexer.l

@@ -71,6 +71,27 @@ static int pop_input_file(void);
 			push_input_file(name);
 		}
 
+<*>^"#"(line)?{WS}+[0-9]+{WS}+{STRING}({WS}+[0-9]+)? {
+			char *line, *tmp, *fn;
+			/* skip text before line # */
+			line = yytext;
+			while (!isdigit(*line))
+				line++;
+			/* skip digits in line # */
+			tmp = line;
+			while (!isspace(*tmp))
+				tmp++;
+			/* "NULL"-terminate line # */
+			*tmp = '\0';
+			/* start of filename */
+			fn = strchr(tmp + 1, '"') + 1;
+			/* strip trailing " from filename */
+			tmp = strchr(fn, '"');
+			*tmp = 0;
+			/* -1 since #line is the number of the next line */
+			srcpos_set_line(xstrdup(fn), atoi(line) - 1);
+		}
+
 <*><<EOF>>		{
 			if (!pop_input_file()) {
 				yyterminate();

srcpos.c

@@ -328,3 +328,9 @@ srcpos_warn(struct srcpos *pos, char const *fmt, ...)
 
 	va_end(va);
 }
+
+void srcpos_set_line(char *f, int l)
+{
+	current_srcfile->name = f;
+	current_srcfile->lineno = l;
+}

srcpos.h

@@ -113,4 +113,6 @@ extern void srcpos_error(struct srcpos *pos, char const *, ...)
 extern void srcpos_warn(struct srcpos *pos, char const *, ...)
      __attribute__((format(printf, 2, 3)));
 
+extern void srcpos_set_line(char *f, int l);
+
 #endif /* _SRCPOS_H_ */

tests/line_directives.dts

@@ -0,0 +1,11 @@
+/dts-v1/;
+
+/* common format */
+#line 3 "foo.dts"
+/* newer gcc format */
+# 9 "baz.dts" 1
+/* flags are optional */
+# 6 "bar.dts"
+
+/ {
+};

tests/run_tests.sh

@@ -257,6 +257,8 @@ dtc_tests () {
     run_dtc_test -I dts -O dtb -o dtc_escapes.test.dtb propname_escapes.dts
     run_test propname_escapes dtc_escapes.test.dtb
 
+    run_dtc_test -I dts -O dtb -o line_directives.test.dtb line_directives.dts
+
     run_dtc_test -I dts -O dtb -o dtc_escapes.test.dtb escapes.dts
     run_test string_escapes dtc_escapes.test.dtb