show: Implement simple images filtering

The -F|--fields option specifies which fields (by name, comma
separated) should be printed.

For nested fields all names in path should be specified.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

crtools.c

@@ -98,7 +98,7 @@ int main(int argc, char *argv[])
 		return 1;
 
 	while (1) {
-		static const char short_opts[] = "dsRf:t:p:hcD:o:n:v::xVr:jlW:L:";
+		static const char short_opts[] = "dsRf:F:t:p:hcD:o:n:v::xVr:jlW:L:";
 		static struct option long_opts[] = {
 			{ "tree", required_argument, 0, 't' },
 			{ "pid", required_argument, 0, 'p' },
@@ -108,6 +108,7 @@ int main(int argc, char *argv[])
 			{ "daemon", no_argument, 0, 'd' },
 			{ "contents", no_argument, 0, 'c' },
 			{ "file", required_argument, 0, 'f' },
+			{ "fields", required_argument, 0, 'F' },
 			{ "images-dir", required_argument, 0, 'D' },
 			{ "work-dir", required_argument, 0, 'W' },
 			{ "log-file", required_argument, 0, 'o' },
@@ -163,6 +164,9 @@ int main(int argc, char *argv[])
 		case 'f':
 			opts.show_dump_file = optarg;
 			break;
+		case 'F':
+			opts.show_fmt = optarg;
+			break;
 		case 'r':
 			opts.root = optarg;
 			break;
@@ -451,6 +455,7 @@ usage:
 "\n"
 "Show options:\n"
 "  -f|--file FILE        show contents of a checkpoint file\n"
+"  -F|--fields FIELDS    show specified fields (comma separated)\n"
 "  -D|--images-dir DIR   directory where to get images from\n"
 "  -c|--contents         show contents of pages dumped in hexdump format\n"
 "  -p|--pid PID          show files relevant to PID (filter -D flood)\n"

include/cr_options.h

@@ -13,6 +13,7 @@ struct script {
 struct cr_options {
 	int			final_state;
 	char			*show_dump_file;
+	char			*show_fmt;
 	bool			check_ms_kernel;
 	bool			show_pages_content;
 	bool			restore_detach;

protobuf.c

@@ -16,6 +16,7 @@
 #include "util.h"
 #include "string.h"
 #include "sockets.h"
+#include "cr_options.h"
 
 #include "protobuf.h"
 
@@ -408,6 +409,29 @@ static int pb_optional_field_present(const ProtobufCFieldDescriptor *field,
 	return 1;
 }
 
+static bool should_show_field(const char *name)
+{
+	char *s, *e;
+	int len;
+
+	if (!opts.show_fmt)
+		return true;
+
+	len = strlen(name);
+	s = opts.show_fmt;
+
+	while (1) {
+		e = strchrnul(s, ',');
+		if (e - s == len) {
+			if (!strncmp(name, s, len))
+				return true;
+		}
+		if (*e == '\0')
+			return false;
+		s = e + 1;
+	}
+}
+
 static void pb_show_msg(const void *msg, pb_pr_ctl_t *ctl)
 {
 	int i;
@@ -428,6 +452,9 @@ static void pb_show_msg(const void *msg, pb_pr_ctl_t *ctl)
 				continue;
 		}
 
+		if (!should_show_field(fd.name))
+			continue;
+
 		if (fd.label == PROTOBUF_C_LABEL_REPEATED) {
 			nr_fields = *(size_t *)(msg + fd.quantifier_offset);
 			data = (unsigned long *)*data;