[PATCH v4 1/5] libtraceevent: Add dynamic_offset()

["Yordan Karadzhov (VMware)" <y.karadz@gmail.com>]

The total allocated length of the dynamic array is stored in the top half
of the corresponding 32 bit field and the offset is in the bottom half of
the same field. Since the decoding of the length and offset is performed
in multiple locations is the code, we define a static helper function to
replace/cleanup the existing open coded conversions.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
---
 src/event-parse.c | 134 ++++++++++++++++++++++------------------------
 1 file changed, 63 insertions(+), 71 deletions(-)

diff --git a/src/event-parse.c b/src/event-parse.c
index f42ae38..fd6d916 100644
--- a/src/event-parse.c
+++ b/src/event-parse.c
@@ -3858,6 +3858,36 @@ static unsigned long long test_for_symbol(struct tep_handle *tep,
 	return val;
 }
 
+#define TEP_OFFSET_LEN_MASK		0xffff
+#define TEP_LEN_SHIFT			16
+
+static void dynamic_offset(struct tep_handle *tep, int size, void *data,
+			   unsigned int *offset, unsigned int *len)
+{
+	unsigned long long val;
+
+	/*
+	 * The total allocated length of the dynamic array is
+	 * stored in the top half of the field and the offset
+	 * is in the bottom half of the 32 bit field.
+	 */
+	val = tep_read_number(tep, data, size);
+
+	if (offset)
+		*offset = (unsigned int)(val & TEP_OFFSET_LEN_MASK);
+	if (len)
+		*len = (unsigned int)((val >> TEP_LEN_SHIFT) & TEP_OFFSET_LEN_MASK);
+}
+
+static inline void dynamic_offset_field(struct tep_handle *tep,
+					struct tep_format_field *field,
+					void *data,
+					unsigned int *offset,
+					unsigned int *len)
+{
+	dynamic_offset(tep, field->size, data + field->offset, offset, len);
+}
+
 static unsigned long long
 eval_num_arg(void *data, int size, struct tep_event *event, struct tep_print_arg *arg)
 {
@@ -3866,7 +3896,7 @@ eval_num_arg(void *data, int size, struct tep_event *event, struct tep_print_arg
 	unsigned long long left, right;
 	struct tep_print_arg *typearg = NULL;
 	struct tep_print_arg *larg;
-	unsigned long offset;
+	unsigned int offset;
 	unsigned int field_size;
 
 	switch (arg->type) {
@@ -3930,18 +3960,11 @@ eval_num_arg(void *data, int size, struct tep_event *event, struct tep_print_arg
 
 			switch (larg->type) {
 			case TEP_PRINT_DYNAMIC_ARRAY:
-				offset = tep_read_number(tep,
-						   data + larg->dynarray.field->offset,
-						   larg->dynarray.field->size);
+				dynamic_offset_field(tep, larg->dynarray.field, data,
+						     &offset, NULL);
+				offset += right;
 				if (larg->dynarray.field->elementsize)
 					field_size = larg->dynarray.field->elementsize;
-				/*
-				 * The actual length of the dynamic array is stored
-				 * in the top half of the field, and the offset
-				 * is in the bottom half of the 32 bit field.
-				 */
-				offset &= 0xffff;
-				offset += right;
 				break;
 			case TEP_PRINT_FIELD:
 				if (!larg->field.field) {
@@ -4060,27 +4083,14 @@ eval_num_arg(void *data, int size, struct tep_event *event, struct tep_print_arg
 		}
 		break;
 	case TEP_PRINT_DYNAMIC_ARRAY_LEN:
-		offset = tep_read_number(tep,
-					 data + arg->dynarray.field->offset,
-					 arg->dynarray.field->size);
-		/*
-		 * The total allocated length of the dynamic array is
-		 * stored in the top half of the field, and the offset
-		 * is in the bottom half of the 32 bit field.
-		 */
-		val = (unsigned long long)(offset >> 16);
+		dynamic_offset_field(tep, arg->dynarray.field, data,
+				     NULL, &field_size);
+		val = (unsigned long long) field_size;
 		break;
 	case TEP_PRINT_DYNAMIC_ARRAY:
 		/* Without [], we pass the address to the dynamic data */
-		offset = tep_read_number(tep,
-					 data + arg->dynarray.field->offset,
-					 arg->dynarray.field->size);
-		/*
-		 * The total allocated length of the dynamic array is
-		 * stored in the top half of the field, and the offset
-		 * is in the bottom half of the 32 bit field.
-		 */
-		offset &= 0xffff;
+		dynamic_offset_field(tep, arg->dynarray.field, data,
+				     &offset, NULL);
 		val = (unsigned long long)((unsigned long)data + offset);
 		break;
 	default: /* not sure what to do there */
@@ -4209,12 +4219,13 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
 	struct tep_print_flag_sym *flag;
 	struct tep_format_field *field;
 	struct printk_map *printk;
+	unsigned int offset, len;
 	long long val, fval;
 	unsigned long long addr;
 	char *str;
 	unsigned char *hex;
 	int print;
-	int i, len;
+	int i;
 
 	switch (arg->type) {
 	case TEP_PRINT_NULL:
@@ -4318,11 +4329,9 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
 	case TEP_PRINT_HEX:
 	case TEP_PRINT_HEX_STR:
 		if (arg->hex.field->type == TEP_PRINT_DYNAMIC_ARRAY) {
-			unsigned long offset;
-			offset = tep_read_number(tep,
-				data + arg->hex.field->dynarray.field->offset,
-				arg->hex.field->dynarray.field->size);
-			hex = data + (offset & 0xffff);
+			dynamic_offset_field(tep, arg->hex.field->dynarray.field, data,
+				             &offset, NULL);
+			hex = data + offset;
 		} else {
 			field = arg->hex.field->field.field;
 			if (!field) {
@@ -4347,13 +4356,9 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
 		int el_size;
 
 		if (arg->int_array.field->type == TEP_PRINT_DYNAMIC_ARRAY) {
-			unsigned long offset;
-			struct tep_format_field *field =
-				arg->int_array.field->dynarray.field;
-			offset = tep_read_number(tep,
-						 data + field->offset,
-						 field->size);
-			num = data + (offset & 0xffff);
+			dynamic_offset_field(tep, arg->int_array.field->dynarray.field, data,
+					     &offset, NULL);
+			num = data + offset;
 		} else {
 			field = arg->int_array.field->field.field;
 			if (!field) {
@@ -4393,42 +4398,33 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
 	case TEP_PRINT_TYPE:
 		break;
 	case TEP_PRINT_STRING: {
-		int str_offset;
-		int len;
-
 		if (arg->string.offset == -1) {
 			struct tep_format_field *f;
 
 			f = tep_find_any_field(event, arg->string.string);
 			arg->string.offset = f->offset;
 		}
-		str_offset = data2host4(tep, *(unsigned int *)(data + arg->string.offset));
-		len = (str_offset >> 16) & 0xffff;
+		dynamic_offset(tep, 4, data + arg->string.offset, &offset, &len);
 		/* Do not attempt to save zero length dynamic strings */
 		if (!len)
 			break;
-		str_offset &= 0xffff;
-		print_str_to_seq(s, format, len_arg, ((char *)data) + str_offset);
+		offset &= TEP_OFFSET_LEN_MASK;
+		print_str_to_seq(s, format, len_arg, ((char *)data) + offset);
 		break;
 	}
 	case TEP_PRINT_BSTRING:
 		print_str_to_seq(s, format, len_arg, arg->string.string);
 		break;
 	case TEP_PRINT_BITMASK: {
-		int bitmask_offset;
-		int bitmask_size;
-
 		if (arg->bitmask.offset == -1) {
 			struct tep_format_field *f;
 
 			f = tep_find_any_field(event, arg->bitmask.bitmask);
 			arg->bitmask.offset = f->offset;
 		}
-		bitmask_offset = data2host4(tep, *(unsigned int *)(data + arg->bitmask.offset));
-		bitmask_size = bitmask_offset >> 16;
-		bitmask_offset &= 0xffff;
+		dynamic_offset(tep, 4, data + arg->bitmask.offset, &offset, &len);
 		print_bitmask_to_seq(tep, s, format, len_arg,
-				     data + bitmask_offset, bitmask_size);
+				     data + offset, len);
 		break;
 	}
 	case TEP_PRINT_OP:
@@ -5271,13 +5267,12 @@ static int print_raw_buff_arg(struct trace_seq *s, const char *ptr,
 			      void *data, int size, struct tep_event *event,
 			      struct tep_print_arg *arg, int print_len)
 {
+	unsigned int offset, arr_len;
 	int plen = print_len;
 	char *delim = " ";
 	int ret = 0;
 	char *buf;
 	int i;
-	unsigned long offset;
-	int arr_len;
 
 	switch (*(ptr + 1)) {
 	case 'C':
@@ -5304,11 +5299,9 @@ static int print_raw_buff_arg(struct trace_seq *s, const char *ptr,
 		return ret;
 	}
 
-	offset = tep_read_number(event->tep,
-				 data + arg->dynarray.field->offset,
-				 arg->dynarray.field->size);
-	arr_len = (unsigned long long)(offset >> 16);
-	buf = data + (offset & 0xffff);
+	dynamic_offset_field(event->tep, arg->dynarray.field, data,
+			     &offset, &arr_len);
+	buf = data + offset;
 
 	if (arr_len < plen)
 		plen = arr_len;
@@ -5336,19 +5329,18 @@ static int is_printable_array(char *p, unsigned int len)
 void tep_print_field(struct trace_seq *s, void *data,
 		     struct tep_format_field *field)
 {
-	unsigned long long val;
-	unsigned int offset, len, i;
 	struct tep_handle *tep = field->event->tep;
+	unsigned int offset, len, i;
+	unsigned long long val;
 
 	if (field->flags & TEP_FIELD_IS_ARRAY) {
-		offset = field->offset;
-		len = field->size;
 		if (field->flags & TEP_FIELD_IS_DYNAMIC) {
-			val = tep_read_number(tep, data + offset, len);
-			offset = val;
-			len = offset >> 16;
-			offset &= 0xffff;
+			dynamic_offset_field(tep, field, data, &offset, &len);
+		} else {
+			offset = field->offset;
+			len = field->size;
 		}
+
 		if (field->flags & TEP_FIELD_IS_STRING &&
 		    is_printable_array(data + offset, len)) {
 			trace_seq_printf(s, "%s", (char *)data + offset);
-- 
2.30.2