ultask: --jmp: dump original data first

The Original data use to restore --jmp.

    $ ./tests/hello/hello

    $ ultask -p $(pidof hello) --jmp from=0x000000004012e3,to=0x00000000401283
    Original data bytes: f3 0f 1e fa 55 48 89 e5 48 83 ec 10 48 89 7d f8

Signed-off-by: Rong Tao <rtoax@foxmail.com>

src/tests/utils/string.c

@@ -34,6 +34,11 @@ TEST(Utils_str, memshow, 0)
 	return 0;
 }
 
+TEST(Utils_str, fmembytes, 0)
+{
+	return fmembytes(stdout, docs, sizeof(docs));
+}
+
 TEST(Utils_str, print, 0)
 {
 	print_string_hex(stdout, NULL, (void *)docs, sizeof(docs));

src/ultask.c

@@ -821,6 +821,18 @@ int ultask(int argc, char *argv[])
 		new_insn = (void *)&jmp_entry;
 		insn_sz = sizeof(struct jmp_table_entry);
 
+		char buf[sizeof(struct jmp_table_entry)] = {};
+
+		n = memcpy_from_task(target_task, buf, jmp_addr_from, insn_sz);
+		if (n == -1 || n < insn_sz) {
+			ulp_error("failed read target process.\n");
+			ret = -1;
+			goto done;
+		}
+
+		fprintf(stdout, "Original data bytes: ");
+		fmembytes(stdout, buf, insn_sz);
+
 		n = memcpy_to_task(target_task, jmp_addr_from, new_insn,
 					insn_sz);
 		if (n == -1 || n < insn_sz) {

src/utils/string.c

@@ -87,6 +87,20 @@ int print_bytes(FILE *fp, void *mem, size_t len)
 	return ret;
 }
 
+int fmembytes(FILE *fp, const void *data, int data_len)
+{
+	int i;
+	const uint8_t *b;
+
+	if (!fp)
+		fp = stdout;
+
+	for (i = 0, b = data; i < data_len; i++, b++)
+		fprintf(fp, "%02x%s", *b, i < (data_len - 1) ? " " : "");
+	fprintf(fp, "\n");
+	return 0;
+}
+
 /* Return TRUE if the start of STR matches PREFIX, FALSE otherwise.  */
 int ulp_startswith(const char *str, const char *prefix)
 {
@@ -201,4 +215,3 @@ unsigned long str2addr(const char *str)
 
 	return addr;
 }
-

src/utils/util.h

@@ -227,6 +227,7 @@ void free_strstr_list(struct list_head *list);
 unsigned long str2size(const char *str);
 unsigned long str2addr(const char *str);
 
+int fmembytes(FILE *fp, const void *data, int data_len);
 
 #define strstr_for_each_node_safe(iter, tmp, list)	\
 	list_for_each_entry_safe(iter, tmp, list, node)

tests/hello/hello.c

@@ -53,6 +53,9 @@ void sig_handler(int sig)
 	}
 }
 
+/**
+ * This maybe use to test 'ultash --jmp ...'
+ */
 void patch_hello2(unsigned long ul)
 {
 	printf("Hello World. %ld, %ld, patched\n", count, ul);