[Qemu-devel] [RFC 4/5] scripts/dump-guest-memory.py: Cleanup functions

[Janosch Frank <frankja@linux.vnet.ibm.com>]

Increase readability by adding newlines and comments, as well as
removing wrong whitespaces and C style braces around conditionals and
loops.

Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
---
 scripts/dump-guest-memory.py | 71 +++++++++++++++++++++++++++++++-------------
 1 file changed, 50 insertions(+), 21 deletions(-)

diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py
index fe93135..2110494 100644
--- a/scripts/dump-guest-memory.py
+++ b/scripts/dump-guest-memory.py
@@ -69,35 +69,60 @@ ELF64_PHDR = ("I"  # p_type
           )
 
 def int128_get64(val):
-    assert (val["hi"] == 0)
+    """Returns low 64bit part of Int128 struct."""
+
+    assert val["hi"] == 0
     return val["lo"]
 
+
 def qlist_foreach(head, field_str):
+    """Generator for qlists."""
+
     var_p = head["lh_first"]
-    while (var_p != 0):
+    while var_p != 0:
         var = var_p.dereference()
-        yield var
         var_p = var[field_str]["le_next"]
+        yield var
+
 
 def qemu_get_ram_block(ram_addr):
+    """Returns the RAMBlock struct to which the given address belongs."""
+
     ram_blocks = gdb.parse_and_eval("ram_list.blocks")
+
     for block in qlist_foreach(ram_blocks, "next"):
-        if (ram_addr - block["offset"] < block["used_length"]):
+        if (ram_addr - block["offset"]) < block["used_length"]:
             return block
+
     raise gdb.GdbError("Bad ram offset %x" % ram_addr)
 
+
 def qemu_get_ram_ptr(ram_addr):
+    """Returns qemu vaddr for given guest physical address."""
+
     block = qemu_get_ram_block(ram_addr)
     return block["host"] + (ram_addr - block["offset"])
 
-def memory_region_get_ram_ptr(mr):
-    if (mr["alias"] != 0):
-        return (memory_region_get_ram_ptr(mr["alias"].dereference()) +
-                mr["alias_offset"])
-    return qemu_get_ram_ptr(mr["ram_addr"] & TARGET_PAGE_MASK)
+
+def memory_region_get_ram_ptr(memory_region):
+    if memory_region["alias"] != 0:
+        return (memory_region_get_ram_ptr(memory_region["alias"].dereference())
+                + memory_region["alias_offset"])
+
+    return qemu_get_ram_ptr(memory_region["ram_addr"] & TARGET_PAGE_MASK)
+
 
 def get_guest_phys_blocks():
+    """Returns a list of ram blocks.
+
+    Each block entry contains:
+    'target_start': guest block phys start address
+    'target_end':   guest block phys end address
+    'host_addr':    qemu vaddr of the block's start
+    """
+
     guest_phys_blocks = []
+
     print("guest RAM blocks:")
     print("target_start     target_end       host_addr        message "
           "count")
@@ -106,30 +131,34 @@ def get_guest_phys_blocks():
 
     current_map_p = gdb.parse_and_eval("address_space_memory.current_map")
     current_map = current_map_p.dereference()
+
+    # Conversion to int is needed for python 3
+    # compatibility. Otherwise range doesn't cast the value itself and
+    # breaks.
     for cur in range(int(current_map["nr"])):
-        flat_range   = (current_map["ranges"] + cur).dereference()
-        mr           = flat_range["mr"].dereference()
+        flat_range = (current_map["ranges"] + cur).dereference()
+        memory_region = flat_range["mr"].dereference()
 
         # we only care about RAM
-        if (not mr["ram"]):
+        if not memory_region["ram"]:
             continue
 
         section_size = int128_get64(flat_range["addr"]["size"])
         target_start = int128_get64(flat_range["addr"]["start"])
-        target_end   = target_start + section_size
-        host_addr    = (memory_region_get_ram_ptr(mr) +
-                        flat_range["offset_in_region"])
+        target_end = target_start + section_size
+        host_addr = (memory_region_get_ram_ptr(memory_region) +
+                     flat_range["offset_in_region"])
         predecessor = None
 
         # find continuity in guest physical address space
-        if (len(guest_phys_blocks) > 0):
+        if len(guest_phys_blocks) > 0:
             predecessor = guest_phys_blocks[-1]
             predecessor_size = (predecessor["target_end"] -
-                                    predecessor["target_start"])
+                                predecessor["target_start"])
 
             # the memory API guarantees monotonically increasing
             # traversal
-            assert (predecessor["target_end"] <= target_start)
+            assert predecessor["target_end"] <= target_start
 
             # we want continuity in both guest-physical and
             # host-virtual memory
@@ -137,11 +166,11 @@ def get_guest_phys_blocks():
                 predecessor["host_addr"] + predecessor_size != host_addr):
                 predecessor = None
 
-        if (predecessor is None):
+        if predecessor is None:
             # isolated mapping, add it to the list
             guest_phys_blocks.append({"target_start": target_start,
-                                      "target_end"  : target_end,
-                                      "host_addr"   : host_addr})
+                                      "target_end":   target_end,
+                                      "host_addr":    host_addr})
             message = "added"
         else:
             # expand predecessor until @target_end; predecessor's
-- 
2.3.0