Fix repeated write to the same file.

Author: markshannon

source/microbit/filesystem.c

@@ -266,6 +266,14 @@ mp_obj_t microbit_file_name(file_descriptor_obj *fd) {
 
 static file_descriptor_obj *microbit_file_descriptor_new(uint8_t start_chunk, bool write, bool binary);
 
+static void clear_file(uint8_t chunk) {
+    do {
+        persistent_write_byte_unchecked(&(file_system_chunks[chunk].marker), FREED_CHUNK);
+        DEBUG(("FILE DEBUG: Freeing chunk %d.\n", chunk));
+        chunk = file_system_chunks[chunk].next_chunk;
+    } while (chunk <= chunks_in_file_system);
+}
+
 file_descriptor_obj *microbit_file_open(const char *name, uint32_t name_len, bool write, bool binary) {
     if (name_len > MAX_FILENAME_LENGTH) {
         return NULL;
@@ -274,7 +282,7 @@ file_descriptor_obj *microbit_file_open(const char *name, uint32_t name_len, boo
     if (write) {
         if (index != FILE_NOT_FOUND) {
             // Free old file
-            persistent_write_byte_unchecked(&(file_system_chunks[index].marker), FREED_CHUNK);
+            clear_file(index);
         }
         index = find_chunk_and_erase();
         if (index == FILE_NOT_FOUND) {
@@ -307,14 +315,6 @@ static file_descriptor_obj *microbit_file_descriptor_new(uint8_t start_chunk, bo
     return res;
 }
 
-static void clear_file(uint8_t chunk) {
-    do {
-        persistent_write_byte_unchecked(&(file_system_chunks[chunk].marker), FREED_CHUNK);
-        DEBUG(("FILE DEBUG: Freeing chunk %d.\n", chunk));
-        chunk = file_system_chunks[chunk].next_chunk;
-    } while (chunk <= chunks_in_file_system);
-}
-
 mp_obj_t microbit_remove(mp_obj_t filename) {
     mp_uint_t name_len;
     const char *name = mp_obj_str_get_data(filename, &name_len);

tests/test_files.py

@@ -83,18 +83,17 @@ def test_text_file():
     os.remove("test2.txt")
     assert not os.listdir()
 
-
 def test_many_files():
-    for i in range(100):
+    for i in range(80):
         name = "%d.dat" % i
         write_data_to_file(name, i*3, 16, 4)
         verify_file(name, data_stream(i*3), 16, 4, 'b')
-    for i in range(100):
+    for i in range(80):
         os.remove("%d.dat" % i)
         name = "_%d.dat" % i
         write_data_to_file(name, i*3, 16, 4)
         verify_file(name, data_stream(i*3), 16, 4, 'b')
-    for i in range(100):
+    for i in range(80):
         os.remove("_%d.dat" % i)
     assert not os.listdir()
 

tests/test_files2.py

@@ -49,18 +49,18 @@ def clear_files():
         os.remove(f)
 
 def test_interleaved_small_files():
-    for i in range(100):
+    for i in range(80):
         name = "%d.dat" % i
         write_data_to_file(name, i*3, 16, 6)
-    for i in range(0, 100, 2):
+    for i in range(0, 80, 2):
         os.remove("%d.dat" % i)
-    for i in range(100, 150):
+    for i in range(80, 120):
         name = "%d.dat" % i
         write_data_to_file(name, i*3, 16, 6)
         verify_file(name, data_stream(i*3), 16, 6, 'b')
-    for i in range(1, 100, 2):
+    for i in range(1, 80, 2):
         os.remove("%d.dat" % i)
-    for i in range(100, 150):
+    for i in range(80, 120):
         os.remove("%d.dat" % i)
     assert not os.listdir()
 
@@ -70,21 +70,21 @@ def test_interleaved_large_files():
         out_buf[i] = 100-i
     with open("test1.dat", "wb") as fd1:
         with open("test2.dat", "wb") as fd2:
-            for i in range(90):
+            for i in range(60):
                 fd1.write(out_buf)
                 fd2.write(out_buf)
     os.remove("test2.dat")
     with open("test3.dat", "wb") as fd3:
-        for i in range(90):
+        for i in range(60):
             fd3.write(out_buf)
     assert sorted(os.listdir()) == [ "test1.dat", "test3.dat" ]
     in_buf = bytearray(100)
     with open("test1.dat", "rb") as fd:
-        for i in range(90):
+        for i in range(60):
             fd.readinto(in_buf)
             assert in_buf == out_buf
     with open("test3.dat", "rb") as fd:
-        for i in range(90):
+        for i in range(60):
             fd.readinto(in_buf)
             assert in_buf == out_buf
 

tests/test_files3.py

@@ -5,39 +5,39 @@
 #We don't have space for Beowolf, so here's the next best thing...
 text = """
 ’Twas brillig, and the slithy toves
-      Did gyre and gimble in the wabe:
+  Did gyre and gimble in the wabe:
 All mimsy were the borogoves,
-      And the mome raths outgrabe.
+  And the mome raths outgrabe.
 
 “Beware the Jabberwock, my son!
-      The jaws that bite, the claws that catch!
+  The jaws that bite, the claws that catch!
 Beware the Jubjub bird, and shun
-      The frumious Bandersnatch!”
+ The frumious Bandersnatch!”
 
 He took his vorpal sword in hand;
-      Long time the manxome foe he sought—
+  Long time the manxome foe he sought—
 So rested he by the Tumtum tree
-      And stood awhile in thought.
+  And stood awhile in thought.
 
 And, as in uffish thought he stood,
-      The Jabberwock, with eyes of flame,
+  The Jabberwock, with eyes of flame,
 Came whiffling through the tulgey wood,
-      And burbled as it came!
+  And burbled as it came!
 
 One, two! One, two! And through and through
-      The vorpal blade went snicker-snack!
+  The vorpal blade went snicker-snack!
 He left it dead, and with its head
-      He went galumphing back.
+  He went galumphing back.
 
 “And hast thou slain the Jabberwock?
-      Come to my arms, my beamish boy!
+  Come to my arms, my beamish boy!
 O frabjous day! Callooh! Callay!”
-      He chortled in his joy.
+  He chortled in his joy.
 
 ’Twas brillig, and the slithy toves
-      Did gyre and gimble in the wabe:
+  Did gyre and gimble in the wabe:
 All mimsy were the borogoves,
-      And the mome raths outgrabe.
+  And the mome raths outgrabe.
 """
 
 def test_read_while_writing():
@@ -73,11 +73,17 @@ def test_removing_mid_write():
     except OSError:
         pass
 
+def test_repeated_write():
+    for i in range(40):
+        with open("jabbawocky.txt", "w") as j:
+            j.write(text)
+
 display.clear()
 try:
     test_read_while_writing()
     test_removing_mid_read()
     test_removing_mid_write()
+    test_repeated_write()
     print("File test: PASS")
     display.show(Image.HAPPY)
 except Exception as ae: