bloblist: Support resizing a blob

Sometimes a blob needs to expand, e.g. because it needs to hold more log
data. Add support for this. Note that the bloblist must have sufficient
spare space for this to work.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/bloblist.c

@@ -57,13 +57,22 @@ static struct bloblist_rec *bloblist_first_blob(struct bloblist_hdr *hdr)
 	return (struct bloblist_rec *)((void *)hdr + hdr->hdr_size);
 }
 
-static struct bloblist_rec *bloblist_next_blob(struct bloblist_hdr *hdr,
+static ulong bloblist_blob_end_ofs(struct bloblist_hdr *hdr,
-					       struct bloblist_rec *rec)
+				   struct bloblist_rec *rec)
 {
 	ulong offset;
 
 	offset = (void *)rec - (void *)hdr;
 	offset += rec->hdr_size + ALIGN(rec->size, BLOBLIST_ALIGN);
+
+	return offset;
+}
+
+static struct bloblist_rec *bloblist_next_blob(struct bloblist_hdr *hdr,
+					       struct bloblist_rec *rec)
+{
+	ulong offset = bloblist_blob_end_ofs(hdr, rec);
+
 	if (offset >= hdr->alloced)
 		return NULL;
 	return (struct bloblist_rec *)((void *)hdr + offset);
@@ -215,6 +224,64 @@ int bloblist_ensure_size_ret(uint tag, int *sizep, void **blobp)
 	return 0;
 }
 
+static int bloblist_resize_rec(struct bloblist_hdr *hdr,
+			       struct bloblist_rec *rec,
+			       int new_size)
+{
+	int expand_by;	/* Number of bytes to expand by (-ve to contract) */
+	int new_alloced;	/* New value for @hdr->alloced */
+	ulong next_ofs;	/* Offset of the record after @rec */
+
+	expand_by = ALIGN(new_size - rec->size, BLOBLIST_ALIGN);
+	new_alloced = ALIGN(hdr->alloced + expand_by, BLOBLIST_ALIGN);
+	if (new_size < 0) {
+		log(LOGC_BLOBLIST, LOGL_DEBUG,
+		    "Attempt to shrink blob size below 0 (%x)\n", new_size);
+		return log_msg_ret("size", -EINVAL);
+	}
+	if (new_alloced > hdr->size) {
+		log(LOGC_BLOBLIST, LOGL_ERR,
+		    "Failed to allocate %x bytes size=%x, need size=%x\n",
+		    new_size, hdr->size, new_alloced);
+		return log_msg_ret("alloc", -ENOSPC);
+	}
+
+	/* Move the following blobs up or down, if this is not the last */
+	next_ofs = bloblist_blob_end_ofs(hdr, rec);
+	if (next_ofs != hdr->alloced) {
+		memmove((void *)hdr + next_ofs + expand_by,
+			(void *)hdr + next_ofs, new_alloced - next_ofs);
+	}
+	hdr->alloced = new_alloced;
+
+	/* Zero the new part of the blob */
+	if (expand_by > 0) {
+		memset((void *)rec + rec->hdr_size + rec->size, '\0',
+		       new_size - rec->size);
+	}
+
+	/* Update the size of this blob */
+	rec->size = new_size;
+
+	return 0;
+}
+
+int bloblist_resize(uint tag, int new_size)
+{
+	struct bloblist_hdr *hdr = gd->bloblist;
+	struct bloblist_rec *rec;
+	int ret;
+
+	rec = bloblist_findrec(tag);
+	if (!rec)
+		return log_msg_ret("find", -ENOENT);
+	ret = bloblist_resize_rec(hdr, rec, new_size);
+	if (ret)
+		return log_msg_ret("resize", ret);
+
+	return 0;
+}
+
 static u32 bloblist_calc_chksum(struct bloblist_hdr *hdr)
 {
 	struct bloblist_rec *rec;

include/bloblist.h

@@ -179,6 +179,19 @@ void *bloblist_ensure(uint tag, int size);
  */
 int bloblist_ensure_size_ret(uint tag, int *sizep, void **blobp);
 
+/**
+ * bloblist_resize() - resize a blob
+ *
+ * Any blobs above this one are relocated up or down. The resized blob remains
+ * in the same place.
+ *
+ * @tag:	Tag to add (enum bloblist_tag_t)
+ * @new_size:	New size of the blob (>0 to expand, <0 to contract)
+ * @return 0 if OK, -ENOSPC if the bloblist does not have enough space, -ENOENT
+ *	if the tag is not found
+ */
+int bloblist_resize(uint tag, int new_size);
+
 /**
  * bloblist_new() - Create a new, empty bloblist of a given size
  *

test/bloblist.c

@@ -33,6 +33,9 @@ enum {
 	ERASE_BYTE		= '\xff',
 };
 
+static const char test1_str[] = "the eyes are open";
+static const char test2_str[] = "the mouth moves";
+
 static struct bloblist_hdr *clear_bloblist(void)
 {
 	struct bloblist_hdr *hdr;
@@ -384,6 +387,195 @@ static int bloblist_test_reloc(struct unit_test_state *uts)
 }
 BLOBLIST_TEST(bloblist_test_reloc, 0);
 
+/* Test expansion of a blob */
+static int bloblist_test_grow(struct unit_test_state *uts)
+{
+	const uint small_size = 0x20;
+	void *blob1, *blob2, *blob1_new;
+	struct bloblist_hdr *hdr;
+	void *ptr;
+
+	ptr = map_sysmem(TEST_ADDR, TEST_BLOBLIST_SIZE);
+	hdr = ptr;
+	memset(hdr, ERASE_BYTE, TEST_BLOBLIST_SIZE);
+
+	/* Create two blobs */
+	ut_assertok(bloblist_new(TEST_ADDR, TEST_BLOBLIST_SIZE, 0));
+	blob1 = bloblist_add(TEST_TAG, small_size, 0);
+	ut_assertnonnull(blob1);
+	ut_assertok(check_zero(blob1, small_size));
+	strcpy(blob1, test1_str);
+
+	blob2 = bloblist_add(TEST_TAG2, small_size, 0);
+	ut_assertnonnull(blob2);
+	strcpy(blob2, test2_str);
+
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2,
+		    hdr->alloced);
+
+	/* Resize the first one */
+	ut_assertok(bloblist_resize(TEST_TAG, small_size + 4));
+
+	/* The first one should not have moved, just got larger */
+	blob1_new = bloblist_find(TEST_TAG, small_size + 4);
+	ut_asserteq_ptr(blob1, blob1_new);
+
+	/* The new space should be zeroed */
+	ut_assertok(check_zero(blob1 + small_size, 4));
+
+	/* The second one should have moved */
+	blob2 = bloblist_find(TEST_TAG2, small_size);
+	ut_assertnonnull(blob2);
+	ut_asserteq_str(test2_str, blob2);
+
+	/* The header should have more bytes in use */
+	hdr = ptr;
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2 +
+		    BLOBLIST_ALIGN,
+		    hdr->alloced);
+
+	return 0;
+}
+BLOBLIST_TEST(bloblist_test_grow, 0);
+
+/* Test shrinking of a blob */
+static int bloblist_test_shrink(struct unit_test_state *uts)
+{
+	const uint small_size = 0x20;
+	void *blob1, *blob2, *blob1_new;
+	struct bloblist_hdr *hdr;
+	int new_size;
+	void *ptr;
+
+	ptr = map_sysmem(TEST_ADDR, TEST_BLOBLIST_SIZE);
+
+	/* Create two blobs */
+	ut_assertok(bloblist_new(TEST_ADDR, TEST_BLOBLIST_SIZE, 0));
+	blob1 = bloblist_add(TEST_TAG, small_size, 0);
+	ut_assertnonnull(blob1);
+	strcpy(blob1, test1_str);
+
+	blob2 = bloblist_add(TEST_TAG2, small_size, 0);
+	ut_assertnonnull(blob2);
+	strcpy(blob2, test2_str);
+
+	hdr = ptr;
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2,
+		    hdr->alloced);
+
+	/* Resize the first one */
+	new_size = small_size - BLOBLIST_ALIGN - 4;
+	ut_assertok(bloblist_resize(TEST_TAG, new_size));
+
+	/* The first one should not have moved, just got smaller */
+	blob1_new = bloblist_find(TEST_TAG, new_size);
+	ut_asserteq_ptr(blob1, blob1_new);
+
+	/* The second one should have moved */
+	blob2 = bloblist_find(TEST_TAG2, small_size);
+	ut_assertnonnull(blob2);
+	ut_asserteq_str(test2_str, blob2);
+
+	/* The header should have fewer bytes in use */
+	hdr = ptr;
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2 -
+		    BLOBLIST_ALIGN,
+		    hdr->alloced);
+
+	return 0;
+}
+BLOBLIST_TEST(bloblist_test_shrink, 0);
+
+/* Test failing to adjust a blob size */
+static int bloblist_test_resize_fail(struct unit_test_state *uts)
+{
+	const uint small_size = 0x20;
+	struct bloblist_hdr *hdr;
+	void *blob1, *blob2;
+	int new_size;
+	void *ptr;
+
+	ptr = map_sysmem(TEST_ADDR, TEST_BLOBLIST_SIZE);
+
+	/* Create two blobs */
+	ut_assertok(bloblist_new(TEST_ADDR, TEST_BLOBLIST_SIZE, 0));
+	blob1 = bloblist_add(TEST_TAG, small_size, 0);
+	ut_assertnonnull(blob1);
+
+	blob2 = bloblist_add(TEST_TAG2, small_size, 0);
+	ut_assertnonnull(blob2);
+
+	hdr = ptr;
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2,
+		    hdr->alloced);
+
+	/* Resize the first one, to check the boundary conditions */
+	ut_asserteq(-EINVAL, bloblist_resize(TEST_TAG, -1));
+
+	new_size = small_size + (hdr->size - hdr->alloced);
+	ut_asserteq(-ENOSPC, bloblist_resize(TEST_TAG, new_size + 1));
+	ut_assertok(bloblist_resize(TEST_TAG, new_size));
+
+	return 0;
+}
+BLOBLIST_TEST(bloblist_test_resize_fail, 0);
+
+/* Test expanding the last blob in a bloblist */
+static int bloblist_test_resize_last(struct unit_test_state *uts)
+{
+	const uint small_size = 0x20;
+	struct bloblist_hdr *hdr;
+	void *blob1, *blob2, *blob2_new;
+	int alloced_val;
+	void *ptr;
+
+	ptr = map_sysmem(TEST_ADDR, TEST_BLOBLIST_SIZE);
+	memset(ptr, ERASE_BYTE, TEST_BLOBLIST_SIZE);
+	hdr = ptr;
+
+	/* Create two blobs */
+	ut_assertok(bloblist_new(TEST_ADDR, TEST_BLOBLIST_SIZE, 0));
+	blob1 = bloblist_add(TEST_TAG, small_size, 0);
+	ut_assertnonnull(blob1);
+
+	blob2 = bloblist_add(TEST_TAG2, small_size, 0);
+	ut_assertnonnull(blob2);
+
+	/* Check the byte after the last blob */
+	alloced_val = sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2;
+	ut_asserteq(alloced_val, hdr->alloced);
+	ut_asserteq_ptr((void *)hdr + alloced_val, blob2 + small_size);
+	ut_asserteq((u8)ERASE_BYTE, *((u8 *)hdr + hdr->alloced));
+
+	/* Resize the second one, checking nothing changes */
+	ut_asserteq(0, bloblist_resize(TEST_TAG2, small_size + 4));
+
+	blob2_new = bloblist_find(TEST_TAG2, small_size + 4);
+	ut_asserteq_ptr(blob2, blob2_new);
+
+	/*
+	 * the new blob should encompass the byte we checked now, so it should
+	 * be zeroed. This zeroing should affect only the four new bytes added
+	 * to the blob.
+	 */
+	ut_asserteq(0, *((u8 *)hdr + alloced_val));
+	ut_asserteq((u8)ERASE_BYTE, *((u8 *)hdr + alloced_val + 4));
+
+	/* Check that the new top of the allocated blobs has not been touched */
+	alloced_val += BLOBLIST_ALIGN;
+	ut_asserteq(alloced_val, hdr->alloced);
+	ut_asserteq((u8)ERASE_BYTE, *((u8 *)hdr + hdr->alloced));
+
+	return 0;
+}
+BLOBLIST_TEST(bloblist_test_resize_last, 0);
+
 int do_ut_bloblist(struct cmd_tbl *cmdtp, int flag, int argc,
 		   char *const argv[])
 {