diff --git a/src/apk_blob.h b/src/apk_blob.h
index bea2d08..9ad79c4 100644
--- a/src/apk_blob.h
+++ b/src/apk_blob.h
@@ -44,13 +44,15 @@ int apk_blob_rsplit(apk_blob_t blob, char split, apk_blob_t *l, apk_blob_t *r);
 unsigned long apk_blob_hash_seed(apk_blob_t, unsigned long seed);
 unsigned long apk_blob_hash(apk_blob_t str);
 int apk_blob_compare(apk_blob_t a, apk_blob_t b);
-unsigned int apk_blob_parse_uint(apk_blob_t *b, int radix);
-int apk_blob_parse_char(apk_blob_t *b);
-
 int apk_blob_for_each_segment(apk_blob_t blob, const char *split,
 			      apk_blob_cb cb, void *ctx);
 
-int apk_hexdump_parse(apk_blob_t to, apk_blob_t from);
-int apk_hexdump_format(int tolen, char *to, apk_blob_t from);
+void apk_blob_push_blob(apk_blob_t *to, apk_blob_t literal);
+void apk_blob_push_uint(apk_blob_t *to, unsigned int value, int radix);
+void apk_blob_push_hexdump(apk_blob_t *to, apk_blob_t binary);
+
+void apk_blob_pull_char(apk_blob_t *b, int expected);
+unsigned int apk_blob_pull_uint(apk_blob_t *b, int radix);
+void apk_blob_pull_hexdump(apk_blob_t *b, apk_blob_t to);
 
 #endif
diff --git a/src/archive.c b/src/archive.c
index 7e5a926..450c956 100644
--- a/src/archive.c
+++ b/src/archive.c
@@ -48,7 +48,7 @@ struct tar_header {
 static int get_octal(char *s, size_t l)
 {
 	apk_blob_t b = APK_BLOB_PTR_LEN(s, l);
-	return apk_blob_parse_uint(&b, 8);
+	return apk_blob_pull_uint(&b, 8);
 }
 
 struct apk_tar_entry_istream {
diff --git a/src/blob.c b/src/blob.c
index 9f253cb..cbcb312 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -151,62 +151,117 @@ static inline int dx(int c)
 	return -1;
 }
 
-unsigned int apk_blob_parse_uint(apk_blob_t *blob, int base)
+void apk_blob_push_blob(apk_blob_t *to, apk_blob_t literal)
+{
+	if (APK_BLOB_IS_NULL(*to))
+		return;
+
+	if (to->len < literal.len) {
+		*to = APK_BLOB_NULL;
+		return;
+	}
+
+	memcpy(to->ptr, literal.ptr, literal.len);
+	to->ptr += literal.len;
+	to->len -= literal.len;
+}
+
+static const char *xd = "0123456789abcdefghijklmnopqrstuvwxyz";
+
+void apk_blob_push_uint(apk_blob_t *to, unsigned int value, int radix)
+{
+	char buf[64];
+	char *ptr = &buf[sizeof(buf)-1];
+
+	if (value == 0) {
+		apk_blob_push_blob(to, APK_BLOB_STR("0"));
+		return;
+	}
+
+	while (value != 0) {
+		*(ptr--) = xd[value % radix];
+		value /= radix;
+	}
+
+	apk_blob_push_blob(to, APK_BLOB_PTR_PTR(ptr+1, &buf[sizeof(buf)-1]));
+}
+
+void apk_blob_push_hexdump(apk_blob_t *to, apk_blob_t binary)
+{
+	char *d;
+	int i;
+
+	if (APK_BLOB_IS_NULL(*to))
+		return;
+
+	if (to->len < binary.len * 2) {
+		*to = APK_BLOB_NULL;
+		return;
+	}
+
+	for (i = 0, d = to->ptr; i < binary.len; i++) {
+		*(d++) = xd[(binary.ptr[i] >> 4) & 0xf];
+		*(d++) = xd[binary.ptr[i] & 0xf];
+	}
+	to->ptr = d;
+	to->len -= binary.len * 2;
+}
+
+void apk_blob_pull_char(apk_blob_t *b, int expected)
+{
+	if (APK_BLOB_IS_NULL(*b))
+		return;
+	if (b->len < 1 || b->ptr[0] != expected) {
+		*b = APK_BLOB_NULL;
+		return;
+	}
+	b->ptr ++;
+	b->len --;
+}
+
+unsigned int apk_blob_pull_uint(apk_blob_t *b, int radix)
 {
 	unsigned int val;
 	int ch;
 
 	val = 0;
-	while (blob->len && blob->ptr[0] != 0) {
-		ch = dx(blob->ptr[0]);
-		if (ch < 0 || ch >= base)
+	while (b->len && b->ptr[0] != 0) {
+		ch = dx(b->ptr[0]);
+		if (ch < 0 || ch >= radix)
 			break;
-		val *= base;
+		val *= radix;
 		val += ch;
 
-		blob->ptr++;
-		blob->len--;
+		b->ptr++;
+		b->len--;
 	}
 
 	return val;
 }
 
-int apk_blob_parse_char(apk_blob_t *blob)
+void apk_blob_pull_hexdump(apk_blob_t *b, apk_blob_t to)
 {
-	int r;
+	char *s, *d;
+	int i, r1, r2;
 
-	if (blob->len == 0 || blob->ptr == NULL)
-		return -1;
-	r = blob->ptr[0];
-	blob->ptr++;
-	blob->len--;
+	if (APK_BLOB_IS_NULL(*b))
+		return;
 
-	return r;
-}
+	if (to.len > b->len * 2)
+		goto err;
 
-int apk_hexdump_parse(apk_blob_t to, apk_blob_t from)
-{
-	int i;
-
-	if (to.len * 2 != from.len)
-		return -1;
-
-	for (i = 0; i < from.len / 2; i++)
-		to.ptr[i] = (dx(from.ptr[i*2]) << 4) + dx(from.ptr[i*2+1]);
-
-	return 0;
-}
-
-int apk_hexdump_format(int tolen, char *to, apk_blob_t from)
-{
-	static const char *xd = "0123456789abcdef";
-	int i;
-
-	for (i = 0; i < from.len && i*2+2 < tolen; i++) {
-		to[i*2+0] = xd[(from.ptr[i] >> 4) & 0xf];
-		to[i*2+1] = xd[from.ptr[i] & 0xf];
+	for (i = 0, s = b->ptr, d = to.ptr; i < to.len; i++) {
+		r1 = dx(*(s++));
+		if (r1 < 0)
+			goto err;
+		r2 = dx(*(s++));
+		if (r2 < 0)
+			goto err;
+		*(d++) = (r1 << 4) + r2;
 	}
-	to[i*2] = 0;
-
-	return i*2;
+	b->ptr = s;
+	b->len -= to.len * 2;
+	return;
+err:
+	*b = APK_BLOB_NULL;
 }
diff --git a/src/cache.c b/src/cache.c
index 6efbfe1..423af72 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -71,6 +71,7 @@ static int cache_clean(struct apk_database *db)
 	struct apk_package *pkg;
 	char path[256];
 	int delete, i;
+	apk_blob_t b;
 	csum_t csum;
 
 	snprintf(path, sizeof(path), "%s/%s", db->root, db->cache_dir);
@@ -88,9 +89,9 @@ static int cache_clean(struct apk_database *db)
 		do {
 			if (strlen(de->d_name) <= sizeof(csum_t)*2+2)
 				break;
-			if (apk_hexdump_parse(APK_BLOB_BUF(csum),
-					      APK_BLOB_PTR_LEN(de->d_name,
-					        sizeof(csum_t) * 2)) != 0)
+			b = APK_BLOB_PTR_LEN(de->d_name, sizeof(csum_t) * 2);
+			apk_blob_pull_hexdump(&b, APK_BLOB_BUF(csum));
+			if (APK_BLOB_IS_NULL(b))
 				break;
 			if (de->d_name[sizeof(csum_t)*2] != '.')
 				break;
diff --git a/src/database.c b/src/database.c
index 9aeab77..5767b97 100644
--- a/src/database.c
+++ b/src/database.c
@@ -454,13 +454,11 @@ int apk_db_index_read(struct apk_database *db, struct apk_bstream *bs, int repo)
 				apk_error("FDB directory metadata entry before directory entry");
 				return -1;
 			}
-			diri->uid = apk_blob_parse_uint(&l, 10);
-			if (apk_blob_parse_char(&l) != ':')
-				goto bad_mode;
-			diri->gid = apk_blob_parse_uint(&l, 10);
-			if (apk_blob_parse_char(&l) != ':')
-				goto bad_mode;
-			diri->mode = apk_blob_parse_uint(&l, 8);
+			diri->uid = apk_blob_pull_uint(&l, 10);
+			apk_blob_pull_char(&l, ':');
+			diri->gid = apk_blob_pull_uint(&l, 10);
+			apk_blob_pull_char(&l, ':');
+			diri->mode = apk_blob_pull_uint(&l, 8);
 			break;
 		case 'R':
 			if (diri == NULL) {
@@ -475,21 +473,20 @@ int apk_db_index_read(struct apk_database *db, struct apk_bstream *bs, int repo)
 				apk_error("FDB checksum entry before file entry");
 				return -1;
 			}
-			if (apk_hexdump_parse(APK_BLOB_BUF(file->csum), l)) {
-				apk_error("Not a valid checksum");
-				return -1;
-			}
+
+			apk_blob_pull_hexdump(&l, APK_BLOB_BUF(file->csum));
 			break;
 		default:
 			apk_error("FDB entry '%c' unsupported", field);
 			return -1;
 		}
+		if (APK_BLOB_IS_NULL(l)) {
+			apk_error("FDB format error in entry '%c'", field);
+			return -1;
+		}
 	}
 
 	return 0;
-bad_mode:
-	apk_error("FDB bad directory mode entry");
-	return -1;
 }
 
 static int apk_db_write_fdb(struct apk_database *db, struct apk_ostream *os)
@@ -499,7 +496,8 @@ static int apk_db_write_fdb(struct apk_database *db, struct apk_ostream *os)
 	struct apk_db_file *file;
 	struct hlist_node *c1, *c2;
 	char buf[1024];
-	int n = 0, r;
+	apk_blob_t bbuf = APK_BLOB_BUF(buf);
+	int r;
 
 	list_for_each_entry(pkg, &db->installed.packages, installed_pkgs_list) {
 		r = apk_pkg_write_index_entry(pkg, os);
@@ -507,30 +505,32 @@ static int apk_db_write_fdb(struct apk_database *db, struct apk_ostream *os)
 			return r;
 
 		hlist_for_each_entry(diri, c1, &pkg->owned_dirs, pkg_dirs_list) {
-			n += snprintf(&buf[n], sizeof(buf)-n,
-				      "F:%s\n"
-				      "M:%d:%d:%o\n",
-				      diri->dir->name,
-				      diri->uid, diri->gid, diri->mode);
+			apk_blob_push_blob(&bbuf, APK_BLOB_STR("F:"));
+			apk_blob_push_blob(&bbuf, APK_BLOB_PTR_LEN(diri->dir->name, diri->dir->namelen));
+			apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nM:"));
+			apk_blob_push_uint(&bbuf, diri->uid, 10);
+			apk_blob_push_blob(&bbuf, APK_BLOB_STR(":"));
+			apk_blob_push_uint(&bbuf, diri->gid, 10);
+			apk_blob_push_blob(&bbuf, APK_BLOB_STR(":"));
+			apk_blob_push_uint(&bbuf, diri->mode, 8);
+			apk_blob_push_blob(&bbuf, APK_BLOB_STR("\n"));
 
 			hlist_for_each_entry(file, c2, &diri->owned_files, diri_files_list) {
-				n += snprintf(&buf[n], sizeof(buf)-n,
-					      "R:%s\n",
-					      file->name);
+				apk_blob_push_blob(&bbuf, APK_BLOB_STR("R:"));
+				apk_blob_push_blob(&bbuf, APK_BLOB_PTR_LEN(file->name, file->namelen));
 				if (csum_valid(file->csum)) {
-					n += snprintf(&buf[n], sizeof(buf)-n, "Z:");
-					n += apk_hexdump_format(sizeof(buf)-n, &buf[n],
-								APK_BLOB_BUF(file->csum));
-					n += snprintf(&buf[n], sizeof(buf)-n, "\n");
+					apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nZ:"));
+					apk_blob_push_hexdump(&bbuf, APK_BLOB_BUF(file->csum));
 				}
+				apk_blob_push_blob(&bbuf, APK_BLOB_STR("\n"));
 
-				if (os->write(os, buf, n) != n)
+				if (os->write(os, buf, bbuf.ptr - buf) != bbuf.ptr - buf)
 					return -1;
-				n = 0;
+				bbuf = APK_BLOB_BUF(buf);
 			}
-			if (n != 0 && os->write(os, buf, n) != n)
+			if (os->write(os, buf, bbuf.ptr - buf) != bbuf.ptr - buf)
 				return -1;
-			n = 0;
+			bbuf = APK_BLOB_BUF(buf);
 		}
 		os->write(os, "\n", 1);
 	}
@@ -943,9 +943,12 @@ static void apk_db_cache_get_name(char *buf, size_t bufsz,
 				  const char *file, int temp)
 {
 	char csumstr[sizeof(csum_t)*2+1];
+	apk_blob_t bbuf = APK_BLOB_BUF(csumstr);
+
+	apk_blob_push_hexdump(&bbuf,
+			      APK_BLOB_PTR_LEN((void *)csum, sizeof(csum_t)));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR(""));
 
-	apk_hexdump_format(sizeof(csumstr), csumstr,
-			   APK_BLOB_PTR_LEN((void *)csum, sizeof(csum_t)));
 	snprintf(buf, bufsz, "%s/%s/%s.%s%s",
 		 db->root, db->cache_dir, csumstr, file, temp ? ".new" : "");
 }
diff --git a/src/package.c b/src/package.c
index 1b72f1c..c6c6737 100644
--- a/src/package.c
+++ b/src/package.c
@@ -290,17 +290,19 @@ int apk_pkg_add_info(struct apk_database *db, struct apk_package *pkg,
 		apk_deps_parse(db, &pkg->depends, value);
 		break;
 	case 'C':
-		apk_hexdump_parse(APK_BLOB_BUF(pkg->csum), value);
+		apk_blob_pull_hexdump(&value, APK_BLOB_BUF(pkg->csum));
 		break;
 	case 'S':
-		pkg->size = apk_blob_parse_uint(&value, 10);
+		pkg->size = apk_blob_pull_uint(&value, 10);
 		break;
 	case 'I':
-		pkg->installed_size = apk_blob_parse_uint(&value, 10);
+		pkg->installed_size = apk_blob_pull_uint(&value, 10);
 		break;
 	default:
 		return -1;
 	}
+	if (APK_BLOB_IS_NULL(value))
+		return -1;
 	return 0;
 }
 
@@ -643,22 +645,29 @@ int apk_pkg_write_index_entry(struct apk_package *info,
 			      struct apk_ostream *os)
 {
 	char buf[512];
-	int n, r, t = 0;
+	apk_blob_t bbuf = APK_BLOB_BUF(buf);
+	int r;
 
-	n = snprintf(buf, sizeof(buf),
-		     "P:%s\n"
-		     "V:%s\n"
-		     "S:%zu\n"
-		     "I:%zu\n"
-		     "T:%s\n"
-		     "U:%s\n"
-		     "L:%s\n",
-		     info->name->name, info->version,
-		     info->size, info->installed_size,
-		     info->description, info->url, info->license);
-	if (os->write(os, buf, n) != n)
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("C:"));
+	apk_blob_push_hexdump(&bbuf, APK_BLOB_BUF(info->csum));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nP:"));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR(info->name->name));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nV:"));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR(info->version));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nS:"));
+	apk_blob_push_uint(&bbuf, info->size, 10);
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nI:"));
+	apk_blob_push_uint(&bbuf, info->installed_size, 10);
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nT:"));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR(info->description));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nU:"));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR(info->url));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("\nL:"));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR(info->license));
+	apk_blob_push_blob(&bbuf, APK_BLOB_STR("\n"));
+
+	if (os->write(os, buf, bbuf.ptr - buf) != bbuf.ptr - buf)
 		return -1;
-	t += n;
 
 	if (info->depends != NULL) {
 		if (os->write(os, "D:", 2) != 2)
@@ -668,18 +677,9 @@ int apk_pkg_write_index_entry(struct apk_package *info,
 			return r;
 		if (os->write(os, "\n", 1) != 1)
 			return -1;
-		t += r + 3;
 	}
 
-	n = snprintf(buf, sizeof(buf), "C:");
-	n += apk_hexdump_format(sizeof(buf)-n, &buf[n], APK_BLOB_BUF(info->csum));
-	n += snprintf(&buf[n], sizeof(buf)-n, "\n");
-
-	if (os->write(os, buf, n) != n)
-		return -1;
-	t += n;
-
-	return n;
+	return 0;
 }
 
 int apk_pkg_version_compare(struct apk_package *a, struct apk_package *b)