From 844fdd42f03a633f1dbce5d90b2ecf44698cf8b0 Mon Sep 17 00:00:00 2001
From: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Date: Fri, 18 Nov 2022 00:57:01 +0100
Subject: Add a single, central base64 decoder
Similar to the hex blob decoder, we need this once for tar and
once for the filemap xattr parser.
Simply add a single, central implementation to libutil, with a
simple unit test, and then use it in both libtar and gensquashfs.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
---
lib/tar/pax_header.c | 62 +++++-----------------------
lib/util/Makemodule.am | 1 +
lib/util/base64_decode.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 113 insertions(+), 53 deletions(-)
create mode 100644 lib/util/base64_decode.c
(limited to 'lib')
diff --git a/lib/tar/pax_header.c b/lib/tar/pax_header.c
index cc2f2b0..b61aab6 100644
--- a/lib/tar/pax_header.c
+++ b/lib/tar/pax_header.c
@@ -11,56 +11,6 @@
#include <string.h>
#include <stdlib.h>
-static sqfs_u8 base64_convert(char in)
-{
- if (isupper(in))
- return in - 'A';
- if (islower(in))
- return in - 'a' + 26;
- if (isdigit(in))
- return in - '0' + 52;
- if (in == '+')
- return 62;
- if (in == '/' || in == '-')
- return 63;
- return 0;
-}
-
-static size_t base64_decode(sqfs_u8 *out, const char *in, size_t len)
-{
- sqfs_u8 *start = out;
-
- while (len > 0) {
- unsigned int diff = 0, value = 0;
-
- while (diff < 4 && len > 0) {
- if (*in == '=' || *in == '_' || *in == '\0') {
- len = 0;
- } else {
- value = (value << 6) | base64_convert(*(in++));
- --len;
- ++diff;
- }
- }
-
- if (diff < 2)
- break;
-
- value <<= 6 * (4 - diff);
-
- switch (diff) {
- case 4: out[2] = value & 0xff; /* fall-through */
- case 3: out[1] = (value >> 8) & 0xff; /* fall-through */
- default: out[0] = (value >> 16) & 0xff;
- }
-
- out += (diff * 3) / 4;
- }
-
- *out = '\0';
- return out - start;
-}
-
static int pax_read_decimal(const char *str, sqfs_u64 *out)
{
sqfs_u64 result = 0;
@@ -201,10 +151,16 @@ static int pax_xattr_schily(tar_header_decoded_t *out,
static int pax_xattr_libarchive(tar_header_decoded_t *out,
tar_xattr_t *xattr)
{
+ int ret;
+
+ ret = base64_decode((const char *)xattr->value, xattr->value_len,
+ xattr->value, &xattr->value_len);
+ if (ret)
+ return -1;
+
urldecode(xattr->key);
- xattr->value_len = base64_decode(xattr->value,
- (const char *)xattr->value,
- xattr->value_len);
+
+ xattr->value[xattr->value_len] = '\0';
xattr->next = out->xattr;
out->xattr = xattr;
return 0;
diff --git a/lib/util/Makemodule.am b/lib/util/Makemodule.am
index 4f1f0da..ec38b7a 100644
--- a/lib/util/Makemodule.am
+++ b/lib/util/Makemodule.am
@@ -15,6 +15,7 @@ libutil_a_SOURCES += lib/util/filename_sane.c
libutil_a_SOURCES += lib/util/source_date_epoch.c
libutil_a_SOURCES += lib/util/file_cmp.c
libutil_a_SOURCES += lib/util/hex_decode.c
+libutil_a_SOURCES += lib/util/base64_decode.c
libutil_a_CFLAGS = $(AM_CFLAGS)
libutil_a_CPPFLAGS = $(AM_CPPFLAGS)
diff --git a/lib/util/base64_decode.c b/lib/util/base64_decode.c
new file mode 100644
index 0000000..b1cf5b6
--- /dev/null
+++ b/lib/util/base64_decode.c
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * base64_decode.c
+ *
+ * Copyright (C) 2022 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+#include "util/util.h"
+#include "util/test.h"
+
+#include <ctype.h>
+
+static int base64_digit(int c)
+{
+ if (isupper(c))
+ return c - 'A';
+ if (islower(c))
+ return c - 'a' + 26;
+ if (isdigit(c))
+ return c - '0' + 52;
+ if (c == '+')
+ return 62;
+ if (c == '/' || c == '-')
+ return 63;
+ return -1;
+}
+
+int base64_decode(const char *in, size_t in_len, sqfs_u8 *out, size_t *out_len)
+{
+ int i1, i2, i3, i4;
+ size_t count = 0;
+
+ while (in_len >= 4) {
+ i1 = base64_digit(*(in++));
+ i2 = base64_digit(*(in++));
+ i3 = *(in++);
+ i4 = *(in++);
+ in_len -= 4;
+
+ if (i1 < 0 || i2 < 0 || count >= *out_len)
+ goto fail;
+
+ out[count++] = (i1 << 2) | (i2 >> 4);
+
+ if (i3 == '=' || i3 == '_') {
+ if ((i4 != '=' && i4 != '_') || in_len > 0)
+ goto fail;
+ break;
+ }
+
+ i3 = base64_digit(i3);
+ if (i3 < 0 || count >= *out_len)
+ goto fail;
+
+ out[count++] = ((i2 & 0x0F) << 4) | (i3 >> 2);
+
+ if (i4 == '=' || i4 == '_') {
+ if (in_len > 0)
+ goto fail;
+ break;
+ }
+
+ i4 = base64_digit(i4);
+ if (i4 < 0 || count >= *out_len)
+ goto fail;
+
+ out[count++] = ((i3 & 0x3) << 6) | i4;
+ }
+
+ /* libarchive has this bizarre bastardization of truncated base64 */
+ if (in_len > 0) {
+ if (in_len == 1)
+ goto fail;
+
+ i1 = base64_digit(*(in++));
+ i2 = base64_digit(*(in++));
+ in_len -= 2;
+
+ if (i1 < 0 || i2 < 0 || count >= *out_len)
+ goto fail;
+
+ out[count++] = (i1 << 2) | (i2 >> 4);
+
+ if (in_len > 0) {
+ i3 = *(in++);
+ --in_len;
+
+ if (i3 != '=' && i3 != '_') {
+ i3 = base64_digit(i3);
+ if (i3 < 0 || count >= *out_len)
+ goto fail;
+
+ out[count++] = ((i2 & 0x0F) << 4) | (i3 >> 2);
+ }
+ }
+ }
+
+ *out_len = count;
+ return 0;
+fail:
+ *out_len = 0;
+ return -1;
+}
--
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