/* vi: set sw=4 ts=4: */
/*
- * Copyright 2006 Rob Landley <rob@landley.net>
+ * Copyright 2003, Glenn McGrath
+ * Copyright 2006, Rob Landley <rob@landley.net>
+ * Copyright 2010, Denys Vlasenko
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
/* Conversion table. for base 64 */
-const char bb_uuenc_tbl_base64[65 + 2] ALIGN1 = {
+const char bb_uuenc_tbl_base64[65 + 1] ALIGN1 = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '+', '/',
'=' /* termination character */,
- '\n', '\0' /* needed for uudecode.c */
+ '\0' /* needed for uudecode.c only */
};
const char bb_uuenc_tbl_std[65] ALIGN1 = {
length++;
}
}
+
+/*
+ * Decode base64 encoded string. Stops on '\0'.
+ *
+ * Returns: pointer to the undecoded part of source.
+ * If points to '\0', then the source was fully decoded.
+ * (*pp_dst): advanced past the last written byte.
+ */
+const char* FAST_FUNC decode_base64(char **pp_dst, const char *src)
+{
+ char *dst = *pp_dst;
+ const char *src_tail;
+
+ while (1) {
+ unsigned char six_bit[4];
+ int count = 0;
+
+ /* Fetch up to four 6-bit values */
+ src_tail = src;
+ while (count < 4) {
+ char *table_ptr;
+ int ch;
+
+ /* Get next _valid_ character.
+ * bb_uuenc_tbl_base64[] contains this string:
+ * 0 1 2 3 4 5 6
+ * 01234567890123456789012345678901234567890123456789012345678901234
+ * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
+ */
+ do {
+ ch = *src;
+ if (ch == '\0') {
+ if (count == 0) {
+ /* Example:
+ * If we decode "QUJD <NUL>", we want
+ * to return ptr to NUL, not to ' ',
+ * because we did fully decode
+ * the string (to "ABC").
+ */
+ src_tail = src;
+ }
+ goto ret;
+ }
+ src++;
+ table_ptr = strchr(bb_uuenc_tbl_base64, ch);
+//TODO: add BASE64_FLAG_foo to die on bad char?
+ } while (!table_ptr);
+
+ /* Convert encoded character to decimal */
+ ch = table_ptr - bb_uuenc_tbl_base64;
+
+ /* ch is 64 if char was '=', otherwise 0..63 */
+ if (ch == 64)
+ break;
+ six_bit[count] = ch;
+ count++;
+ }
+
+ /* Transform 6-bit values to 8-bit ones.
+ * count can be < 4 when we decode the tail:
+ * "eQ==" -> "y", not "y NUL NUL".
+ * Note that (count > 1) is always true,
+ * "x===" encoding is not valid:
+ * even a single zero byte encodes as "AA==".
+ * However, with current logic we come here with count == 1
+ * when we decode "==" tail.
+ */
+ if (count > 1)
+ *dst++ = six_bit[0] << 2 | six_bit[1] >> 4;
+ if (count > 2)
+ *dst++ = six_bit[1] << 4 | six_bit[2] >> 2;
+ if (count > 3)
+ *dst++ = six_bit[2] << 6 | six_bit[3];
+ /* Note that if we decode "AA==" and ate first '=',
+ * we just decoded one char (count == 2) and now we'll
+ * do the loop once more to decode second '='.
+ */
+ } /* while (1) */
+ ret:
+ *pp_dst = dst;
+ return src_tail;
+}
+
+/*
+ * Decode base64 encoded stream.
+ * Can stop on EOF, specified char, or on uuencode-style "====" line:
+ * flags argument controls it.
+ */
+void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags)
+{
+/* Note that EOF _can_ be passed as exit_char too */
+#define exit_char ((int)(signed char)flags)
+#define uu_style_end (flags & BASE64_FLAG_UU_STOP)
+
+ /* uuencoded files have 61 byte lines. Use 64 byte buffer
+ * to process line at a time.
+ */
+ enum { BUFFER_SIZE = 64 };
+
+ char in_buf[BUFFER_SIZE + 2];
+ char out_buf[BUFFER_SIZE / 4 * 3 + 2];
+ char *out_tail;
+ const char *in_tail;
+ int term_seen = 0;
+ int in_count = 0;
+
+ while (1) {
+ while (in_count < BUFFER_SIZE) {
+ int ch = fgetc(src_stream);
+ if (ch == exit_char) {
+ if (in_count == 0)
+ return;
+ term_seen = 1;
+ break;
+ }
+ if (ch == EOF) {
+ term_seen = 1;
+ break;
+ }
+ /* Prevent "====" line to be split: stop if we see '\n'.
+ * We can also skip other whitespace and skirt the problem
+ * of files with NULs by stopping on any control char or space:
+ */
+ if (ch <= ' ')
+ break;
+ in_buf[in_count++] = ch;
+ }
+ in_buf[in_count] = '\0';
+
+ /* Did we encounter "====" line? */
+ if (uu_style_end && strcmp(in_buf, "====") == 0)
+ return;
+
+ out_tail = out_buf;
+ in_tail = decode_base64(&out_tail, in_buf);
+
+ fwrite(out_buf, (out_tail - out_buf), 1, dst_stream);
+
+ if (term_seen) {
+ /* Did we consume ALL characters? */
+ if (*in_tail == '\0')
+ return;
+ /* No */
+ bb_error_msg_and_die("truncated base64 input");
+ }
+
+ /* It was partial decode */
+ in_count = strlen(in_tail);
+ memmove(in_buf, in_tail, in_count);
+ }
+}
projects / oweals / busybox.git / blobdiff