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-rw-r--r--libbb/base64.c78
1 files changed, 78 insertions, 0 deletions
diff --git a/libbb/base64.c b/libbb/base64.c
new file mode 100644
index 0000000..b9d47ae
--- /dev/null
+++ b/libbb/base64.c
@@ -0,0 +1,78 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Utility routines.
+ *
+ * Copyright 2003, Glenn McGrath
+ * Copyright 2010, Denys Vlasenko
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+#include "libbb.h"
+
+//kbuild:lib-y += base64.o
+
+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_UUEND)
+
+ int term_count = 0;
+
+ while (1) {
+ unsigned char translated[4];
+ int count = 0;
+
+ /* Process one group of 4 chars */
+ 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
+ * 012345678901234567890123456789012345678901234567890123456789012345
+ * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n"
+ */
+ do {
+ ch = fgetc(src_stream);
+ if (ch == exit_char && count == 0)
+ return;
+ if (ch == EOF)
+ bb_error_msg_and_die("truncated base64 input");
+ table_ptr = strchr(bb_uuenc_tbl_base64, ch);
+//TODO: add BASE64_FLAG_foo to die on bad char?
+//Note that then we may need to still allow '\r' (for mail processing)
+ } while (!table_ptr);
+
+ /* Convert encoded character to decimal */
+ ch = table_ptr - bb_uuenc_tbl_base64;
+
+ if (ch == 65 /* '\n' */) {
+ /* Terminating "====" line? */
+ if (uu_style_end && term_count == 4)
+ return; /* yes */
+ continue;
+ }
+ /* ch is 64 if char was '=', otherwise 0..63 */
+ translated[count] = ch & 63; /* 64 -> 0 */
+ if (ch == 64) {
+ term_count++;
+ break;
+ }
+ term_count = 0;
+ count++;
+ }
+
+ /* Merge 6 bit chars to 8 bit.
+ * count can be < 4 when we decode the tail:
+ * "eQ==" -> "y", not "y NUL NUL"
+ */
+ if (count > 1)
+ fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
+ if (count > 2)
+ fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
+ if (count > 3)
+ fputc(translated[2] << 6 | translated[3], dst_stream);
+ } /* while (1) */
+}