diff options
Diffstat (limited to 'libbb/base64.c')
-rw-r--r-- | libbb/base64.c | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/libbb/base64.c b/libbb/base64.c new file mode 100644 index 000000000..b9d47ae08 --- /dev/null +++ b/libbb/base64.c | |||
@@ -0,0 +1,78 @@ | |||
1 | /* vi: set sw=4 ts=4: */ | ||
2 | /* | ||
3 | * Utility routines. | ||
4 | * | ||
5 | * Copyright 2003, Glenn McGrath | ||
6 | * Copyright 2010, Denys Vlasenko | ||
7 | * | ||
8 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. | ||
9 | */ | ||
10 | #include "libbb.h" | ||
11 | |||
12 | //kbuild:lib-y += base64.o | ||
13 | |||
14 | void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags) | ||
15 | { | ||
16 | /* Note that EOF _can_ be passed as exit_char too */ | ||
17 | #define exit_char ((int)(signed char)flags) | ||
18 | #define uu_style_end (flags & BASE64_FLAG_UUEND) | ||
19 | |||
20 | int term_count = 0; | ||
21 | |||
22 | while (1) { | ||
23 | unsigned char translated[4]; | ||
24 | int count = 0; | ||
25 | |||
26 | /* Process one group of 4 chars */ | ||
27 | while (count < 4) { | ||
28 | char *table_ptr; | ||
29 | int ch; | ||
30 | |||
31 | /* Get next _valid_ character. | ||
32 | * bb_uuenc_tbl_base64[] contains this string: | ||
33 | * 0 1 2 3 4 5 6 | ||
34 | * 012345678901234567890123456789012345678901234567890123456789012345 | ||
35 | * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n" | ||
36 | */ | ||
37 | do { | ||
38 | ch = fgetc(src_stream); | ||
39 | if (ch == exit_char && count == 0) | ||
40 | return; | ||
41 | if (ch == EOF) | ||
42 | bb_error_msg_and_die("truncated base64 input"); | ||
43 | table_ptr = strchr(bb_uuenc_tbl_base64, ch); | ||
44 | //TODO: add BASE64_FLAG_foo to die on bad char? | ||
45 | //Note that then we may need to still allow '\r' (for mail processing) | ||
46 | } while (!table_ptr); | ||
47 | |||
48 | /* Convert encoded character to decimal */ | ||
49 | ch = table_ptr - bb_uuenc_tbl_base64; | ||
50 | |||
51 | if (ch == 65 /* '\n' */) { | ||
52 | /* Terminating "====" line? */ | ||
53 | if (uu_style_end && term_count == 4) | ||
54 | return; /* yes */ | ||
55 | continue; | ||
56 | } | ||
57 | /* ch is 64 if char was '=', otherwise 0..63 */ | ||
58 | translated[count] = ch & 63; /* 64 -> 0 */ | ||
59 | if (ch == 64) { | ||
60 | term_count++; | ||
61 | break; | ||
62 | } | ||
63 | term_count = 0; | ||
64 | count++; | ||
65 | } | ||
66 | |||
67 | /* Merge 6 bit chars to 8 bit. | ||
68 | * count can be < 4 when we decode the tail: | ||
69 | * "eQ==" -> "y", not "y NUL NUL" | ||
70 | */ | ||
71 | if (count > 1) | ||
72 | fputc(translated[0] << 2 | translated[1] >> 4, dst_stream); | ||
73 | if (count > 2) | ||
74 | fputc(translated[1] << 4 | translated[2] >> 2, dst_stream); | ||
75 | if (count > 3) | ||
76 | fputc(translated[2] << 6 | translated[3], dst_stream); | ||
77 | } /* while (1) */ | ||
78 | } | ||