X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=gnulib%2Fbase64.c;h=8aff43002fbd53d2bb3d02c428f6d4d094d8bd8c;hb=fd48f3e498442f0cbff5f3606c7c403d0566150e;hp=188b36ac73d1fc4505634584f650a26f7b4e6d98;hpb=96f35b20267e8b1a1c846d476f27fcd330e0b018;p=debian%2Famanda diff --git a/gnulib/base64.c b/gnulib/base64.c index 188b36a..8aff430 100644 --- a/gnulib/base64.c +++ b/gnulib/base64.c @@ -4,7 +4,7 @@ This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 3, or (at your option) + the Free Software Foundation; either version 2, or (at your option) any later version. This program is distributed in the hope that it will be useful, @@ -52,6 +52,8 @@ /* Get UCHAR_MAX. */ #include +#include + /* C89 compliant way to cast 'char' to 'unsigned char'. */ static inline unsigned char to_uchar (char ch) @@ -64,8 +66,8 @@ to_uchar (char ch) possible. If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero terminate the output buffer. */ void -base64_encode (const char *in, size_t inlen, - char *out, size_t outlen) +base64_encode (const char *restrict in, size_t inlen, + char *restrict out, size_t outlen) { static const char b64str[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; @@ -300,89 +302,237 @@ isbase64 (char ch) return uchar_in_range (to_uchar (ch)) && 0 <= b64[to_uchar (ch)]; } -/* Decode base64 encoded input array IN of length INLEN to output - array OUT that can hold *OUTLEN bytes. Return true if decoding was - successful, i.e. if the input was valid base64 data, false - otherwise. If *OUTLEN is too small, as many bytes as possible will - be written to OUT. On return, *OUTLEN holds the length of decoded - bytes in OUT. Note that as soon as any non-alphabet characters are - encountered, decoding is stopped and false is returned. This means - that, when applicable, you must remove any line terminators that is - part of the data stream before calling this function. */ -bool -base64_decode (const char *in, size_t inlen, - char *out, size_t *outlen) +/* Initialize decode-context buffer, CTX. */ +void +base64_decode_ctx_init (struct base64_decode_context *ctx) { - size_t outleft = *outlen; + ctx->i = 0; +} - while (inlen >= 2) - { - if (!isbase64 (in[0]) || !isbase64 (in[1])) - break; +/* If CTX->i is 0 or 4, there are four or more bytes in [*IN..IN_END), and + none of those four is a newline, then return *IN. Otherwise, copy up to + 4 - CTX->i non-newline bytes from that range into CTX->buf, starting at + index CTX->i and setting CTX->i to reflect the number of bytes copied, + and return CTX->buf. In either case, advance *IN to point to the byte + after the last one processed, and set *N_NON_NEWLINE to the number of + verified non-newline bytes accessible through the returned pointer. */ +static inline char * +get_4 (struct base64_decode_context *ctx, + char const *restrict *in, char const *restrict in_end, + size_t *n_non_newline) +{ + if (ctx->i == 4) + ctx->i = 0; - if (outleft) + if (ctx->i == 0) + { + char const *t = *in; + if (4 <= in_end - *in && memchr (t, '\n', 4) == NULL) { - *out++ = ((b64[to_uchar (in[0])] << 2) - | (b64[to_uchar (in[1])] >> 4)); - outleft--; + /* This is the common case: no newline. */ + *in += 4; + *n_non_newline = 4; + return (char *) t; } + } - if (inlen == 2) - break; + { + /* Copy non-newline bytes into BUF. */ + char const *p = *in; + while (p < in_end) + { + char c = *p++; + if (c != '\n') + { + ctx->buf[ctx->i++] = c; + if (ctx->i == 4) + break; + } + } + + *in = p; + *n_non_newline = ctx->i; + return ctx->buf; + } +} + +#define return_false \ + do \ + { \ + *outp = out; \ + return false; \ + } \ + while (false) + +/* Decode up to four bytes of base64-encoded data, IN, of length INLEN + into the output buffer, *OUT, of size *OUTLEN bytes. Return true if + decoding is successful, false otherwise. If *OUTLEN is too small, + as many bytes as possible are written to *OUT. On return, advance + *OUT to point to the byte after the last one written, and decrement + *OUTLEN to reflect the number of bytes remaining in *OUT. */ +static inline bool +decode_4 (char const *restrict in, size_t inlen, + char *restrict *outp, size_t *outleft) +{ + char *out = *outp; + if (inlen < 2) + return false; + + if (!isbase64 (in[0]) || !isbase64 (in[1])) + return false; + + if (*outleft) + { + *out++ = ((b64[to_uchar (in[0])] << 2) + | (b64[to_uchar (in[1])] >> 4)); + --*outleft; + } + + if (inlen == 2) + return_false; + + if (in[2] == '=') + { + if (inlen != 4) + return_false; + + if (in[3] != '=') + return_false; + } + else + { + if (!isbase64 (in[2])) + return_false; - if (in[2] == '=') + if (*outleft) { - if (inlen != 4) - break; + *out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0) + | (b64[to_uchar (in[2])] >> 2)); + --*outleft; + } - if (in[3] != '=') - break; + if (inlen == 3) + return_false; + if (in[3] == '=') + { + if (inlen != 4) + return_false; } else { - if (!isbase64 (in[2])) - break; + if (!isbase64 (in[3])) + return_false; - if (outleft) + if (*outleft) { - *out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0) - | (b64[to_uchar (in[2])] >> 2)); - outleft--; + *out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0) + | b64[to_uchar (in[3])]); + --*outleft; } + } + } - if (inlen == 3) - break; + *outp = out; + return true; +} - if (in[3] == '=') - { - if (inlen != 4) - break; - } - else +/* Decode base64-encoded input array IN of length INLEN to output array + OUT that can hold *OUTLEN bytes. The input data may be interspersed + with newlines. Return true if decoding was successful, i.e. if the + input was valid base64 data, false otherwise. If *OUTLEN is too + small, as many bytes as possible will be written to OUT. On return, + *OUTLEN holds the length of decoded bytes in OUT. Note that as soon + as any non-alphabet, non-newline character is encountered, decoding + is stopped and false is returned. If INLEN is zero, then process + only whatever data is stored in CTX. + + Initially, CTX must have been initialized via base64_decode_ctx_init. + Subsequent calls to this function must reuse whatever state is recorded + in that buffer. It is necessary for when a quadruple of base64 input + bytes spans two input buffers. + + If CTX is NULL then newlines are treated as garbage and the input + buffer is processed as a unit. */ + +bool +base64_decode_ctx (struct base64_decode_context *ctx, + const char *restrict in, size_t inlen, + char *restrict out, size_t *outlen) +{ + size_t outleft = *outlen; + bool ignore_newlines = ctx != NULL; + bool flush_ctx = false; + unsigned int ctx_i = 0; + + if (ignore_newlines) + { + ctx_i = ctx->i; + flush_ctx = inlen == 0; + } + + + while (true) + { + size_t outleft_save = outleft; + if (ctx_i == 0 && !flush_ctx) + { + while (true) { - if (!isbase64 (in[3])) + /* Save a copy of outleft, in case we need to re-parse this + block of four bytes. */ + outleft_save = outleft; + if (!decode_4 (in, inlen, &out, &outleft)) break; - if (outleft) - { - *out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0) - | b64[to_uchar (in[3])]); - outleft--; - } + in += 4; + inlen -= 4; } } - in += 4; - inlen -= 4; + if (inlen == 0 && !flush_ctx) + break; + + /* Handle the common case of 72-byte wrapped lines. + This also handles any other multiple-of-4-byte wrapping. */ + if (inlen && *in == '\n' && ignore_newlines) + { + ++in; + --inlen; + continue; + } + + /* Restore OUT and OUTLEFT. */ + out -= outleft_save - outleft; + outleft = outleft_save; + + { + char const *in_end = in + inlen; + char const *non_nl; + + if (ignore_newlines) + non_nl = get_4 (ctx, &in, in_end, &inlen); + else + non_nl = in; /* Might have nl in this case. */ + + /* If the input is empty or consists solely of newlines (0 non-newlines), + then we're done. Likewise if there are fewer than 4 bytes when not + flushing context and not treating newlines as garbage. */ + if (inlen == 0 || (inlen < 4 && !flush_ctx && ignore_newlines)) + { + inlen = 0; + break; + } + if (!decode_4 (non_nl, inlen, &out, &outleft)) + break; + + inlen = in_end - in; + } } *outlen -= outleft; - if (inlen != 0) - return false; - - return true; + return inlen == 0; } /* Allocate an output buffer in *OUT, and decode the base64 encoded @@ -397,12 +547,13 @@ base64_decode (const char *in, size_t inlen, input was invalid, in which case *OUT is NULL and *OUTLEN is undefined. */ bool -base64_decode_alloc (const char *in, size_t inlen, char **out, - size_t *outlen) +base64_decode_alloc_ctx (struct base64_decode_context *ctx, + const char *in, size_t inlen, char **out, + size_t *outlen) { - /* This may allocate a few bytes too much, depending on input, - but it's not worth the extra CPU time to compute the exact amount. - The exact amount is 3 * inlen / 4, minus 1 if the input ends + /* This may allocate a few bytes too many, depending on input, + but it's not worth the extra CPU time to compute the exact size. + The exact size is 3 * inlen / 4, minus 1 if the input ends with "=" and minus another 1 if the input ends with "==". Dividing before multiplying avoids the possibility of overflow. */ size_t needlen = 3 * (inlen / 4) + 2; @@ -411,7 +562,7 @@ base64_decode_alloc (const char *in, size_t inlen, char **out, if (!*out) return true; - if (!base64_decode (in, inlen, *out, &needlen)) + if (!base64_decode_ctx (ctx, in, inlen, *out, &needlen)) { free (*out); *out = NULL;