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252712111f
Each window in a subversion delta (svndiff0-format file) starts with a window header, consisting of five integers with variable-length representation: source view offset source view length output length instructions length auxiliary data length Parse it. The result is not usable for deltas with nonempty postimage yet; in fact, this only adds support for deltas without any instructions or auxiliary data. This is a good place to stop, though, since that little support lets us add some simple passing tests concerning error handling to the test suite. Improved-by: Ramkumar Ramachandra <artagnon@gmail.com> Improved-by: David Barr <david.barr@cordelta.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
135 lines
3.1 KiB
C
135 lines
3.1 KiB
C
/*
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* Licensed under a two-clause BSD-style license.
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* See LICENSE for details.
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*/
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#include "git-compat-util.h"
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#include "line_buffer.h"
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#include "svndiff.h"
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/*
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* svndiff0 applier
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*
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* See http://svn.apache.org/repos/asf/subversion/trunk/notes/svndiff.
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*
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* svndiff0 ::= 'SVN\0' window*
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* window ::= int int int int int instructions inline_data;
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* int ::= highdigit* lowdigit;
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* highdigit ::= # binary 1000 0000 OR-ed with 7 bit value;
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* lowdigit ::= # 7 bit value;
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*/
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#define VLI_CONTINUE 0x80
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#define VLI_DIGIT_MASK 0x7f
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#define VLI_BITS_PER_DIGIT 7
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static int error_short_read(struct line_buffer *input)
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{
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if (buffer_ferror(input))
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return error("error reading delta: %s", strerror(errno));
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return error("invalid delta: unexpected end of file");
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}
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static int read_magic(struct line_buffer *in, off_t *len)
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{
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static const char magic[] = {'S', 'V', 'N', '\0'};
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struct strbuf sb = STRBUF_INIT;
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if (*len < sizeof(magic) ||
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buffer_read_binary(in, &sb, sizeof(magic)) != sizeof(magic)) {
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error_short_read(in);
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strbuf_release(&sb);
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return -1;
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}
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if (memcmp(sb.buf, magic, sizeof(magic))) {
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strbuf_release(&sb);
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return error("invalid delta: unrecognized file type");
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}
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*len -= sizeof(magic);
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strbuf_release(&sb);
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return 0;
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}
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static int read_int(struct line_buffer *in, uintmax_t *result, off_t *len)
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{
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uintmax_t rv = 0;
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off_t sz;
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for (sz = *len; sz; sz--) {
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const int ch = buffer_read_char(in);
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if (ch == EOF)
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break;
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rv <<= VLI_BITS_PER_DIGIT;
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rv += (ch & VLI_DIGIT_MASK);
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if (ch & VLI_CONTINUE)
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continue;
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*result = rv;
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*len = sz - 1;
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return 0;
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}
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return error_short_read(in);
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}
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static int read_offset(struct line_buffer *in, off_t *result, off_t *len)
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{
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uintmax_t val;
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if (read_int(in, &val, len))
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return -1;
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if (val > maximum_signed_value_of_type(off_t))
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return error("unrepresentable offset in delta: %"PRIuMAX"", val);
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*result = val;
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return 0;
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}
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static int read_length(struct line_buffer *in, size_t *result, off_t *len)
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{
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uintmax_t val;
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if (read_int(in, &val, len))
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return -1;
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if (val > SIZE_MAX)
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return error("unrepresentable length in delta: %"PRIuMAX"", val);
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*result = val;
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return 0;
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}
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static int apply_one_window(struct line_buffer *delta, off_t *delta_len)
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{
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size_t out_len;
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size_t instructions_len;
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size_t data_len;
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assert(delta_len);
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/* "source view" offset and length already handled; */
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if (read_length(delta, &out_len, delta_len) ||
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read_length(delta, &instructions_len, delta_len) ||
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read_length(delta, &data_len, delta_len))
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return -1;
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if (instructions_len)
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return error("What do you think I am? A delta applier?");
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if (data_len)
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return error("No support for inline data yet");
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return 0;
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}
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int svndiff0_apply(struct line_buffer *delta, off_t delta_len,
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struct sliding_view *preimage, FILE *postimage)
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{
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assert(delta && preimage && postimage);
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if (read_magic(delta, &delta_len))
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return -1;
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while (delta_len) { /* For each window: */
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off_t pre_off;
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size_t pre_len;
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if (read_offset(delta, &pre_off, &delta_len) ||
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read_length(delta, &pre_len, &delta_len) ||
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apply_one_window(delta, &delta_len))
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return -1;
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}
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return 0;
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}
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