[PATCH 06/11] vcs-svn: Implement copyfrom_data delta instruction
- From
Jonathan Nieder <jrnieder@gmail.com>
- Date
- Oct 13, 2010, 09:39 UTC
- Message-ID
- <20101013093944.GG32608@burratino>
- In-Reply-To
- <20101013091714.GA32608@burratino>
The copyfrom_data instruction copies a few bytes verbatim from the auxiliary data section of a window to the postimage.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> --- t/t9011-svn-da.sh | 31 +++++++++++++++++++ vcs-svn/svndiff.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 112 insertions(+), 5 deletions(-)
diff --git a/t/t9011-svn-da.sh b/t/t9011-svn-da.sh index 1383263..9279924 100755 --- a/t/t9011-svn-da.sh +++ b/t/t9011-svn-da.sh @@ -134,4 +134,35 @@ test_expect_success 'truncated inline data (after instruction section)' ' test_must_fail test-svn-fe -d preimage insn.trunc 11 ' +test_expect_success 'copyfrom_data' ' + echo hi >expect && + printf "SVNQ%b%b%b" "QQ\003\001\003" "\0203" "hi\n" | q_to_nul >copydat && + test-svn-fe -d preimage copydat 13 >actual && + test_cmp expect actual +' + +test_expect_success 'multiple copyfrom_data' ' + echo hi >expect && + printf "SVNQ%b%b%b%b%b" "QQ\003\002\003" "\0201\0202" "hi\n" \ + "QQQ\002Q" "\0200Q" | q_to_nul >copy.multi && + len=$(wc -c <copy.multi) && + test-svn-fe -d preimage copy.multi $len >actual && + test_cmp expect actual +' + +test_expect_success 'incomplete multiple insn' ' + printf "SVNQ%b%b%b" "QQ\003\002\003" "\0203\0200" "hi\n" | + q_to_nul >copy.partial && + len=$(wc -c <copy.partial) && + test_must_fail test-svn-fe -d preimage copy.partial $len +' + +test_expect_success 'catch attempt to copy missing data' ' + printf "SVNQ%b%b%s%b%s" "QQ\002\002\001" "\0201\0201" "X" \ + "QQQQ\002" "YZ" | + q_to_nul >copy.incomplete && + len=$(wc -c <copy.incomplete) && + test_must_fail test-svn-fe -d preimage copy.incomplete $len +' + test_done diff --git a/vcs-svn/svndiff.c b/vcs-svn/svndiff.c index 72fe716..ac776e0 100644 --- a/vcs-svn/svndiff.c +++ b/vcs-svn/svndiff.c @@ -14,20 +14,40 @@ * * svndiff0 ::= 'SVN\0' window window*; * window ::= int int int int int instructions inline_data; + * instructions ::= instruction*; + * instruction ::= view_selector int int + * | copyfrom_data int + * | packed_view_selector int + * | packed_copyfrom_data + * ; + * copyfrom_data ::= # binary 10 000000; + * packed_copyfrom_data ::= # copyfrom_data OR-ed with 6 bit value; * int ::= highdigit* lowdigit; * highdigit ::= # binary 1000 0000 OR-ed with 7 bit value; * lowdigit ::= # 7 bit value; */ +#define INSN_MASK 0xc0 +#define INSN_COPYFROM_DATA 0x80 +#define OPERAND_MASK 0x3f + #define VLI_CONTINUE 0x80 #define VLI_DIGIT_MASK 0x7f #define VLI_BITS_PER_DIGIT 7 struct window { + struct strbuf out; struct strbuf instructions; struct strbuf data; }; +static int write_strbuf(struct strbuf *sb, FILE *out) +{ + if (fwrite(sb->buf, 1, sb->len, out) == sb->len) /* Success. */ + return 0; + return error("Cannot write: %s\n", strerror(errno)); +} + static int read_magic(struct line_buffer *in, off_t *len) { static const char magic[] = {'S', 'V', 'N', '\0'}; @@ -118,9 +138,63 @@ static int read_chunk(struct line_buffer *delta, off_t *delta_len, return 0; } -static int apply_one_window(struct line_buffer *delta, off_t *delta_len) +static int copyfrom_data(struct window *ctx, size_t *data_pos, size_t nbytes) { - struct window ctx = {STRBUF_INIT, STRBUF_INIT}; + const size_t pos = *data_pos; + if (unsigned_add_overflows(pos, nbytes) || + pos + nbytes > ctx->data.len) + return error("Invalid delta: copies unavailable inline data."); + strbuf_add(&ctx->out, ctx->data.buf + pos, nbytes); + *data_pos += nbytes; + return 0; +} + +static int parse_first_operand(const char **buf, size_t *out, const char *end) +{ + size_t result = (unsigned char) *(*buf)++ & OPERAND_MASK; + if (result) { + *out = result; + return 0; + } + return parse_int(buf, out, end); +} + +static int step(struct window *ctx, const char **instructions, size_t *data_pos) +{ + unsigned int instruction; + const char *insns_end = ctx->instructions.buf + ctx->instructions.len; + size_t nbytes; + assert(ctx); + assert(instructions && *instructions); + assert(data_pos); + + instruction = (unsigned char) **instructions; + if (parse_first_operand(instructions, &nbytes, insns_end)) + return -1; + if ((instruction & INSN_MASK) != INSN_COPYFROM_DATA) + return error("Unknown instruction %x", instruction); + return copyfrom_data(ctx, data_pos, nbytes); +} + +static int apply_window_in_core(struct window *ctx) +{ + const char *insn = ctx->instructions.buf; + size_t data_pos = 0; + + /* + * Populate ctx->out.buf using data from the source, target, + * and inline data views. + */ + while (insn != ctx->instructions.buf + ctx->instructions.len) + if (step(ctx, &insn, &data_pos)) + return -1; + return 0; +} + +static int apply_one_window(struct line_buffer *delta, off_t *delta_len, + FILE *out) +{ + struct window ctx = {STRBUF_INIT, STRBUF_INIT, STRBUF_INIT}; size_t out_len; size_t instructions_len; size_t data_len; @@ -146,8 +220,10 @@ static int apply_one_window(struct line_buffer *delta, off_t *delta_len) rv = error("Cannot read delta: %s", strerror(errno)); goto done; } - if (instructions_len > 0) - return error("What do you think I am? A delta applier?"); + if (apply_window_in_core(&ctx) || write_strbuf(&ctx.out, out)) { + rv = -1; + goto done; + } done: strbuf_release(&ctx.data); strbuf_release(&ctx.instructions); @@ -168,7 +244,7 @@ int svndiff0_apply(struct line_buffer *delta, off_t delta_len, if (read_offset(delta, &pre_off, &delta_len) || read_length(delta, &pre_len, &delta_len) || move_window(&preimage_view, pre_off, pre_len) || - apply_one_window(delta, &delta_len)) + apply_one_window(delta, &delta_len, postimage)) goto fail; if (delta_len && buffer_at_eof(delta)) { error("Delta ends early! (%"PRIu64" bytes remaining)",
-- 1.7.2.3