[PATCH 09/16] vcs-svn: read inline data from deltas
From: David Barr <hidden>
Date: 2016-06-15 22:50:48
Subsystem:
the rest · Maintainer:
Linus Torvalds
From: Jonathan Nieder <redacted> Each window of an svndiff0-format delta includes a section for new data that will be copied into the preimage (in the order it appears in the window, possibly interspersed with other data). Read this data when encountering it. It is not actually necessary to do so --- it would be just as easy to copy straight from the delta to output when interpreting the relevant instructions --- but this way, the code that interprets svndiff0 instructions can proceed more quickly because it does not require any I/O. Subversion's implementation rejects deltas that do not consume all the auxiliary data that is available. Do not check that for now, because it would make it impossible to test the function of this patch until the instructions to consume data are implemented. Do check for truncated data sections. Since Subversion's applier rejects deltas that end before the new-data section is declared to end, it should be safe for this applier to reject such deltas, too. Improved-by: Ramkumar Ramachandra [off-list ref] Improved-by: David Barr [off-list ref] Signed-off-by: Jonathan Nieder <redacted> Acked-by: Ramkumar Ramachandra <redacted> Signed-off-by: David Barr <redacted> --- t/t9011-svn-da.sh | 12 ++++++++++++ vcs-svn/svndiff.c | 46 +++++++++++++++++++++++++++++++++++----------- 2 files changed, 47 insertions(+), 11 deletions(-)
diff --git a/t/t9011-svn-da.sh b/t/t9011-svn-da.sh
index 986dce6..4919fae 100755
--- a/t/t9011-svn-da.sh
+++ b/t/t9011-svn-da.sh@@ -123,4 +123,16 @@ test_expect_success 'preimage view: reject truncated preimage' ' test_must_fail test-svn-fe -d preimage clear.longread 9 ' +test_expect_success 'inline data' ' + printf "SVNQ%b%s%b%s" "QQQQ\003" "bar" "QQQQ\001" "x" | + q_to_nul >inline.clear && + test-svn-fe -d preimage inline.clear 18 >actual && + test_cmp empty actual +' + +test_expect_success 'reject truncated inline data' ' + printf "SVNQ%b%s" "QQQQ\003" "b" | q_to_nul >inline.trunc && + test_must_fail test-svn-fe -d preimage inline.trunc 10 +' + test_done
diff --git a/vcs-svn/svndiff.c b/vcs-svn/svndiff.c
index 1020275..74e0401 100644
--- a/vcs-svn/svndiff.c
+++ b/vcs-svn/svndiff.c@@ -24,6 +24,17 @@ #define VLI_DIGIT_MASK 0x7f #define VLI_BITS_PER_DIGIT 7 +struct window { + struct strbuf data; +}; + +#define WINDOW_INIT { STRBUF_INIT } + +static void window_release(struct window *ctx) +{ + strbuf_release(&ctx->data); +} + static int error_short_read(struct line_buffer *input) { if (buffer_ferror(input))
@@ -31,24 +42,30 @@ static int error_short_read(struct line_buffer *input) return error("invalid delta: unexpected end of file"); } +static int read_chunk(struct line_buffer *delta, off_t *delta_len, + struct strbuf *buf, size_t len) +{ + strbuf_reset(buf); + if (len > *delta_len || + buffer_read_binary(delta, buf, len) != len) + return error_short_read(delta); + *delta_len -= buf->len; + return 0; +} + static int read_magic(struct line_buffer *in, off_t *len) { static const char magic[] = {'S', 'V', 'N', '\0'}; struct strbuf sb = STRBUF_INIT; - if (*len < sizeof(magic) || - buffer_read_binary(in, &sb, sizeof(magic)) != sizeof(magic)) { - error_short_read(in); + if (read_chunk(in, len, &sb, sizeof(magic))) { strbuf_release(&sb); return -1; } - if (memcmp(sb.buf, magic, sizeof(magic))) { strbuf_release(&sb); return error("invalid delta: unrecognized file type"); } - - *len -= sizeof(magic); strbuf_release(&sb); return 0; }
@@ -98,6 +115,7 @@ static int read_length(struct line_buffer *in, size_t *result, off_t *len) static int apply_one_window(struct line_buffer *delta, off_t *delta_len) { + struct window ctx = WINDOW_INIT; size_t out_len; size_t instructions_len; size_t data_len;
@@ -107,12 +125,18 @@ static int apply_one_window(struct line_buffer *delta, off_t *delta_len) if (read_length(delta, &out_len, delta_len) || read_length(delta, &instructions_len, delta_len) || read_length(delta, &data_len, delta_len)) - return -1; - if (instructions_len) - return error("What do you think I am? A delta applier?"); - if (data_len) - return error("No support for inline data yet"); + goto error_out; + if (instructions_len) { + error("What do you think I am? A delta applier?"); + goto error_out; + } + if (read_chunk(delta, delta_len, &ctx.data, data_len)) + goto error_out; + window_release(&ctx); return 0; +error_out: + window_release(&ctx); + return -1; } int svndiff0_apply(struct line_buffer *delta, off_t delta_len,
--
1.7.3.2.846.gf4b062