2 * Licensed under a two-clause BSD-style license.
3 * See LICENSE for details.
6 #include "git-compat-util.h"
7 #include "sliding_window.h"
8 #include "line_buffer.h"
14 * See http://svn.apache.org/repos/asf/subversion/trunk/notes/svndiff.
16 * svndiff0 ::= 'SVN\0' window*
17 * window ::= int int int int int instructions inline_data;
18 * int ::= highdigit* lowdigit;
19 * highdigit ::= # binary 1000 0000 OR-ed with 7 bit value;
20 * lowdigit ::= # 7 bit value;
23 #define VLI_CONTINUE 0x80
24 #define VLI_DIGIT_MASK 0x7f
25 #define VLI_BITS_PER_DIGIT 7
28 struct strbuf instructions
;
32 #define WINDOW_INIT { STRBUF_INIT, STRBUF_INIT }
34 static void window_release(struct window
*ctx
)
36 strbuf_release(&ctx
->instructions
);
37 strbuf_release(&ctx
->data
);
40 static int error_short_read(struct line_buffer
*input
)
42 if (buffer_ferror(input
))
43 return error("error reading delta: %s", strerror(errno
));
44 return error("invalid delta: unexpected end of file");
47 static int read_chunk(struct line_buffer
*delta
, off_t
*delta_len
,
48 struct strbuf
*buf
, size_t len
)
51 if (len
> *delta_len
||
52 buffer_read_binary(delta
, buf
, len
) != len
)
53 return error_short_read(delta
);
54 *delta_len
-= buf
->len
;
58 static int read_magic(struct line_buffer
*in
, off_t
*len
)
60 static const char magic
[] = {'S', 'V', 'N', '\0'};
61 struct strbuf sb
= STRBUF_INIT
;
63 if (read_chunk(in
, len
, &sb
, sizeof(magic
))) {
67 if (memcmp(sb
.buf
, magic
, sizeof(magic
))) {
69 return error("invalid delta: unrecognized file type");
75 static int read_int(struct line_buffer
*in
, uintmax_t *result
, off_t
*len
)
79 for (sz
= *len
; sz
; sz
--) {
80 const int ch
= buffer_read_char(in
);
84 rv
<<= VLI_BITS_PER_DIGIT
;
85 rv
+= (ch
& VLI_DIGIT_MASK
);
86 if (ch
& VLI_CONTINUE
)
93 return error_short_read(in
);
96 static int read_offset(struct line_buffer
*in
, off_t
*result
, off_t
*len
)
99 if (read_int(in
, &val
, len
))
101 if (val
> maximum_signed_value_of_type(off_t
))
102 return error("unrepresentable offset in delta: %"PRIuMAX
"", val
);
107 static int read_length(struct line_buffer
*in
, size_t *result
, off_t
*len
)
110 if (read_int(in
, &val
, len
))
113 return error("unrepresentable length in delta: %"PRIuMAX
"", val
);
118 static int apply_one_window(struct line_buffer
*delta
, off_t
*delta_len
)
120 struct window ctx
= WINDOW_INIT
;
122 size_t instructions_len
;
126 /* "source view" offset and length already handled; */
127 if (read_length(delta
, &out_len
, delta_len
) ||
128 read_length(delta
, &instructions_len
, delta_len
) ||
129 read_length(delta
, &data_len
, delta_len
) ||
130 read_chunk(delta
, delta_len
, &ctx
.instructions
, instructions_len
))
132 if (instructions_len
) {
133 error("What do you think I am? A delta applier?");
136 if (read_chunk(delta
, delta_len
, &ctx
.data
, data_len
))
138 window_release(&ctx
);
141 window_release(&ctx
);
145 int svndiff0_apply(struct line_buffer
*delta
, off_t delta_len
,
146 struct sliding_view
*preimage
, FILE *postimage
)
148 assert(delta
&& preimage
&& postimage
);
150 if (read_magic(delta
, &delta_len
))
152 while (delta_len
) { /* For each window: */
156 if (read_offset(delta
, &pre_off
, &delta_len
) ||
157 read_length(delta
, &pre_len
, &delta_len
) ||
158 move_window(preimage
, pre_off
, pre_len
) ||
159 apply_one_window(delta
, &delta_len
))