* | packed_view_selector int
* | packed_copyfrom_data
* ;
+ * view_selector ::= copyfrom_source
+ * | copyfrom_target
+ * ;
+ * copyfrom_source ::= # binary 00 000000;
+ * copyfrom_target ::= # binary 01 000000;
* copyfrom_data ::= # binary 10 000000;
+ * packed_view_selector ::= # view_selector OR-ed with 6 bit value;
* packed_copyfrom_data ::= # copyfrom_data OR-ed with 6 bit value;
* int ::= highdigit* lowdigit;
* highdigit ::= # binary 1000 0000 OR-ed with 7 bit value;
*/
#define INSN_MASK 0xc0
+#define INSN_COPYFROM_SOURCE 0x00
+#define INSN_COPYFROM_TARGET 0x40
#define INSN_COPYFROM_DATA 0x80
#define OPERAND_MASK 0x3f
#define VLI_BITS_PER_DIGIT 7
struct window {
+ struct sliding_view *in;
struct strbuf out;
struct strbuf instructions;
struct strbuf data;
};
-#define WINDOW_INIT { STRBUF_INIT, STRBUF_INIT, STRBUF_INIT }
+#define WINDOW_INIT(w) { (w), STRBUF_INIT, STRBUF_INIT, STRBUF_INIT }
static void window_release(struct window *ctx)
{
return 0;
}
+static int copyfrom_source(struct window *ctx, const char **instructions,
+ size_t nbytes, const char *insns_end)
+{
+ size_t offset;
+ if (parse_int(instructions, &offset, insns_end))
+ return -1;
+ if (unsigned_add_overflows(offset, nbytes) ||
+ offset + nbytes > ctx->in->width)
+ return error("invalid delta: copies source data outside view");
+ strbuf_add(&ctx->out, ctx->in->buf.buf + offset, nbytes);
+ return 0;
+}
+
+static int copyfrom_target(struct window *ctx, const char **instructions,
+ size_t nbytes, const char *instructions_end)
+{
+ size_t offset;
+ if (parse_int(instructions, &offset, instructions_end))
+ return -1;
+ if (offset >= ctx->out.len)
+ return error("invalid delta: copies from the future");
+ for (; nbytes > 0; nbytes--)
+ strbuf_addch(&ctx->out, ctx->out.buf[offset++]);
+ return 0;
+}
+
static int copyfrom_data(struct window *ctx, size_t *data_pos, size_t nbytes)
{
const size_t pos = *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);
+ switch (instruction & INSN_MASK) {
+ case INSN_COPYFROM_SOURCE:
+ return copyfrom_source(ctx, instructions, nbytes, insns_end);
+ case INSN_COPYFROM_TARGET:
+ return copyfrom_target(ctx, instructions, nbytes, insns_end);
+ case INSN_COPYFROM_DATA:
+ return copyfrom_data(ctx, data_pos, nbytes);
+ default:
+ return error("invalid delta: unrecognized instruction");
+ }
}
static int apply_window_in_core(struct window *ctx)
}
static int apply_one_window(struct line_buffer *delta, off_t *delta_len,
- FILE *out)
+ struct sliding_view *preimage, FILE *out)
{
- struct window ctx = WINDOW_INIT;
+ struct window ctx = WINDOW_INIT(preimage);
size_t out_len;
size_t instructions_len;
size_t data_len;
if (read_magic(delta, &delta_len))
return -1;
while (delta_len) { /* For each window: */
- off_t pre_off;
+ off_t pre_off = pre_off; /* stupid GCC... */
size_t pre_len;
if (read_offset(delta, &pre_off, &delta_len) ||
read_length(delta, &pre_len, &delta_len) ||
move_window(preimage, pre_off, pre_len) ||
- apply_one_window(delta, &delta_len, postimage))
+ apply_one_window(delta, &delta_len, preimage, postimage))
return -1;
}
return 0;