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-rw-r--r--vcs-svn/svndiff.c308
1 files changed, 308 insertions, 0 deletions
diff --git a/vcs-svn/svndiff.c b/vcs-svn/svndiff.c
new file mode 100644
index 0000000..9ee41bb
--- /dev/null
+++ b/vcs-svn/svndiff.c
@@ -0,0 +1,308 @@
+/*
+ * Licensed under a two-clause BSD-style license.
+ * See LICENSE for details.
+ */
+
+#include "git-compat-util.h"
+#include "sliding_window.h"
+#include "line_buffer.h"
+#include "svndiff.h"
+
+/*
+ * svndiff0 applier
+ *
+ * See http://svn.apache.org/repos/asf/subversion/trunk/notes/svndiff.
+ *
+ * svndiff0 ::= 'SVN\0' 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
+ * ;
+ * 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;
+ * lowdigit ::= # 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_CONTINUE 0x80
+#define VLI_DIGIT_MASK 0x7f
+#define VLI_BITS_PER_DIGIT 7
+
+struct window {
+ struct sliding_view *in;
+ struct strbuf out;
+ struct strbuf instructions;
+ struct strbuf data;
+};
+
+#define WINDOW_INIT(w) { (w), STRBUF_INIT, STRBUF_INIT, STRBUF_INIT }
+
+static void window_release(struct window *ctx)
+{
+ strbuf_release(&ctx->out);
+ strbuf_release(&ctx->instructions);
+ strbuf_release(&ctx->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 delta postimage: %s", strerror(errno));
+}
+
+static int error_short_read(struct line_buffer *input)
+{
+ if (buffer_ferror(input))
+ return error("error reading delta: %s", strerror(errno));
+ 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 (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");
+ }
+ strbuf_release(&sb);
+ return 0;
+}
+
+static int read_int(struct line_buffer *in, uintmax_t *result, off_t *len)
+{
+ uintmax_t rv = 0;
+ off_t sz;
+ for (sz = *len; sz; sz--) {
+ const int ch = buffer_read_char(in);
+ if (ch == EOF)
+ break;
+
+ rv <<= VLI_BITS_PER_DIGIT;
+ rv += (ch & VLI_DIGIT_MASK);
+ if (ch & VLI_CONTINUE)
+ continue;
+
+ *result = rv;
+ *len = sz - 1;
+ return 0;
+ }
+ return error_short_read(in);
+}
+
+static int parse_int(const char **buf, size_t *result, const char *end)
+{
+ size_t rv = 0;
+ const char *pos;
+ for (pos = *buf; pos != end; pos++) {
+ unsigned char ch = *pos;
+
+ rv <<= VLI_BITS_PER_DIGIT;
+ rv += (ch & VLI_DIGIT_MASK);
+ if (ch & VLI_CONTINUE)
+ continue;
+
+ *result = rv;
+ *buf = pos + 1;
+ return 0;
+ }
+ return error("invalid delta: unexpected end of instructions section");
+}
+
+static int read_offset(struct line_buffer *in, off_t *result, off_t *len)
+{
+ uintmax_t val;
+ if (read_int(in, &val, len))
+ return -1;
+ if (val > maximum_signed_value_of_type(off_t))
+ return error("unrepresentable offset in delta: %"PRIuMAX"", val);
+ *result = val;
+ return 0;
+}
+
+static int read_length(struct line_buffer *in, size_t *result, off_t *len)
+{
+ uintmax_t val;
+ if (read_int(in, &val, len))
+ return -1;
+ if (val > SIZE_MAX)
+ return error("unrepresentable length in delta: %"PRIuMAX"", val);
+ *result = val;
+ 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;
+ 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) { /* immediate operand */
+ *out = result;
+ return 0;
+ }
+ return parse_int(buf, out, end);
+}
+
+static int execute_one_instruction(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;
+ 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)
+{
+ const char *instructions;
+ size_t data_pos = 0;
+
+ /*
+ * Fill ctx->out.buf using data from the source, target,
+ * and inline data views.
+ */
+ for (instructions = ctx->instructions.buf;
+ instructions != ctx->instructions.buf + ctx->instructions.len;
+ )
+ if (execute_one_instruction(ctx, &instructions, &data_pos))
+ return -1;
+ if (data_pos != ctx->data.len)
+ return error("invalid delta: does not copy all inline data");
+ return 0;
+}
+
+static int apply_one_window(struct line_buffer *delta, off_t *delta_len,
+ struct sliding_view *preimage, FILE *out)
+{
+ struct window ctx = WINDOW_INIT(preimage);
+ size_t out_len;
+ size_t instructions_len;
+ size_t data_len;
+ assert(delta_len);
+
+ /* "source view" offset and length already handled; */
+ if (read_length(delta, &out_len, delta_len) ||
+ read_length(delta, &instructions_len, delta_len) ||
+ read_length(delta, &data_len, delta_len) ||
+ read_chunk(delta, delta_len, &ctx.instructions, instructions_len) ||
+ read_chunk(delta, delta_len, &ctx.data, data_len))
+ goto error_out;
+ strbuf_grow(&ctx.out, out_len);
+ if (apply_window_in_core(&ctx))
+ goto error_out;
+ if (ctx.out.len != out_len) {
+ error("invalid delta: incorrect postimage length");
+ goto error_out;
+ }
+ if (write_strbuf(&ctx.out, out))
+ 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,
+ struct sliding_view *preimage, FILE *postimage)
+{
+ assert(delta && preimage && postimage);
+
+ if (read_magic(delta, &delta_len))
+ return -1;
+ while (delta_len) { /* For each window: */
+ off_t pre_off;
+ 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, preimage, postimage))
+ return -1;
+ }
+ return 0;
+}