From eaea7bbfc2ae6a31ab9444a8be293deb912a9c1d Mon Sep 17 00:00:00 2001
From: Pompolic <pompolic@special-circumstanc.es>
Date: Thu, 7 Oct 2021 20:16:29 +0200
Subject: [PATCH] (WIP) Connect the LZW module to pdf parser, fix up some bugs
---
lzw.c | 65 ++++++++++++++++++++++++++++++++++++++++-------------------
lzw.h | 6 +++---
pdf.c | 54 ++++++++++++++++++++++++++++++++++++-------------
3 files changed, 87 insertions(+), 38 deletions(-)
diff --git a/lzw.c b/lzw.c
index 60de6f1..7d15c93 100644
--- a/lzw.c
+++ b/lzw.c
@@ -33,7 +33,7 @@ typedef struct LZW_context_S
void LZW_clear_table(LZW_context_T *ctx)
{
/*
- * Optimizations: since we leave the entries 0-257 empty, we don't need to free() them explicitly.
+ * Optimizations: since we leave the entries 0-257 fixed or empty, we don't need to free() them explicitly.
* And since codes are added to the table sequentially, we don't need to look past ctx->next;
*/
for(int i = 258; i < ctx->next; ++i)
@@ -110,7 +110,7 @@ validate_LZW_9bitlitspec(HParseResult *p, void *u)
{
LZW_context_T * ctx = (LZW_context_T *) u;
uint64_t code = H_CAST_UINT(p->ast);
- return (ctx->next < 512 && code > 258);
+ return (ctx->next < 512 && code < 258);
}
bool
@@ -162,11 +162,13 @@ HParsedToken*
act_LZW_literal(const HParseResult *p, void *u)
{
uint64_t code = H_CAST_UINT(p->ast);
+ LZW_context_T * ctx = (LZW_context_T *) u;
/*
* Literals go from 0-255, so they are guaranteed to fit into 1 byte. See also: validate_LZW_literal
*/
uint8_t *output = malloc(sizeof(uint8_t));
*output = (uint8_t) code;
+ ctx->old = code;
return H_MAKE_BYTES(output, 1);
}
@@ -198,7 +200,7 @@ act_LZW_codeword(const HParseResult *p, void *u)
output_token = malloc(sizeof(uint8_t) * code_token_length); //XXX: maybe encapsulate working with the code table/HBytes
memcpy(output_token, code_str->token, code_token_length);
- prev_string = ctx->lzw_code_table[ctx->old];
+ prev_string = ctx->lzw_code_table[ctx->old]; //XXX: segfault when reading first codeword, set old if literal, init table with literals, special-case first code
prev_string_length = prev_string->len;
/*
@@ -286,7 +288,7 @@ act_LZW_data(const HParseResult *p, void *u)
total_buffer_size += H_FIELD_BYTES(i).len;
}
- buffer = malloc(sizeof(uint8_t) * total_buffer_size); // XXX arena alloc
+ buffer = malloc(sizeof(uint8_t) * total_buffer_size); // XXX arena alloc, calloc
/* go through parse result, merge bytes */
for(int i = 0; i < num_fragments; i++)
@@ -300,42 +302,63 @@ act_LZW_data(const HParseResult *p, void *u)
}
-void init_lzw_parser()
+void init_LZW_parser()
{
- H_VRULE(LZW_9bitcodeword, h_bits(9, false));
- H_VRULE(LZW_10bitcodeword, h_bits(10, false));
- H_VRULE(LZW_11bitcodeword, h_bits(11, false));
- H_VRULE(LZW_12bitcodeword, h_bits(12, false));
+ context = malloc(sizeof(LZW_context_T));
+ context->next = 258;
+ /* set up literals in LZW code table */
+ for(int i = 0; i < 256; ++i)
+ {
+ uint8_t *token = malloc(sizeof(uint8_t));
+ *token = i;
+ HBytes *lit = malloc(sizeof(HBytes)); // XXX: instead of HBytes*, use HBytes
+ lit->token = token;
+ lit->len = 1;
+ context->lzw_code_table[i] = lit;
+ }
- H_VRULE(LZW_9bitlitspec, h_bits(9, false));
- H_VRULE(LZW_10bitlitspec, h_bits(10, false));
- H_VRULE(LZW_11bitlitspec, h_bits(11, false));
- H_VRULE(LZW_12bitlitspec, h_bits(12, false));
+ H_VDRULE(LZW_9bitcodeword, h_bits(9, false), context);
+ H_VDRULE(LZW_10bitcodeword, h_bits(10, false), context);
+ H_VDRULE(LZW_11bitcodeword, h_bits(11, false), context);
+ H_VDRULE(LZW_12bitcodeword, h_bits(12, false), context);
+
+ H_VDRULE(LZW_9bitlitspec, h_bits(9, false), context);
+ H_VDRULE(LZW_10bitlitspec, h_bits(10, false), context);
+ H_VDRULE(LZW_11bitlitspec, h_bits(11, false), context);
+ H_VDRULE(LZW_12bitlitspec, h_bits(12, false), context);
H_RULE(LZW_remainingbits, h_many(h_bits(1, false))); //XXX: could validate that these bits are 0?
// XXX: p__take_n function to dynamically generate the rule needed to consume remaining bits?
// XXX: user data pointers (VDRULE, VADRULE, etc.)
- H_VARULE(LZW_clear, h_choice(LZW_9bitlitspec, LZW_10bitlitspec, LZW_11bitlitspec, LZW_12bitlitspec, NULL)); //XXX: VARULE or AVRULE?
- H_VRULE(LZW_eod, h_choice(LZW_9bitlitspec, LZW_10bitlitspec, LZW_11bitlitspec, LZW_12bitlitspec, NULL));
- H_VRULE(LZW_literal, h_choice(LZW_9bitlitspec, LZW_10bitlitspec, LZW_11bitlitspec, LZW_12bitlitspec, NULL));
- H_ARULE(LZW_codeword, h_choice(LZW_9bitcodeword, LZW_10bitcodeword, LZW_11bitcodeword, LZW_12bitcodeword, NULL));
+ H_AVDRULE(LZW_clear, h_choice(LZW_9bitlitspec, LZW_10bitlitspec, LZW_11bitlitspec, LZW_12bitlitspec, NULL), context);
+ H_VDRULE(LZW_eod, h_choice(LZW_9bitlitspec, LZW_10bitlitspec, LZW_11bitlitspec, LZW_12bitlitspec, NULL), context);
+ H_VDRULE(LZW_literal, h_choice(LZW_9bitlitspec, LZW_10bitlitspec, LZW_11bitlitspec, LZW_12bitlitspec, NULL), context);
+ H_ADRULE(LZW_codeword, h_choice(LZW_9bitcodeword, LZW_10bitcodeword, LZW_11bitcodeword, LZW_12bitcodeword, NULL), context);
- H_RULE(LZW_data, h_sequence(LZW_clear, h_many1(h_butnot(h_choice(LZW_literal, LZW_clear, LZW_codeword, NULL), LZW_eod)), LZW_eod, LZW_remainingbits, NULL));
+ H_ADRULE(LZW_data, h_sequence(LZW_clear, h_many1(h_butnot(h_choice(LZW_literal, LZW_clear, LZW_codeword, NULL), LZW_eod)), LZW_eod, LZW_remainingbits, NULL), context);
p_lzwdata = LZW_data;
}
-HParseResult* parse_lzw_data(const uint8_t* input, size_t length)
+HParseResult* parse_LZW_data(const uint8_t* input, size_t length)
{
return h_parse(p_lzwdata, input, length);
}
void set_LZW_context(LZW_context_T *ctx)
{
- context = ctx;
+ *context = *ctx; // XXX unnecessary, just clear context before each parse
}
void clear_LZW_context()
{
- context = NULL;
+ for(int i = 258; i < 4096; ++i)
+ {
+ if(context->lzw_code_table[i] != NULL)
+ {
+ free(context->lzw_code_table[i]);
+ }
+ }
+ context->next = 258;
+ context->old = 257; //XXX: guaranteed to segfault if old isn't set before
}
diff --git a/lzw.h b/lzw.h
index 1a3b46b..192bc7a 100644
--- a/lzw.h
+++ b/lzw.h
@@ -23,10 +23,10 @@ typedef struct LZW_context_S
uint64_t old;
} LZW_context_T;
-HParser * p_lzwdata;
+HParser * p_lzwdata; // XXX can be internal
-void init_lzw_parser();
-HParseResult * parse_lzw_data(const uint8_t* input, size_t length);
+void init_LZW_parser();
+HParseResult * parse_LZW_data(const uint8_t* input, size_t length);
void set_LZW_context(LZW_context_T *ctx);
void clear_LZW_context();
diff --git a/pdf.c b/pdf.c
index 26a4aac..8e38bbb 100644
--- a/pdf.c
+++ b/pdf.c
@@ -3325,6 +3325,7 @@ int read_lzw_buffer(void)
return ret_value;
}
+#include "lzw.h"
HParseResult *
LZWDecode(const Dict *parms, HBytes b, HParser *p)
@@ -3332,8 +3333,9 @@ LZWDecode(const Dict *parms, HBytes b, HParser *p)
struct predictor pred = {1, 1, 8, 1};
int (*depredict)(struct predictor *, uint8_t *, size_t);
HParseResult *res;
+ HParseResult *tmp_res;
int done;
- int ret;
+ //int ret;
const HParsedToken *v;
/* set up the predictor (if any) */
@@ -3383,23 +3385,46 @@ LZWDecode(const Dict *parms, HBytes b, HParser *p)
err(1, "LZWDecode");
}
- lzwspec *lzw_spec = new_lzw_spec(&b);
- bind_lzw_spec(lzw_spec);
-
- ret = lzw_decompress(write_lzw_buffer, read_lzw_buffer);
- if (ret) {
- fprintf(stderr, "lzw_decompress: error (%d)\n", ret);
- assert(!"LZWDecode: failed to decompress\n");
+ //lzwspec *lzw_spec = new_lzw_spec(&b);
+ //bind_lzw_spec(lzw_spec);
+
+ //ret = lzw_decompress(write_lzw_buffer, read_lzw_buffer);
+ //if (ret) {
+ // fprintf(stderr, "lzw_decompress: error (%d)\n", ret);
+ // assert(!"LZWDecode: failed to decompress\n");
+ //}
+ //done = depredict(&pred, cur_lzw_spec->lzw_buf, cur_lzw_spec->write_head-1);
+ //assert(!done); // XXX ITERATIVE
+ LZW_context_T * ctx = malloc(sizeof(LZW_context_T));
+ ctx->next = 258;
+ clear_LZW_context();
+ tmp_res = parse_LZW_data(b.token, b.len);
+ //clear_LZW_context();
+ free(ctx);
+
+ if(!tmp_res)
+ {
+ fprintf(stderr, "parse error in LZWDecode filter");
+ return NULL;
}
- done = depredict(&pred, cur_lzw_spec->lzw_buf, cur_lzw_spec->write_head-1);
- assert(!done); // XXX ITERATIVE
+
+ assert(tmp_res->ast->token_type == TT_BYTES);
+
+ uint8_t * tmp_buf = malloc(sizeof(uint8_t) * tmp_res->ast->bytes.len);
+ memcpy(tmp_buf, tmp_res->ast->bytes.token, tmp_res->ast->bytes.len);
+ done = depredict(&pred, tmp_buf, tmp_res->ast->bytes.len);
+ assert(!done);
+
+ //done = depredict(&pred, res->ast->bytes.token, res->ast->bytes.len);
+ //assert(!done);
// SR::TODO:: Do a H_MAKE rather than a parse and let the caller do the parse
- res = h_parse(p, pred.out, pred.nout);
- free(pred.out);
+ //res = h_parse(p, pred.out, pred.nout);
+ res = h_parse(p, tmp_res->ast->bytes.token, tmp_res->ast->bytes.len); // XXX depred buffer
+ //free(pred.out);
- bind_lzw_spec(NULL);
- delete_lzw_spec(lzw_spec);
+ //bind_lzw_spec(NULL);
+ //delete_lzw_spec(lzw_spec);
return res;
}
@@ -5594,6 +5619,7 @@ main(int argc, char *argv[])
/* build parsers */
aux = (struct Env){infile, input, sz};
init_parser(&aux);
+ init_LZW_parser();
/* parse all cross-reference sections and trailer dictionaries */
--
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