386 lines
8.8 KiB
C
386 lines
8.8 KiB
C
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#include "fitz.h"
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#include "mupdf.h"
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/*
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* Check if an object is a stream or not.
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*/
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int
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pdf_is_stream(pdf_xref *xref, int num, int gen)
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{
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fz_error error;
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if (num < 0 || num >= xref->len)
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return 0;
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error = pdf_cache_object(xref, num, gen);
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if (error)
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{
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fz_catch(error, "cannot load object, ignoring error");
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return 0;
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}
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return xref->table[num].stm_ofs > 0;
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}
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/*
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* Scan stream dictionary for an explicit /Crypt filter
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*/
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static int
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pdf_stream_has_crypt(fz_obj *stm)
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{
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fz_obj *filters;
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fz_obj *obj;
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int i;
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filters = fz_dict_getsa(stm, "Filter", "F");
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if (filters)
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{
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if (!strcmp(fz_to_name(filters), "Crypt"))
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return 1;
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if (fz_is_array(filters))
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{
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for (i = 0; i < fz_array_len(filters); i++)
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{
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obj = fz_array_get(filters, i);
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if (!strcmp(fz_to_name(obj), "Crypt"))
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return 1;
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}
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}
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}
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return 0;
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}
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/*
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* Create a filter given a name and param dictionary.
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*/
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static fz_stream *
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build_filter(fz_stream *chain, pdf_xref * xref, fz_obj * f, fz_obj * p, int num, int gen)
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{
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fz_error error;
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char *s;
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s = fz_to_name(f);
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if (!strcmp(s, "ASCIIHexDecode") || !strcmp(s, "AHx"))
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return fz_open_ahxd(chain);
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else if (!strcmp(s, "ASCII85Decode") || !strcmp(s, "A85"))
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return fz_open_a85d(chain);
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else if (!strcmp(s, "CCITTFaxDecode") || !strcmp(s, "CCF"))
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return fz_open_faxd(chain, p);
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else if (!strcmp(s, "DCTDecode") || !strcmp(s, "DCT"))
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return fz_open_dctd(chain, p);
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else if (!strcmp(s, "RunLengthDecode") || !strcmp(s, "RL"))
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return fz_open_rld(chain);
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else if (!strcmp(s, "FlateDecode") || !strcmp(s, "Fl"))
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{
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fz_obj *obj = fz_dict_gets(p, "Predictor");
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if (fz_to_int(obj) > 1)
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return fz_open_predict(fz_open_flated(chain), p);
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return fz_open_flated(chain);
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}
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else if (!strcmp(s, "LZWDecode") || !strcmp(s, "LZW"))
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{
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fz_obj *obj = fz_dict_gets(p, "Predictor");
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if (fz_to_int(obj) > 1)
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return fz_open_predict(fz_open_lzwd(chain, p), p);
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return fz_open_lzwd(chain, p);
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}
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else if (!strcmp(s, "JBIG2Decode"))
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{
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fz_obj *obj = fz_dict_gets(p, "JBIG2Globals");
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if (obj)
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{
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fz_buffer *globals;
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error = pdf_load_stream(&globals, xref, fz_to_num(obj), fz_to_gen(obj));
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if (error)
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fz_catch(error, "cannot load jbig2 global segments");
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chain = fz_open_jbig2d(chain, globals);
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fz_drop_buffer(globals);
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return chain;
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}
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return fz_open_jbig2d(chain, NULL);
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}
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else if (!strcmp(s, "JPXDecode"))
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return chain; /* JPX decoding is special cased in the image loading code */
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else if (!strcmp(s, "Crypt"))
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{
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fz_obj *name;
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if (!xref->crypt)
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{
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fz_warn("crypt filter in unencrypted document");
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return chain;
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}
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name = fz_dict_gets(p, "Name");
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if (fz_is_name(name))
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return pdf_open_crypt_with_filter(chain, xref->crypt, fz_to_name(name), num, gen);
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return chain;
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}
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fz_warn("unknown filter name (%s)", s);
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return chain;
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}
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/*
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* Build a chain of filters given filter names and param dicts.
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* If head is given, start filter chain with it.
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* Assume ownership of head.
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*/
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static fz_stream *
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build_filter_chain(fz_stream *chain, pdf_xref *xref, fz_obj *fs, fz_obj *ps, int num, int gen)
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{
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fz_obj *f;
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fz_obj *p;
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int i;
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for (i = 0; i < fz_array_len(fs); i++)
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{
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f = fz_array_get(fs, i);
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p = fz_array_get(ps, i);
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chain = build_filter(chain, xref, f, p, num, gen);
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}
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return chain;
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}
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/*
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* Build a filter for reading raw stream data.
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* This is a null filter to constrain reading to the
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* stream length, followed by a decryption filter.
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*/
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static fz_stream *
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pdf_open_raw_filter(fz_stream *chain, pdf_xref *xref, fz_obj *stmobj, int num, int gen)
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{
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int hascrypt;
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int len;
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/* don't close chain when we close this filter */
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fz_keep_stream(chain);
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len = fz_to_int(fz_dict_gets(stmobj, "Length"));
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chain = fz_open_null(chain, len);
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hascrypt = pdf_stream_has_crypt(stmobj);
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if (xref->crypt && !hascrypt)
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chain = pdf_open_crypt(chain, xref->crypt, num, gen);
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return chain;
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}
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/*
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* Construct a filter to decode a stream, constraining
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* to stream length and decrypting.
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*/
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static fz_stream *
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pdf_open_filter(fz_stream *chain, pdf_xref *xref, fz_obj *stmobj, int num, int gen)
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{
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fz_obj *filters;
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fz_obj *params;
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filters = fz_dict_getsa(stmobj, "Filter", "F");
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params = fz_dict_getsa(stmobj, "DecodeParms", "DP");
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chain = pdf_open_raw_filter(chain, xref, stmobj, num, gen);
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if (fz_is_name(filters))
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return build_filter(chain, xref, filters, params, num, gen);
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if (fz_array_len(filters) > 0)
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return build_filter_chain(chain, xref, filters, params, num, gen);
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return chain;
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}
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/*
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* Construct a filter to decode a stream, without
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* constraining to stream length, and without decryption.
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*/
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fz_stream *
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pdf_open_inline_stream(fz_stream *chain, pdf_xref *xref, fz_obj *stmobj, int length)
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{
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fz_obj *filters;
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fz_obj *params;
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filters = fz_dict_getsa(stmobj, "Filter", "F");
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params = fz_dict_getsa(stmobj, "DecodeParms", "DP");
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/* don't close chain when we close this filter */
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fz_keep_stream(chain);
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if (fz_is_name(filters))
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return build_filter(chain, xref, filters, params, 0, 0);
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if (fz_array_len(filters) > 0)
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return build_filter_chain(chain, xref, filters, params, 0, 0);
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return fz_open_null(chain, length);
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}
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/*
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* Open a stream for reading the raw (compressed but decrypted) data.
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* Using xref->file while this is open is a bad idea.
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*/
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fz_error
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pdf_open_raw_stream(fz_stream **stmp, pdf_xref *xref, int num, int gen)
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{
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pdf_xref_entry *x;
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fz_error error;
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if (num < 0 || num >= xref->len)
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return fz_throw("object id out of range (%d %d R)", num, gen);
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x = xref->table + num;
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error = pdf_cache_object(xref, num, gen);
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if (error)
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return fz_rethrow(error, "cannot load stream object (%d %d R)", num, gen);
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if (x->stm_ofs)
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{
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*stmp = pdf_open_raw_filter(xref->file, xref, x->obj, num, gen);
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fz_seek(xref->file, x->stm_ofs, 0);
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return fz_okay;
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}
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return fz_throw("object is not a stream");
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}
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/*
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* Open a stream for reading uncompressed data.
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* Put the opened file in xref->stream.
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* Using xref->file while a stream is open is a Bad idea.
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*/
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fz_error
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pdf_open_stream(fz_stream **stmp, pdf_xref *xref, int num, int gen)
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{
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pdf_xref_entry *x;
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fz_error error;
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if (num < 0 || num >= xref->len)
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return fz_throw("object id out of range (%d %d R)", num, gen);
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x = xref->table + num;
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error = pdf_cache_object(xref, num, gen);
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if (error)
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return fz_rethrow(error, "cannot load stream object (%d %d R)", num, gen);
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if (x->stm_ofs)
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{
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*stmp = pdf_open_filter(xref->file, xref, x->obj, num, gen);
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fz_seek(xref->file, x->stm_ofs, 0);
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return fz_okay;
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}
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return fz_throw("object is not a stream");
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}
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fz_error
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pdf_open_stream_at(fz_stream **stmp, pdf_xref *xref, int num, int gen, fz_obj *dict, int stm_ofs)
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{
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if (stm_ofs)
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{
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*stmp = pdf_open_filter(xref->file, xref, dict, num, gen);
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fz_seek(xref->file, stm_ofs, 0);
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return fz_okay;
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}
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return fz_throw("object is not a stream");
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}
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/*
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* Load raw (compressed but decrypted) contents of a stream into buf.
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*/
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fz_error
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pdf_load_raw_stream(fz_buffer **bufp, pdf_xref *xref, int num, int gen)
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{
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fz_error error;
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fz_stream *stm;
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fz_obj *dict;
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int len;
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error = pdf_load_object(&dict, xref, num, gen);
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if (error)
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return fz_rethrow(error, "cannot load stream dictionary (%d %d R)", num, gen);
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len = fz_to_int(fz_dict_gets(dict, "Length"));
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fz_drop_obj(dict);
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error = pdf_open_raw_stream(&stm, xref, num, gen);
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if (error)
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return fz_rethrow(error, "cannot open raw stream (%d %d R)", num, gen);
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error = fz_read_all(bufp, stm, len);
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if (error)
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{
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fz_close(stm);
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return fz_rethrow(error, "cannot read raw stream (%d %d R)", num, gen);
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}
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fz_close(stm);
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return fz_okay;
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}
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static int
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pdf_guess_filter_length(int len, char *filter)
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{
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if (!strcmp(filter, "ASCIIHexDecode"))
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return len / 2;
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if (!strcmp(filter, "ASCII85Decode"))
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return len * 4 / 5;
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if (!strcmp(filter, "FlateDecode"))
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return len * 3;
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if (!strcmp(filter, "RunLengthDecode"))
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return len * 3;
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if (!strcmp(filter, "LZWDecode"))
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return len * 2;
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return len;
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}
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/*
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* Load uncompressed contents of a stream into buf.
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*/
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fz_error
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pdf_load_stream(fz_buffer **bufp, pdf_xref *xref, int num, int gen)
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{
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fz_error error;
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fz_stream *stm;
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fz_obj *dict, *obj;
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int i, len;
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error = pdf_open_stream(&stm, xref, num, gen);
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if (error)
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return fz_rethrow(error, "cannot open stream (%d %d R)", num, gen);
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error = pdf_load_object(&dict, xref, num, gen);
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if (error)
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return fz_rethrow(error, "cannot load stream dictionary (%d %d R)", num, gen);
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len = fz_to_int(fz_dict_gets(dict, "Length"));
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obj = fz_dict_gets(dict, "Filter");
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len = pdf_guess_filter_length(len, fz_to_name(obj));
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for (i = 0; i < fz_array_len(obj); i++)
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len = pdf_guess_filter_length(len, fz_to_name(fz_array_get(obj, i)));
|
||
|
|
|
||
|
|
fz_drop_obj(dict);
|
||
|
|
|
||
|
|
error = fz_read_all(bufp, stm, len);
|
||
|
|
if (error)
|
||
|
|
{
|
||
|
|
fz_close(stm);
|
||
|
|
return fz_rethrow(error, "cannot read raw stream (%d %d R)", num, gen);
|
||
|
|
}
|
||
|
|
|
||
|
|
fz_close(stm);
|
||
|
|
return fz_okay;
|
||
|
|
}
|