| 0,0 → 1,463 |
|---|
| #include "fitz.h" |
| #include "mupdf.h" |
| |
| /* Scan file for objects and reconstruct xref table */ |
| |
| struct entry |
| { |
| int num; |
| int gen; |
| int ofs; |
| int stm_ofs; |
| int stm_len; |
| }; |
| |
| static fz_error |
| pdf_repair_obj(fz_stream *file, char *buf, int cap, int *stmofsp, int *stmlenp, fz_obj **encrypt, fz_obj **id) |
| { |
| fz_error error; |
| int tok; |
| int stm_len; |
| int len; |
| int n; |
| |
| *stmofsp = 0; |
| *stmlenp = -1; |
| |
| stm_len = 0; |
| |
| error = pdf_lex(&tok, file, buf, cap, &len); |
| if (error) |
| return fz_rethrow(error, "cannot parse object"); |
| if (tok == PDF_TOK_OPEN_DICT) |
| { |
| fz_obj *dict, *obj; |
| |
| /* Send NULL xref so we don't try to resolve references */ |
| error = pdf_parse_dict(&dict, NULL, file, buf, cap); |
| if (error) |
| return fz_rethrow(error, "cannot parse object"); |
| |
| obj = fz_dict_gets(dict, "Type"); |
| if (fz_is_name(obj) && !strcmp(fz_to_name(obj), "XRef")) |
| { |
| obj = fz_dict_gets(dict, "Encrypt"); |
| if (obj) |
| { |
| if (*encrypt) |
| fz_drop_obj(*encrypt); |
| *encrypt = fz_keep_obj(obj); |
| } |
| |
| obj = fz_dict_gets(dict, "ID"); |
| if (obj) |
| { |
| if (*id) |
| fz_drop_obj(*id); |
| *id = fz_keep_obj(obj); |
| } |
| } |
| |
| obj = fz_dict_gets(dict, "Length"); |
| if (fz_is_int(obj)) |
| stm_len = fz_to_int(obj); |
| |
| fz_drop_obj(dict); |
| } |
| |
| while ( tok != PDF_TOK_STREAM && |
| tok != PDF_TOK_ENDOBJ && |
| tok != PDF_TOK_ERROR && |
| tok != PDF_TOK_EOF ) |
| { |
| error = pdf_lex(&tok, file, buf, cap, &len); |
| if (error) |
| return fz_rethrow(error, "cannot scan for endobj or stream token"); |
| } |
| |
| if (tok == PDF_TOK_STREAM) |
| { |
| int c = fz_read_byte(file); |
| if (c == '\r') { |
| c = fz_peek_byte(file); |
| if (c == '\n') |
| fz_read_byte(file); |
| } |
| |
| *stmofsp = fz_tell(file); |
| if (*stmofsp < 0) |
| return fz_throw("cannot seek in file"); |
| |
| if (stm_len > 0) |
| { |
| fz_seek(file, *stmofsp + stm_len, 0); |
| error = pdf_lex(&tok, file, buf, cap, &len); |
| if (error) |
| fz_catch(error, "cannot find endstream token, falling back to scanning"); |
| if (tok == PDF_TOK_ENDSTREAM) |
| goto atobjend; |
| fz_seek(file, *stmofsp, 0); |
| } |
| |
| n = fz_read(file, (unsigned char *) buf, 9); |
| if (n < 0) |
| return fz_rethrow(n, "cannot read from file"); |
| |
| while (memcmp(buf, "endstream", 9) != 0) |
| { |
| c = fz_read_byte(file); |
| if (c == EOF) |
| break; |
| memmove(buf, buf + 1, 8); |
| buf[8] = c; |
| } |
| |
| *stmlenp = fz_tell(file) - *stmofsp - 9; |
| |
| atobjend: |
| error = pdf_lex(&tok, file, buf, cap, &len); |
| if (error) |
| return fz_rethrow(error, "cannot scan for endobj token"); |
| if (tok != PDF_TOK_ENDOBJ) |
| fz_warn("object missing 'endobj' token"); |
| } |
| |
| return fz_okay; |
| } |
| |
| static fz_error |
| pdf_repair_obj_stm(pdf_xref *xref, int num, int gen) |
| { |
| fz_error error; |
| fz_obj *obj; |
| fz_stream *stm; |
| int tok; |
| int i, n, count; |
| char buf[256]; |
| |
| error = pdf_load_object(&obj, xref, num, gen); |
| if (error) |
| return fz_rethrow(error, "cannot load object stream object (%d %d R)", num, gen); |
| |
| count = fz_to_int(fz_dict_gets(obj, "N")); |
| |
| fz_drop_obj(obj); |
| |
| error = pdf_open_stream(&stm, xref, num, gen); |
| if (error) |
| return fz_rethrow(error, "cannot open object stream object (%d %d R)", num, gen); |
| |
| for (i = 0; i < count; i++) |
| { |
| error = pdf_lex(&tok, stm, buf, sizeof buf, &n); |
| if (error || tok != PDF_TOK_INT) |
| { |
| fz_close(stm); |
| return fz_rethrow(error, "corrupt object stream (%d %d R)", num, gen); |
| } |
| |
| n = atoi(buf); |
| if (n >= xref->len) |
| pdf_resize_xref(xref, n + 1); |
| |
| xref->table[n].ofs = num; |
| xref->table[n].gen = i; |
| xref->table[n].stm_ofs = 0; |
| xref->table[n].obj = NULL; |
| xref->table[n].type = 'o'; |
| |
| error = pdf_lex(&tok, stm, buf, sizeof buf, &n); |
| if (error || tok != PDF_TOK_INT) |
| { |
| fz_close(stm); |
| return fz_rethrow(error, "corrupt object stream (%d %d R)", num, gen); |
| } |
| } |
| |
| fz_close(stm); |
| return fz_okay; |
| } |
| |
| fz_error |
| pdf_repair_xref(pdf_xref *xref, char *buf, int bufsize) |
| { |
| fz_error error; |
| fz_obj *dict, *obj; |
| fz_obj *length; |
| |
| fz_obj *encrypt = NULL; |
| fz_obj *id = NULL; |
| fz_obj *root = NULL; |
| fz_obj *info = NULL; |
| |
| struct entry *list = NULL; |
| int listlen; |
| int listcap; |
| int maxnum = 0; |
| |
| int num = 0; |
| int gen = 0; |
| int tmpofs, numofs = 0, genofs = 0; |
| int stm_len, stm_ofs = 0; |
| int tok; |
| int next; |
| int i, n, c; |
| |
| fz_seek(xref->file, 0, 0); |
| |
| listlen = 0; |
| listcap = 1024; |
| list = fz_calloc(listcap, sizeof(struct entry)); |
| |
| /* look for '%PDF' version marker within first kilobyte of file */ |
| n = fz_read(xref->file, (unsigned char *)buf, MAX(bufsize, 1024)); |
| if (n < 0) |
| { |
| error = fz_rethrow(n, "cannot read from file"); |
| goto cleanup; |
| } |
| |
| fz_seek(xref->file, 0, 0); |
| for (i = 0; i < n - 4; i++) |
| { |
| if (memcmp(buf + i, "%PDF", 4) == 0) |
| { |
| fz_seek(xref->file, i + 8, 0); /* skip "%PDF-X.Y" */ |
| break; |
| } |
| } |
| |
| /* skip comment line after version marker since some generators |
| * forget to terminate the comment with a newline */ |
| c = fz_read_byte(xref->file); |
| while (c >= 0 && (c == ' ' || c == '%')) |
| c = fz_read_byte(xref->file); |
| fz_unread_byte(xref->file); |
| |
| while (1) |
| { |
| tmpofs = fz_tell(xref->file); |
| if (tmpofs < 0) |
| { |
| error = fz_throw("cannot tell in file"); |
| goto cleanup; |
| } |
| |
| error = pdf_lex(&tok, xref->file, buf, bufsize, &n); |
| if (error) |
| { |
| fz_catch(error, "ignoring the rest of the file"); |
| break; |
| } |
| |
| if (tok == PDF_TOK_INT) |
| { |
| numofs = genofs; |
| num = gen; |
| genofs = tmpofs; |
| gen = atoi(buf); |
| } |
| |
| else if (tok == PDF_TOK_OBJ) |
| { |
| error = pdf_repair_obj(xref->file, buf, bufsize, &stm_ofs, &stm_len, &encrypt, &id); |
| if (error) |
| { |
| error = fz_rethrow(error, "cannot parse object (%d %d R)", num, gen); |
| goto cleanup; |
| } |
| |
| if (listlen + 1 == listcap) |
| { |
| listcap = (listcap * 3) / 2; |
| list = fz_realloc(list, listcap, sizeof(struct entry)); |
| } |
| |
| list[listlen].num = num; |
| list[listlen].gen = gen; |
| list[listlen].ofs = numofs; |
| list[listlen].stm_ofs = stm_ofs; |
| list[listlen].stm_len = stm_len; |
| listlen ++; |
| |
| if (num > maxnum) |
| maxnum = num; |
| } |
| |
| /* trailer dictionary */ |
| else if (tok == PDF_TOK_OPEN_DICT) |
| { |
| error = pdf_parse_dict(&dict, xref, xref->file, buf, bufsize); |
| if (error) |
| { |
| error = fz_rethrow(error, "cannot parse object"); |
| goto cleanup; |
| } |
| |
| obj = fz_dict_gets(dict, "Encrypt"); |
| if (obj) |
| { |
| if (encrypt) |
| fz_drop_obj(encrypt); |
| encrypt = fz_keep_obj(obj); |
| } |
| |
| obj = fz_dict_gets(dict, "ID"); |
| if (obj) |
| { |
| if (id) |
| fz_drop_obj(id); |
| id = fz_keep_obj(obj); |
| } |
| |
| obj = fz_dict_gets(dict, "Root"); |
| if (obj) |
| { |
| if (root) |
| fz_drop_obj(root); |
| root = fz_keep_obj(obj); |
| } |
| |
| obj = fz_dict_gets(dict, "Info"); |
| if (obj) |
| { |
| if (info) |
| fz_drop_obj(info); |
| info = fz_keep_obj(obj); |
| } |
| |
| fz_drop_obj(dict); |
| } |
| |
| else if (tok == PDF_TOK_ERROR) |
| fz_read_byte(xref->file); |
| |
| else if (tok == PDF_TOK_EOF) |
| break; |
| } |
| |
| /* make xref reasonable */ |
| |
| pdf_resize_xref(xref, maxnum + 1); |
| |
| for (i = 0; i < listlen; i++) |
| { |
| xref->table[list[i].num].type = 'n'; |
| xref->table[list[i].num].ofs = list[i].ofs; |
| xref->table[list[i].num].gen = list[i].gen; |
| |
| xref->table[list[i].num].stm_ofs = list[i].stm_ofs; |
| |
| /* corrected stream length */ |
| if (list[i].stm_len >= 0) |
| { |
| error = pdf_load_object(&dict, xref, list[i].num, list[i].gen); |
| if (error) |
| { |
| error = fz_rethrow(error, "cannot load stream object (%d %d R)", list[i].num, list[i].gen); |
| goto cleanup; |
| } |
| |
| length = fz_new_int(list[i].stm_len); |
| fz_dict_puts(dict, "Length", length); |
| fz_drop_obj(length); |
| |
| fz_drop_obj(dict); |
| } |
| |
| } |
| |
| xref->table[0].type = 'f'; |
| xref->table[0].ofs = 0; |
| xref->table[0].gen = 65535; |
| xref->table[0].stm_ofs = 0; |
| xref->table[0].obj = NULL; |
| |
| next = 0; |
| for (i = xref->len - 1; i >= 0; i--) |
| { |
| if (xref->table[i].type == 'f') |
| { |
| xref->table[i].ofs = next; |
| if (xref->table[i].gen < 65535) |
| xref->table[i].gen ++; |
| next = i; |
| } |
| } |
| |
| /* create a repaired trailer, Root will be added later */ |
| |
| xref->trailer = fz_new_dict(5); |
| |
| obj = fz_new_int(maxnum + 1); |
| fz_dict_puts(xref->trailer, "Size", obj); |
| fz_drop_obj(obj); |
| |
| if (root) |
| { |
| fz_dict_puts(xref->trailer, "Root", root); |
| fz_drop_obj(root); |
| } |
| if (info) |
| { |
| fz_dict_puts(xref->trailer, "Info", info); |
| fz_drop_obj(info); |
| } |
| |
| if (encrypt) |
| { |
| if (fz_is_indirect(encrypt)) |
| { |
| /* create new reference with non-NULL xref pointer */ |
| obj = fz_new_indirect(fz_to_num(encrypt), fz_to_gen(encrypt), xref); |
| fz_drop_obj(encrypt); |
| encrypt = obj; |
| } |
| fz_dict_puts(xref->trailer, "Encrypt", encrypt); |
| fz_drop_obj(encrypt); |
| } |
| |
| if (id) |
| { |
| if (fz_is_indirect(id)) |
| { |
| /* create new reference with non-NULL xref pointer */ |
| obj = fz_new_indirect(fz_to_num(id), fz_to_gen(id), xref); |
| fz_drop_obj(id); |
| id = obj; |
| } |
| fz_dict_puts(xref->trailer, "ID", id); |
| fz_drop_obj(id); |
| } |
| |
| fz_free(list); |
| return fz_okay; |
| |
| cleanup: |
| if (encrypt) fz_drop_obj(encrypt); |
| if (id) fz_drop_obj(id); |
| if (root) fz_drop_obj(root); |
| if (info) fz_drop_obj(info); |
| fz_free(list); |
| return error; /* already rethrown */ |
| } |
| |
| fz_error |
| pdf_repair_obj_stms(pdf_xref *xref) |
| { |
| fz_obj *dict; |
| int i; |
| |
| for (i = 0; i < xref->len; i++) |
| { |
| if (xref->table[i].stm_ofs) |
| { |
| pdf_load_object(&dict, xref, i, 0); |
| if (!strcmp(fz_to_name(fz_dict_gets(dict, "Type")), "ObjStm")) |
| pdf_repair_obj_stm(xref, i, 0); |
| fz_drop_obj(dict); |
| } |
| } |
| |
| return fz_okay; |
| } |