/* File: file_gif.c Copyright (C) 1998-2007 Christophe GRENIER This software is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #if !defined(SINGLE_FORMAT) || defined(SINGLE_FORMAT_gif) #ifdef HAVE_CONFIG_H #include #endif #ifdef HAVE_STRING_H #include #endif #include #include "types.h" #include "filegen.h" #include "log.h" /*@ requires valid_register_header_check(file_stat); */ static void register_header_check_gif(file_stat_t *file_stat); static data_check_t data_check_gif2(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery); const file_hint_t file_hint_gif= { .extension="gif", .description="Graphic Interchange Format", .max_filesize=PHOTOREC_MAX_FILE_SIZE, .recover=1, .enable_by_default=1, .register_header_check=®ister_header_check_gif }; /*@ @ requires file_recovery->file_check == &file_check_gif; @ requires valid_file_check_param(file_recovery); @ ensures valid_file_check_result(file_recovery); @ assigns *file_recovery->handle, errno, file_recovery->file_size; @ assigns Frama_C_entropy_source; @*/ static void file_check_gif(file_recovery_t *file_recovery) { const char gif_footer[2]= {0x00, 0x3b}; char buffer[2]; /* file_recovery->calculated_file_size is always >= */ if(file_recovery->calculated_file_size < 2 || file_recovery->calculated_file_size >= 0x8000000000000000 || my_fseek(file_recovery->handle, file_recovery->calculated_file_size-2, SEEK_SET)<0 || fread(buffer, 2, 1, file_recovery->handle)!=1) { file_recovery->file_size=0; return; } #ifdef __FRAMAC__ Frama_C_make_unknown(&buffer, sizeof(buffer)); #endif if(memcmp(buffer, gif_footer, sizeof(gif_footer))!=0) { file_recovery->file_size=0; return; } file_recovery->file_size=file_recovery->calculated_file_size; } /*@ @ requires file_recovery->data_check==&data_check_gif; @ requires valid_data_check_param(buffer, buffer_size, file_recovery); @ ensures valid_data_check_result(\result, file_recovery); @ ensures file_recovery->data_check == &data_check_gif || file_recovery->data_check == &data_check_gif2; @ assigns file_recovery->calculated_file_size, file_recovery->data_check; @*/ static data_check_t data_check_gif(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery) { /*@ assert file_recovery->calculated_file_size <= PHOTOREC_MAX_FILE_SIZE; */ /*@ assert file_recovery->file_size <= PHOTOREC_MAX_FILE_SIZE; */ if(file_recovery->calculated_file_size + buffer_size/2 >= file_recovery->file_size && file_recovery->calculated_file_size + 1 < file_recovery->file_size + buffer_size/2) { const unsigned int i=file_recovery->calculated_file_size + buffer_size/2 - file_recovery->file_size; /*@ assert 0 <= i < buffer_size - 1; */ #ifdef DEBUG_GIF log_info("data_check_gif calculated_file_size=0x%llx: 0x%02x\n", (long long unsigned)file_recovery->calculated_file_size, buffer[i]); #endif switch(buffer[i]) { case 0x21: /* Plain Text Extension 21 01 ... */ /* Graphic Control Extension 21 f9 04 XX XX XX XX 00 */ /* Comment Extension 21 fe ... */ /* Application Extension 21 ff */ file_recovery->calculated_file_size+=2; if(file_recovery->calculated_file_size >= PHOTOREC_MAX_FILE_SIZE) return DC_STOP; /*@ assert file_recovery->calculated_file_size < PHOTOREC_MAX_FILE_SIZE; */ file_recovery->data_check=&data_check_gif2; return data_check_gif2(buffer, buffer_size, file_recovery); case 0x2c: if(i + 20 < buffer_size) { unsigned int j=10+1; /* 1 Image Descriptor id=0x2c * 4: NW corner * 4: width, heigth, * 1: is a local color table present ? */ if(((buffer[i+9]>>7)&0x1)>0) { /* local color table */ j+=3<<((buffer[i+9]&7)+1); } file_recovery->calculated_file_size+=j; /* 1: Start of image - LZW minimum code size */ /* Table Based Image Data */ if(file_recovery->calculated_file_size >= PHOTOREC_MAX_FILE_SIZE) return DC_STOP; file_recovery->data_check=&data_check_gif2; return data_check_gif2(buffer, buffer_size, file_recovery); } return DC_CONTINUE; case 0x3b: /* Trailer */ file_recovery->calculated_file_size++; return DC_STOP; default: return DC_ERROR; } } return DC_CONTINUE; } /*@ @ requires file_recovery->data_check==&data_check_gif2; @ requires valid_data_check_param(buffer, buffer_size, file_recovery); @ ensures valid_data_check_result(\result, file_recovery); @ ensures file_recovery->data_check == &data_check_gif || file_recovery->data_check == &data_check_gif2; @ assigns file_recovery->calculated_file_size, file_recovery->data_check; @*/ static data_check_t data_check_gif2(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery) { /*@ assert file_recovery->calculated_file_size <= PHOTOREC_MAX_FILE_SIZE; */ /*@ assert file_recovery->file_size <= PHOTOREC_MAX_FILE_SIZE; */ /*@ @ loop invariant file_recovery->data_check == &data_check_gif || file_recovery->data_check == &data_check_gif2; @ loop assigns file_recovery->calculated_file_size, file_recovery->data_check; @ loop variant file_recovery->file_size + buffer_size/2 - (file_recovery->calculated_file_size + 1); @*/ while(file_recovery->calculated_file_size + buffer_size/2 >= file_recovery->file_size && file_recovery->calculated_file_size + 1 < file_recovery->file_size + buffer_size/2) { const unsigned int i=file_recovery->calculated_file_size + buffer_size/2 - file_recovery->file_size; /*@ assert file_recovery->data_check==&data_check_gif2; */ /*@ assert 0 <= i < buffer_size - 1; */ #ifdef DEBUG_GIF log_info("data_check_gif2 calculated_file_size=0x%llx\n", (long long unsigned)file_recovery->calculated_file_size); #endif file_recovery->calculated_file_size+=(uint64_t)1+buffer[i]; if(file_recovery->calculated_file_size >= PHOTOREC_MAX_FILE_SIZE) return DC_STOP; /*@ assert file_recovery->calculated_file_size < PHOTOREC_MAX_FILE_SIZE; */ if(buffer[i]==0) { file_recovery->data_check=&data_check_gif; return data_check_gif(buffer, buffer_size, file_recovery); } /*@ assert file_recovery->data_check==&data_check_gif2; */ } /*@ assert file_recovery->data_check==&data_check_gif2; */ return DC_CONTINUE; } /*@ @ requires buffer_size >= 6+7+(3<<8)+1; @ requires separation: \separated(&file_hint_gif, buffer+(..), file_recovery, file_recovery_new); @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new); @ terminates \true; @ ensures valid_header_check_result(\result, file_recovery_new); @ ensures (\result == 1) ==> file_recovery_new->file_size == 0; @ ensures (\result == 1) ==> (file_recovery_new->extension == file_hint_gif.extension); @ ensures (\result == 1) ==> (file_recovery_new->time == 0); @ ensures (\result == 1 && file_recovery_new->blocksize>=2) ==> (file_recovery_new->calculated_file_size >= 6+7); @ ensures (\result == 1 && file_recovery_new->blocksize>=2) ==> (file_recovery_new->data_check == &data_check_gif); @ ensures (\result == 1 && file_recovery_new->blocksize>=2) ==> (file_recovery_new->file_check == &file_check_gif); @ assigns *file_recovery_new; @*/ static int header_check_gif(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new) { uint64_t offset; offset=6; /* Header */ offset+=7; /* Logical Screen Descriptor */ if((buffer[10]>>7)&0x1) { /* Global Color Table */ offset+=3<<((buffer[10]&7)+1); } if(offset < buffer_size && buffer[offset]!=0x21 && buffer[offset]!=0x2c) return 0; reset_file_recovery(file_recovery_new); file_recovery_new->extension=file_hint_gif.extension; file_recovery_new->min_filesize=42; if(file_recovery_new->blocksize < 2) return 1; file_recovery_new->calculated_file_size=offset; file_recovery_new->file_check=&file_check_gif; file_recovery_new->data_check=&data_check_gif; return 1; } static void register_header_check_gif(file_stat_t *file_stat) { static const unsigned char gif_header[6]= { 'G','I','F','8','7','a'}; static const unsigned char gif_header2[6]= { 'G','I','F','8','9','a'}; register_header_check(0, gif_header,sizeof(gif_header), &header_check_gif, file_stat); #ifndef DISABLED_FOR_FRAMAC register_header_check(0, gif_header2,sizeof(gif_header2), &header_check_gif, file_stat); #endif } #endif