/* 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. */ #ifdef HAVE_CONFIG_H #include #endif #ifdef HAVE_STRING_H #include #endif #include #include "types.h" #include "filegen.h" #include "log.h" #if defined(HAVE_FSEEKO) && !defined(__MINGW32__) #define my_fseek fseeko #else #define my_fseek fseek #endif static void register_header_check_gif(file_stat_t *file_stat); 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); static void file_check_gif(file_recovery_t *file_recovery); static data_check_t data_check_gif(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery); 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 }; 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->file_check=&file_check_gif; file_recovery_new->calculated_file_size=offset; file_recovery_new->data_check=&data_check_gif; return 1; } static void file_check_gif(file_recovery_t *file_recovery) { const unsigned char gif_footer[2]= {0x00, 0x3b}; unsigned char buffer[2]; if(my_fseek(file_recovery->handle, file_recovery->calculated_file_size-2, SEEK_SET)<0 || fread(buffer, 2, 1, file_recovery->handle)!=1 || memcmp(buffer, gif_footer, sizeof(gif_footer))!=0) { file_recovery->file_size=0; return; } file_recovery->file_size=file_recovery->calculated_file_size; } static data_check_t data_check_gif(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery) { while(file_recovery->calculated_file_size + buffer_size/2 >= file_recovery->file_size && file_recovery->calculated_file_size + 2 < file_recovery->file_size + buffer_size/2) { const unsigned int i=file_recovery->calculated_file_size - file_recovery->file_size + buffer_size/2; #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; return data_check_gif2(buffer, buffer_size, file_recovery); case 0x2c: if(file_recovery->calculated_file_size + 20 < file_recovery->file_size + buffer_size/2) { 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 */ 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; } } file_recovery->data_check=&data_check_gif; return DC_CONTINUE; } static data_check_t data_check_gif2(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery) { while(file_recovery->calculated_file_size + buffer_size/2 >= file_recovery->file_size && file_recovery->calculated_file_size + 2 < file_recovery->file_size + buffer_size/2) { const unsigned int i=file_recovery->calculated_file_size - file_recovery->file_size + buffer_size/2; #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+=buffer[i]+1; if(buffer[i]==0) { return data_check_gif(buffer, buffer_size, file_recovery); } } file_recovery->data_check=&data_check_gif2; return DC_CONTINUE; } 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); register_header_check(0, gif_header2,sizeof(gif_header2), &header_check_gif, file_stat); }