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src/file_gif.c: fix some errors reported by frama-c

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This commit is contained in:
Christophe Grenier 2020-09-14 18:34:17 +02:00
parent 7d42371fbe
commit 5cf21cf78f
1 changed files with 81 additions and 30 deletions
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111
src/file_gif.c
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@ -33,8 +33,6 @@
#include "log.h"
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);
@ -47,36 +45,36 @@ const file_hint_t file_hint_gif= {
.register_header_check=&register_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;
}
/*@
@ requires \valid(file_recovery);
@ requires \valid(file_recovery->handle);
@ requires \valid_read(&file_recovery->extension);
@ requires valid_read_string(file_recovery->extension);
@ requires \separated(file_recovery, file_recovery->handle, file_recovery->extension, &errno, &Frama_C_entropy_source);
@ requires \initialized(&file_recovery->time);
@
@ requires file_recovery->file_check == &file_check_gif;
@ assigns *file_recovery->handle, errno, file_recovery->file_size;
@ assigns Frama_C_entropy_source;
@
@ ensures \valid(file_recovery->handle);
@*/
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)
const char gif_footer[2]= {0x00, 0x3b};
char buffer[2];
/* file_recovery->calculated_file_size is always >= */
if(file_recovery->calculated_file_size < 2 ||
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;
@ -154,6 +152,59 @@ static data_check_t data_check_gif2(const unsigned char *buffer, const unsigned
return DC_CONTINUE;
}
/*@
@ requires buffer_size > 0;
@ requires \valid_read(buffer+(0..buffer_size-1));
@ requires \valid_read(file_recovery);
@ requires file_recovery->file_stat==\null || valid_read_string((char*)file_recovery->filename);
@ requires \valid(file_recovery_new);
@ requires file_recovery_new->blocksize > 0;
@
@ requires buffer_size >= 6+7+(3<<8)+1;
@ requires separation: \separated(&file_hint_gif, buffer+(..), file_recovery, file_recovery_new);
@
@ ensures \result == 0 || \result == 1;
@ ensures (\result == 1) ==> (file_recovery_new->file_stat == \null);
@ ensures (\result == 1) ==> (file_recovery_new->handle == \null);
@ ensures (\result == 1) ==> \initialized(&file_recovery_new->time);
@ ensures (\result == 1) ==> \initialized(&file_recovery_new->calculated_file_size);
@ ensures (\result == 1) ==> file_recovery_new->file_size == 0;
@ ensures (\result == 1) ==> \initialized(&file_recovery_new->min_filesize);
@ ensures (\result == 1) ==> (file_recovery_new->data_check == \null || \valid_function(file_recovery_new->data_check));
@ ensures (\result == 1) ==> (file_recovery_new->file_check == \null || \valid_function(file_recovery_new->file_check));
@ ensures (\result == 1) ==> (file_recovery_new->file_rename == \null || \valid_function(file_recovery_new->file_rename));
@ ensures (\result != 0) ==> file_recovery_new->extension != \null;
@ ensures (\result == 1) ==> (valid_read_string(file_recovery_new->extension));
@ ensures (\result == 1) ==> \separated(file_recovery_new, file_recovery_new->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->extension == file_hint_gif.extension);
@ ensures (\result == 1 && file_recovery_new->blocksize>=2) ==> (file_recovery_new->file_check == &file_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->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'};