URL: https://linuxfr.org/forums/programmation-c--2/posts/manipuler-fichier-binaire
Title: manipuler fichier binaire
Authors: demo2000
Date: 2005年10月04日T19:01:55+02:00
Tags: 
Score: 0
voilà : 
fichier binaire : 
 
 £spaces£ £/spaces£A1 A2 A3 A4 30 81 03 B1 B2 B3 
 £spaces£ £/spaces£A1 A2 A3 A4 30 82 00 04 B1 B2 B3 B4 
 £spaces£ £/spaces£A1 A2 A3 A4 30 83 00 00 03 B1 B2 B3 B4 B5 
 £spaces£ £/spaces£A1 A2 A3 A4 30 84 00 00 00 04 B1 B2 B3 B4 B5 
 £spaces£ £/spaces£A1 A2 A3 A4 30 07 B1 B2 B3 B4 B5 B6 B7 
 
apres traitement : 
 
 £spaces£ £/spaces30ドル 81 03 B1 B2 B3 
 £spaces£ £/spaces30ドル 82 00 04 B1 B2 B3 B4 
 £spaces£ £/spaces30ドル 83 00 00 03 B1 B2 B3 B4 B5 
 £spaces£ £/spaces30ドル 84 00 00 00 04 B1 B2 B3 B4 B5 
 £spaces£ £/spaces30ドル 07 B1 B2 B3 B4 B5 B6 B7 
 
1- supprimer les 4 premier octets . 
2- lire le tag suivant '30' . 
3- lire le tag suivant INDIC 
4- lire le length de l'information : 
si INDIC est 81 le length de l'information est sur 1 octet, 82 --> 2octet, 83 -->3octet, 84 -->4 octet. 
si non INDIC = length de l'information (dernière ligne dans l'exemple). 
NB : le contenu de length est en hexadecmal . 
 
voilà ou je suis : 
 
#include <stdio.h> 
#include <string.h> 
#include <stdlib.h> 
 
int main(int argc, char argv) { 
FILE *infile; 
FILE *outfile; 
char buf[256]; // buffer de lecture 
static const char sequence[4] = {0x81,0x82,0x83,0x84}; 
char header[4]; // header 
unsigned char nb; 
unsigned char step; 
unsigned char tag[2]; 
unsigned long nbcdrall=0; 
int i,offset=24,nbcdrerr=0; 
unsigned char name; 
 
if ((infile = fopen(argv[1], "rb")) == NULL) 
{ 
fprintf(stderr, "Pb ouverture infile !n"); 
return(EXIT_FAILURE); 
} 
if((name = strdup(argv[1])) == NULL) 
{ 
fprintf(stderr,"Pb avec strdup !n"); 
return(EXIT_FAILURE); 
} 
if((outfile = fopen(strcat(argv[1],".NEW"),"wb")) == NULL) 
{ 
fprintf(stderr, "Pb ouverture outfile !n"); 
fclose(infile); 
return(EXIT_FAILURE); 
} 
while (fread(header, 1, 4, infile) > 0) 
{ 
if(!fread(tag, 1, 2, infile)) // read tag '30' and cdt 
{ 
fprintf(stderr,"fread tag Failure !n"); 
return(EXIT_FAILURE); 
} 
 
if((unsigned char)tag[1] == (unsigned char)sequence[0]) 
{ 
step='1'; 
} 
else if((unsigned char)tag[1] == (unsigned char)sequence[1]) 
{ 
step='2'; 
} 
else if((unsigned char)tag[1] == (unsigned char)sequence[2]) 
{ 
step='3'; 
} 
else if((unsigned char)tag[1] == (unsigned char)sequence[3]) 
{ 
step='4'; 
} 
else 
step='0'; 
 
/* 
switch (((unsigned char)tag[1])) 
{ 
case ((unsigned char)sequence[0]):step=1;break; 
case ((unsigned char)sequence[1]):step=2;break; 
case ((unsigned char)sequence[2]):step=3;break; 
case ((unsigned char)sequence[3]):step=4;break; 
case default:step=0; 
} 
/* 
if(!fread(&nb, 1, step, infile)) 
{ 
fclose(infile); 
fclose(outfile); 
fprintf(stderr, "Pb lecture infile !n"); 
return(EXIT_FAILURE); 
} 
if(fread(buf, 1, nb, infile) != (unsigned int) nb) 
{ 
fclose(infile); 
fclose(outfile); 
fprintf(stderr, "Pb lecture infile !n"); 
return(EXIT_FAILURE); 
} 
 
if((fwrite(tag, 1, 1, outfile)==0)|| (fwrite(buf, 1, nb , outfile)==0)) 
{ 
fprintf(stderr,"fwrite failure !n"); 
return(EXIT_FAILURE); 
} 
} 
if(rename(argv[1],name)!=0) 
{ 
fprintf(stderr,"rename failure !n"); 
return(EXIT_FAILURE); 
} 
return(EXIT_SUCCESS); 
} 
 
 
mon problème c'est que je n'arrive pas à avoir le bloc "nb" 
quand je fais : 
si step est superieur à 1 alors : 
 
 £spaces£ £/spaces£fread(&nb, 1, step, infile) 
 
il lis seulement le premier octet. 
c.a.d: 
Fichier binaire : 
 
 £spaces£ £/spaces£A1 A2 A3 A4 30 81 03 B1 B2 B3 // nb=03 --> OK 
 £spaces£ £/spaces£A1 A2 A3 A4 30 82 00 04 B1 B2 B3 B4 //nb=00 au lieu 0004 
 £spaces£ £/spaces£A1 A2 A3 A4 30 83 00 00 03 B1 B2 B3 B4 B5 //nb=00 au lieu de 000003 
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