44 lines
864 B
C
44 lines
864 B
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <string.h>
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#define STDOUT 1
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#define STDERR 2
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#define SZBUF 256
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int main(int argc, char** argv){
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int descripteur, curseur, nb;
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long int offset, i;
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char buf[SZBUF];
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if (argc < 2){
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fprintf(stderr, "Usage : %s <file-name>\n",argv[0]);
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exit(1);
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}
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descripteur = open(argv[1], O_RDONLY);
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if (descripteur==-1){
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perror("opening file fail !");
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exit(2);
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}
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i = strtol(argv[2],NULL,0);
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offset = i*4;
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curseur = lseek(descripteur, offset, SEEK_SET);
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if (curseur == -1){
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perror("lseek fail");
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exit(3);
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}
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nb = read(descripteur,&x,4);
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if (nb == -1){
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perror("Read in file fail");
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exit(4);
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}
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if (nb == 0){
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perror("out of range");
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exit(5);
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}
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printf("The number at offset %d is 0x%08x --> %d\n",i,x,x);
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exit(0);
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}
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