Ajouter exo3.c

exo3.c

@@ -0,0 +1,90 @@
+include <stdio.h>
+#include <stdlib.h>
+
+void deplacerPremierOctet(const char *filename) {
+    FILE *file;
+    unsigned char first_byte;
+    long file_size;
+    unsigned char *buffer;
+
+
+    file = fopen(filename, "r+b");
+    if (file == NULL) {
+        perror("Erreur d'ouverture");
+        exit(EXIT_FAILURE);
+    }
+
+    if (fread(&first_byte, 1, 1, file) != 1) {
+        perror("Erreur de lecture");
+        fclose(file);
+        exit(EXIT_FAILURE);
+    }
+
+    fseek(file, 0, SEEK_END);
+    if (fwrite(&first_byte, 1, 1, file) != 1) {
+        perror("Erreur d'écriture");
+        fclose(file);
+        exit(EXIT_FAILURE);
+    }
+
+    file_size = ftell(file);
+    fclose(file);
+
+    file = fopen(filename, "r+b");
+    if (file == NULL) {
+        perror("Erreur d'ouverture");
+        exit(EXIT_FAILURE);
+    }
+
+    buffer = (unsigned char *)malloc(file_size - 1);
+    if (buffer == NULL) {
+        perror("Erreur d'allocation mémoire");
+        fclose(file);
+        exit(EXIT_FAILURE);
+    }
+
+    fseek(file, 1, SEEK_SET);
+    if (fread(buffer, 1, file_size - 1, file) != file_size - 1) {
+        perror("Erreur de lecture");
+        free(buffer);
+        fclose(file);
+        exit(EXIT_FAILURE);
+    }
+    fclose(file);
+
+    file = fopen(filename, "wb");
+    if (file == NULL) {
+        perror("Erreur d'ouverture");
+        free(buffer);
+        exit(EXIT_FAILURE);
+    }
+
+    if (fwrite(buffer, 1, file_size - 1, file) != file_size - 1) {
+        perror("Erreur d'écriture");
+        free(buffer);
+        fclose(file);
+        exit(EXIT_FAILURE);
+    }
+
+    if (fwrite(&first_byte, 1, 1, file) != 1) {
+        perror("Erreur d'écriture");
+        free(buffer);
+        fclose(file);
+        exit(EXIT_FAILURE);
+    }
+
+    free(buffer);
+    fclose(file);
+
+    printf("Modification effectuée.\n");
+}
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <toto.c>\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+
+    deplacerPremierOctet(argv[1]);
+    return 0;
+}