tp

DEV4.4/TP0/base_64.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <unistd.h>
+
+
+static const char base64_table[] = {
+  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
+  'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
+  'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
+  'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
+  'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
+  'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
+  'w', 'x', 'y', 'z', '0', '1', '2', '3',
+  '4', '5', '6', '7', '8', '9', '+', '/'
+};
+
+void base64_encode_file(char * file, char * file_encoded)
+{
+	int  i = 0;
+	int fdin, fdout ;
+	unsigned char buffer[3]; // octets a encoder
+	unsigned char tmp[4];    // valeurs des 4 groupes de 6 bits
+	char buffer_encoded[4];  // octets encodes
+	ssize_t nb_read;
+
+
+
+	fdin = open(file,O_RDONLY);
+	fdout = open(file_encoded,O_WRONLY|O_TRUNC|O_CREAT,0644);
+
+	assert(fdin  >= 0);
+	assert(fdout >= 0);
+
+	while(1){
+		nb_read = read(fdin,buffer,3);
+
+		if (nb_read < 3)
+			break;
+		// TODO 
+		// calculer la valeur des 4 groupes de 6 bits de buffer
+		
+		tmp[0] = buffer[0] >> 2;
+		tmp[1] = buffer[0] << 4 + buffer[1] << 4;
+		tmp[2] = buffer[1] << 2 + buffer[2] << 6;
+		tmp[3] = buffer[2];
+
+		for (i = 0; i < 4 ;i++)
+			buffer_encoded[i] = base64_table[tmp[i]];
+
+		write(fdout,buffer_encoded,4);
+
+	}
+
+	// TODO 
+	/* il reste quelque chose ? */
+
+	if ( nb_read != 0){
+		for( i = nb_read; i < 3; i++)
+			buffer[i] = 0;
+
+		tmp[0] = 0;
+		tmp[1] = 0;
+		tmp[2] = 0;
+		tmp[3] = 0;
+
+		for (i = 0; i < nb_read + 1 ;i++)
+			buffer_encoded[i] = base64_table[tmp[i]];
+
+		for (i = nb_read + 1; i < 4 ;i++)
+			buffer_encoded[i] = '=';
+
+
+		write(fdout,buffer_encoded,4);
+	}
+
+	close(fdin);
+	close(fdout);
+}
+
+int main(int argc, char *argv[])
+{
+	assert(argc >= 3);
+	base64_encode_file(argv[1],argv[2]);
+	return 0;
+}
+