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