coreutils/uudecode.c

   1 /*
   2  *  GPLv2
   3  *  Copyright 2003, Glenn McGrath <bug1@optushome.com.au>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License version 2 as published
   7  *  by the Free Software Foundation; either version 2 of the License.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU Library General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; if not, write to the Free Software
  16  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  *  Based on specification from
  19  *  http://www.opengroup.org/onlinepubs/007904975/utilities/uuencode.html
  20  *
  21  *  Bugs: the spec doesnt mention anything about "`\n`\n" prior to the "end" line
  22  */
  23
  24
  25 #include <stdio.h>
  26 #include <errno.h>
  27 #include <getopt.h>
  28 #include <string.h>
  29 #include <stdlib.h>
  30
  31 #include "libbb.h"
  32
  33 static int read_stduu(FILE *src_stream, FILE *dst_stream)
  34 {
  35         char *line;
  36
  37         while ((line = bb_get_chomped_line_from_file(src_stream)) != NULL) {
  38                 int length;
  39                 char *line_ptr = line;
  40
  41                 if (strcmp(line, "end") == 0) {
  42                         return(EXIT_SUCCESS);
  43                 }
  44                 length = ((*line_ptr - 0x20) & 0x3f)* 4 / 3;
  45
  46                 if (length <= 0) {
  47                         /* Ignore the "`\n" line, why is it even in the encode file ? */
  48                         continue;
  49                 }
  50                 if (length > 60) {
  51                         bb_error_msg_and_die("Line too long");
  52                 }
  53
  54                 line_ptr++;
  55                 /* Tolerate an overly long line to acomadate a possible exta '`' */
  56                 if (strlen(line_ptr) < length) {
  57                         bb_error_msg_and_die("Short file");
  58                 }
  59
  60                 while (length > 0) {
  61                         /* Merge four 6 bit chars to three 8 bit chars */
  62                     fputc(((line_ptr[0] - 0x20) & 077) << 2 | ((line_ptr[1] - 0x20) & 077) >> 4, dst_stream);
  63                         line_ptr++;
  64                         length--;
  65                         if (length == 0) {
  66                                 break;
  67                         }
  68
  69                         fputc(((line_ptr[0] - 0x20) & 077) << 4 | ((line_ptr[1] - 0x20) & 077) >> 2, dst_stream);
  70                         line_ptr++;
  71                         length--;
  72                         if (length == 0) {
  73                                 break;
  74                         }
  75
  76                         fputc(((line_ptr[0] - 0x20) & 077) << 6 | ((line_ptr[1] - 0x20) & 077), dst_stream);
  77                         line_ptr += 2;
  78                         length -= 2;
  79                 }
  80                 free(line);
  81         }
  82         bb_error_msg_and_die("Short file");
  83 }
  84
  85 static int read_base64(FILE *src_stream, FILE *dst_stream)
  86 {
  87         const char *base64_table =
  88                 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n";
  89         char term_count = 0;
  90
  91         while (1) {
  92                 char translated[4];
  93                 int count = 0;
  94
  95                 while (count < 4) {
  96                         char *table_ptr;
  97                         char ch;
  98
  99                         /* Get next _valid_ character */
 100                         do {
 101                                 ch = fgetc(src_stream);
 102                                 if (ch == EOF) {
 103                                         bb_error_msg_and_die("Short file");
 104                                 }
 105                         } while ((table_ptr = strchr(base64_table, ch)) == NULL);
 106
 107                         /* Convert encoded charcter to decimal */
 108                         ch = table_ptr - base64_table;
 109
 110                         if (*table_ptr == '=') {
 111                                 if (term_count == 0) {
 112                                         translated[count] = 0;
 113                                         break;
 114                                 }
 115                                 term_count++;
 116                         }
 117                         else if (*table_ptr == '\n') {
 118                                 /* Check for terminating line */
 119                                 if (term_count == 5) {
 120                                         return(EXIT_SUCCESS);
 121                                 }
 122                                 term_count = 1;
 123                                 continue;
 124                         } else {
 125                                 translated[count] = ch;
 126                                 count++;
 127                                 term_count = 0;
 128                         }
 129                 }
 130
 131                 /* Merge 6 bit chars to 8 bit */
 132             fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
 133                 if (count > 2) {
 134                         fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
 135                 }
 136                 if (count > 3) {
 137                         fputc(translated[2] << 6 | translated[3], dst_stream);
 138                 }
 139         }
 140 }
 141
 142 extern int uudecode_main(int argc, char **argv)
 143 {
 144         int (*decode_fn_ptr) (FILE * src, FILE * dst);
 145         FILE *src_stream;
 146         char *outname = NULL;
 147         char *line;
 148         int opt;
 149
 150         opt = bb_getopt_ulflags(argc, argv, "o:", &outname);
 151
 152         if (optind == argc) {
 153                 src_stream = stdin;
 154         } else if (optind + 1 == argc) {
 155                 src_stream = bb_xfopen(argv[optind], "r");
 156         } else {
 157                 bb_show_usage();
 158         }
 159
 160         /* Search for the start of the encoding */
 161         while ((line = bb_get_chomped_line_from_file(src_stream)) != NULL) {
 162                 char *line_ptr = NULL;
 163
 164                 if (line == NULL) {
 165                         break;
 166                 } else if (strncmp(line, "begin-base64 ", 13) == 0) {
 167                         line_ptr = line + 13;
 168                         decode_fn_ptr = read_base64;
 169                 } else if (strncmp(line, "begin ", 6) == 0) {
 170                         line_ptr = line + 6;
 171                         decode_fn_ptr = read_stduu;
 172                 }
 173
 174                 if (line_ptr) {
 175                         FILE *dst_stream;
 176                         int mode;
 177                         int ret;
 178
 179                         mode = strtoul(line_ptr, NULL, 8);
 180                         if (outname == NULL) {
 181                                 outname = strchr(line_ptr, ' ');
 182                                 if ((outname == NULL) || (*outname == '\0')) {
 183                                         break;
 184                                 }
 185                                 outname++;
 186                         }
 187                         if (strcmp(outname, "-") == 0) {
 188                                 dst_stream = stdout;
 189                         } else {
 190                                 dst_stream = bb_xfopen(outname, "w");
 191                                 chmod(outname, mode & (S_IRWXU | S_IRWXG | S_IRWXO));
 192                         }
 193                         free(line);
 194                         ret = decode_fn_ptr(src_stream, dst_stream);
 195                         bb_fclose_nonstdin(src_stream);
 196                         return(ret);
 197                 }
 198                 free(line);
 199         }
 200         bb_error_msg_and_die("No `begin' line");
 201 }