coreutils/uudecode.c

   1 /*
   2  *  Copyright 2003, Glenn McGrath <bug1@iinet.net.au>
   3  *
   4  *  Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   5  *
   6  *  Based on specification from
   7  *  http://www.opengroup.org/onlinepubs/007904975/utilities/uuencode.html
   8  *
   9  *  Bugs: the spec doesn't mention anything about "`\n`\n" prior to the
  10  *        "end" line
  11  */
  12
  13
  14 #include <stdio.h>
  15 #include <errno.h>
  16 #include <getopt.h> /* optind */
  17 #include <string.h>
  18 #include <stdlib.h>
  19 #include "busybox.h"
  20
  21 static int read_stduu(FILE *src_stream, FILE *dst_stream)
  22 {
  23         char *line;
  24
  25         while ((line = bb_get_chomped_line_from_file(src_stream)) != NULL) {
  26                 int length;
  27                 char *line_ptr = line;
  28
  29                 if (strcmp(line, "end") == 0) {
  30                         return(EXIT_SUCCESS);
  31                 }
  32                 length = ((*line_ptr - 0x20) & 0x3f)* 4 / 3;
  33
  34                 if (length <= 0) {
  35                         /* Ignore the "`\n" line, why is it even in the encode file ? */
  36                         continue;
  37                 }
  38                 if (length > 60) {
  39                         bb_error_msg_and_die("Line too long");
  40                 }
  41
  42                 line_ptr++;
  43                 /* Tolerate an overly long line to acomadate a possible exta '`' */
  44                 if (strlen(line_ptr) < (size_t)length) {
  45                         bb_error_msg_and_die("Short file");
  46                 }
  47
  48                 while (length > 0) {
  49                         /* Merge four 6 bit chars to three 8 bit chars */
  50                         fputc(((line_ptr[0] - 0x20) & 077) << 2 | ((line_ptr[1] - 0x20) & 077) >> 4, dst_stream);
  51                         line_ptr++;
  52                         length--;
  53                         if (length == 0) {
  54                                 break;
  55                         }
  56
  57                         fputc(((line_ptr[0] - 0x20) & 077) << 4 | ((line_ptr[1] - 0x20) & 077) >> 2, dst_stream);
  58                         line_ptr++;
  59                         length--;
  60                         if (length == 0) {
  61                                 break;
  62                         }
  63
  64                         fputc(((line_ptr[0] - 0x20) & 077) << 6 | ((line_ptr[1] - 0x20) & 077), dst_stream);
  65                         line_ptr += 2;
  66                         length -= 2;
  67                 }
  68                 free(line);
  69         }
  70         bb_error_msg_and_die("Short file");
  71 }
  72
  73 static int read_base64(FILE *src_stream, FILE *dst_stream)
  74 {
  75         static const char base64_table[] =
  76                 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n";
  77         char term_count = 0;
  78
  79         while (1) {
  80                 char translated[4];
  81                 int count = 0;
  82
  83                 while (count < 4) {
  84                         char *table_ptr;
  85                         int ch;
  86
  87                         /* Get next _valid_ character */
  88                         do {
  89                                 ch = fgetc(src_stream);
  90                                 if (ch == EOF) {
  91                                         bb_error_msg_and_die("Short file");
  92                                 }
  93                         } while ((table_ptr = strchr(base64_table, ch)) == NULL);
  94
  95                         /* Convert encoded charcter to decimal */
  96                         ch = table_ptr - base64_table;
  97
  98                         if (*table_ptr == '=') {
  99                                 if (term_count == 0) {
 100                                         translated[count] = 0;
 101                                         break;
 102                                 }
 103                                 term_count++;
 104                         }
 105                         else if (*table_ptr == '\n') {
 106                                 /* Check for terminating line */
 107                                 if (term_count == 5) {
 108                                         return(EXIT_SUCCESS);
 109                                 }
 110                                 term_count = 1;
 111                                 continue;
 112                         } else {
 113                                 translated[count] = ch;
 114                                 count++;
 115                                 term_count = 0;
 116                         }
 117                 }
 118
 119                 /* Merge 6 bit chars to 8 bit */
 120             fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
 121                 if (count > 2) {
 122                         fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
 123                 }
 124                 if (count > 3) {
 125                         fputc(translated[2] << 6 | translated[3], dst_stream);
 126                 }
 127         }
 128 }
 129
 130 int uudecode_main(int argc, char **argv)
 131 {
 132         int (*decode_fn_ptr) (FILE * src, FILE * dst);
 133         FILE *src_stream;
 134         char *outname = NULL;
 135         char *line;
 136         int opt;
 137
 138         opt = bb_getopt_ulflags(argc, argv, "o:", &outname);
 139
 140         if (optind == argc) {
 141                 src_stream = stdin;
 142         } else if (optind + 1 == argc) {
 143                 src_stream = bb_xfopen(argv[optind], "r");
 144         } else {
 145                 bb_show_usage();
 146         }
 147
 148         /* Search for the start of the encoding */
 149         while ((line = bb_get_chomped_line_from_file(src_stream)) != NULL) {
 150                 char *line_ptr = NULL;
 151
 152                 if (line == NULL) {
 153                         break;
 154                 } else if (strncmp(line, "begin-base64 ", 13) == 0) {
 155                         line_ptr = line + 13;
 156                         decode_fn_ptr = read_base64;
 157                 } else if (strncmp(line, "begin ", 6) == 0) {
 158                         line_ptr = line + 6;
 159                         decode_fn_ptr = read_stduu;
 160                 }
 161
 162                 if (line_ptr) {
 163                         FILE *dst_stream;
 164                         int mode;
 165                         int ret;
 166
 167                         mode = strtoul(line_ptr, NULL, 8);
 168                         if (outname == NULL) {
 169                                 outname = strchr(line_ptr, ' ');
 170                                 if ((outname == NULL) || (*outname == '\0')) {
 171                                         break;
 172                                 }
 173                                 outname++;
 174                         }
 175                         if (strcmp(outname, "-") == 0) {
 176                                 dst_stream = stdout;
 177                         } else {
 178                                 dst_stream = bb_xfopen(outname, "w");
 179                                 chmod(outname, mode & (S_IRWXU | S_IRWXG | S_IRWXO));
 180                         }
 181                         free(line);
 182                         ret = decode_fn_ptr(src_stream, dst_stream);
 183                         bb_fclose_nonstdin(src_stream);
 184                         return(ret);
 185                 }
 186                 free(line);
 187         }
 188         bb_error_msg_and_die("No `begin' line");
 189 }