coreutils/uudecode.c

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