busybox/coreutils/uudecode.c
2007-01-11 17:20:00 +00:00

182 lines
4.0 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Copyright 2003, Glenn McGrath <bug1@iinet.net.au>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*
* Based on specification from
* http://www.opengroup.org/onlinepubs/007904975/utilities/uuencode.html
*
* Bugs: the spec doesn't mention anything about "`\n`\n" prior to the
* "end" line
*/
#include "busybox.h"
static int read_stduu(FILE *src_stream, FILE *dst_stream)
{
char *line;
while ((line = xmalloc_getline(src_stream)) != NULL) {
int length;
char *line_ptr = line;
if (strcmp(line, "end") == 0) {
return EXIT_SUCCESS;
}
length = ((*line_ptr - 0x20) & 0x3f)* 4 / 3;
if (length <= 0) {
/* Ignore the "`\n" line, why is it even in the encode file ? */
continue;
}
if (length > 60) {
bb_error_msg_and_die("line too long");
}
line_ptr++;
/* Tolerate an overly long line to accomodate a possible exta '`' */
if (strlen(line_ptr) < (size_t)length) {
bb_error_msg_and_die("short file");
}
while (length > 0) {
/* Merge four 6 bit chars to three 8 bit chars */
fputc(((line_ptr[0] - 0x20) & 077) << 2 | ((line_ptr[1] - 0x20) & 077) >> 4, dst_stream);
line_ptr++;
length--;
if (length == 0) {
break;
}
fputc(((line_ptr[0] - 0x20) & 077) << 4 | ((line_ptr[1] - 0x20) & 077) >> 2, dst_stream);
line_ptr++;
length--;
if (length == 0) {
break;
}
fputc(((line_ptr[0] - 0x20) & 077) << 6 | ((line_ptr[1] - 0x20) & 077), dst_stream);
line_ptr += 2;
length -= 2;
}
free(line);
}
bb_error_msg_and_die("short file");
}
static int read_base64(FILE *src_stream, FILE *dst_stream)
{
static const char base64_table[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n";
char term_count = 0;
while (1) {
char translated[4];
int count = 0;
while (count < 4) {
char *table_ptr;
int ch;
/* Get next _valid_ character */
do {
ch = fgetc(src_stream);
if (ch == EOF) {
bb_error_msg_and_die("short file");
}
} while ((table_ptr = strchr(base64_table, ch)) == NULL);
/* Convert encoded charcter to decimal */
ch = table_ptr - base64_table;
if (*table_ptr == '=') {
if (term_count == 0) {
translated[count] = 0;
break;
}
term_count++;
}
else if (*table_ptr == '\n') {
/* Check for terminating line */
if (term_count == 5) {
return EXIT_SUCCESS;
}
term_count = 1;
continue;
} else {
translated[count] = ch;
count++;
term_count = 0;
}
}
/* Merge 6 bit chars to 8 bit */
fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
if (count > 2) {
fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
}
if (count > 3) {
fputc(translated[2] << 6 | translated[3], dst_stream);
}
}
}
int uudecode_main(int argc, char **argv)
{
FILE *src_stream;
char *outname = NULL;
char *line;
getopt32(argc, argv, "o:", &outname);
if (optind == argc) {
src_stream = stdin;
} else if (optind + 1 == argc) {
src_stream = xfopen(argv[optind], "r");
} else {
bb_show_usage();
}
/* Search for the start of the encoding */
while ((line = xmalloc_getline(src_stream)) != NULL) {
int (*decode_fn_ptr)(FILE * src, FILE * dst);
char *line_ptr;
FILE *dst_stream;
int mode;
int ret;
if (strncmp(line, "begin-base64 ", 13) == 0) {
line_ptr = line + 13;
decode_fn_ptr = read_base64;
} else if (strncmp(line, "begin ", 6) == 0) {
line_ptr = line + 6;
decode_fn_ptr = read_stduu;
} else {
free(line);
continue;
}
mode = strtoul(line_ptr, NULL, 8);
if (outname == NULL) {
outname = strchr(line_ptr, ' ');
if ((outname == NULL) || (*outname == '\0')) {
break;
}
outname++;
}
if (LONE_DASH(outname)) {
dst_stream = stdout;
} else {
dst_stream = xfopen(outname, "w");
chmod(outname, mode & (S_IRWXU | S_IRWXG | S_IRWXO));
}
free(line);
ret = decode_fn_ptr(src_stream, dst_stream);
fclose_if_not_stdin(src_stream);
return ret;
}
bb_error_msg_and_die("no 'begin' line");
}