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sortix--sortix/utils/echo.cpp
Jonas 'Sortie' Termansen 0708482d9b Rewrite echo(1).
2013-12-17 14:30:46 +01:00

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6.1 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2013.
This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <http://www.gnu.org/licenses/>.
echo.cpp
Write arguments to standard output.
*******************************************************************************/
#include <errno.h>
#include <error.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#if !defined(VERSIONSTR)
#define VERSIONSTR "unknown version"
#endif
static void help(FILE* fp, const char* argv0)
{
fprintf(fp, "Usage: %s [SHORT-OPTION]... [STRING]...\n", argv0);
fprintf(fp, " or: %s [LONG-OPTION]\n", argv0);
fprintf(fp, "Echo the STRING(s) to standard output.\n");
fprintf(fp, "\n");
fprintf(fp, " -n do not output the trailing newline\n");
fprintf(fp, " -e enable interpretation of backslash escapes\n");
fprintf(fp, " -E disable interpretation of backslash escapes (default)\n");
fprintf(fp, " --help display this help and exit\n");
fprintf(fp, " --version output version information and exit\n");
fprintf(fp, "\n");
fprintf(fp, "If -e is in effect, the following sequences are recognized:\n");
fprintf(fp, "\n");
fprintf(fp, " \\\\ backslash\n");
fprintf(fp, " \\a alert (BEL)\n");
fprintf(fp, " \\b backspace\n");
fprintf(fp, " \\c produce no further output\n");
fprintf(fp, " \\e escape\n");
fprintf(fp, " \\f form feed\n");
fprintf(fp, " \\n new line\n");
fprintf(fp, " \\r carriage return\n");
fprintf(fp, " \\t horizontal tab\n");
fprintf(fp, " \\v vertical tab\n");
fprintf(fp, " \\0NNN byte with octal value NNN (1 to 3 digits)\n");
fprintf(fp, " \\xHH byte with hexadecimal value HH (1 to 2 digits)\n");
fprintf(fp, "\n");
}
static void version(FILE* fp, const char* argv0)
{
fprintf(fp, "%s (Sortix) %s\n", argv0, VERSIONSTR);
fprintf(fp, "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.\n");
fprintf(fp, "This is free software: you are free to change and redistribute it.\n");
fprintf(fp, "There is NO WARRANTY, to the extent permitted by law.\n");
}
static bool is_allowed_short_argument(const char* argument)
{
if ( argument[0] != '-' )
return false;
if ( !argument[1] )
return false;
for ( size_t i = 1; argument[i]; i++ )
{
switch ( argument[i] )
{
case 'e': break;
case 'E': break;
case 'n': break;
default: return false;
}
}
return true;
}
int main(int argc, char* argv[])
{
bool newline = true;
bool escape_sequences = false;
if ( 2 == argc && !strcmp(argv[1], "--help") )
help(stdout, argv[0]), exit(0);
if ( 2 == argc && !strcmp(argv[1], "--version") )
version(stdout, argv[0]), exit(0);
for ( int i = 1; i < argc; i++ )
{
const char* arg = argv[i];
if ( !is_allowed_short_argument(arg) )
break;
argv[i] = NULL;
for ( size_t n = 1; arg[n]; n++ )
{
switch ( arg[n] )
{
case 'e': escape_sequences = true; break;
case 'E': escape_sequences = false; break;
case 'n': newline = false; break;
default: break;
}
}
}
const char* prefix = "";
for ( int i = 1; i < argc; i++ )
{
const char* arg = argv[i];
if ( !arg )
continue;
if ( !escape_sequences )
{
if ( printf("%s%s", prefix, arg) < 0 )
error(1, errno, "<stdout>");
}
else
{
if ( printf("%s", prefix) < 0 )
error(1, errno, "<stdout>");
bool escaped = false;
for ( size_t i = 0; arg[i]; i++ )
{
char c = arg[i];
if ( escaped && (escaped = false, true) )
{
if ( c == '0' && (i++, true) )
{
int value = 0;
if ( '0' <= arg[i] && arg[i] <= '7' )
value = value * 8 + arg[i] - '0', i++;
if ( '0' <= arg[i] && arg[i] <= '7' )
value = value * 8 + arg[i] - '0', i++;
if ( '0' <= arg[i] && arg[i] <= '7' )
value = value * 8 + arg[i] - '0', i++;
if ( 255 < value )
value &= 255;
if ( putchar(value) == EOF )
error(1, errno, "<stdout>");
i--;
continue;
}
if ( c == 'x' && (i++, true) )
{
int value = 0;
if ( '0' <= arg[i] && arg[i] <= '7' )
value = value * 16 + arg[i] - '0', i++;
else if ( 'a' <= arg[i] && arg[i] <= 'f' )
value = value * 16 + arg[i] - 'a' + 10, i++;
else if ( 'A' <= arg[i] && arg[i] <= 'F' )
value = value * 16 + arg[i] - 'A' + 10, i++;
if ( '0' <= arg[i] && arg[i] <= '7' )
value = value * 16 + arg[i] - '0', i++;
else if ( 'a' <= arg[i] && arg[i] <= 'f' )
value = value * 16 + arg[i] - 'a' + 10, i++;
else if ( 'A' <= arg[i] && arg[i] <= 'F' )
value = value * 16 + arg[i] - 'A' + 10, i++;
if ( putchar(value) == EOF )
error(1, errno, "<stdout>");
i--;
continue;
}
switch ( c )
{
case '\\': c = '\\'; break;
case 'a': c = '\a'; break;
case 'b': c = '\b'; break;
case 'c': goto no_futher_output;
case 'e': c = '\e'; break;
case 'f': c = '\f'; break;
case 'n': c = '\n'; break;
case 'r': c = '\r'; break;
case 't': c = '\t'; break;
case 'v': c = '\v'; break;
default: break;
}
}
else if ( c == '\\' )
{
escaped = true;
continue;
}
if ( putchar((unsigned char) c) == EOF )
error(1, errno, "<stdout>");
}
if ( escaped && putchar('\\') == EOF )
error(1, errno, "<stdout>");
}
prefix = " ";
}
if ( newline && printf("\n") < 0 )
error(1, errno, "<stdout>");
no_futher_output:
if ( fflush(stdout) != 0 || fsync(1) != 0 )
error(1, errno, "<stdout>");
return 0;
}