busybox/coreutils/echo.c

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/* vi: set sw=4 ts=4: */
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/*
* echo implementation for busybox
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*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
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*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*
* Original copyright notice is retained at the end of this file.
*/
/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
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*
* Because of behavioral differences, implemented configurable SUSv3
* or 'fancy' gnu-ish behaviors. Also, reduced size and fixed bugs.
* 1) In handling '\c' escape, the previous version only suppressed the
* trailing newline. SUSv3 specifies _no_ output after '\c'.
* 2) SUSv3 specifies that octal escapes are of the form \0{#{#{#}}}.
* The previous version did not allow 4-digit octals.
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*/
//config:config ECHO
//config: bool "echo (basic SuSv3 version taking no options)"
//config: default y
//config: help
//config: echo is used to print a specified string to stdout.
//config:
//config:# this entry also appears in shell/Config.in, next to the echo builtin
//config:config FEATURE_FANCY_ECHO
//config: bool "Enable echo options (-n and -e)"
//config: default y
//config: depends on ECHO || ASH_BUILTIN_ECHO || HUSH
//config: help
//config: This adds options (-n and -e) to echo.
//applet:IF_ECHO(APPLET_NOFORK(echo, echo, BB_DIR_BIN, BB_SUID_DROP, echo))
//kbuild:lib-$(CONFIG_ECHO) += echo.o
/* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */
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//usage:#define echo_trivial_usage
//usage: IF_FEATURE_FANCY_ECHO("[-neE] ") "[ARG]..."
//usage:#define echo_full_usage "\n\n"
//usage: "Print the specified ARGs to stdout"
//usage: IF_FEATURE_FANCY_ECHO( "\n"
//usage: "\n -n Suppress trailing newline"
//usage: "\n -e Interpret backslash escapes (i.e., \\t=tab)"
//usage: "\n -E Don't interpret backslash escapes (default)"
//usage: )
//usage:
//usage:#define echo_example_usage
//usage: "$ echo \"Erik is cool\"\n"
//usage: "Erik is cool\n"
//usage: IF_FEATURE_FANCY_ECHO("$ echo -e \"Erik\\nis\\ncool\"\n"
//usage: "Erik\n"
//usage: "is\n"
//usage: "cool\n"
//usage: "$ echo \"Erik\\nis\\ncool\"\n"
//usage: "Erik\\nis\\ncool\n")
#include "libbb.h"
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/* This is a NOFORK applet. Be very careful! */
/* NB: can be used by shell even if not enabled as applet */
/*
* NB2: we don't use stdio, we need better error handing.
* Examples include writing into non-opened stdout and error on write.
*
* With stdio, output gets shoveled into stdout buffer, and even
* fflush cannot clear it out. It seems that even if libc receives
* EBADF on write attempts, it feels determined to output data no matter what.
* If echo is called by shell, it will try writing again later, and possibly
* will clobber future output. Not good.
*
* Solaris has fpurge which discards buffered input. glibc has __fpurge.
* But this function is not standard.
*/
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int echo_main(int argc UNUSED_PARAM, char **argv)
{
char **pp;
const char *arg;
char *out;
char *buffer;
unsigned buflen;
#if !ENABLE_FEATURE_FANCY_ECHO
enum {
eflag = 0, /* 0 -- disable escape sequences */
nflag = 1, /* 1 -- print '\n' */
};
argv++;
#else
char nflag = 1;
char eflag = 0;
while ((arg = *++argv) != NULL) {
char n, e;
if (arg[0] != '-')
break; /* not an option arg, echo it */
/* If it appears that we are handling options, then make sure
* that all of the options specified are actually valid.
* Otherwise, the string should just be echoed.
*/
arg++;
n = nflag;
e = eflag;
do {
if (*arg == 'n')
n = 0;
else if (*arg == 'e')
e = '\\';
else if (*arg != 'E') {
/* "-ccc" arg with one of c's invalid, echo it */
/* arg consisting from just "-" also handled here */
goto just_echo;
}
} while (*++arg);
nflag = n;
eflag = e;
}
just_echo:
#endif
buflen = 0;
pp = argv;
while ((arg = *pp) != NULL) {
buflen += strlen(arg) + 1;
pp++;
}
out = buffer = xmalloc(buflen + 1); /* +1 is needed for "no args" case */
while ((arg = *argv) != NULL) {
int c;
if (!eflag) {
/* optimization for very common case */
out = stpcpy(out, arg);
} else
while ((c = *arg++) != '\0') {
if (c == eflag) {
/* This is an "\x" sequence */
if (*arg == 'c') {
/* "\c" means cancel newline and
* ignore all subsequent chars. */
goto do_write;
}
/* Since SUSv3 mandates a first digit of 0, 4-digit octals
* of the form \0### are accepted. */
if (*arg == '0') {
if ((unsigned char)(arg[1] - '0') < 8) {
/* 2nd char is 0..7: skip leading '0' */
arg++;
}
}
/* bb_process_escape_sequence handles NUL correctly
* ("...\" case). */
{
/* optimization: don't force arg to be on-stack,
* use another variable for that. ~30 bytes win */
const char *z = arg;
c = bb_process_escape_sequence(&z);
arg = z;
}
}
*out++ = c;
}
if (!*++argv)
break;
*out++ = ' ';
}
if (nflag) {
*out++ = '\n';
}
do_write:
/* Careful to error out on partial writes too (think ENOSPC!) */
errno = 0;
/*r =*/ full_write(STDOUT_FILENO, buffer, out - buffer);
free(buffer);
if (/*WRONG:r < 0*/ errno) {
bb_perror_msg(bb_msg_write_error);
return 1;
}
return 0;
}
/*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Kenneth Almquist.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
* ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
*
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)echo.c 8.1 (Berkeley) 5/31/93
*/
#ifdef VERSION_WITH_WRITEV
/* We can't use stdio.
* The reason for this is highly non-obvious.
* echo_main is used from shell. Shell must correctly handle "echo foo"
* if stdout is closed. With stdio, output gets shoveled into
* stdout buffer, and even fflush cannot clear it out. It seems that
* even if libc receives EBADF on write attempts, it feels determined
* to output data no matter what. So it will try later,
* and possibly will clobber future output. Not good.
*
* Using writev instead, with 'direct' conversion of argv vector.
*/
int echo_main(int argc, char **argv)
{
struct iovec io[argc];
struct iovec *cur_io = io;
char *arg;
char *p;
#if !ENABLE_FEATURE_FANCY_ECHO
enum {
eflag = '\\',
nflag = 1, /* 1 -- print '\n' */
};
arg = *++argv;
if (!arg)
goto newline_ret;
#else
char nflag = 1;
char eflag = 0;
while (1) {
arg = *++argv;
if (!arg)
goto newline_ret;
if (*arg != '-')
break;
/* If it appears that we are handling options, then make sure
* that all of the options specified are actually valid.
* Otherwise, the string should just be echoed.
*/
p = arg + 1;
if (!*p) /* A single '-', so echo it. */
goto just_echo;
do {
if (!strchr("neE", *p))
goto just_echo;
} while (*++p);
/* All of the options in this arg are valid, so handle them. */
p = arg + 1;
do {
if (*p == 'n')
nflag = 0;
if (*p == 'e')
eflag = '\\';
} while (*++p);
}
just_echo:
#endif
while (1) {
/* arg is already == *argv and isn't NULL */
int c;
cur_io->iov_base = p = arg;
if (!eflag) {
/* optimization for very common case */
p += strlen(arg);
} else while ((c = *arg++)) {
if (c == eflag) {
/* This is an "\x" sequence */
if (*arg == 'c') {
/* "\c" means cancel newline and
* ignore all subsequent chars. */
cur_io->iov_len = p - (char*)cur_io->iov_base;
cur_io++;
goto ret;
}
/* Since SUSv3 mandates a first digit of 0, 4-digit octals
* of the form \0### are accepted. */
if (*arg == '0' && (unsigned char)(arg[1] - '0') < 8) {
arg++;
}
/* bb_process_escape_sequence can handle nul correctly */
c = bb_process_escape_sequence( (void*) &arg);
}
*p++ = c;
}
arg = *++argv;
if (arg)
*p++ = ' ';
cur_io->iov_len = p - (char*)cur_io->iov_base;
cur_io++;
if (!arg)
break;
}
newline_ret:
if (nflag) {
cur_io->iov_base = (char*)"\n";
cur_io->iov_len = 1;
cur_io++;
}
ret:
/* TODO: implement and use full_writev? */
return writev(1, io, (cur_io - io)) >= 0;
}
#endif