source: MondoRescue/branches/3.3/mindi-busybox/coreutils/echo.c@ 3621

/* vi: set sw=4 ts=4: */
/*
 * echo implementation for busybox
 *
 * Copyright (c) 1991, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Original copyright notice is retained at the end of this file.
 */

/* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */

/* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
 *
 * 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.
 */

//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"

/* 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.
 */

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