release/src/router/busybox/coreutils/echo.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * echo implementation for busybox
   4  *
   5  * Copyright (c) 1991, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9  *
  10  * Original copyright notice is retained at the end of this file.
  11  */
  12
  13 /* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
  14 /* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */
  15
  16 /* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
  17  *
  18  * Because of behavioral differences, implemented configurable SUSv3
  19  * or 'fancy' gnu-ish behaviors.  Also, reduced size and fixed bugs.
  20  * 1) In handling '\c' escape, the previous version only suppressed the
  21  *     trailing newline.  SUSv3 specifies _no_ output after '\c'.
  22  * 2) SUSv3 specifies that octal escapes are of the form \0{#{#{#}}}.
  23  *    The previous version did not allow 4-digit octals.
  24  */
  25
  26 //usage:#define echo_trivial_usage
  27 //usage:        IF_FEATURE_FANCY_ECHO("[-neE] ") "[ARG]..."
  28 //usage:#define echo_full_usage "\n\n"
  29 //usage:       "Print the specified ARGs to stdout"
  30 //usage:        IF_FEATURE_FANCY_ECHO( "\n"
  31 //usage:     "\n        -n      Suppress trailing newline"
  32 //usage:     "\n        -e      Interpret backslash escapes (i.e., \\t=tab)"
  33 //usage:     "\n        -E      Don't interpret backslash escapes (default)"
  34 //usage:        )
  35 //usage:
  36 //usage:#define echo_example_usage
  37 //usage:       "$ echo \"Erik is cool\"\n"
  38 //usage:       "Erik is cool\n"
  39 //usage:        IF_FEATURE_FANCY_ECHO("$ echo -e \"Erik\\nis\\ncool\"\n"
  40 //usage:       "Erik\n"
  41 //usage:       "is\n"
  42 //usage:       "cool\n"
  43 //usage:       "$ echo \"Erik\\nis\\ncool\"\n"
  44 //usage:       "Erik\\nis\\ncool\n")
  45
  46 #include "libbb.h"
  47
  48 /* This is a NOFORK applet. Be very careful! */
  49
  50 /* NB: can be used by shell even if not enabled as applet */
  51
  52 /*
  53  * NB2: we don't use stdio, we need better error handing.
  54  * Examples include writing into non-opened stdout and error on write.
  55  *
  56  * With stdio, output gets shoveled into stdout buffer, and even
  57  * fflush cannot clear it out. It seems that even if libc receives
  58  * EBADF on write attempts, it feels determined to output data no matter what.
  59  * If echo is called by shell, it will try writing again later, and possibly
  60  * will clobber future output. Not good.
  61  *
  62  * Solaris has fpurge which discards buffered input. glibc has __fpurge.
  63  * But this function is not standard.
  64  */
  65
  66 int echo_main(int argc UNUSED_PARAM, char **argv)
  67 {
  68         char **pp;
  69         const char *arg;
  70         char *out;
  71         char *buffer;
  72         unsigned buflen;
  73 #if !ENABLE_FEATURE_FANCY_ECHO
  74         enum {
  75                 eflag = '\\',
  76                 nflag = 1,  /* 1 -- print '\n' */
  77         };
  78
  79         argv++;
  80 #else
  81         char nflag = 1;
  82         char eflag = 0;
  83
  84         while ((arg = *++argv) != NULL) {
  85                 char n, e;
  86
  87                 if (arg[0] != '-')
  88                         break; /* not an option arg, echo it */
  89
  90                 /* If it appears that we are handling options, then make sure
  91                  * that all of the options specified are actually valid.
  92                  * Otherwise, the string should just be echoed.
  93                  */
  94                 arg++;
  95                 n = nflag;
  96                 e = eflag;
  97                 do {
  98                         if (*arg == 'n')
  99                                 n = 0;
 100                         else if (*arg == 'e')
 101                                 e = '\\';
 102                         else if (*arg != 'E') {
 103                                 /* "-ccc" arg with one of c's invalid, echo it */
 104                                 /* arg consisting from just "-" also handled here */
 105                                 goto just_echo;
 106                         }
 107                 } while (*++arg);
 108                 nflag = n;
 109                 eflag = e;
 110         }
 111  just_echo:
 112 #endif
 113
 114         buflen = 0;
 115         pp = argv;
 116         while ((arg = *pp) != NULL) {
 117                 buflen += strlen(arg) + 1;
 118                 pp++;
 119         }
 120         out = buffer = xmalloc(buflen + 1); /* +1 is needed for "no args" case */
 121
 122         while ((arg = *argv) != NULL) {
 123                 int c;
 124
 125                 if (!eflag) {
 126                         /* optimization for very common case */
 127                         out = stpcpy(out, arg);
 128                 } else
 129                 while ((c = *arg++) != '\0') {
 130                         if (c == eflag) {
 131                                 /* This is an "\x" sequence */
 132
 133                                 if (*arg == 'c') {
 134                                         /* "\c" means cancel newline and
 135                                          * ignore all subsequent chars. */
 136                                         goto do_write;
 137                                 }
 138                                 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
 139                                 * of the form \0### are accepted. */
 140                                 if (*arg == '0') {
 141                                         if ((unsigned char)(arg[1] - '0') < 8) {
 142                                                 /* 2nd char is 0..7: skip leading '0' */
 143                                                 arg++;
 144                                         }
 145                                 }
 146                                 /* bb_process_escape_sequence handles NUL correctly
 147                                  * ("...\" case). */
 148                                 {
 149                                         /* optimization: don't force arg to be on-stack,
 150                                          * use another variable for that. ~30 bytes win */
 151                                         const char *z = arg;
 152                                         c = bb_process_escape_sequence(&z);
 153                                         arg = z;
 154                                 }
 155                         }
 156                         *out++ = c;
 157                 }
 158
 159                 if (!*++argv)
 160                         break;
 161                 *out++ = ' ';
 162         }
 163
 164         if (nflag) {
 165                 *out++ = '\n';
 166         }
 167
 168  do_write:
 169         /* Careful to error out on partial writes too (think ENOSPC!) */
 170         errno = 0;
 171         /*r =*/ full_write(STDOUT_FILENO, buffer, out - buffer);
 172         free(buffer);
 173         if (/*WRONG:r < 0*/ errno) {
 174                 bb_perror_msg(bb_msg_write_error);
 175                 return 1;
 176         }
 177         return 0;
 178 }
 179
 180 /*
 181  * Copyright (c) 1991, 1993
 182  *      The Regents of the University of California.  All rights reserved.
 183  *
 184  * This code is derived from software contributed to Berkeley by
 185  * Kenneth Almquist.
 186  *
 187  * Redistribution and use in source and binary forms, with or without
 188  * modification, are permitted provided that the following conditions
 189  * are met:
 190  * 1. Redistributions of source code must retain the above copyright
 191  *    notice, this list of conditions and the following disclaimer.
 192  * 2. Redistributions in binary form must reproduce the above copyright
 193  *    notice, this list of conditions and the following disclaimer in the
 194  *    documentation and/or other materials provided with the distribution.
 195  *
 196  * 3. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
 197  *              ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
 198  *
 199  *      California, Berkeley and its contributors.
 200  * 4. Neither the name of the University nor the names of its contributors
 201  *    may be used to endorse or promote products derived from this software
 202  *    without specific prior written permission.
 203  *
 204  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 205  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 206  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 207  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 208  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 209  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 210  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 211  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 212  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 213  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 214  * SUCH DAMAGE.
 215  *
 216  *      @(#)echo.c      8.1 (Berkeley) 5/31/93
 217  */
 218
 219 #ifdef VERSION_WITH_WRITEV
 220 /* We can't use stdio.
 221  * The reason for this is highly non-obvious.
 222  * echo_main is used from shell. Shell must correctly handle "echo foo"
 223  * if stdout is closed. With stdio, output gets shoveled into
 224  * stdout buffer, and even fflush cannot clear it out. It seems that
 225  * even if libc receives EBADF on write attempts, it feels determined
 226  * to output data no matter what. So it will try later,
 227  * and possibly will clobber future output. Not good.
 228  *
 229  * Using writev instead, with 'direct' conversion of argv vector.
 230  */
 231
 232 int echo_main(int argc, char **argv)
 233 {
 234         struct iovec io[argc];
 235         struct iovec *cur_io = io;
 236         char *arg;
 237         char *p;
 238 #if !ENABLE_FEATURE_FANCY_ECHO
 239         enum {
 240                 eflag = '\\',
 241                 nflag = 1,  /* 1 -- print '\n' */
 242         };
 243         arg = *++argv;
 244         if (!arg)
 245                 goto newline_ret;
 246 #else
 247         char nflag = 1;
 248         char eflag = 0;
 249
 250         while (1) {
 251                 arg = *++argv;
 252                 if (!arg)
 253                         goto newline_ret;
 254                 if (*arg != '-')
 255                         break;
 256
 257                 /* If it appears that we are handling options, then make sure
 258                  * that all of the options specified are actually valid.
 259                  * Otherwise, the string should just be echoed.
 260                  */
 261                 p = arg + 1;
 262                 if (!*p)        /* A single '-', so echo it. */
 263                         goto just_echo;
 264
 265                 do {
 266                         if (!strchr("neE", *p))
 267                                 goto just_echo;
 268                 } while (*++p);
 269
 270                 /* All of the options in this arg are valid, so handle them. */
 271                 p = arg + 1;
 272                 do {
 273                         if (*p == 'n')
 274                                 nflag = 0;
 275                         if (*p == 'e')
 276                                 eflag = '\\';
 277                 } while (*++p);
 278         }
 279  just_echo:
 280 #endif
 281
 282         while (1) {
 283                 /* arg is already == *argv and isn't NULL */
 284                 int c;
 285
 286                 cur_io->iov_base = p = arg;
 287
 288                 if (!eflag) {
 289                         /* optimization for very common case */
 290                         p += strlen(arg);
 291                 } else while ((c = *arg++)) {
 292                         if (c == eflag) {
 293                                 /* This is an "\x" sequence */
 294
 295                                 if (*arg == 'c') {
 296                                         /* "\c" means cancel newline and
 297                                          * ignore all subsequent chars. */
 298                                         cur_io->iov_len = p - (char*)cur_io->iov_base;
 299                                         cur_io++;
 300                                         goto ret;
 301                                 }
 302                                 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
 303                                 * of the form \0### are accepted. */
 304                                 if (*arg == '0' && (unsigned char)(arg[1] - '0') < 8) {
 305                                         arg++;
 306                                 }
 307                                 /* bb_process_escape_sequence can handle nul correctly */
 308                                 c = bb_process_escape_sequence( (void*) &arg);
 309                         }
 310                         *p++ = c;
 311                 }
 312
 313                 arg = *++argv;
 314                 if (arg)
 315                         *p++ = ' ';
 316                 cur_io->iov_len = p - (char*)cur_io->iov_base;
 317                 cur_io++;
 318                 if (!arg)
 319                         break;
 320         }
 321
 322  newline_ret:
 323         if (nflag) {
 324                 cur_io->iov_base = (char*)"\n";
 325                 cur_io->iov_len = 1;
 326                 cur_io++;
 327         }
 328  ret:
 329         /* TODO: implement and use full_writev? */
 330         return writev(1, io, (cur_io - io)) >= 0;
 331 }
 332 #endif