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 /* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
  13  *
  14  * Because of behavioral differences, implemented configurable SUSv3
  15  * or 'fancy' gnu-ish behaviors.  Also, reduced size and fixed bugs.
  16  * 1) In handling '\c' escape, the previous version only suppressed the
  17  *     trailing newline.  SUSv3 specifies _no_ output after '\c'.
  18  * 2) SUSv3 specifies that octal escapes are of the form \0{#{#{#}}}.
  19  *    The previous version did not allow 4-digit octals.
  20  */
  21 //config:config ECHO
  22 //config:       bool "echo (2 kb)"
  23 //config:       default y
  24 //config:       help
  25 //config:       echo prints a specified string to stdout.
  26 //config:
  27 //config:# this entry also appears in shell/Config.in, next to the echo builtin
  28 //config:config FEATURE_FANCY_ECHO
  29 //config:       bool "Enable -n and -e options"
  30 //config:       default y
  31 //config:       depends on ECHO || ASH_ECHO || HUSH_ECHO
  32
  33 //applet:IF_ECHO(APPLET_NOFORK(echo, echo, BB_DIR_BIN, BB_SUID_DROP, echo))
  34
  35 //kbuild:lib-$(CONFIG_ECHO) += echo.o
  36
  37 //kbuild:lib-$(CONFIG_ASH_ECHO)  += echo.o
  38 //kbuild:lib-$(CONFIG_HUSH_ECHO) += echo.o
  39
  40 /* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
  41 /* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */
  42
  43 //usage:#define echo_trivial_usage
  44 //usage:        IF_FEATURE_FANCY_ECHO("[-neE] ") "[ARG]..."
  45 //usage:#define echo_full_usage "\n\n"
  46 //usage:       "Print ARGs to stdout"
  47 //usage:        IF_FEATURE_FANCY_ECHO( "\n"
  48 //usage:     "\n        -n      No trailing newline"
  49 //usage:     "\n        -e      Interpret backslash escapes (\\t=tab etc)"
  50 //usage:     "\n        -E      Don't interpret backslash escapes (default)"
  51 //usage:        )
  52 //usage:
  53 //usage:#define echo_example_usage
  54 //usage:       "$ echo \"Erik is cool\"\n"
  55 //usage:       "Erik is cool\n"
  56 //usage:        IF_FEATURE_FANCY_ECHO("$ echo -e \"Erik\\nis\\ncool\"\n"
  57 //usage:       "Erik\n"
  58 //usage:       "is\n"
  59 //usage:       "cool\n"
  60 //usage:       "$ echo \"Erik\\nis\\ncool\"\n"
  61 //usage:       "Erik\\nis\\ncool\n")
  62
  63 #include "libbb.h"
  64
  65 /* This is a NOFORK applet. Be very careful! */
  66
  67 /* NB: can be used by shell even if not enabled as applet */
  68
  69 /*
  70  * NB2: we don't use stdio, we need better error handing.
  71  * Examples include writing into non-opened stdout and error on write.
  72  *
  73  * With stdio, output gets shoveled into stdout buffer, and even
  74  * fflush cannot clear it out. It seems that even if libc receives
  75  * EBADF on write attempts, it feels determined to output data no matter what.
  76  * If echo is called by shell, it will try writing again later, and possibly
  77  * will clobber future output. Not good.
  78  *
  79  * Solaris has fpurge which discards buffered input. glibc has __fpurge.
  80  * But this function is not standard.
  81  */
  82
  83 int echo_main(int argc UNUSED_PARAM, char **argv)
  84 {
  85         char **pp;
  86         const char *arg;
  87         char *out;
  88         char *buffer;
  89         unsigned buflen;
  90         int err;
  91 #if !ENABLE_FEATURE_FANCY_ECHO
  92         enum {
  93                 eflag = 0,  /* 0 -- disable escape sequences */
  94                 nflag = 1,  /* 1 -- print '\n' */
  95         };
  96
  97         argv++;
  98 #else
  99         char nflag = 1;
 100         char eflag = 0;
 101
 102         while ((arg = *++argv) != NULL) {
 103                 char n, e;
 104
 105                 if (arg[0] != '-')
 106                         break; /* not an option arg, echo it */
 107
 108                 /* If it appears that we are handling options, then make sure
 109                  * that all of the options specified are actually valid.
 110                  * Otherwise, the string should just be echoed.
 111                  */
 112                 arg++;
 113                 n = nflag;
 114                 e = eflag;
 115                 do {
 116                         if (*arg == 'n')
 117                                 n = 0;
 118                         else if (*arg == 'e')
 119                                 e = '\\';
 120                         else if (*arg != 'E') {
 121                                 /* "-ccc" arg with one of c's invalid, echo it */
 122                                 /* arg consisting from just "-" also handled here */
 123                                 goto just_echo;
 124                         }
 125                 } while (*++arg);
 126                 nflag = n;
 127                 eflag = e;
 128         }
 129  just_echo:
 130 #endif
 131
 132         buflen = 0;
 133         pp = argv;
 134         while ((arg = *pp) != NULL) {
 135                 buflen += strlen(arg) + 1;
 136                 pp++;
 137         }
 138         out = buffer = xmalloc(buflen + 1); /* +1 is needed for "no args" case */
 139
 140         while ((arg = *argv) != NULL) {
 141                 int c;
 142
 143                 if (!eflag) {
 144                         /* optimization for very common case */
 145                         out = stpcpy(out, arg);
 146                 } else
 147                 while ((c = *arg++) != '\0') {
 148                         if (c == eflag) {
 149                                 /* This is an "\x" sequence */
 150
 151                                 if (*arg == 'c') {
 152                                         /* "\c" means cancel newline and
 153                                          * ignore all subsequent chars. */
 154                                         goto do_write;
 155                                 }
 156                                 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
 157                                 * of the form \0### are accepted. */
 158                                 if (*arg == '0') {
 159                                         if ((unsigned char)(arg[1] - '0') < 8) {
 160                                                 /* 2nd char is 0..7: skip leading '0' */
 161                                                 arg++;
 162                                         }
 163                                 }
 164                                 /* bb_process_escape_sequence handles NUL correctly
 165                                  * ("...\" case). */
 166                                 {
 167                                         /* optimization: don't force arg to be on-stack,
 168                                          * use another variable for that. ~30 bytes win */
 169                                         const char *z = arg;
 170                                         c = bb_process_escape_sequence(&z);
 171                                         arg = z;
 172                                 }
 173                         }
 174                         *out++ = c;
 175                 }
 176
 177                 if (!*++argv)
 178                         break;
 179                 *out++ = ' ';
 180         }
 181
 182         if (nflag) {
 183                 *out++ = '\n';
 184         }
 185
 186  do_write:
 187         /* Careful to error out on partial writes too (think ENOSPC!) */
 188         errno = 0;
 189         err = full_write(STDOUT_FILENO, buffer, out - buffer) != out - buffer;
 190         if (err) {
 191                 bb_simple_perror_msg(bb_msg_write_error);
 192         }
 193         free(buffer);
 194         return err;
 195 }
 196
 197 /*
 198  * Copyright (c) 1991, 1993
 199  *      The Regents of the University of California.  All rights reserved.
 200  *
 201  * This code is derived from software contributed to Berkeley by
 202  * Kenneth Almquist.
 203  *
 204  * Redistribution and use in source and binary forms, with or without
 205  * modification, are permitted provided that the following conditions
 206  * are met:
 207  * 1. Redistributions of source code must retain the above copyright
 208  *    notice, this list of conditions and the following disclaimer.
 209  * 2. Redistributions in binary form must reproduce the above copyright
 210  *    notice, this list of conditions and the following disclaimer in the
 211  *    documentation and/or other materials provided with the distribution.
 212  *
 213  * 3. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
 214  *              ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
 215  *
 216  *      California, Berkeley and its contributors.
 217  * 4. Neither the name of the University nor the names of its contributors
 218  *    may be used to endorse or promote products derived from this software
 219  *    without specific prior written permission.
 220  *
 221  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND
 222  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 223  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 224  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 225  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 226  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 227  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 228  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 229  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 230  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 231  * SUCH DAMAGE.
 232  *
 233  *      @(#)echo.c      8.1 (Berkeley) 5/31/93
 234  */
 235
 236 #ifdef VERSION_WITH_WRITEV
 237 /* We can't use stdio.
 238  * The reason for this is highly non-obvious.
 239  * echo_main is used from shell. Shell must correctly handle "echo foo"
 240  * if stdout is closed. With stdio, output gets shoveled into
 241  * stdout buffer, and even fflush cannot clear it out. It seems that
 242  * even if libc receives EBADF on write attempts, it feels determined
 243  * to output data no matter what. So it will try later,
 244  * and possibly will clobber future output. Not good.
 245  *
 246  * Using writev instead, with 'direct' conversion of argv vector.
 247  */
 248
 249 int echo_main(int argc, char **argv)
 250 {
 251         struct iovec io[argc];
 252         struct iovec *cur_io = io;
 253         char *arg;
 254         char *p;
 255 #if !ENABLE_FEATURE_FANCY_ECHO
 256         enum {
 257                 eflag = '\\',
 258                 nflag = 1,  /* 1 -- print '\n' */
 259         };
 260         arg = *++argv;
 261         if (!arg)
 262                 goto newline_ret;
 263 #else
 264         char nflag = 1;
 265         char eflag = 0;
 266
 267         while (1) {
 268                 arg = *++argv;
 269                 if (!arg)
 270                         goto newline_ret;
 271                 if (*arg != '-')
 272                         break;
 273
 274                 /* If it appears that we are handling options, then make sure
 275                  * that all of the options specified are actually valid.
 276                  * Otherwise, the string should just be echoed.
 277                  */
 278                 p = arg + 1;
 279                 if (!*p)        /* A single '-', so echo it. */
 280                         goto just_echo;
 281
 282                 do {
 283                         if (!strchr("neE", *p))
 284                                 goto just_echo;
 285                 } while (*++p);
 286
 287                 /* All of the options in this arg are valid, so handle them. */
 288                 p = arg + 1;
 289                 do {
 290                         if (*p == 'n')
 291                                 nflag = 0;
 292                         if (*p == 'e')
 293                                 eflag = '\\';
 294                 } while (*++p);
 295         }
 296  just_echo:
 297 #endif
 298
 299         while (1) {
 300                 /* arg is already == *argv and isn't NULL */
 301                 int c;
 302
 303                 cur_io->iov_base = p = arg;
 304
 305                 if (!eflag) {
 306                         /* optimization for very common case */
 307                         p += strlen(arg);
 308                 } else while ((c = *arg++)) {
 309                         if (c == eflag) {
 310                                 /* This is an "\x" sequence */
 311
 312                                 if (*arg == 'c') {
 313                                         /* "\c" means cancel newline and
 314                                          * ignore all subsequent chars. */
 315                                         cur_io->iov_len = p - (char*)cur_io->iov_base;
 316                                         cur_io++;
 317                                         goto ret;
 318                                 }
 319                                 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
 320                                 * of the form \0### are accepted. */
 321                                 if (*arg == '0' && (unsigned char)(arg[1] - '0') < 8) {
 322                                         arg++;
 323                                 }
 324 //FIXME? we also accept non-0 starting sequences (see echo-prints-slash_41 test)
 325 // echo -ne '-\41-' prints "-!-". bash 5.0.17 does not (prints "-\41-").
 326                                 /* bb_process_escape_sequence can handle nul correctly */
 327                                 c = bb_process_escape_sequence( (void*) &arg);
 328                         }
 329                         *p++ = c;
 330                 }
 331
 332                 arg = *++argv;
 333                 if (arg)
 334                         *p++ = ' ';
 335                 cur_io->iov_len = p - (char*)cur_io->iov_base;
 336                 cur_io++;
 337                 if (!arg)
 338                         break;
 339         }
 340
 341  newline_ret:
 342         if (nflag) {
 343                 cur_io->iov_base = (char*)"\n";
 344                 cur_io->iov_len = 1;
 345                 cur_io++;
 346         }
 347  ret:
 348         /* TODO: implement and use full_writev? */
 349         return writev(1, io, (cur_io - io)) >= 0;
 350 }
 351 #endif