src/stdbuf.c

   1 /* stdbuf -- setup the standard streams for a command
   2    Copyright (C) 2009 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Pádraig Brady.  */
  18
  19 #include <config.h>
  20 #include <stdio.h>
  21 #include <getopt.h>
  22 #include <sys/types.h>
  23 #include <assert.h>
  24
  25 #include "system.h"
  26 #include "error.h"
  27 #include "posixver.h"
  28 #include "quote.h"
  29 #include "xstrtol.h"
  30 #include "c-ctype.h"
  31
  32 /* The official name of this program (e.g., no `g' prefix).  */
  33 #define PROGRAM_NAME "stdbuf"
  34 #define LIB_NAME "libstdbuf.so" /* FIXME: don't hardcode  */
  35
  36 #define AUTHORS proper_name_utf8 ("Padraig Brady", "P\303\241draig Brady")
  37
  38 /* Internal error  */
  39 enum { EXIT_CANCELED = 125 };
  40
  41 static char *program_path;
  42
  43 extern char **environ;
  44
  45 static struct
  46 {
  47   size_t size;
  48   int optc;
  49   char *optarg;
  50 } stdbuf[3];
  51
  52 static struct option const longopts[] =
  53 {
  54   {"input", required_argument, NULL, 'i'},
  55   {"output", required_argument, NULL, 'o'},
  56   {"error", required_argument, NULL, 'e'},
  57   {GETOPT_HELP_OPTION_DECL},
  58   {GETOPT_VERSION_OPTION_DECL},
  59   {NULL, 0, NULL, 0}
  60 };
  61
  62 /* Set size to the value of STR, interpreted as a decimal integer,
  63    optionally multiplied by various values.
  64    Return -1 on error, 0 on success.
  65
  66    This supports dd BLOCK size suffixes.
  67    Note we don't support dd's b=512, c=1, w=2 or 21x512MiB formats.  */
  68 static int
  69 parse_size (char const *str, size_t *size)
  70 {
  71   uintmax_t tmp_size;
  72   enum strtol_error e = xstrtoumax (str, NULL, 10, &tmp_size, "EGkKMPTYZ0");
  73   if (e == LONGINT_OK && tmp_size > SIZE_MAX)
  74     e = LONGINT_OVERFLOW;
  75
  76   if (e == LONGINT_OK)
  77     {
  78       errno = 0;
  79       *size = tmp_size;
  80       return 0;
  81     }
  82
  83   errno = (e == LONGINT_OVERFLOW ? EOVERFLOW : 0);
  84   return -1;
  85 }
  86
  87 void
  88 usage (int status)
  89 {
  90   if (status != EXIT_SUCCESS)
  91     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  92              program_name);
  93   else
  94     {
  95       printf (_("Usage: %s OPTION... COMMAND\n"), program_name);
  96       fputs (_("\
  97 Run COMMAND, with modified buffering operations for its standard streams.\n\
  98 \n\
  99 "), stdout);
 100       fputs (_("\
 101 Mandatory arguments to long options are mandatory for short options too.\n\
 102 "), stdout);
 103       fputs (_("\
 104   -i, --input=MODE   Adjust standard input stream buffering\n\
 105   -o, --output=MODE  Adjust standard output stream buffering\n\
 106   -e, --error=MODE   Adjust standard error stream buffering\n\
 107 "), stdout);
 108       fputs (HELP_OPTION_DESCRIPTION, stdout);
 109       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 110       fputs (_("\n\
 111 If MODE is `L' then corresponding stream will be line buffered.\n\
 112 This option is invalid with standard input.\n"), stdout);
 113       fputs (_("\n\
 114 If MODE is `0' then corresponding stream will be unbuffered.\n\
 115 "), stdout);
 116       fputs (_("\n\
 117 Otherwise MODE is a number which may be followed by one of the following:\n\
 118 KB 1000, K 1024, MB 1000*1000, M 1024*1024, and so on for G, T, P, E, Z, Y.\n\
 119 In this case the corresponding stream will be fully buffered with the buffer\n\
 120 size set to MODE bytes.\n\
 121 "), stdout);
 122       fputs (_("\n\
 123 NOTE: If COMMAND adjusts the buffering of its standard streams (`tee' does\n\
 124 for e.g.) then that will override corresponding settings changed by `stdbuf'.\n\
 125 Also some filters (like `dd' and `cat' etc.) don't use streams for I/O,\n\
 126 and are thus unaffected by `stdbuf' settings.\n\
 127 "), stdout);
 128       emit_bug_reporting_address ();
 129     }
 130   exit (status);
 131 }
 132
 133 /* argv[0] can be anything really, but generally it contains
 134    the path to the executable or just a name if it was executed
 135    using $PATH. In the latter case to get the path we can:
 136    search getenv("PATH"), readlink("/prof/self/exe"), getenv("_"),
 137    dladdr(), pstat_getpathname(), etc.  */
 138
 139 static void
 140 set_program_path (const char *arg)
 141 {
 142   if (strchr (arg, '/'))        /* Use absolute or relative paths directly.  */
 143     {
 144       program_path = dir_name (arg);
 145     }
 146   else
 147     {
 148       char *path;
 149       char tmppath[PATH_MAX + 1];
 150       ssize_t len = readlink ("/proc/self/exe", tmppath, sizeof (tmppath) - 1);
 151       if (len > 0)
 152         {
 153           tmppath[len] = '\0';
 154           program_path = dir_name (tmppath);
 155         }
 156       else if ((path = getenv ("PATH")))
 157         {
 158           char *dir;
 159           path = xstrdup (path);
 160           for (dir = strtok (path, ":"); dir != NULL; dir = strtok (NULL, ":"))
 161             {
 162               int req = snprintf (tmppath, sizeof (tmppath), "%s/%s", dir, arg);
 163               if (req >= sizeof (tmppath))
 164                 {
 165                   error (0, 0, _("path truncated when looking for %s"),
 166                          quote (arg));
 167                 }
 168               else if (access (tmppath, X_OK) == 0)
 169                 {
 170                   program_path = dir_name (tmppath);
 171                   break;
 172                 }
 173             }
 174           free (path);
 175         }
 176     }
 177 }
 178
 179 static int
 180 optc_to_fileno (int c)
 181 {
 182   int ret = -1;
 183
 184   switch (c)
 185     {
 186     case 'e':
 187       ret = STDERR_FILENO;
 188       break;
 189     case 'i':
 190       ret = STDIN_FILENO;
 191       break;
 192     case 'o':
 193       ret = STDOUT_FILENO;
 194       break;
 195     }
 196
 197   return ret;
 198 }
 199
 200 static void
 201 set_LD_PRELOAD (void)
 202 {
 203   int ret;
 204   char *old_libs = getenv ("LD_PRELOAD");
 205   char *LD_PRELOAD;
 206
 207   /* Note this would auto add the appropriate search path for "libstdbuf.so":
 208      gcc stdbuf.c -Wl,-rpath,'$ORIGIN' -Wl,-rpath,$PKGLIBDIR
 209      However we want the lookup done for the exec'd command not stdbuf.
 210
 211      Since we don't link against libstdbuf.so add it to LIBDIR rather than
 212      LIBEXECDIR, as we'll search for it in the "sys default" case below.  */
 213   char const *const search_path[] = {
 214     program_path,
 215     PKGLIBDIR,
 216     "",                         /* sys default */
 217     NULL
 218   };
 219
 220   char const *const *path = search_path;
 221   char *libstdbuf;
 222
 223   do
 224     {
 225       struct stat sb;
 226
 227       if (!**path)              /* system default  */
 228         {
 229           libstdbuf = xstrdup (LIB_NAME);
 230           break;
 231         }
 232       ret = asprintf (&libstdbuf, "%s/%s", *path, LIB_NAME);
 233       if (ret < 0)
 234         xalloc_die ();
 235       if (stat (libstdbuf, &sb) == 0)   /* file_exists  */
 236         break;
 237       free (libstdbuf);
 238     }
 239   while (*++path);
 240
 241   /* FIXME: Do we need to support libstdbuf.dll, c:, '\' separators etc?  */
 242
 243   if (old_libs)
 244     ret = asprintf (&LD_PRELOAD, "LD_PRELOAD=%s:%s", old_libs, libstdbuf);
 245   else
 246     ret = asprintf (&LD_PRELOAD, "LD_PRELOAD=%s", libstdbuf);
 247
 248   if (ret < 0)
 249     xalloc_die ();
 250
 251   free (libstdbuf);
 252
 253   ret = putenv (LD_PRELOAD);
 254
 255   if (ret != 0)
 256     {
 257       error (EXIT_CANCELED, errno,
 258              _("failed to update the environment with %s"),
 259              quote (LD_PRELOAD));
 260     }
 261 }
 262
 263 /* Populate environ with _STDBUF_I=$MODE _STDBUF_O=$MODE _STDBUF_E=$MODE  */
 264
 265 static void
 266 set_libstdbuf_options (void)
 267 {
 268   int i;
 269
 270   for (i = 0; i < ARRAY_CARDINALITY (stdbuf); i++)
 271     {
 272       if (stdbuf[i].optarg)
 273         {
 274           char *var;
 275           int ret;
 276
 277           if (*stdbuf[i].optarg == 'L')
 278             ret = asprintf (&var, "%s%c=L", "_STDBUF_",
 279                             toupper (stdbuf[i].optc));
 280           else
 281             ret = asprintf (&var, "%s%c=%" PRIuMAX, "_STDBUF_",
 282                             toupper (stdbuf[i].optc),
 283                             (uintmax_t) stdbuf[i].size);
 284           if (ret < 0)
 285             xalloc_die ();
 286
 287           if (putenv (var) != 0)
 288             {
 289               error (EXIT_CANCELED, errno,
 290                      _("failed to update the environment with %s"),
 291                      quote (var));
 292             }
 293         }
 294     }
 295 }
 296
 297 int
 298 main (int argc, char **argv)
 299 {
 300   int c;
 301
 302   initialize_main (&argc, &argv);
 303   set_program_name (argv[0]);
 304   setlocale (LC_ALL, "");
 305   bindtextdomain (PACKAGE, LOCALEDIR);
 306   textdomain (PACKAGE);
 307
 308   initialize_exit_failure (EXIT_CANCELED);
 309   atexit (close_stdout);
 310
 311   while ((c = getopt_long (argc, argv, "+i:o:e:", longopts, NULL)) != -1)
 312     {
 313       int opt_fileno;
 314
 315       switch (c)
 316         {
 317         /* Old McDonald had a farm ei...  */
 318         case 'e':
 319         case 'i':
 320         case 'o':
 321           opt_fileno = optc_to_fileno (c);
 322           assert (0 <= opt_fileno && opt_fileno < ARRAY_CARDINALITY (stdbuf));
 323           stdbuf[opt_fileno].optc = c;
 324           while (c_isspace (*optarg))
 325             optarg++;
 326           stdbuf[opt_fileno].optarg = optarg;
 327           if (c == 'i' && *optarg == 'L')
 328             {
 329               /* -oL will be by far the most common use of this utility,
 330                  but one could easily think -iL might have the same affect,
 331                  so disallow it as it could be confusing.  */
 332               error (0, 0, _("line buffering stdin is meaningless"));
 333               usage (EXIT_CANCELED);
 334             }
 335
 336           if (!STREQ (optarg, "L")
 337               && parse_size (optarg, &stdbuf[opt_fileno].size) == -1)
 338             error (EXIT_CANCELED, errno, _("invalid mode %s"), quote (optarg));
 339
 340           break;
 341
 342         case_GETOPT_HELP_CHAR;
 343
 344         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 345
 346         default:
 347           usage (EXIT_CANCELED);
 348         }
 349     }
 350
 351   argv += optind;
 352   argc -= optind;
 353
 354   /* must specify at least 1 command.  */
 355   if (argc < 1)
 356     {
 357       error (0, 0, _("missing operand"));
 358       usage (EXIT_CANCELED);
 359     }
 360
 361   /* FIXME: Should we mandate at least one option?  */
 362
 363   set_libstdbuf_options ();
 364
 365   /* Try to preload libstdbuf first from the same path as
 366      stdbuf is running from.  */
 367   set_program_path (argv[0]);
 368   if (!program_path)
 369     program_path = xstrdup (PKGLIBDIR);  /* Need to init to non NULL.  */
 370   set_LD_PRELOAD ();
 371   free (program_path);
 372
 373   execvp (*argv, argv);
 374
 375   {
 376     int exit_status = (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
 377     error (0, errno, _("failed to run command %s"), quote (argv[0]));
 378     exit (exit_status);
 379   }
 380 }
 381
 382 /*
 383  * Local variables:
 384  *  indent-tabs-mode: nil
 385  * End:
 386  */