lib/command-line.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2013, 2014 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "command-line.h"
  19 #include <getopt.h>
  20 #include <limits.h>
  21 #include <stdlib.h>
  22 #include "dynamic-string.h"
  23 #include "ovs-thread.h"
  24 #include "util.h"
  25 #include "openvswitch/vlog.h"
  26
  27 VLOG_DEFINE_THIS_MODULE(command_line);
  28
  29 /* Given the GNU-style long options in 'options', returns a string that may be
  30  * passed to getopt() with the corresponding short options.  The caller is
  31  * responsible for freeing the string. */
  32 char *
  33 ovs_cmdl_long_options_to_short_options(const struct option options[])
  34 {
  35     char short_options[UCHAR_MAX * 3 + 1];
  36     char *p = short_options;
  37
  38     for (; options->name; options++) {
  39         const struct option *o = options;
  40         if (o->flag == NULL && o->val > 0 && o->val <= UCHAR_MAX) {
  41             *p++ = o->val;
  42             if (o->has_arg == required_argument) {
  43                 *p++ = ':';
  44             } else if (o->has_arg == optional_argument) {
  45                 *p++ = ':';
  46                 *p++ = ':';
  47             }
  48         }
  49     }
  50     *p = '\0';
  51
  52     return xstrdup(short_options);
  53 }
  54
  55 /* Given the 'struct ovs_cmdl_command' array, prints the usage of all commands. */
  56 void
  57 ovs_cmdl_print_commands(const struct ovs_cmdl_command commands[])
  58 {
  59     struct ds ds = DS_EMPTY_INITIALIZER;
  60
  61     ds_put_cstr(&ds, "The available commands are:\n");
  62     for (; commands->name; commands++) {
  63         const struct ovs_cmdl_command *c = commands;
  64         ds_put_format(&ds, "  %-23s %s\n", c->name, c->usage ? c->usage : "");
  65     }
  66     printf("%s", ds.string);
  67     ds_destroy(&ds);
  68 }
  69
  70 /* Given the GNU-style options in 'options', prints all options. */
  71 void
  72 ovs_cmdl_print_options(const struct option options[])
  73 {
  74     struct ds ds = DS_EMPTY_INITIALIZER;
  75
  76     for (; options->name; options++) {
  77         const struct option *o = options;
  78         const char *arg = o->has_arg == required_argument ? "ARG" : "[ARG]";
  79
  80         ds_put_format(&ds, "--%s%s%s\n", o->name, o->has_arg ? "=" : "",
  81                       o->has_arg ? arg : "");
  82         if (o->flag == NULL && o->val > 0 && o->val <= UCHAR_MAX) {
  83             ds_put_format(&ds, "-%c %s\n", o->val, o->has_arg ? arg : "");
  84         }
  85     }
  86     printf("%s", ds.string);
  87     ds_destroy(&ds);
  88 }
  89
  90 /* Runs the command designated by argv[0] within the command table specified by
  91  * 'commands', which must be terminated by a command whose 'name' member is a
  92  * null pointer.
  93  *
  94  * Command-line options should be stripped off, so that a typical invocation
  95  * looks like:
  96  *    struct ovs_cmdl_context ctx = {
  97  *        .argc = argc - optind,
  98  *        .argv = argv + optind,
  99  *    };
 100  *    ovs_cmdl_run_command(&ctx, my_commands);
 101  * */
 102 void
 103 ovs_cmdl_run_command(struct ovs_cmdl_context *ctx, const struct ovs_cmdl_command commands[])
 104 {
 105     const struct ovs_cmdl_command *p;
 106
 107     if (ctx->argc < 1) {
 108         ovs_fatal(0, "missing command name; use --help for help");
 109     }
 110
 111     for (p = commands; p->name != NULL; p++) {
 112         if (!strcmp(p->name, ctx->argv[0])) {
 113             int n_arg = ctx->argc - 1;
 114             if (n_arg < p->min_args) {
 115                 VLOG_FATAL( "'%s' command requires at least %d arguments",
 116                             p->name, p->min_args);
 117             } else if (n_arg > p->max_args) {
 118                 VLOG_FATAL("'%s' command takes at most %d arguments",
 119                            p->name, p->max_args);
 120             } else {
 121                 p->handler(ctx);
 122                 if (ferror(stdout)) {
 123                     VLOG_FATAL("write to stdout failed");
 124                 }
 125                 if (ferror(stderr)) {
 126                     VLOG_FATAL("write to stderr failed");
 127                 }
 128                 return;
 129             }
 130         }
 131     }
 132
 133     VLOG_FATAL("unknown command '%s'; use --help for help", ctx->argv[0]);
 134 }
 135 \f
 136 /* Process title. */
 137
 138 #ifdef __linux__
 139 static struct ovs_mutex proctitle_mutex = OVS_MUTEX_INITIALIZER;
 140
 141 /* Start of command-line arguments in memory. */
 142 static char *argv_start OVS_GUARDED_BY(proctitle_mutex);
 143
 144 /* Number of bytes of command-line arguments. */
 145 static size_t argv_size OVS_GUARDED_BY(proctitle_mutex);
 146
 147 /* Saved command-line arguments. */
 148 static char *saved_proctitle OVS_GUARDED_BY(proctitle_mutex);
 149
 150 /* Prepares the process so that proctitle_set() can later succeed.
 151  *
 152  * This modifies the argv[] array so that it no longer points into the memory
 153  * that it originally does.  Later, proctitle_set() might overwrite that
 154  * memory.  That means that this function should be called before anything else
 155  * that accesses the process's argv[] array.  Ideally, it should be called
 156  * before anything else, period, at the very beginning of program
 157  * execution.  */
 158 void
 159 ovs_cmdl_proctitle_init(int argc, char **argv)
 160 {
 161     int i;
 162
 163     assert_single_threaded();
 164     if (!argc || !argv[0]) {
 165         /* This situation should never occur, but... */
 166         return;
 167     }
 168
 169     ovs_mutex_lock(&proctitle_mutex);
 170     /* Specialized version of first loop iteration below. */
 171     argv_start = argv[0];
 172     argv_size = strlen(argv[0]) + 1;
 173     argv[0] = xstrdup(argv[0]);
 174
 175     for (i = 1; i < argc; i++) {
 176         size_t size = strlen(argv[i]) + 1;
 177
 178         /* Add (argv[i], strlen(argv[i])+1) to (argv_start, argv_size). */
 179         if (argv[i] + size == argv_start) {
 180             /* Arguments grow downward in memory. */
 181             argv_start -= size;
 182             argv_size += size;
 183         } else if (argv[i] == argv_start + argv_size) {
 184             /* Arguments grow upward in memory. */
 185             argv_size += size;
 186         } else {
 187             /* Arguments not contiguous.  (Is this really Linux?) */
 188         }
 189
 190         /* Copy out the old argument so we can reuse the space. */
 191         argv[i] = xstrdup(argv[i]);
 192     }
 193     ovs_mutex_unlock(&proctitle_mutex);
 194 }
 195
 196 /* Changes the name of the process, as shown by "ps", to the program name
 197  * followed by 'format', which is formatted as if by printf(). */
 198 void
 199 ovs_cmdl_proctitle_set(const char *format, ...)
 200 {
 201     va_list args;
 202     int n;
 203
 204     ovs_mutex_lock(&proctitle_mutex);
 205     if (!argv_start || argv_size < 8) {
 206         goto out;
 207     }
 208
 209     if (!saved_proctitle) {
 210         saved_proctitle = xmemdup(argv_start, argv_size);
 211     }
 212
 213     va_start(args, format);
 214     n = snprintf(argv_start, argv_size, "%s: ", program_name);
 215     if (n < argv_size) {
 216         n += vsnprintf(argv_start + n, argv_size - n, format, args);
 217     }
 218     if (n >= argv_size) {
 219         /* The name is too long, so add an ellipsis at the end. */
 220         strcpy(&argv_start[argv_size - 4], "...");
 221     } else {
 222         /* Fill the extra space with null bytes, so that trailing bytes don't
 223          * show up in the command line. */
 224         memset(&argv_start[n], '\0', argv_size - n);
 225     }
 226     va_end(args);
 227
 228 out:
 229     ovs_mutex_unlock(&proctitle_mutex);
 230 }
 231
 232 /* Restores the process's original command line, as seen by "ps". */
 233 void
 234 ovs_cmdl_proctitle_restore(void)
 235 {
 236     ovs_mutex_lock(&proctitle_mutex);
 237     if (saved_proctitle) {
 238         memcpy(argv_start, saved_proctitle, argv_size);
 239         free(saved_proctitle);
 240         saved_proctitle = NULL;
 241     }
 242     ovs_mutex_unlock(&proctitle_mutex);
 243 }
 244 #else  /* !__linux__ */
 245 /* Stubs that don't do anything on non-Linux systems. */
 246
 247 void
 248 ovs_cmdl_proctitle_init(int argc OVS_UNUSED, char **argv OVS_UNUSED)
 249 {
 250 }
 251
 252 #if !(defined(__FreeBSD__) || defined(__NetBSD__))
 253 /* On these platforms we #define this to setproctitle. */
 254 void
 255 ovs_cmdl_proctitle_set(const char *format OVS_UNUSED, ...)
 256 {
 257 }
 258 #endif
 259
 260 void
 261 ovs_cmdl_proctitle_restore(void)
 262 {
 263 }
 264 #endif  /* !__linux__ */