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 "ovs-thread.h"
  23 #include "util.h"
  24 #include "vlog.h"
  25
  26 VLOG_DEFINE_THIS_MODULE(command_line);
  27
  28 /* Given the GNU-style long options in 'options', returns a string that may be
  29  * passed to getopt() with the corresponding short options.  The caller is
  30  * responsible for freeing the string. */
  31 char *
  32 long_options_to_short_options(const struct option options[])
  33 {
  34     char short_options[UCHAR_MAX * 3 + 1];
  35     char *p = short_options;
  36
  37     for (; options->name; options++) {
  38         const struct option *o = options;
  39         if (o->flag == NULL && o->val > 0 && o->val <= UCHAR_MAX) {
  40             *p++ = o->val;
  41             if (o->has_arg == required_argument) {
  42                 *p++ = ':';
  43             } else if (o->has_arg == optional_argument) {
  44                 *p++ = ':';
  45                 *p++ = ':';
  46             }
  47         }
  48     }
  49     *p = '\0';
  50
  51     return xstrdup(short_options);
  52 }
  53
  54 /* Runs the command designated by argv[0] within the command table specified by
  55  * 'commands', which must be terminated by a command whose 'name' member is a
  56  * null pointer.
  57  *
  58  * Command-line options should be stripped off, so that a typical invocation
  59  * looks like "run_command(argc - optind, argv + optind, my_commands);". */
  60 void
  61 run_command(int argc, char *argv[], const struct command commands[])
  62 {
  63     const struct command *p;
  64
  65     if (argc < 1) {
  66         ovs_fatal(0, "missing command name; use --help for help");
  67     }
  68
  69     for (p = commands; p->name != NULL; p++) {
  70         if (!strcmp(p->name, argv[0])) {
  71             int n_arg = argc - 1;
  72             if (n_arg < p->min_args) {
  73                 VLOG_FATAL( "'%s' command requires at least %d arguments",
  74                             p->name, p->min_args);
  75             } else if (n_arg > p->max_args) {
  76                 VLOG_FATAL("'%s' command takes at most %d arguments",
  77                            p->name, p->max_args);
  78             } else {
  79                 p->handler(argc, argv);
  80                 if (ferror(stdout)) {
  81                     VLOG_FATAL("write to stdout failed");
  82                 }
  83                 if (ferror(stderr)) {
  84                     VLOG_FATAL("write to stderr failed");
  85                 }
  86                 return;
  87             }
  88         }
  89     }
  90
  91     VLOG_FATAL("unknown command '%s'; use --help for help", argv[0]);
  92 }
  93 \f
  94 /* Process title. */
  95
  96 #ifdef __linux__
  97 static struct ovs_mutex proctitle_mutex = OVS_MUTEX_INITIALIZER;
  98
  99 /* Start of command-line arguments in memory. */
 100 static char *argv_start OVS_GUARDED_BY(proctitle_mutex);
 101
 102 /* Number of bytes of command-line arguments. */
 103 static size_t argv_size OVS_GUARDED_BY(proctitle_mutex);
 104
 105 /* Saved command-line arguments. */
 106 static char *saved_proctitle OVS_GUARDED_BY(proctitle_mutex);
 107
 108 /* Prepares the process so that proctitle_set() can later succeed.
 109  *
 110  * This modifies the argv[] array so that it no longer points into the memory
 111  * that it originally does.  Later, proctitle_set() might overwrite that
 112  * memory.  That means that this function should be called before anything else
 113  * that accesses the process's argv[] array.  Ideally, it should be called
 114  * before anything else, period, at the very beginning of program
 115  * execution.  */
 116 void
 117 proctitle_init(int argc, char **argv)
 118 {
 119     int i;
 120
 121     assert_single_threaded();
 122     if (!argc || !argv[0]) {
 123         /* This situation should never occur, but... */
 124         return;
 125     }
 126
 127     ovs_mutex_lock(&proctitle_mutex);
 128     /* Specialized version of first loop iteration below. */
 129     argv_start = argv[0];
 130     argv_size = strlen(argv[0]) + 1;
 131     argv[0] = xstrdup(argv[0]);
 132
 133     for (i = 1; i < argc; i++) {
 134         size_t size = strlen(argv[i]) + 1;
 135
 136         /* Add (argv[i], strlen(argv[i])+1) to (argv_start, argv_size). */
 137         if (argv[i] + size == argv_start) {
 138             /* Arguments grow downward in memory. */
 139             argv_start -= size;
 140             argv_size += size;
 141         } else if (argv[i] == argv_start + argv_size) {
 142             /* Arguments grow upward in memory. */
 143             argv_size += size;
 144         } else {
 145             /* Arguments not contiguous.  (Is this really Linux?) */
 146         }
 147
 148         /* Copy out the old argument so we can reuse the space. */
 149         argv[i] = xstrdup(argv[i]);
 150     }
 151     ovs_mutex_unlock(&proctitle_mutex);
 152 }
 153
 154 /* Changes the name of the process, as shown by "ps", to the program name
 155  * followed by 'format', which is formatted as if by printf(). */
 156 void
 157 proctitle_set(const char *format, ...)
 158 {
 159     va_list args;
 160     int n;
 161
 162     ovs_mutex_lock(&proctitle_mutex);
 163     if (!argv_start || argv_size < 8) {
 164         goto out;
 165     }
 166
 167     if (!saved_proctitle) {
 168         saved_proctitle = xmemdup(argv_start, argv_size);
 169     }
 170
 171     va_start(args, format);
 172     n = snprintf(argv_start, argv_size, "%s: ", program_name);
 173     if (n < argv_size) {
 174         n += vsnprintf(argv_start + n, argv_size - n, format, args);
 175     }
 176     if (n >= argv_size) {
 177         /* The name is too long, so add an ellipsis at the end. */
 178         strcpy(&argv_start[argv_size - 4], "...");
 179     } else {
 180         /* Fill the extra space with null bytes, so that trailing bytes don't
 181          * show up in the command line. */
 182         memset(&argv_start[n], '\0', argv_size - n);
 183     }
 184     va_end(args);
 185
 186 out:
 187     ovs_mutex_unlock(&proctitle_mutex);
 188 }
 189
 190 /* Restores the process's original command line, as seen by "ps". */
 191 void
 192 proctitle_restore(void)
 193 {
 194     ovs_mutex_lock(&proctitle_mutex);
 195     if (saved_proctitle) {
 196         memcpy(argv_start, saved_proctitle, argv_size);
 197         free(saved_proctitle);
 198         saved_proctitle = NULL;
 199     }
 200     ovs_mutex_unlock(&proctitle_mutex);
 201 }
 202 #else  /* !__linux__ */
 203 /* Stubs that don't do anything on non-Linux systems. */
 204
 205 void
 206 proctitle_init(int argc OVS_UNUSED, char **argv OVS_UNUSED)
 207 {
 208 }
 209
 210 #if !(defined(__FreeBSD__) || defined(__NetBSD__))
 211 /* On these platforms we #define this to setproctitle. */
 212 void
 213 proctitle_set(const char *format OVS_UNUSED, ...)
 214 {
 215 }
 216 #endif
 217
 218 void
 219 proctitle_restore(void)
 220 {
 221 }
 222 #endif  /* !__linux__ */