lib/command-line.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011 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 "util.h"
  23 #include "vlog.h"
  24
  25 VLOG_DEFINE_THIS_MODULE(command_line);
  26
  27 /* Given the GNU-style long options in 'options', returns a string that may be
  28  * passed to getopt() with the corresponding short options.  The caller is
  29  * responsible for freeing the string. */
  30 char *
  31 long_options_to_short_options(const struct option options[])
  32 {
  33     char short_options[UCHAR_MAX * 3 + 1];
  34     char *p = short_options;
  35
  36     for (; options->name; options++) {
  37         const struct option *o = options;
  38         if (o->flag == NULL && o->val > 0 && o->val <= UCHAR_MAX) {
  39             *p++ = o->val;
  40             if (o->has_arg == required_argument) {
  41                 *p++ = ':';
  42             } else if (o->has_arg == optional_argument) {
  43                 *p++ = ':';
  44                 *p++ = ':';
  45             }
  46         }
  47     }
  48     *p = '\0';
  49
  50     return xstrdup(short_options);
  51 }
  52
  53 /* Runs the command designated by argv[0] within the command table specified by
  54  * 'commands', which must be terminated by a command whose 'name' member is a
  55  * null pointer.
  56  *
  57  * Command-line options should be stripped off, so that a typical invocation
  58  * looks like "run_command(argc - optind, argv + optind, my_commands);". */
  59 void
  60 run_command(int argc, char *argv[], const struct command commands[])
  61 {
  62     const struct command *p;
  63
  64     if (argc < 1) {
  65         ovs_fatal(0, "missing command name; use --help for help");
  66     }
  67
  68     for (p = commands; p->name != NULL; p++) {
  69         if (!strcmp(p->name, argv[0])) {
  70             int n_arg = argc - 1;
  71             if (n_arg < p->min_args) {
  72                 VLOG_FATAL( "'%s' command requires at least %d arguments",
  73                             p->name, p->min_args);
  74             } else if (n_arg > p->max_args) {
  75                 VLOG_FATAL("'%s' command takes at most %d arguments",
  76                            p->name, p->max_args);
  77             } else {
  78                 p->handler(argc, argv);
  79                 if (ferror(stdout)) {
  80                     VLOG_FATAL("write to stdout failed");
  81                 }
  82                 if (ferror(stderr)) {
  83                     VLOG_FATAL("write to stderr failed");
  84                 }
  85                 return;
  86             }
  87         }
  88     }
  89
  90     VLOG_FATAL("unknown command '%s'; use --help for help", argv[0]);
  91 }
  92 \f
  93 /* Process title. */
  94
  95 #ifdef __linux__
  96 static char *argv_start;       /* Start of command-line arguments in memory. */
  97 static size_t argv_size;       /* Number of bytes of command-line arguments. */
  98 static char *saved_proctitle;  /* Saved command-line arguments. */
  99
 100 /* Prepares the process so that proctitle_set() can later succeed.
 101  *
 102  * This modifies the argv[] array so that it no longer points into the memory
 103  * that it originally does.  Later, proctitle_set() might overwrite that
 104  * memory.  That means that this function should be called before anything else
 105  * that accesses the process's argv[] array.  Ideally, it should be called
 106  * before anything else, period, at the very beginning of program
 107  * execution.  */
 108 void
 109 proctitle_init(int argc, char **argv)
 110 {
 111     int i;
 112
 113     if (!argc || !argv[0]) {
 114         /* This situation should never occur, but... */
 115         return;
 116     }
 117
 118     /* Specialized version of first loop iteration below. */
 119     argv_start = argv[0];
 120     argv_size = strlen(argv[0]) + 1;
 121     argv[0] = xstrdup(argv[0]);
 122
 123     for (i = 1; i < argc; i++) {
 124         size_t size = strlen(argv[i]) + 1;
 125
 126         /* Add (argv[i], strlen(argv[i])+1) to (argv_start, argv_size). */
 127         if (argv[i] + size == argv_start) {
 128             /* Arguments grow downward in memory. */
 129             argv_start -= size;
 130             argv_size += size;
 131         } else if (argv[i] == argv_start + argv_size) {
 132             /* Arguments grow upward in memory. */
 133             argv_size += size;
 134         } else {
 135             /* Arguments not contiguous.  (Is this really Linux?) */
 136         }
 137
 138         /* Copy out the old argument so we can reuse the space. */
 139         argv[i] = xstrdup(argv[i]);
 140     }
 141 }
 142
 143 /* Changes the name of the process, as shown by "ps", to 'format', which is
 144  * formatted as if by printf(). */
 145 void
 146 proctitle_set(const char *format, ...)
 147 {
 148     va_list args;
 149     int n;
 150
 151     if (!argv_start || argv_size < 8) {
 152         return;
 153     }
 154
 155     if (!saved_proctitle) {
 156         saved_proctitle = xmemdup(argv_start, argv_size);
 157     }
 158
 159     va_start(args, format);
 160     n = vsnprintf(argv_start, argv_size, format, args);
 161     if (n >= argv_size) {
 162         /* The name is too long, so add an ellipsis at the end. */
 163         strcpy(&argv_start[argv_size - 4], "...");
 164     } else {
 165         /* Fill the extra space with null bytes, so that trailing bytes don't
 166          * show up in the command line. */
 167         memset(&argv_start[n], '\0', argv_size - n);
 168     }
 169     va_end(args);
 170 }
 171
 172 /* Restores the process's original command line, as seen by "ps". */
 173 void
 174 proctitle_restore(void)
 175 {
 176     if (saved_proctitle) {
 177         memcpy(argv_start, saved_proctitle, argv_size);
 178         free(saved_proctitle);
 179         saved_proctitle = NULL;
 180     }
 181 }
 182 #else  /* !__linux__ */
 183 /* Stubs that don't do anything on non-Linux systems. */
 184
 185 void
 186 proctitle_init(int argc OVS_UNUSED, char **argv OVS_UNUSED)
 187 {
 188 }
 189
 190 void
 191 proctitle_set(const char *format OVS_UNUSED, ...)
 192 {
 193 }
 194
 195 void
 196 proctitle_restore(void)
 197 {
 198 }
 199 #endif  /* !__linux__ */