daemon/procfs.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2009,2010 Nedko Arnaudov <nedko@arnaudov.name>
   6  *
   7  **************************************************************************
   8  * This file contains the code that interfaces procfs
   9  **************************************************************************
  10  *
  11  * LADI Session Handler is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * LADI Session Handler is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
  23  * or write to the Free Software Foundation, Inc.,
  24  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  25  */
  26
  27 #include <stdbool.h>
  28 #include <string.h>
  29 #include <stdlib.h>
  30 #include <sys/types.h>
  31 #include <sys/stat.h>
  32 #include <fcntl.h>
  33 #include <stdio.h>
  34 #include <unistd.h>
  35 #include <errno.h>
  36
  37 #include "procfs.h"
  38
  39 #define BUFFER_SIZE 4096
  40
  41 static char g_buffer[BUFFER_SIZE];
  42
  43 static
  44 bool
  45 procfs_get_process_file(
  46   unsigned long long pid,
  47   const char * filename,
  48   char ** buffer_ptr_ptr,
  49   size_t * size_ptr)
  50 {
  51   int fd;
  52   ssize_t ret;
  53   size_t max;
  54   char * buffer_ptr;
  55   char * read_ptr;
  56   size_t buffer_size;
  57   size_t used_size;
  58
  59   sprintf(g_buffer, "/proc/%llu/%s", pid, filename);
  60
  61   fd = open(g_buffer, O_RDONLY);
  62   if (fd == -1)
  63   {
  64     return false;
  65   }
  66
  67   buffer_size = BUFFER_SIZE;
  68   buffer_ptr = malloc(buffer_size);
  69   if (buffer_ptr == NULL)
  70   {
  71     log_error("malloc failed to allocate buffer with size %zu", buffer_size);
  72     close(fd);
  73     return false;
  74   }
  75
  76   used_size = 0;
  77   read_ptr = buffer_ptr;
  78 loop:
  79   max = buffer_size - used_size;
  80   if (max < BUFFER_SIZE / 4)
  81   {
  82     buffer_size = used_size + BUFFER_SIZE;
  83     read_ptr = realloc(buffer_ptr, buffer_size);
  84     if (read_ptr == NULL)
  85     {
  86       log_error("realloc failed to allocate buffer with size %zu", buffer_size);
  87       free(buffer_ptr);
  88       close(fd);
  89       return false;
  90     }
  91
  92     buffer_ptr = read_ptr;
  93     read_ptr = buffer_ptr + used_size;
  94     max = BUFFER_SIZE;
  95   }
  96
  97   ret = read(fd, read_ptr, max);
  98   if (ret > 0)
  99   {
 100     ASSERT(ret <= max);
 101     read_ptr += ret;
 102     used_size += ret;
 103     ASSERT(used_size <= buffer_size);
 104     goto loop;
 105   }
 106
 107   close(fd);
 108
 109   if (ret < 0)
 110   {
 111     ASSERT(ret == -1);
 112     return false;
 113   }
 114
 115   if (used_size == buffer_size)
 116   {
 117     read_ptr = realloc(buffer_ptr, buffer_size + 1);
 118     if (read_ptr == NULL)
 119     {
 120       log_error("realloc failed to allocate buffer with size %zu", buffer_size + 1);
 121       free(buffer_ptr);
 122       return false;
 123     }
 124
 125     buffer_ptr = read_ptr;
 126   }
 127
 128   buffer_ptr[used_size] = 0;
 129
 130   *buffer_ptr_ptr = buffer_ptr;
 131   *size_ptr = used_size;
 132
 133   return true;
 134 }
 135
 136 static
 137 char *
 138 procfs_get_process_link(
 139   unsigned long long pid,
 140   const char * filename)
 141 {
 142   int fd;
 143   ssize_t ret;
 144   char * buffer_ptr;
 145
 146   sprintf(g_buffer, "/proc/%llu/%s", pid, filename);
 147
 148   fd = open(g_buffer, O_RDONLY);
 149   if (fd == -1)
 150   {
 151     return NULL;
 152   }
 153
 154   ret = readlink(g_buffer, g_buffer, sizeof(g_buffer));
 155   if (ret != 0)
 156   {
 157     g_buffer[ret] = 0;
 158     buffer_ptr = strdup(g_buffer);
 159     log_debug("process %llu %s symlink points to \"%s\"", pid, filename, buffer_ptr);
 160   }
 161   else
 162   {
 163     ASSERT(ret == -1);
 164     buffer_ptr = NULL;
 165   }
 166
 167   close(fd);
 168
 169   return buffer_ptr;
 170 }
 171
 172 bool
 173 procfs_get_process_cmdline(
 174   unsigned long long pid,
 175   int * argc_ptr,
 176   char *** argv_ptr)
 177 {
 178   char * cmdline_ptr;
 179   char * temp_ptr;
 180   size_t cmdline_size;
 181   int i;
 182   int argc;
 183   char ** argv;
 184
 185   if (!procfs_get_process_file(pid, "cmdline", &cmdline_ptr, &cmdline_size))
 186   {
 187     return false;
 188   }
 189
 190   argc = 0;
 191   temp_ptr = cmdline_ptr;
 192
 193   while (temp_ptr - cmdline_ptr < cmdline_size)
 194   {
 195     if (*temp_ptr == 0)
 196     {
 197       argc++;
 198     }
 199
 200     temp_ptr++;
 201   }
 202
 203   ASSERT(*(temp_ptr - 1) == 0); /* the last nul char */
 204
 205   argv = malloc((argc + 1) * sizeof(char *));
 206   if (argv == NULL)
 207   {
 208     free(cmdline_ptr);
 209     return false;
 210   }
 211
 212   temp_ptr = cmdline_ptr;
 213
 214   for (i = 0; i < argc; i++)
 215   {
 216     ASSERT(temp_ptr - cmdline_ptr < cmdline_size);
 217
 218     argv[i] = strdup(temp_ptr);
 219     if (argv[i] == NULL)
 220     {
 221       /* rollback */
 222       while (i > 0)
 223       {
 224         i--;
 225         free(argv[i]);
 226       }
 227
 228       free(argv);
 229       free(cmdline_ptr);
 230       return false;
 231     }
 232
 233     temp_ptr += strlen(temp_ptr) + 1;
 234   }
 235
 236   /* Make sure that the array is NULL terminated */
 237   argv[argc] = NULL;
 238
 239   *argc_ptr = argc;
 240   *argv_ptr = argv;
 241
 242   free(cmdline_ptr);
 243
 244   return true;
 245 }
 246
 247 char *
 248 procfs_get_process_cwd(
 249   unsigned long long pid)
 250 {
 251   return procfs_get_process_link(pid, "cwd");
 252 }
 253
 254 unsigned long long
 255 procfs_get_process_parent(
 256   unsigned long long pid)
 257 {
 258   char * buffer_ptr;
 259   size_t buffer_size;
 260   char * begin;
 261   char * end;
 262   unsigned long long ppid;
 263
 264   if (!procfs_get_process_file(pid, "status", &buffer_ptr, &buffer_size))
 265   {
 266     return 0;
 267   }
 268
 269   begin = strstr(buffer_ptr, "\nPPid:\t");
 270   if (begin == NULL)
 271   {
 272     log_error("parent pid not parsed for %llu", pid);
 273     log_error("-----------------------------");
 274     log_error("%s", buffer_ptr);
 275     log_error("-----------------------------");
 276     free(buffer_ptr);
 277     return 0;
 278   }
 279
 280   begin += 7;
 281
 282   end = strchr(begin, '\n');
 283   if (end == NULL)
 284   {
 285     log_error("parent pid not parsed for %llu (end)", pid);
 286     log_error("-----------------------------");
 287     log_error("%s", buffer_ptr);
 288     log_error("-----------------------------");
 289     free(buffer_ptr);
 290     return 0;
 291   }
 292
 293   *end = 0;
 294   //log_info("parent pid is %s", begin);
 295
 296   errno = 0;
 297   ppid = strtoull(begin, &end, 10);
 298   if (errno != 0)
 299   {
 300     log_error("strtoull failed to convert '%s' to integer", begin);
 301     ppid = 0;
 302   }
 303   else
 304   {
 305     //log_info("parent pid is %llu", ppid);
 306   }
 307
 308   /* avoid infinite cycles (should not happen because init has pid 1 and parent 0) */
 309   if (ppid == pid)
 310   {
 311     ppid = 0;
 312   }
 313
 314   free(buffer_ptr);
 315
 316   return ppid;
 317 }