daemon/procfs.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2009 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     return false;
  73   }
  74
  75   used_size = 0;
  76   read_ptr = buffer_ptr;
  77 loop:
  78   max = buffer_size - used_size;
  79   if (max < BUFFER_SIZE / 4)
  80   {
  81     buffer_size = used_size + BUFFER_SIZE;
  82     read_ptr = realloc(buffer_ptr, buffer_size);
  83     if (read_ptr == NULL)
  84     {
  85       log_error("realloc failed to allocate buffer with size %zu", buffer_size);
  86       free(buffer_ptr);
  87       close(fd);
  88       return false;
  89     }
  90
  91     buffer_ptr = read_ptr;
  92     read_ptr = buffer_ptr + used_size;
  93     max = BUFFER_SIZE;
  94   }
  95
  96   ret = read(fd, read_ptr, max);
  97   if (ret > 0)
  98   {
  99     ASSERT(ret <= max);
 100     read_ptr += ret;
 101     used_size += ret;
 102     ASSERT(used_size <= buffer_size);
 103     goto loop;
 104   }
 105
 106   close(fd);
 107
 108   if (ret < 0)
 109   {
 110     ASSERT(ret == -1);
 111     close(fd);
 112     return false;
 113   }
 114
 115   if (used_size == buffer_size)
 116   {
 117     buffer_ptr = realloc(buffer_ptr, buffer_size + 1);
 118     if (buffer_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
 126   buffer_ptr[buffer_size] = 0;
 127
 128   *buffer_ptr_ptr = buffer_ptr;
 129   *size_ptr = used_size;
 130
 131   return true;
 132 }
 133
 134 static
 135 char *
 136 procfs_get_process_link(
 137   unsigned long long pid,
 138   const char * filename)
 139 {
 140   int fd;
 141   ssize_t ret;
 142   char * buffer_ptr;
 143
 144   sprintf(g_buffer, "/proc/%llu/%s", pid, filename);
 145
 146   fd = open(g_buffer, O_RDONLY);
 147   if (fd == -1)
 148   {
 149     return NULL;
 150   }
 151
 152   ret = readlink(g_buffer, g_buffer, sizeof(g_buffer));
 153   if (ret != 0)
 154   {
 155     g_buffer[ret] = 0;
 156     buffer_ptr = strdup(g_buffer);
 157     log_debug("process %llu %s symlink points to \"%s\"", pid, filename, buffer_ptr);
 158   }
 159   else
 160   {
 161     ASSERT(ret == -1);
 162     buffer_ptr = NULL;
 163   }
 164
 165   close(fd);
 166
 167   return buffer_ptr;
 168 }
 169
 170 bool
 171 procfs_get_process_cmdline(
 172   unsigned long long pid,
 173   int * argc_ptr,
 174   char *** argv_ptr)
 175 {
 176   char * cmdline_ptr;
 177   char * temp_ptr;
 178   size_t cmdline_size;
 179   int i;
 180   int argc;
 181   char ** argv;
 182
 183   if (!procfs_get_process_file(pid, "cmdline", &cmdline_ptr, &cmdline_size))
 184   {
 185     return false;
 186   }
 187
 188   argc = 0;
 189   temp_ptr = cmdline_ptr;
 190
 191   while (temp_ptr - cmdline_ptr < cmdline_size)
 192   {
 193     if (*temp_ptr == 0)
 194     {
 195       argc++;
 196     }
 197
 198     temp_ptr++;
 199   }
 200
 201   ASSERT(*(temp_ptr - 1) == 0); /* the last nul char */
 202
 203   argv = malloc((argc + 1) * sizeof(char *));
 204   if (argv == NULL)
 205   {
 206     free(cmdline_ptr);
 207     return false;
 208   }
 209
 210   temp_ptr = cmdline_ptr;
 211
 212   for (i = 0; i < argc; i++)
 213   {
 214     ASSERT(temp_ptr - cmdline_ptr < cmdline_size);
 215
 216     argv[i] = strdup(temp_ptr);
 217     if (argv[i] == NULL)
 218     {
 219       /* rollback */
 220       while (i > 0)
 221       {
 222         i--;
 223         free(argv[i]);
 224       }
 225
 226       free(argv);
 227       free(cmdline_ptr);
 228       return false;
 229     }
 230
 231     temp_ptr += strlen(temp_ptr) + 1;
 232   }
 233
 234   /* Make sure that the array is NULL terminated */
 235   argv[argc] = NULL;
 236
 237   *argc_ptr = argc;
 238   *argv_ptr = argv;
 239
 240   free(cmdline_ptr);
 241
 242   return true;
 243 }
 244
 245 char *
 246 procfs_get_process_cwd(
 247   unsigned long long pid)
 248 {
 249   return procfs_get_process_link(pid, "cwd");
 250 }
 251
 252 unsigned long long
 253 procfs_get_process_parent(
 254   unsigned long long pid)
 255 {
 256   char * buffer_ptr;
 257   size_t buffer_size;
 258   char * begin;
 259   char * end;
 260   unsigned long long ppid;
 261
 262   if (!procfs_get_process_file(pid, "status", &buffer_ptr, &buffer_size))
 263   {
 264     return 0;
 265   }
 266
 267   begin = strstr(buffer_ptr, "\nPPid:\t");
 268   if (begin == NULL)
 269   {
 270     log_error("parent pid not parsed for %llu", pid);
 271     log_error("-----------------------------");
 272     log_error("%s", buffer_ptr);
 273     log_error("-----------------------------");
 274     free(buffer_ptr);
 275     return 0;
 276   }
 277
 278   begin += 7;
 279
 280   end = strchr(begin, '\n');
 281   if (end == NULL)
 282   {
 283     log_error("parent pid not parsed for %llu (end)", pid);
 284     log_error("-----------------------------");
 285     log_error("%s", buffer_ptr);
 286     log_error("-----------------------------");
 287     free(buffer_ptr);
 288     return 0;
 289   }
 290
 291   *end = 0;
 292   //log_info("parent pid is %s", begin);
 293
 294   errno = 0;
 295   ppid = strtoull(begin, &end, 10);
 296   if (errno != 0)
 297   {
 298     log_error("strtoull failed to convert '%s' to integer", begin);
 299     ppid = 0;
 300   }
 301   else
 302   {
 303     //log_info("parent pid is %llu", ppid);
 304   }
 305
 306   /* avoid infinite cycles (should not happen because init has pid 1 and parent 0) */
 307   if (ppid == pid)
 308   {
 309     ppid = 0;
 310   }
 311
 312   free(buffer_ptr);
 313
 314   return ppid;
 315 }