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       return false;
 122     }
 123   }
 124
 125   buffer_ptr[buffer_size] = 0;
 126
 127   *buffer_ptr_ptr = buffer_ptr;
 128   *size_ptr = used_size;
 129
 130   return true;
 131 }
 132
 133 static
 134 char *
 135 procfs_get_process_link(
 136   unsigned long long pid,
 137   const char * filename)
 138 {
 139   int fd;
 140   ssize_t ret;
 141   char * buffer_ptr;
 142
 143   sprintf(g_buffer, "/proc/%llu/%s", pid, filename);
 144
 145   fd = open(g_buffer, O_RDONLY);
 146   if (fd == -1)
 147   {
 148     return NULL;
 149   }
 150
 151   ret = readlink(g_buffer, g_buffer, sizeof(g_buffer));
 152   if (ret != 0)
 153   {
 154     g_buffer[ret] = 0;
 155     buffer_ptr = strdup(g_buffer);
 156     log_debug("process %llu %s symlink points to \"%s\"", pid, filename, buffer_ptr);
 157   }
 158   else
 159   {
 160     ASSERT(ret == -1);
 161     buffer_ptr = NULL;
 162   }
 163
 164   close(fd);
 165
 166   return buffer_ptr;
 167 }
 168
 169 bool
 170 procfs_get_process_cmdline(
 171   unsigned long long pid,
 172   int * argc_ptr,
 173   char *** argv_ptr)
 174 {
 175   char * cmdline_ptr;
 176   char * temp_ptr;
 177   size_t cmdline_size;
 178   int i;
 179   int argc;
 180   char ** argv;
 181
 182   if (!procfs_get_process_file(pid, "cmdline", &cmdline_ptr, &cmdline_size))
 183   {
 184     return false;
 185   }
 186
 187   argc = 0;
 188   temp_ptr = cmdline_ptr;
 189
 190   while (temp_ptr - cmdline_ptr < cmdline_size)
 191   {
 192     if (*temp_ptr == 0)
 193     {
 194       argc++;
 195     }
 196
 197     temp_ptr++;
 198   }
 199
 200   ASSERT(*(temp_ptr - 1) == 0); /* the last nul char */
 201
 202   argv = malloc((argc + 1) * sizeof(char *));
 203   if (argv == NULL)
 204   {
 205     free(cmdline_ptr);
 206     return false;
 207   }
 208
 209   temp_ptr = cmdline_ptr;
 210
 211   for (i = 0; i < argc; i++)
 212   {
 213     ASSERT(temp_ptr - cmdline_ptr < cmdline_size);
 214
 215     argv[i] = strdup(temp_ptr);
 216     if (argv[i] == NULL)
 217     {
 218       /* rollback */
 219       while (i > 0)
 220       {
 221         i--;
 222         free(argv[i]);
 223       }
 224
 225       free(argv);
 226       free(cmdline_ptr);
 227       return false;
 228     }
 229
 230     temp_ptr += strlen(temp_ptr) + 1;
 231   }
 232
 233   /* Make sure that the array is NULL terminated */
 234   argv[argc] = NULL;
 235
 236   *argc_ptr = argc;
 237   *argv_ptr = argv;
 238
 239   free(cmdline_ptr);
 240
 241   return true;
 242 }
 243
 244 char *
 245 procfs_get_process_cwd(
 246   unsigned long long pid)
 247 {
 248   return procfs_get_process_link(pid, "cwd");
 249 }
 250
 251 unsigned long long
 252 procfs_get_process_parent(
 253   unsigned long long pid)
 254 {
 255   char * buffer_ptr;
 256   size_t buffer_size;
 257   char * begin;
 258   char * end;
 259   unsigned long long ppid;
 260
 261   if (!procfs_get_process_file(pid, "status", &buffer_ptr, &buffer_size))
 262   {
 263     return 0;
 264   }
 265
 266   begin = strstr(buffer_ptr, "\nPPid:\t");
 267   if (begin == NULL)
 268   {
 269     log_error("parent pid not parsed for %llu", pid);
 270     log_error("-----------------------------");
 271     log_error("%s", buffer_ptr);
 272     log_error("-----------------------------");
 273     return 0;
 274   }
 275
 276   begin += 7;
 277
 278   end = strchr(begin, '\n');
 279   if (end == NULL)
 280   {
 281     log_error("parent pid not parsed for %llu (end)", pid);
 282     log_error("-----------------------------");
 283     log_error("%s", buffer_ptr);
 284     log_error("-----------------------------");
 285     return 0;
 286   }
 287
 288   *end = 0;
 289   //log_info("parent pid is %s", begin);
 290
 291   errno = 0;
 292   ppid = strtoull(begin, &end, 10);
 293   if (errno != 0)
 294   {
 295     log_error("strtoull failed to convert '%s' to integer", begin);
 296     ppid = 0;
 297   }
 298   else
 299   {
 300     //log_info("parent pid is %llu", ppid);
 301   }
 302
 303   /* avoid infinite cycles (should not happen because init has pid 1 and parent 0) */
 304   if (ppid == pid)
 305   {
 306     ppid = 0;
 307   }
 308
 309   free(buffer_ptr);
 310
 311   return ppid;
 312 }