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 <assert.h>
  30 #include <stdlib.h>
  31 #include <sys/types.h>
  32 #include <sys/stat.h>
  33 #include <fcntl.h>
  34 #include <stdio.h>
  35 #include <unistd.h>
  36
  37 #include "procfs.h"
  38 #include "../common/debug.h"
  39
  40 #define BUFFER_SIZE 4096
  41
  42 static char g_buffer[BUFFER_SIZE];
  43
  44 static
  45 bool
  46 procfs_get_process_file(
  47   unsigned long long pid,
  48   const char * filename,
  49   char ** buffer_ptr_ptr,
  50   size_t * size_ptr)
  51 {
  52   int fd;
  53   ssize_t ret;
  54   size_t max;
  55   char * buffer_ptr;
  56   char * read_ptr;
  57   size_t buffer_size;
  58   size_t used_size;
  59
  60   sprintf(g_buffer, "/proc/%llu/%s", pid, filename);
  61
  62   fd = open(g_buffer, O_RDONLY);
  63   if (fd == -1)
  64   {
  65     return false;
  66   }
  67
  68   buffer_size = BUFFER_SIZE;
  69   buffer_ptr = malloc(buffer_size);
  70   if (buffer_ptr == NULL)
  71   {
  72     lash_error("malloc failed to allocate buffer with size %zu", buffer_size);
  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       lash_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     close(fd);
 113     return false;
 114   }
 115
 116   *buffer_ptr_ptr = buffer_ptr;
 117   *size_ptr = used_size;
 118
 119   return true;
 120 }
 121
 122 static
 123 char *
 124 procfs_get_process_link(
 125   unsigned long long pid,
 126   const char * filename)
 127 {
 128   int fd;
 129   ssize_t ret;
 130   char * buffer_ptr;
 131
 132   sprintf(g_buffer, "/proc/%llu/%s", pid, filename);
 133
 134   fd = open(g_buffer, O_RDONLY);
 135   if (fd == -1)
 136   {
 137     return NULL;
 138   }
 139
 140   ret = readlink(g_buffer, g_buffer, sizeof(g_buffer));
 141   if (ret != 0)
 142   {
 143     g_buffer[ret] = 0;
 144     buffer_ptr = strdup(g_buffer);
 145     lash_debug("process %llu %s symlink points to \"%s\"", pid, filename, buffer_ptr);
 146   }
 147   else
 148   {
 149     assert(ret == -1);
 150     buffer_ptr = NULL;
 151   }
 152
 153   close(fd);
 154
 155   return buffer_ptr;
 156 }
 157
 158 bool
 159 procfs_get_process_cmdline(
 160   unsigned long long pid,
 161   int * argc_ptr,
 162   char *** argv_ptr)
 163 {
 164   char * cmdline_ptr;
 165   char * temp_ptr;
 166   size_t cmdline_size;
 167   int i;
 168   int argc;
 169   char ** argv;
 170
 171   if (!procfs_get_process_file(pid, "cmdline", &cmdline_ptr, &cmdline_size))
 172   {
 173     return false;
 174   }
 175
 176   argc = 0;
 177   temp_ptr = cmdline_ptr;
 178
 179   while (temp_ptr - cmdline_ptr < cmdline_size)
 180   {
 181     if (*temp_ptr == 0)
 182     {
 183       argc++;
 184     }
 185
 186     temp_ptr++;
 187   }
 188
 189   assert(*(temp_ptr - 1) == 0); /* the last nul char */
 190
 191   argv = malloc((argc + 1) * sizeof(char *));
 192   if (argv == NULL)
 193   {
 194     free(cmdline_ptr);
 195     return false;
 196   }
 197
 198   temp_ptr = cmdline_ptr;
 199
 200   for (i = 0; i < argc; i++)
 201   {
 202     assert(temp_ptr - cmdline_ptr < cmdline_size);
 203
 204     argv[i] = strdup(temp_ptr);
 205     if (argv[i] == NULL)
 206     {
 207       /* rollback */
 208       while (i > 0)
 209       {
 210         i--;
 211         free(argv[i]);
 212       }
 213
 214       free(argv);
 215       free(cmdline_ptr);
 216       return false;
 217     }
 218
 219     temp_ptr += strlen(temp_ptr) + 1;
 220   }
 221
 222   /* Make sure that the array is NULL terminated */
 223   argv[argc] = NULL;
 224
 225   *argc_ptr = argc;
 226   *argv_ptr = argv;
 227
 228   free(cmdline_ptr);
 229
 230   return true;
 231 }
 232
 233 char *
 234 procfs_get_process_cwd(
 235   unsigned long long pid)
 236 {
 237   return procfs_get_process_link(pid, "cwd");
 238 }