libbb/find_pid_by_name.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) 1999,2000,2001 by Erik Andersen <andersee@debian.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  */
  21
  22 #include <stdio.h>
  23 #include <ctype.h>
  24 #include <string.h>
  25 #include <dirent.h>
  26 #include <stdlib.h>
  27 #include "libbb.h"
  28
  29 #define READ_BUF_SIZE   50
  30
  31
  32 /* For Erik's nifty devps device driver */
  33 #ifdef CONFIG_FEATURE_USE_DEVPS_PATCH
  34 #include <linux/devps.h>
  35
  36 /* find_pid_by_name()
  37  *
  38  *  This finds the pid of the specified process,
  39  *  by using the /dev/ps device driver.
  40  *
  41  *  Returns a list of all matching PIDs
  42  */
  43 extern pid_t* find_pid_by_name( char* pidName)
  44 {
  45         int fd, i, j;
  46         char device[] = "/dev/ps";
  47         pid_t num_pids;
  48         pid_t* pid_array = NULL;
  49         pid_t* pidList=NULL;
  50
  51         /* open device */
  52         fd = open(device, O_RDONLY);
  53         if (fd < 0)
  54                 perror_msg_and_die("open failed for `%s'", device);
  55
  56         /* Find out how many processes there are */
  57         if (ioctl (fd, DEVPS_GET_NUM_PIDS, &num_pids)<0)
  58                 perror_msg_and_die("\nDEVPS_GET_PID_LIST");
  59
  60         /* Allocate some memory -- grab a few extras just in case
  61          * some new processes start up while we wait. The kernel will
  62          * just ignore any extras if we give it too many, and will trunc.
  63          * the list if we give it too few.  */
  64         pid_array = (pid_t*) xcalloc( num_pids+10, sizeof(pid_t));
  65         pid_array[0] = num_pids+10;
  66
  67         /* Now grab the pid list */
  68         if (ioctl (fd, DEVPS_GET_PID_LIST, pid_array)<0)
  69                 perror_msg_and_die("\nDEVPS_GET_PID_LIST");
  70
  71         /* Now search for a match */
  72         for (i=1, j=0; i<pid_array[0] ; i++) {
  73                 char* p;
  74                 struct pid_info info;
  75
  76             info.pid = pid_array[i];
  77             if (ioctl (fd, DEVPS_GET_PID_INFO, &info)<0)
  78                         perror_msg_and_die("\nDEVPS_GET_PID_INFO");
  79
  80                 /* Make sure we only match on the process name */
  81                 p=info.command_line+1;
  82                 while ((*p != 0) && !isspace(*(p)) && (*(p-1) != '\\')) {
  83                         (p)++;
  84                 }
  85                 if (isspace(*(p)))
  86                                 *p='\0';
  87
  88                 if ((strstr(info.command_line, pidName) != NULL)
  89                                 && (strlen(pidName) == strlen(info.command_line))) {
  90                         pidList=xrealloc( pidList, sizeof(pid_t) * (j+2));
  91                         pidList[j++]=info.pid;
  92                 }
  93         }
  94         if (pidList) {
  95                 pidList[j]=0;
  96         } else if ( strcmp(pidName, "init")==0) {
  97                 /* If we found nothing and they were trying to kill "init",
  98                  * guess PID 1 and call it good...  Perhaps we should simply
  99                  * exit if /proc isn't mounted, but this will do for now. */
 100                 pidList=xrealloc( pidList, sizeof(pid_t));
 101                 pidList[0]=1;
 102         } else {
 103                 pidList=xrealloc( pidList, sizeof(pid_t));
 104                 pidList[0]=-1;
 105         }
 106
 107         /* Free memory */
 108         free( pid_array);
 109
 110         /* close device */
 111         if (close (fd) != 0)
 112                 perror_msg_and_die("close failed for `%s'", device);
 113
 114         return pidList;
 115 }
 116
 117 #else           /* CONFIG_FEATURE_USE_DEVPS_PATCH */
 118
 119 /* find_pid_by_name()
 120  *
 121  *  This finds the pid of the specified process.
 122  *  Currently, it's implemented by rummaging through
 123  *  the proc filesystem.
 124  *
 125  *  Returns a list of all matching PIDs
 126  */
 127 extern pid_t* find_pid_by_name( char* pidName)
 128 {
 129         DIR *dir;
 130         struct dirent *next;
 131         pid_t* pidList=NULL;
 132         int i=0;
 133
 134         dir = opendir("/proc");
 135         if (!dir)
 136                 perror_msg_and_die("Cannot open /proc");
 137
 138         while ((next = readdir(dir)) != NULL) {
 139                 FILE *status;
 140                 char filename[READ_BUF_SIZE];
 141                 char buffer[READ_BUF_SIZE];
 142                 char name[READ_BUF_SIZE];
 143
 144                 /* Must skip ".." since that is outside /proc */
 145                 if (strcmp(next->d_name, "..") == 0)
 146                         continue;
 147
 148                 /* If it isn't a number, we don't want it */
 149                 if (!isdigit(*next->d_name))
 150                         continue;
 151
 152                 sprintf(filename, "/proc/%s/status", next->d_name);
 153                 if (! (status = fopen(filename, "r")) ) {
 154                         continue;
 155                 }
 156                 if (fgets(buffer, READ_BUF_SIZE-1, status) == NULL) {
 157                         fclose(status);
 158                         continue;
 159                 }
 160                 fclose(status);
 161
 162                 /* Buffer should contain a string like "Name:   binary_name" */
 163                 sscanf(buffer, "%*s %s", name);
 164                 if (strcmp(name, pidName) == 0) {
 165                         pidList=xrealloc( pidList, sizeof(pid_t) * (i+2));
 166                         pidList[i++]=strtol(next->d_name, NULL, 0);
 167                 }
 168         }
 169
 170         if (pidList)
 171                 pidList[i]=0;
 172         else if ( strcmp(pidName, "init")==0) {
 173                 /* If we found nothing and they were trying to kill "init",
 174                  * guess PID 1 and call it good...  Perhaps we should simply
 175                  * exit if /proc isn't mounted, but this will do for now. */
 176                 pidList=xrealloc( pidList, sizeof(pid_t));
 177                 pidList[0]=1;
 178         } else {
 179                 pidList=xrealloc( pidList, sizeof(pid_t));
 180                 pidList[0]=-1;
 181         }
 182         return pidList;
 183 }
 184 #endif                                                  /* CONFIG_FEATURE_USE_DEVPS_PATCH */
 185
 186 /* END CODE */
 187 /*
 188 Local Variables:
 189 c-file-style: "linux"
 190 c-basic-offset: 4
 191 tab-width: 4
 192 End:
 193 */