/* $Id: plugin_exec.c,v 1.5 2004/06/26 09:27:21 reinelt Exp $ * * plugin for external processes * * Copyright 2004 Michael Reinelt * Copyright 2004 The LCD4Linux Team * * based on the old 'exec' client which is * Copyright 2001 Leopold Tötsch * * * This file is part of LCD4Linux. * * LCD4Linux is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2, or (at your option) * any later version. * * LCD4Linux is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * * $Log: plugin_exec.c,v $ * Revision 1.5 2004/06/26 09:27:21 reinelt * * added '-W' to CFLAGS * changed all C++ comments to C ones ('//' => '/* */') * cleaned up a lot of signed/unsigned mistakes * * Revision 1.4 2004/06/20 10:09:56 reinelt * * 'const'ified the whole source * * Revision 1.3 2004/06/17 06:23:43 reinelt * * hash handling rewritten to solve performance issues * * Revision 1.2 2004/04/08 10:48:25 reinelt * finished plugin_exec * modified thread handling * added '%x' format to qprintf (hexadecimal) * * Revision 1.1 2004/03/20 11:49:40 reinelt * forgot to add plugin_exec.c ... * */ /* * exported functions: * * int plugin_init_exec (void) * adds functions to start external pocesses * */ #include "config.h" #include #include #include #include #include #include "debug.h" #include "plugin.h" #include "hash.h" #include "cfg.h" #include "thread.h" #include "qprintf.h" #define NUM_THREADS 16 #define SHM_SIZE 256 typedef struct { int delay; int mutex; pid_t pid; int shmid; char *cmd; char *key; char *ret; } EXEC_THREAD; static EXEC_THREAD Thread[NUM_THREADS]; static int max_thread = -1; static HASH EXEC; /* x^0 + x^5 + x^12 */ #define CRCPOLY 0x8408 static unsigned short CRC (const char *s) { int i; unsigned short crc; /* seed value */ crc = 0xffff; while (*s != '\0') { crc ^= *s++; for (i = 0; i < 8; i++) crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY : 0); } return crc; } static void exec_thread (void *data) { EXEC_THREAD *Thread = (EXEC_THREAD*)data; FILE *pipe; char buffer[SHM_SIZE]; int len; /* use a safe path */ putenv ("PATH=/usr/local/bin:/usr/bin:/bin"); /* forever... */ while (1) { pipe = popen(Thread->cmd, "r"); if (pipe == NULL) { error("exec error: could not run pipe '%s': %s", Thread->cmd, strerror(errno)); len = 0; } else { len = fread(buffer, 1, SHM_SIZE-1, pipe); if (len <= 0) { error("exec error: could not read from pipe '%s': %s", Thread->cmd, strerror(errno)); len = 0; } pclose(pipe); } /* force trailing zero */ buffer[len] = '\0'; /* remove trailing CR/LF */ while (len>0 && (buffer[len-1]=='\n' || buffer[len-1]=='\r')) { buffer[--len]='\0'; } /* lock shared memory */ mutex_lock(Thread->mutex); /* write data */ strncpy(Thread->ret, buffer, SHM_SIZE); /* unlock shared memory */ mutex_unlock(Thread->mutex); usleep (Thread->delay); } } static void destroy_exec_thread (const int n) { if (Thread[n].mutex != 0) mutex_destroy(Thread[n].mutex); if (Thread[n].cmd) free (Thread[n].cmd); if (Thread[n].key) free (Thread[n].key); if (Thread[n].ret) shm_destroy (Thread[n].shmid, Thread[n].ret); Thread[n].delay = 0; Thread[n].mutex = 0; Thread[n].pid = 0; Thread[n].shmid = 0; Thread[n].cmd = NULL; Thread[n].key = NULL; Thread[n].ret = NULL; } static int create_exec_thread (const char *cmd, const char *key, const int delay) { char name[10]; if (max_thread >= NUM_THREADS) { error ("cannot create exec thread <%s>: thread buffer full!", cmd); return -1; } max_thread++; Thread[max_thread].delay = delay; Thread[max_thread].mutex = mutex_create(); Thread[max_thread].pid = -1; Thread[max_thread].cmd = strdup(cmd); Thread[max_thread].key = strdup(key); Thread[max_thread].ret = NULL; /* create communication buffer */ Thread[max_thread].shmid = shm_create ((void**)&Thread[max_thread].ret, SHM_SIZE); /* catch error */ if (Thread[max_thread].shmid < 0) { error ("cannot create exec thread <%s>: shared memory allocation failed!", cmd); destroy_exec_thread (max_thread--); return -1; } /* create thread */ qprintf(name, sizeof(name), "exec-%s", key); Thread[max_thread].pid = thread_create (name, exec_thread, &Thread[max_thread]); /* catch error */ if (Thread[max_thread].pid < 0) { error ("cannot create exec thread <%s>: fork failed?!", cmd); destroy_exec_thread (max_thread--); return -1; } return 0; } static int do_exec (const char *cmd, const char *key, int delay) { int i, age; age = hash_age(&EXEC, key); if (age < 0) { hash_put (&EXEC, key, ""); /* first-time call: create thread */ if (delay < 10) { error ("exec(%s): delay %d is too short! using 10 msec", cmd, delay); delay = 10; } if (create_exec_thread (cmd, key, 1000*delay)) { return -1; } return 0; } /* reread every 10 msec only */ if (age > 0 && age <= 10) return 0; /* find thread */ for (i = 0; i <= max_thread; i++) { if (strcmp(key, Thread[i].key) == 0) { /* lock shared memory */ mutex_lock(Thread[i].mutex); /* copy data */ hash_put (&EXEC, key, Thread[i].ret); /* unlock shared memory */ mutex_unlock(Thread[i].mutex); return 0; } } error ("internal error: could not find thread exec-%s", key); return -1; } static void my_exec (RESULT *result, RESULT *arg1, RESULT *arg2) { char *cmd, key[5], *val; int delay; cmd = R2S(arg1); delay = (int)R2N(arg2); qprintf (key, sizeof(key), "%x", CRC(cmd)); if (do_exec(cmd, key, delay) < 0) { SetResult(&result, R_STRING, ""); return; } val = hash_get(&EXEC, key, NULL); if (val == NULL) val = ""; SetResult(&result, R_STRING, val); } int plugin_init_exec (void) { hash_create(&EXEC); AddFunction ("exec", 2, my_exec); return 0; } void plugin_exit_exec(void) { int i; for (i=0; i<=max_thread; i++) { destroy_exec_thread(i); } hash_destroy(&EXEC); }