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-rw-r--r--plugin_exec.c284
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+/* $Id: plugin_exec.c 840 2007-09-09 12:17:42Z michael $
+ * $URL: https://ssl.bulix.org/svn/lcd4linux/trunk/plugin_exec.c $
+ *
+ * plugin for external processes
+ *
+ * Copyright (C) 2004 Michael Reinelt <michael@reinelt.co.at>
+ * Copyright (C) 2004 The LCD4Linux Team <lcd4linux-devel@users.sourceforge.net>
+ *
+ * based on the old 'exec' client which is
+ * Copyright (C) 2001 Leopold Tötsch <lt@toetsch.at>
+ *
+ *
+ * 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.
+ *
+ */
+
+/*
+ * exported functions:
+ *
+ * int plugin_init_exec (void)
+ * adds functions to start external pocesses
+ *
+ */
+
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+#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 4096
+
+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)
+{
+ thread_destroy(Thread[n].pid);
+
+ 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);
+}
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