conky/src/tailhead.c

/* Conky, a system monitor, based on torsmo
 *
 * Any original torsmo code is licensed under the BSD license
 *
 * All code written since the fork of torsmo is licensed under the GPL
 *
 * Please see COPYING for details
 *
 * Copyright (c) 2004, Hannu Saransaari and Lauri Hakkarainen
 * Copyright (c) 2005-2009 Brenden Matthews, Philip Kovacs, et. al.
 *	(see AUTHORS)
 * All rights reserved.
 *
 * This program 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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, see <http://www.gnu.org/licenses/>.
 *
 */
#include "config.h"
#include "conky.h"
#include "logging.h"
#include "tailhead.h"
#include "text_object.h"

#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifndef HAVE_MEMRCHR
static void *memrchr(const void *buffer, char c, size_t n)
{
	const unsigned char *p = buffer;

	for (p += n; n; n--) {
		if (*--p == c) {
			return (void *) p;
		}
	}
	return NULL;
}
#endif

int init_tailhead_object(enum tailhead_type type,
		struct text_object *obj, const char *arg)
{
	char buf[128];
	int n1, n2;
	struct stat st;
	FILE *fp = NULL;
	int fd;
	int numargs;
	const char *me;

	/* FIXME: use #define for that */
	me = (type == TAIL) ? "tail" : "head";

	if (!arg) {
		ERR("%s needs arguments", me);
		return 1;
	}

	numargs = sscanf(arg, "%127s %i %i", buf, &n1, &n2);

	if (numargs < 2 || numargs > 3) {
		ERR("incorrect number of arguments given to %s object", me);
		return 1;
	}

	if (n1 < 1 || n1 > MAX_TAIL_LINES) {
		ERR("invalid arg for %s, number of lines must be "
				"between 1 and %i", me, MAX_TAIL_LINES);
		return 1;
	}

	obj->data.tail.fd = -1;

	if (type == HEAD) {
		goto NO_FIFO;
	}
	to_real_path(buf, buf);
	if (stat(buf, &st) == 0) {
		if (S_ISFIFO(st.st_mode)) {
			fd = open(buf, O_RDONLY | O_NONBLOCK);

			if (fd == -1) {
				ERR("%s logfile does not exist, or you do "
				    "not have correct permissions", me);
				return 1;
			}

			obj->data.tail.fd = fd;
		} else {
NO_FIFO:
			fp = fopen(buf, "r");
		}
	}

	if (fp || obj->data.tail.fd != -1) {
		obj->data.tail.logfile = malloc(text_buffer_size);
		strcpy(obj->data.tail.logfile, buf);
		obj->data.tail.wantedlines = n1;
		obj->data.tail.interval = update_interval * 2;

		if (obj->data.tail.fd == -1) {
			fclose(fp);
		}
	} else {
		// fclose(fp);
		ERR("%s logfile does not exist, or you do not have "
				"correct permissions", me);
		return 1;
	}
	/* XXX: the following implies update_interval >= 1 ?! */
	if (numargs == 3 && (n2 < 1 || n2 < update_interval)) {
		ERR("%s interval must be greater than "
		    "0 and "PACKAGE_NAME"'s interval, ignoring", me);
	} else if (numargs == 3) {
			obj->data.tail.interval = n2;
	}
	/* asumming all else worked */
	obj->data.tail.buffer = malloc(text_buffer_size * 20);
	return 0;
}

/* Allows reading from a FIFO (i.e., /dev/xconsole).
 * The file descriptor is set to non-blocking which makes this possible.
 *
 * FIXME: Since lseek cannot seek a file descriptor long lines will break. */
static void tail_pipe(struct text_object *obj, char *dst, size_t dst_size)
{
#define TAIL_PIPE_BUFSIZE	4096
	int lines = 0;
	int line_len = 0;
	int last_line = 0;
	int fd = obj->data.tail.fd;

	while (1) {
		char buf[TAIL_PIPE_BUFSIZE];
		ssize_t len = read(fd, buf, sizeof(buf));
		int i;

		if (len == -1) {
			if (errno != EAGAIN) {
				strcpy(obj->data.tail.buffer, "Logfile Read Error");
				snprintf(dst, dst_size, "Logfile Read Error");
			}

			break;
		} else if (len == 0) {
			strcpy(obj->data.tail.buffer, "Logfile Empty");
			snprintf(dst, dst_size, "Logfile Empty");
			break;
		}

		for (line_len = 0, i = 0; i < len; i++) {
			int pos = 0;
			char *p;

			if (buf[i] == '\n') {
				lines++;

				if (obj->data.tail.readlines > 0) {
					int n;
					int olines = 0;
					int first_line = 0;

					for (n = 0; obj->data.tail.buffer[n]; n++) {
						if (obj->data.tail.buffer[n] == '\n') {
							if (!first_line) {
								first_line = n + 1;
							}

							if (++olines < obj->data.tail.wantedlines) {
								pos = n + 1;
								continue;
							}

							n++;
							p = obj->data.tail.buffer + first_line;
							pos = n - first_line;
							memmove(obj->data.tail.buffer,
									obj->data.tail.buffer + first_line, strlen(p));
							obj->data.tail.buffer[pos] = 0;
							break;
						}
					}
				}

				p = buf + last_line;
				line_len++;
				memcpy(&(obj->data.tail.buffer[pos]), p, line_len);
				obj->data.tail.buffer[pos + line_len] = 0;
				last_line = i + 1;
				line_len = 0;
				obj->data.tail.readlines = lines;
				continue;
			}

			line_len++;
		}
	}

	snprintf(dst, dst_size, "%s", obj->data.tail.buffer);
}

static long rev_fcharfind(FILE *fp, char val, unsigned int step)
{
#define BUFSZ 0x1000
	long ret = -1;
	unsigned int count = 0;
	static char buf[BUFSZ];
	long orig_pos = ftell(fp);
	long buf_pos = -1;
	long file_pos = orig_pos;
	long buf_size = BUFSZ;
	char *cur_found;

	while (count < step) {
		if (buf_pos <= 0) {
			if (file_pos > BUFSZ) {
				fseek(fp, file_pos - BUFSZ, SEEK_SET);
			} else {
				buf_size = file_pos;
				fseek(fp, 0, SEEK_SET);
			}
			file_pos = ftell(fp);
			buf_pos = fread(buf, 1, buf_size, fp);
		}
		cur_found = memrchr(buf, val, (size_t) buf_pos);
		if (cur_found != NULL) {
			buf_pos = cur_found - buf;
			count++;
		} else {
			buf_pos = -1;
			if (file_pos == 0) {
				break;
			}
		}
	}
	fseek(fp, orig_pos, SEEK_SET);
	if (count == step) {
		ret = file_pos + buf_pos;
	}
	return ret;
}

int print_tail_object(struct text_object *obj, char *p, size_t p_max_size)
{
	FILE *fp;
	long nl = 0, bsize;
	int iter;

	if (current_update_time - obj->data.tail.last_update < obj->data.tail.interval) {
		snprintf(p, p_max_size, "%s", obj->data.tail.buffer);
		return 0;
	}

	obj->data.tail.last_update = current_update_time;

	if (obj->data.tail.fd != -1) {
		tail_pipe(obj, p, p_max_size);
		return 0;
	}

	fp = fopen(obj->data.tail.logfile, "rt");
	if (fp == NULL) {
		/* Send one message, but do not consistently spam
		 * on missing logfiles. */
		if (obj->data.tail.readlines != 0) {
			ERR("tail logfile failed to open");
			strcpy(obj->data.tail.buffer, "Logfile Missing");
		}
		obj->data.tail.readlines = 0;
		snprintf(p, p_max_size, "Logfile Missing");
	} else {
		obj->data.tail.readlines = 0;
		/* -1 instead of 0 to avoid counting a trailing
		 * newline */
		fseek(fp, -1, SEEK_END);
		bsize = ftell(fp) + 1;
		for (iter = obj->data.tail.wantedlines; iter > 0;
				iter--) {
			nl = rev_fcharfind(fp, '\n', iter);
			if (nl >= 0) {
				break;
			}
		}
		obj->data.tail.readlines = iter;
		if (obj->data.tail.readlines
				< obj->data.tail.wantedlines) {
			fseek(fp, 0, SEEK_SET);
		} else {
			fseek(fp, nl + 1, SEEK_SET);
			bsize -= ftell(fp);
		}
		/* Make sure bsize is at least 1 byte smaller than the
		 * buffer max size. */
		if (bsize > (long) ((text_buffer_size * 20) - 1)) {
			fseek(fp, bsize - text_buffer_size * 20 - 1,
					SEEK_CUR);
			bsize = text_buffer_size * 20 - 1;
		}
		bsize = fread(obj->data.tail.buffer, 1, bsize, fp);
		fclose(fp);
		if (bsize > 0) {
			/* Clean up trailing newline, make sure the
			 * buffer is null terminated. */
			if (obj->data.tail.buffer[bsize - 1] == '\n') {
				obj->data.tail.buffer[bsize - 1] = '\0';
			} else {
				obj->data.tail.buffer[bsize] = '\0';
			}
			snprintf(p, p_max_size, "%s",
					obj->data.tail.buffer);
		} else {
			strcpy(obj->data.tail.buffer, "Logfile Empty");
			snprintf(p, p_max_size, "Logfile Empty");
		}	/* bsize > 0 */
	}		/* fp == NULL */
	return 0;
}

long fwd_fcharfind(FILE *fp, char val, unsigned int step)
{
#define BUFSZ 0x1000
       long ret = -1;
       unsigned int count = 0;
       static char buf[BUFSZ];
       long orig_pos = ftell(fp);
       long buf_pos = -1;
       long buf_size = BUFSZ;
       char *cur_found = NULL;

       while (count < step) {
               if (cur_found == NULL) {
                       buf_size = fread(buf, 1, buf_size, fp);
                       buf_pos = 0;
               }
               cur_found = memchr(buf + buf_pos, val, buf_size - buf_pos);
               if (cur_found != NULL) {
                       buf_pos = cur_found - buf + 1;
                       count++;
               } else {
                       if (feof(fp)) {
                               break;
                       }
               }
       }
       if (count == step) {
               ret = ftell(fp) - buf_size + buf_pos - 1;
       }
       fseek(fp, orig_pos, SEEK_SET);
       return ret;
}

int print_head_object(struct text_object *obj, char *p, size_t p_max_size)
{
	FILE *fp;
	long nl = 0;
	int iter;

	if (current_update_time - obj->data.tail.last_update < obj->data.tail.interval) {
		snprintf(p, p_max_size, "%s", obj->data.tail.buffer);
		return 0;
	}

	obj->data.tail.last_update = current_update_time;

	fp = fopen(obj->data.tail.logfile, "rt");
	if (fp == NULL) {
		/* Send one message, but do not consistently spam
		 * on missing logfiles. */
		if (obj->data.tail.readlines != 0) {
			ERR("head logfile failed to open");
			strcpy(obj->data.tail.buffer, "Logfile Missing");
		}
		obj->data.tail.readlines = 0;
		snprintf(p, p_max_size, "Logfile Missing");
	} else {
		obj->data.tail.readlines = 0;
		for (iter = obj->data.tail.wantedlines; iter > 0;
				iter--) {
			nl = fwd_fcharfind(fp, '\n', iter);
			if (nl >= 0) {
				break;
			}
		}
		obj->data.tail.readlines = iter;
		/* Make sure nl is at least 1 byte smaller than the
		 * buffer max size. */
		if (nl > (long) ((text_buffer_size * 20) - 1)) {
			nl = text_buffer_size * 20 - 1;
		}
		nl = fread(obj->data.tail.buffer, 1, nl, fp);
		fclose(fp);
		if (nl > 0) {
			/* Clean up trailing newline, make sure the buffer
			 * is null terminated. */
			if (obj->data.tail.buffer[nl - 1] == '\n') {
				obj->data.tail.buffer[nl - 1] = '\0';
			} else {
				obj->data.tail.buffer[nl] = '\0';
			}
			snprintf(p, p_max_size, "%s",
					obj->data.tail.buffer);
		} else {
			strcpy(obj->data.tail.buffer, "Logfile Empty");
			snprintf(p, p_max_size, "Logfile Empty");
		}	/* nl > 0 */
	}		/* if fp == null */
	return 0;
}