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/* -*-mode: c; indent-tabs-mode: nil; c-basic-offset: 2; -*-
*/
/**
* Utilities for the quality of service module mod_qos.
*
* qstail.c: Shows the end of a log file beginning at the
* provided pattern.
*
* See http://mod-qos.sourceforge.net/ for further
* details.
*
* Copyright (C) 2023 Pascal Buchbinder
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
static const char revision[] = "$Id: qstail.c 2654 2022-05-13 09:12:42Z pbuchbinder $";
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include "qs_util.h"
#define BUFFER 2048
static void usage(char *cmd, int man) {
if(man) {
//.TH [name of program] [section number] [center footer] [left footer] [center header]
printf(".TH %s 1 \"%s\" \"mod_qos utilities %s\" \"%s man page\"\n", qs_CMD(cmd), man_date,
man_version, cmd);
}
printf("\n");
if(man) {
printf(".SH NAME\n");
}
qs_man_print(man, "%s - an utility printing the end of a log file"
" starting at the specified pattern.\n", cmd);
printf("\n");
if(man) {
printf(".SH SYNOPSIS\n");
}
qs_man_print(man, "%s%s -i <path> -p <pattern>\n", man ? "" : "Usage: ", cmd);
printf("\n");
if(man) {
printf(".SH DESCRIPTION\n");
} else {
printf("Summary\n");
}
qs_man_print(man, " %s shows the end of a log file beginning with the line containing the\n", cmd);
qs_man_print(man, " specified pattern. This may be used to show all lines which has been written\n");
qs_man_print(man, " after a certain event (e.g., server restart) or time stamp.\n");
printf("\n");
if(man) {
printf(".SH OPTIONS\n");
} else {
printf("Options\n");
}
if(man) printf(".TP\n");
qs_man_print(man, " -i <path>\n");
if(man) printf("\n");
qs_man_print(man, " Input file to read the data from.\n");
if(man) printf("\n.TP\n");
qs_man_print(man, " -p <pattern>\n");
if(man) printf("\n");
qs_man_print(man, " Search pattern (literal string).\n");
printf("\n");
if(man) {
printf(".SH SEE ALSO\n");
printf("qsdt(1), qsexec(1), qsfilter2(1), qsgeo(1), qsgrep(1), qshead(1), qslog(1), qslogger(1), qspng(1), qsre(1), qsrespeed(1), qsrotate(1), qssign(1)\n");
printf(".SH AUTHOR\n");
printf("Pascal Buchbinder, http://mod-qos.sourceforge.net/\n");
} else {
printf("See http://mod-qos.sourceforge.net/ for further details.\n");
}
if(man) {
exit(0);
} else {
exit(1);
}
}
/* search the beginning of the line starting at the provided position */
static void qs_readline(long pos, FILE *f) {
size_t len;
long startpos = pos - BUFFER + 1;
long readlen = BUFFER;
char line[readlen + 1];
if(startpos < 0) {
// we are at the beginning of the file
startpos = 0;
readlen = pos + 1;
}
fseek(f, startpos, SEEK_SET);
len = fread(&line, 1, readlen, f);
if(len > 0) {
char *s = &line[len-1];
line[len] = '\0';
while((s >= line) && (s[0] != CR) && (s[0] != LF)) {
s--;
}
if((s[0] == CR) || (s[0] == LF)) {
s++;
}
printf("%s", s);
}
}
static int qs_tail(const char *cmd, FILE *f, const char *pattern) {
char *cont = NULL;
long search_win_len = (strlen(pattern) * 2) + 32;
char line[search_win_len + 10];
long pos = 0;
size_t len;
char *startpattern = NULL;
fseek(f, 0L, SEEK_END);
pos = ftell(f);
while(pos > search_win_len) {
int offset = 0;
pos = pos - (search_win_len/2);
fseek(f, pos, SEEK_SET);
len = fread(&line, 1, search_win_len, f);
if(len <= 0) {
/* pattern not found / reached end */
return 1;
}
line[len] = '\0';
if((startpattern = strstr(line, pattern)) != NULL) {
int containsend = 0;
char *s = startpattern;
char *end;
offset = startpattern - line;
/* search the beginning of the line */
while((s > line) && (s[0] != CR) && (s[0] != LF)) {
s--;
}
if((s[0] != CR) && (s[0] != LF)) {
// beginning of the line not in the buffer
qs_readline(pos, f);
}
s++;
end = startpattern;
/* search the end of the line */
while((offset < search_win_len) && end[0] && end[0] != CR && end[0] != LF) {
end++;
offset++;
}
/* print the line containing the pattern */
if((end[0] == CR) || (end[0] == LF)) {
end[0] = '\0';
printf("%s\n", s);
containsend = 1;
} else {
printf("%s", s);
}
fseek(f, pos + offset, SEEK_SET);
if(containsend) {
// skip the line at the current position
cont = fgets(line, sizeof(line), f);
} else {
cont = line;
}
if(cont) {
while(fgets(line, sizeof(line), f) != NULL) {
printf("%s", line);
}
}
return 0;
}
}
return 1;
}
int main(int argc, const char * const argv[]) {
FILE *f;
const char *filename = NULL;
const char *pattern = NULL;
char *cmd = strrchr(argv[0], '/');
int status = 0;
if(cmd == NULL) {
cmd = (char *)argv[0];
} else {
cmd++;
}
argc--;
argv++;
while(argc >= 1) {
if(strcmp(*argv,"-i") == 0) {
if (--argc >= 1) {
filename = *(++argv);
}
} else if(strcmp(*argv,"-p") == 0) {
if (--argc >= 1) {
pattern = *(++argv);
}
} else if(strcmp(*argv,"-?") == 0) {
usage(cmd, 0);
} else if(strcmp(*argv,"-help") == 0) {
usage(cmd, 0);
} else if(strcmp(*argv,"--help") == 0) {
usage(cmd, 0);
} else if(strcmp(*argv,"--man") == 0) {
usage(cmd, 1);
}
argc--;
argv++;
}
if(filename == NULL || pattern == NULL) {
usage(cmd, 0);
}
if((f = fopen(filename, "r")) == NULL) {
fprintf(stderr, "[%s]: ERROR, could not open file '%s'\n", cmd, filename);
exit(1);
}
status = qs_tail(cmd, f, pattern);
fclose(f);
return status;
}
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