busybox/tail.c

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/* vi: set sw=4 ts=4: */
/* tail -- output the last part of file(s)
Copyright (C) 89, 90, 91, 95, 1996 Free Software Foundation, Inc.
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 2, 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, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
Original version by Paul Rubin <phr@ocf.berkeley.edu>.
Extensions by David MacKenzie <djm@gnu.ai.mit.edu>.
tail -f for multiple files by Ian Lance Taylor <ian@airs.com>.
Rewrote the option parser, removed locales support,
and generally busyboxed, Erik Andersen <andersen@lineo.com>
Removed superfluous options and associated code ("-c", "-n", "-q").
Removed "tail -f" support for multiple files.
Both changes by Friedrich Vedder <fwv@myrtle.lahn.de>.
Compleate Rewrite to correctly support "-NUM", "+NUM", and "-s" by
E.Allen Soard (esp@espsw.net).
*/
#include <sys/types.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <getopt.h>
#include "busybox.h"
#define STDIN "standard input"
#define LINES 0
#define BYTES 1
static int n_files = 0;
static char **files = NULL;
static char * buffer;
static ssize_t bytes_read=0;
static ssize_t bs;
static ssize_t filelocation=0;
static char pip;
#ifdef BB_FEATURE_SIMPLE_TAIL
static const char unit_type=LINES;
#else
static char unit_type=LINES;
static char verbose = 0;
#endif
static off_t units=0;
static int tail_stream(int fd)
{
ssize_t startpoint;
ssize_t endpoint=0;
ssize_t count=0;
ssize_t filesize=0;
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int direction=1;
filelocation=0;
startpoint=bs=BUFSIZ;
filesize=lseek(fd, -1, SEEK_END)+1;
pip=(filesize<=0);
if(units>=0)
lseek(fd,0,SEEK_SET);
else {
direction=-1;
count=1;
}
while(units != 0) {
if (pip) {
char * line;
ssize_t f_size=0;
bs=BUFSIZ;
line=xmalloc(bs);
while(1) {
bytes_read=read(fd,line,bs);
if(bytes_read<=0)
break;
buffer=xrealloc(buffer,f_size+bytes_read);
memcpy(&buffer[f_size],line,bytes_read);
filelocation=f_size+=bytes_read;
}
bs=f_size;
if(direction<0)
bs--;
if (line)
free(line);
} else {
filelocation = lseek(fd, 0, SEEK_CUR);
if(direction<0) {
if(filelocation<bs)
bs=filelocation;
filelocation = lseek(fd, -bs, SEEK_CUR);
}
bytes_read = read(fd, buffer, bs);
if (bytes_read <= 0)
break;
bs=bytes_read;
}
startpoint=bs;
if(direction>0) {
endpoint=startpoint;
startpoint=0;
}
for(;startpoint!=endpoint;startpoint+=direction) {
#ifndef BB_FEATURE_SIMPLE_TAIL
if(unit_type==BYTES)
count++;
else
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#endif
if(buffer[startpoint-1]=='\n')
count++;
if (!pip)
filelocation=lseek(fd,0,SEEK_CUR);
if(count==units*direction)
break;
}
if((count==units*direction) | pip)
break;
if(direction<0){
filelocation = lseek(fd, -bytes_read, SEEK_CUR);
if(filelocation==0)
break;
}
}
if(pip && (direction<0))
bs++;
bytes_read=bs-startpoint;
memcpy(&buffer[0],&buffer[startpoint],bytes_read);
return 0;
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}
void add_file(char *name)
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{
++n_files;
files = xrealloc(files, n_files);
files[n_files - 1] = (char *) xmalloc(strlen(name) + 1);
strcpy(files[n_files - 1], name);
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}
int tail_main(int argc, char **argv)
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{
int show_headers = 1;
int test;
int opt;
char follow=0;
int sleep_int=1;
int *fd;
opterr = 0;
while ((opt=getopt(argc,argv,"c:fhn:s:q:v")) >0) {
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switch (opt) {
#ifndef BB_FEATURE_SIMPLE_TAIL
case 'c':
unit_type = BYTES;
test = atoi(optarg);
if(test==0)
usage(tail_usage);
if(optarg[strlen(optarg)-1]>'9') {
switch (optarg[strlen(optarg)-1]) {
case 'b':
test *= 512;
break;
case 'k':
test *= 1024;
break;
case 'm':
test *= (1024 * 1024);
break;
default:
fprintf(stderr,"Size must be b,k, or m.");
usage(tail_usage);
}
}
if(optarg[0]=='+')
units=test+1;
else
units=-(test+1);
break;
case 'q':
show_headers = 0;
break;
case 's':
sleep_int = atoi(optarg);
if(sleep_int<1)
sleep_int=1;
break;
case 'v':
verbose = 1;
break;
#endif
case 'f':
follow = 1;
break;
case 'h':
usage(tail_usage);
break;
case 'n':
test = atoi(optarg);
if (test) {
if (optarg[0] == '+')
units = test;
else
units = -(test+1);
} else
usage(tail_usage);
break;
default:
error_msg("\nUnknown arg: %c.\n\n",optopt);
usage(tail_usage);
}
}
while (optind <= argc) {
if(optind==argc) {
if (n_files==0)
add_file(STDIN);
else
break;
}else {
if (!strcmp(argv[optind], "-")) {
add_file(STDIN);
} else {
add_file(argv[optind]);
}
optind++;
}
}
if(units==0)
units=-11;
if(units>0)
units--;
fd=xmalloc(sizeof(int)*n_files);
if (n_files == 1)
#ifndef BB_FEATURE_SIMPLE_TAIL
if (!verbose)
#endif
show_headers = 0;
buffer=xmalloc(BUFSIZ);
for (test = 0; test < n_files; test++) {
if (show_headers)
printf("==> %s <==\n", files[test]);
if (!strcmp(files[test], STDIN))
fd[test] = 0;
else
fd[test] = open(files[test], O_RDONLY);
if (fd[test] == -1)
error_msg_and_die("Unable to open file %s.\n", files[test]);
tail_stream(fd[test]);
bs=BUFSIZ;
while (1) {
if((filelocation>0 || pip)){
write(1,buffer,bytes_read);
}
bytes_read = read(fd[test], buffer, bs);
filelocation+=bytes_read;
if (bytes_read <= 0) {
break;
}
usleep(sleep_int * 1000);
}
if(n_files>1)
printf("\n");
}
while(1){
for (test = 0; test < n_files; test++) {
if(!follow){
close(fd[test]);
continue;
} else {
sleep(sleep_int);
bytes_read = read(fd[test], buffer, bs);
if(bytes_read>0) {
if (show_headers)
printf("==> %s <==\n", files[test]);
write(1,buffer,bytes_read);
if(n_files>1)
printf("\n");
}
}
}
if(!follow)
break;
}
if (fd)
free(fd);
if (buffer)
free(buffer);
if(files)
free(files);
return 0;
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}
/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/