tail.c

   1 /* vi: set sw=4 ts=4: */
   2 /* tail -- output the last part of file(s)
   3    Copyright (C) 89, 90, 91, 95, 1996 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18
  19    Original version by Paul Rubin <phr@ocf.berkeley.edu>.
  20    Extensions by David MacKenzie <djm@gnu.ai.mit.edu>.
  21    tail -f for multiple files by Ian Lance Taylor <ian@airs.com>.
  22
  23    Rewrote the option parser, removed locales support,
  24    and generally busyboxed, Erik Andersen <andersen@lineo.com>
  25
  26    Removed superfluous options and associated code ("-c", "-n", "-q").
  27    Removed "tail -f" support for multiple files.
  28    Both changes by Friedrich Vedder <fwv@myrtle.lahn.de>.
  29
  30    Compleate Rewrite to correctly support "-NUM", "+NUM", and "-s" by
  31    E.Allen Soard (esp@espsw.net).
  32
  33  */
  34 #include <sys/types.h>
  35 #include <sys/stat.h>
  36 #include <fcntl.h>
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include <unistd.h>
  40 #include <string.h>
  41 #include <getopt.h>
  42 #include "internal.h"
  43
  44 #define STDIN "standard input"
  45 #define LINES 0
  46 #define BYTES 1
  47
  48 static int n_files = 0;
  49 static char **files = NULL;
  50 static char * buffer;
  51 static ssize_t bytes_read=0;
  52 static ssize_t bs;
  53 static ssize_t filelocation=0;
  54 static char pip;
  55
  56 #ifdef BB_FEATURE_SIMPLE_TAIL
  57 static const char unit_type=LINES;
  58 #else
  59 static char unit_type=LINES;
  60 static char verbose = 0;
  61 #endif
  62
  63 static off_t units=0;
  64
  65 int tail_stream(int fd)
  66 {
  67         ssize_t startpoint;
  68         ssize_t endpoint=0;
  69         ssize_t count=0;
  70         ssize_t filesize=0;
  71         char direction=1;
  72
  73         filelocation=0;
  74         startpoint=bs=BUFSIZ;
  75
  76         filesize=lseek(fd, -1, SEEK_END)+1;
  77         pip=(filesize<=0);
  78
  79         if(units>=0)
  80                 lseek(fd,0,SEEK_SET);
  81         else {
  82                 direction=-1;
  83                 count=1;
  84         }
  85         while(units != 0) {
  86                 if (pip) {
  87                         char * line;
  88                         ssize_t f_size=0;
  89
  90                         bs=BUFSIZ;
  91                         line=malloc(bs);
  92                         while(1) {
  93                                 bytes_read=read(fd,line,bs);
  94                                 if(bytes_read<=0)
  95                                         break;
  96                                 buffer=realloc(buffer,f_size+bytes_read);
  97                                 memcpy(&buffer[f_size],line,bytes_read);
  98                                 filelocation=f_size+=bytes_read;
  99                         }
 100                         bs=f_size;
 101                         if(direction<0)
 102                                 bs--;
 103                         if (line)
 104                                 free(line);
 105                 } else {
 106                         filelocation = lseek(fd, 0, SEEK_CUR);
 107                         if(direction<0) {
 108                                 if(filelocation<bs)
 109                                         bs=filelocation;
 110                                 filelocation = lseek(fd, -bs, SEEK_CUR);
 111                         }
 112                         bytes_read = read(fd, buffer, bs);
 113                         if (bytes_read <= 0)
 114                                 break;
 115                         bs=bytes_read;
 116                 }
 117                 startpoint=bs;
 118                 if(direction>0) {
 119                         endpoint=startpoint;
 120                         startpoint=0;
 121                 }
 122                 for(;startpoint!=endpoint;startpoint+=direction) {
 123 #ifndef BB_FEATURE_SIMPLE_TAIL
 124                         if(unit_type==BYTES)
 125                                 count++;
 126                         else
 127 #endif
 128                                 if(buffer[startpoint-1]=='\n')
 129                                         count++;
 130                         if (!pip)
 131                                 filelocation=lseek(fd,0,SEEK_CUR);
 132                         if(count==units*direction)
 133                                 break;
 134                 }
 135                 if((count==units*direction) | pip)
 136                         break;
 137                 if(direction<0){
 138                         filelocation = lseek(fd, -bytes_read, SEEK_CUR);
 139                         if(filelocation==0)
 140                                 break;
 141                 }
 142         }
 143         if(pip && (direction<0))
 144                 bs++;
 145         bytes_read=bs-startpoint;
 146         memcpy(&buffer[0],&buffer[startpoint],bytes_read);
 147
 148         return 0;
 149 }
 150
 151 void add_file(char *name)
 152 {
 153         ++n_files;
 154         files = realloc(files, n_files);
 155         files[n_files - 1] = (char *) malloc(strlen(name) + 1);
 156         strcpy(files[n_files - 1], name);
 157 }
 158
 159 void checknumbers(const char* name)
 160 {
 161         int test=atoi(name);
 162         if(test){
 163                 units=test;
 164                 if(units<0)
 165                         units=units-1;
 166         } else {
 167                 fatalError("Unrecognised number '%s'\n", name);
 168         }
 169 }
 170
 171 int tail_main(int argc, char **argv)
 172 {
 173         int show_headers = 1;
 174         int test;
 175         int opt;
 176         char follow=0;
 177         int sleep_int=1;
 178         int *fd;
 179
 180         opterr = 0;
 181
 182         while ((opt=getopt(argc,argv,"c:fhn:s:q:v123456789+")) >0) {
 183
 184                 switch (opt) {
 185                         case '1':case '2':case '3':case '4':case '5':
 186                         case '6':case '7':case '8':case '9':case '0':
 187                                 checknumbers(argv[optind-1]);
 188                                 break;
 189
 190 #ifndef BB_FEATURE_SIMPLE_TAIL
 191                 case 'c':
 192                         unit_type = BYTES;
 193                         test = atoi(optarg);
 194                         if(test==0)
 195                                 usage(tail_usage);
 196                         if(optarg[strlen(optarg)-1]>'9') {
 197                                 switch (optarg[strlen(optarg)-1]) {
 198                                 case 'b':
 199                                         test *= 512;
 200                                         break;
 201                                 case 'k':
 202                                         test *= 1024;
 203                                         break;
 204                                 case 'm':
 205                                         test *= (1024 * 1024);
 206                                         break;
 207                                 default:
 208                                         fprintf(stderr,"Size must be b,k, or m.");
 209                                         usage(tail_usage);
 210                                 }
 211                         }
 212                         if(optarg[0]=='+')
 213                                 units=test+1;
 214                         else
 215                                 units=-(test+1);
 216                         break;
 217                 case 'q':
 218                         show_headers = 0;
 219                         break;
 220                 case 's':
 221                         sleep_int = atoi(optarg);
 222                         if(sleep_int<1)
 223                                 sleep_int=1;
 224                         break;
 225                 case 'v':
 226                         verbose = 1;
 227                         break;
 228 #endif
 229                 case 'f':
 230                         follow = 1;
 231                         break;
 232                 case 'h':
 233                         usage(tail_usage);
 234                         break;
 235                 case 'n':
 236                         test = atoi(optarg);
 237                         if (test) {
 238                                 if (optarg[0] == '+')
 239                                         units = test;
 240                                 else
 241                                         units = -(test+1);
 242                         } else
 243                                 usage(tail_usage);
 244                         break;
 245                 default:
 246                         errorMsg("\nUnknown arg: %c.\n\n",optopt);
 247                         usage(tail_usage);
 248                 }
 249         }
 250         while (optind <= argc) {
 251                 if(optind==argc) {
 252                         if (n_files==0)
 253                                 add_file(STDIN);
 254                         else
 255                                 break;
 256                 }else {
 257                         if (*argv[optind] == '+') {
 258                                 checknumbers(argv[optind]);
 259                         }
 260                         else if (!strcmp(argv[optind], "-")) {
 261                                 add_file(STDIN);
 262                         } else {
 263                                 add_file(argv[optind]);
 264                         }
 265                         optind++;
 266                 }
 267         }
 268         if(units==0)
 269                 units=-11;
 270         if(units>0)
 271                 units--;
 272         fd=malloc(sizeof(int)*n_files);
 273         if (n_files == 1)
 274 #ifndef BB_FEATURE_SIMPLE_TAIL
 275                 if (!verbose)
 276 #endif
 277                         show_headers = 0;
 278         buffer=malloc(BUFSIZ);
 279         for (test = 0; test < n_files; test++) {
 280                 if (show_headers)
 281                         printf("==> %s <==\n", files[test]);
 282                 if (!strcmp(files[test], STDIN))
 283                         fd[test] = 0;
 284                 else
 285                         fd[test] = open(files[test], O_RDONLY);
 286                 if (fd[test] == -1)
 287                         fatalError("Unable to open file %s.\n", files[test]);
 288                 tail_stream(fd[test]);
 289
 290                 bs=BUFSIZ;
 291                 while (1) {
 292                         if((filelocation>0 || pip)){
 293                                 write(1,buffer,bytes_read);
 294                         }
 295                         bytes_read = read(fd[test], buffer, bs);
 296                         filelocation+=bytes_read;
 297                         if (bytes_read <= 0) {
 298                                 break;
 299                         }
 300                         usleep(sleep_int * 1000);
 301                 }
 302                 if(n_files>1)
 303                         printf("\n");
 304         }
 305         while(1){
 306                 for (test = 0; test < n_files; test++) {
 307                         if(!follow){
 308                                 close(fd[test]);
 309                                 continue;
 310                         } else {
 311                                 sleep(sleep_int);
 312                                 bytes_read = read(fd[test], buffer, bs);
 313                                 if(bytes_read>0) {
 314                                         if (show_headers)
 315                                                 printf("==> %s <==\n", files[test]);
 316                                         write(1,buffer,bytes_read);
 317                                         if(n_files>1)
 318                                                 printf("\n");
 319                                 }
 320                         }
 321                 }
 322                 if(!follow)
 323                         break;
 324         }
 325         if (fd)
 326                 free(fd);
 327         if (buffer)
 328                 free(buffer);
 329         if(files)
 330                 free(files);
 331         return 0;
 332 }
 333
 334 /*
 335 Local Variables:
 336 c-file-style: "linux"
 337 c-basic-offset: 4
 338 tab-width: 4
 339 End:
 340 */