coreutils/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 <fcntl.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <unistd.h>
  39 #include <string.h>
  40 #include <getopt.h>
  41 #include "internal.h"
  42
  43 #define STDIN "standard input"
  44 #define LINES 0
  45 #define BYTES 1
  46
  47 static int n_files = 0;
  48 static char **files = NULL;
  49 static char * buffer;
  50 static ssize_t bytes_read=0;
  51 static ssize_t bs;
  52 static ssize_t filelocation=0;
  53 static char pip;
  54
  55 #ifdef BB_FEATURE_SIMPLE_TAIL
  56 static const char unit_type=LINES;
  57 #else
  58 static char unit_type=LINES;
  59 static char verbose = 0;
  60 #endif
  61
  62 static off_t units=0;
  63
  64 int tail_stream(int fd)
  65 {
  66         ssize_t startpoint;
  67         ssize_t endpoint=0;
  68         ssize_t count=0;
  69         ssize_t filesize=0;
  70         int direction=1;
  71
  72         filelocation=0;
  73         startpoint=bs=BUFSIZ;
  74
  75         filesize=lseek(fd, -1, SEEK_END)+1;
  76         pip=(filesize<=0);
  77
  78         if(units>=0)
  79                 lseek(fd,0,SEEK_SET);
  80         else {
  81                 direction=-1;
  82                 count=1;
  83         }
  84         while(units != 0) {
  85                 if (pip) {
  86                         char * line;
  87                         ssize_t f_size=0;
  88
  89                         bs=BUFSIZ;
  90                         line=malloc(bs);
  91                         while(1) {
  92                                 bytes_read=read(fd,line,bs);
  93                                 if(bytes_read<=0)
  94                                         break;
  95                                 buffer=realloc(buffer,f_size+bytes_read);
  96                                 memcpy(&buffer[f_size],line,bytes_read);
  97                                 filelocation=f_size+=bytes_read;
  98                         }
  99                         bs=f_size;
 100                         if(direction<0)
 101                                 bs--;
 102                         if (line)
 103                                 free(line);
 104                 } else {
 105                         filelocation = lseek(fd, 0, SEEK_CUR);
 106                         if(direction<0) {
 107                                 if(filelocation<bs)
 108                                         bs=filelocation;
 109                                 filelocation = lseek(fd, -bs, SEEK_CUR);
 110                         }
 111                         bytes_read = read(fd, buffer, bs);
 112                         if (bytes_read <= 0)
 113                                 break;
 114                         bs=bytes_read;
 115                 }
 116                 startpoint=bs;
 117                 if(direction>0) {
 118                         endpoint=startpoint;
 119                         startpoint=0;
 120                 }
 121                 for(;startpoint!=endpoint;startpoint+=direction) {
 122 #ifndef BB_FEATURE_SIMPLE_TAIL
 123                         if(unit_type==BYTES)
 124                                 count++;
 125                         else
 126 #endif
 127                                 if(buffer[startpoint-1]=='\n')
 128                                         count++;
 129                         if (!pip)
 130                                 filelocation=lseek(fd,0,SEEK_CUR);
 131                         if(count==units*direction)
 132                                 break;
 133                 }
 134                 if((count==units*direction) | pip)
 135                         break;
 136                 if(direction<0){
 137                         filelocation = lseek(fd, -bytes_read, SEEK_CUR);
 138                         if(filelocation==0)
 139                                 break;
 140                 }
 141         }
 142         if(pip && (direction<0))
 143                 bs++;
 144         bytes_read=bs-startpoint;
 145         memcpy(&buffer[0],&buffer[startpoint],bytes_read);
 146
 147         return 0;
 148 }
 149
 150 void add_file(char *name)
 151 {
 152         ++n_files;
 153         files = realloc(files, n_files);
 154         files[n_files - 1] = (char *) malloc(strlen(name) + 1);
 155         strcpy(files[n_files - 1], name);
 156 }
 157
 158 void checknumbers(const char* name)
 159 {
 160         int test=atoi(name);
 161         if(test){
 162                 units=test;
 163                 if(units<0)
 164                         units=units-1;
 165         } else {
 166                 fatalError("Unrecognised number '%s'\n", name);
 167         }
 168 }
 169
 170 int tail_main(int argc, char **argv)
 171 {
 172         int show_headers = 1;
 173         int test;
 174         int opt;
 175         char follow=0;
 176         int sleep_int=1;
 177         int *fd;
 178
 179         opterr = 0;
 180
 181         while ((opt=getopt(argc,argv,"c:fhn:s:q:v123456789+")) >0) {
 182
 183                 switch (opt) {
 184                         case '1':case '2':case '3':case '4':case '5':
 185                         case '6':case '7':case '8':case '9':case '0':
 186                                 checknumbers(argv[optind-1]);
 187                                 break;
 188
 189 #ifndef BB_FEATURE_SIMPLE_TAIL
 190                 case 'c':
 191                         unit_type = BYTES;
 192                         test = atoi(optarg);
 193                         if(test==0)
 194                                 usage(tail_usage);
 195                         if(optarg[strlen(optarg)-1]>'9') {
 196                                 switch (optarg[strlen(optarg)-1]) {
 197                                 case 'b':
 198                                         test *= 512;
 199                                         break;
 200                                 case 'k':
 201                                         test *= 1024;
 202                                         break;
 203                                 case 'm':
 204                                         test *= (1024 * 1024);
 205                                         break;
 206                                 default:
 207                                         fprintf(stderr,"Size must be b,k, or m.");
 208                                         usage(tail_usage);
 209                                 }
 210                         }
 211                         if(optarg[0]=='+')
 212                                 units=test+1;
 213                         else
 214                                 units=-(test+1);
 215                         break;
 216                 case 'q':
 217                         show_headers = 0;
 218                         break;
 219                 case 's':
 220                         sleep_int = atoi(optarg);
 221                         if(sleep_int<1)
 222                                 sleep_int=1;
 223                         break;
 224                 case 'v':
 225                         verbose = 1;
 226                         break;
 227 #endif
 228                 case 'f':
 229                         follow = 1;
 230                         break;
 231                 case 'h':
 232                         usage(tail_usage);
 233                         break;
 234                 case 'n':
 235                         test = atoi(optarg);
 236                         if (test) {
 237                                 if (optarg[0] == '+')
 238                                         units = test;
 239                                 else
 240                                         units = -(test+1);
 241                         } else
 242                                 usage(tail_usage);
 243                         break;
 244                 default:
 245                         errorMsg("\nUnknown arg: %c.\n\n",optopt);
 246                         usage(tail_usage);
 247                 }
 248         }
 249         while (optind <= argc) {
 250                 if(optind==argc) {
 251                         if (n_files==0)
 252                                 add_file(STDIN);
 253                         else
 254                                 break;
 255                 }else {
 256                         if (*argv[optind] == '+') {
 257                                 checknumbers(argv[optind]);
 258                         }
 259                         else if (!strcmp(argv[optind], "-")) {
 260                                 add_file(STDIN);
 261                         } else {
 262                                 add_file(argv[optind]);
 263                         }
 264                         optind++;
 265                 }
 266         }
 267         if(units==0)
 268                 units=-11;
 269         if(units>0)
 270                 units--;
 271         fd=malloc(sizeof(int)*n_files);
 272         if (n_files == 1)
 273 #ifndef BB_FEATURE_SIMPLE_TAIL
 274                 if (!verbose)
 275 #endif
 276                         show_headers = 0;
 277         buffer=malloc(BUFSIZ);
 278         for (test = 0; test < n_files; test++) {
 279                 if (show_headers)
 280                         printf("==> %s <==\n", files[test]);
 281                 if (!strcmp(files[test], STDIN))
 282                         fd[test] = 0;
 283                 else
 284                         fd[test] = open(files[test], O_RDONLY);
 285                 if (fd[test] == -1)
 286                         fatalError("Unable to open file %s.\n", files[test]);
 287                 tail_stream(fd[test]);
 288
 289                 bs=BUFSIZ;
 290                 while (1) {
 291                         if((filelocation>0 || pip)){
 292                                 write(1,buffer,bytes_read);
 293                         }
 294                         bytes_read = read(fd[test], buffer, bs);
 295                         filelocation+=bytes_read;
 296                         if (bytes_read <= 0) {
 297                                 break;
 298                         }
 299                         usleep(sleep_int * 1000);
 300                 }
 301                 if(n_files>1)
 302                         printf("\n");
 303         }
 304         while(1){
 305                 for (test = 0; test < n_files; test++) {
 306                         if(!follow){
 307                                 close(fd[test]);
 308                                 continue;
 309                         } else {
 310                                 sleep(sleep_int);
 311                                 bytes_read = read(fd[test], buffer, bs);
 312                                 if(bytes_read>0) {
 313                                         if (show_headers)
 314                                                 printf("==> %s <==\n", files[test]);
 315                                         write(1,buffer,bytes_read);
 316                                         if(n_files>1)
 317                                                 printf("\n");
 318                                 }
 319                         }
 320                 }
 321                 if(!follow)
 322                         break;
 323         }
 324         if (fd)
 325                 free(fd);
 326         if (buffer)
 327                 free(buffer);
 328         if(files)
 329                 free(files);
 330         return 0;
 331 }
 332
 333 /*
 334 Local Variables:
 335 c-file-style: "linux"
 336 c-basic-offset: 4
 337 tab-width: 4
 338 End:
 339 */