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 <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
 160 int tail_main(int argc, char **argv)
 161 {
 162         int show_headers = 1;
 163         int test;
 164         int opt;
 165         int optc=0;
 166         char **optv=NULL;
 167         char follow=0;
 168         int sleep_int=1;
 169         int *fd;
 170
 171         opterr = 0;
 172
 173         for(opt=0;opt<argc;opt++){
 174                 test=atoi(argv[opt]);
 175                 if(test){
 176                         units=test;
 177                         if(units<0)
 178                                 units=units-1;
 179                 }else{
 180                         optc++;
 181                         optv = realloc(optv, optc);
 182                         optv[optc - 1] = (char *) malloc(strlen(argv[opt]) + 1);
 183                         strcpy(optv[optc - 1], argv[opt]);
 184                 }
 185         }
 186         while ((opt=getopt(optc,optv,"c:fhn:s:q:v")) >0) {
 187
 188                 switch (opt) {
 189
 190 #ifndef BB_FEATURE_SIMPLE_TAIL
 191
 192                 case 'c':
 193                         unit_type = BYTES;
 194                         test = atoi(optarg);
 195                         if(test==0)
 196                                 usage(tail_usage);
 197                         if(optarg[strlen(optarg)-1]>'9') {
 198                                 switch (optarg[strlen(optarg)-1]) {
 199                                 case 'b':
 200                                         test *= 512;
 201                                         break;
 202                                 case 'k':
 203                                         test *= 1024;
 204                                         break;
 205                                 case 'm':
 206                                         test *= (1024 * 1024);
 207                                         break;
 208                                 default:
 209                                         fprintf(stderr,"Size must be b,k, or m.");
 210                                         usage(tail_usage);
 211                                 }
 212                         }
 213                         if(optarg[0]=='+')
 214                                 units=test+1;
 215                         else
 216                                 units=-(test+1);
 217                         break;
 218                 case 'q':
 219                         show_headers = 0;
 220                         break;
 221                 case 's':
 222                         sleep_int = atoi(optarg);
 223                         if(sleep_int<1)
 224                                 sleep_int=1;
 225                         break;
 226                 case 'v':
 227                         verbose = 1;
 228                         break;
 229 #endif
 230                 case 'f':
 231                         follow = 1;
 232                         break;
 233                 case 'h':
 234                         usage(tail_usage);
 235                         break;
 236                 case 'n':
 237                         test = atoi(optarg);
 238                         if (test) {
 239                                 if (optarg[0] == '+')
 240                                         units = test;
 241                                 else
 242                                         units = -(test+1);
 243                         } else
 244                                 usage(tail_usage);
 245                         break;
 246                 default:
 247                         errorMsg("\nUnknown arg: %c.\n\n",optopt);
 248                         usage(tail_usage);
 249                 }
 250         }
 251         while (optind <= optc) {
 252                 if(optind==optc) {
 253                         if (n_files==0)
 254                                 add_file(STDIN);
 255                         else
 256                                 break;
 257                 }else {
 258                         if (!strcmp(optv[optind], "-"))
 259                                 add_file(STDIN);
 260                         else
 261                                 add_file(optv[optind]);
 262                         optind++;
 263                 }
 264         }
 265         if(units==0)
 266                 units=-11;
 267         if(units>0)
 268                 units--;
 269         fd=malloc(sizeof(int)*n_files);
 270         if (n_files == 1)
 271 #ifndef BB_FEATURE_SIMPLE_TAIL
 272                 if (!verbose)
 273 #endif
 274                         show_headers = 0;
 275         buffer=malloc(BUFSIZ);
 276         for (test = 0; test < n_files; test++) {
 277                 if (show_headers)
 278                         printf("==> %s <==\n", files[test]);
 279                 if (!strcmp(files[test], STDIN))
 280                         fd[test] = 0;
 281                 else
 282                         fd[test] = open(files[test], O_RDONLY);
 283                 if (fd[test] == -1)
 284                         fatalError("Unable to open file %s.\n", files[test]);
 285                 tail_stream(fd[test]);
 286
 287                 bs=BUFSIZ;
 288                 while (1) {
 289                         if((filelocation>0 || pip)){
 290                                 write(1,buffer,bytes_read);
 291                         }
 292                         bytes_read = read(fd[test], buffer, bs);
 293                         filelocation+=bytes_read;
 294                         if (bytes_read <= 0) {
 295                                 break;
 296                         }
 297                         usleep(sleep_int * 1000);
 298                 }
 299                 if(n_files>1)
 300                         printf("\n");
 301         }
 302         while(1){
 303                 for (test = 0; test < n_files; test++) {
 304                         if(!follow){
 305                                 close(fd[test]);
 306                                 continue;
 307                         } else {
 308                                 sleep(sleep_int);
 309                                 bytes_read = read(fd[test], buffer, bs);
 310                                 if(bytes_read>0) {
 311                                         if (show_headers)
 312                                                 printf("==> %s <==\n", files[test]);
 313                                         write(1,buffer,bytes_read);
 314                                         if(n_files>1)
 315                                                 printf("\n");
 316                                 }
 317                         }
 318                 }
 319                 if(!follow)
 320                         break;
 321         }
 322         if (fd)
 323                 free(fd);
 324         if (buffer)
 325                 free(buffer);
 326         if(files)
 327                 free(files);
 328         if(optv)
 329                 free(optv);
 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 */