date and time created 80/10/06 23:53:23 by root

SCCS-vsn: usr.bin/tail/tail.c 4.1

diff --git a/usr/src/usr.bin/tail/tail.c b/usr/src/usr.bin/tail/tail.c
new file mode 100644 (file)
index 0000000..4e9476e
--- /dev/null
+++ b/usr/src/usr.bin/tail/tail.c
@@ -0,0 +1,213 @@
+static char *sccsid = "@(#)tail.c      4.1 (Berkeley) %G%";
+/* tail command 
+ *
+ *     tail where [file]
+ *     where is +\b_n[type]
+ *     - means n lines before end
+ *     + means nth line from beginning
+ *     type 'b' means tail n blocks, not lines
+ *     type 'c' means tail n characters
+ *     Type 'r' means in lines in reverse order from end
+ *      (for -r, default is entire buffer )
+ *     option 'f' means loop endlessly trying to read more
+ *             characters after the end of file, on the  assumption
+ *             that the file is growing
+*/
+
+#include       <stdio.h>
+#include       <ctype.h>
+#include       <sys/types.h>
+#include       <sys/stat.h>
+#include       <errno.h>
+
+#define LBIN 4097
+struct stat    statb;
+int    follow;
+int    piped;
+char bin[LBIN];
+int errno;
+
+main(argc,argv)
+char **argv;
+{
+       long n,di;
+       register i,j,k;
+       char    *arg;
+       int partial,bylines,bkwds,fromend,lastnl;
+       char *p;
+
+       lseek(0,(long)0,1);
+       piped = errno==ESPIPE;
+       arg = argv[1];
+       if(argc<=1 || *arg!='-'&&*arg!='+') {
+               arg = "-10l";
+               argc++;
+               argv--;
+       }
+       fromend = *arg=='-';
+       arg++;
+       n = 0;
+       while(isdigit(*arg))
+               n = n*10 + *arg++ - '0';
+       if(!fromend&&n>0)
+               n--;
+       if(argc>2) {
+               close(0);
+               if(open(argv[2],0)!=0) {
+                       perror(argv[2]);
+                       exit(1);
+               }
+       }
+       bylines = -1; bkwds = 0;
+       while(*arg)
+       switch(*arg++) {
+
+       case 'b':
+               n <<= 9;
+               if(bylines!=-1) goto errcom;
+               bylines=0;
+               break;
+       case 'c':
+               if(bylines!=-1) goto errcom;
+               bylines=0;
+               break;
+       case 'f':
+               follow = 1;
+               break;
+       case 'r':
+               if(n==0) n = LBIN;
+               bkwds = 1; fromend = 1; bylines = 1;
+               break;
+       case 'l':
+               if(bylines!=-1) goto errcom;
+               bylines = 1;
+               break;
+       default:
+               goto errcom;
+       }
+       if (n==0) n = 10;
+       if(bylines==-1) bylines = 1;
+       if(bkwds) follow=0;
+       if(fromend)
+               goto keep;
+
+                       /*seek from beginning */
+
+       if(bylines) {
+               j = 0;
+               while(n-->0) {
+                       do {
+                               if(j--<=0) {
+                                       p = bin;
+                                       j = read(0,p,BUFSIZ);
+                                       if(j--<=0)
+                                               fexit();
+                               }
+                       } while(*p++ != '\n');
+               }
+               write(1,p,j);
+       } else  if(n>0) {
+               if(!piped)
+                       fstat(0,&statb);
+               if(piped||(statb.st_mode&S_IFMT)==S_IFCHR)
+                       while(n>0) {
+                               i = n>BUFSIZ?BUFSIZ:n;
+                               i = read(0,bin,i);
+                               if(i<=0)
+                                       fexit();
+                               n -= i;
+                       }
+               else
+                       lseek(0,n,0);
+       }
+copy:
+       while((i=read(0,bin,BUFSIZ))>0)
+               write(1,bin,i);
+       fexit();
+
+                       /*seek from end*/
+
+keep:
+       if(n <= 0)
+               fexit();
+       if(!piped) {
+               fstat(0,&statb);
+               di = !bylines&&n<LBIN?n:LBIN-1;
+               if(statb.st_size > di)
+                       lseek(0,-di,2);
+               if(!bylines)
+                       goto copy;
+       }
+       partial = 1;
+       for(;;) {
+               i = 0;
+               do {
+                       j = read(0,&bin[i],LBIN-i);
+                       if(j<=0)
+                               goto brka;
+                       i += j;
+               } while(i<LBIN);
+               partial = 0;
+       }
+brka:
+       if(!bylines) {
+               k =
+                   n<=i ? i-n:
+                   partial ? 0:
+                   n>=LBIN ? i+1:
+                   i-n+LBIN;
+               k--;
+       } else {
+               if(bkwds && bin[i==0?LBIN-1:i-1]!='\n'){        /* force trailing newline */
+                       bin[i]='\n';
+                       if(++i>=LBIN) {i = 0; partial = 0;}
+               }
+               k = i;
+               j = 0;
+               do {
+                       lastnl = k;
+                       do {
+                               if(--k<0) {
+                                       if(partial) {
+                                               if(bkwds) write(1,bin,lastnl+1);
+                                               goto brkb;
+                                       }
+                                       k = LBIN -1;
+                               }
+                       } while(bin[k]!='\n'&&k!=i);
+                       if(bkwds && j>0){
+                               if(k<lastnl) write(1,&bin[k+1],lastnl-k);
+                               else {
+                                       write(1,&bin[k+1],LBIN-k-1);
+                                       write(1,bin,lastnl+1);
+                               }
+                       }
+               } while(j++<n&&k!=i);
+brkb:
+               if(bkwds) exit(0);
+               if(k==i) do {
+                       if(++k>=LBIN)
+                               k = 0;
+               } while(bin[k]!='\n'&&k!=i);
+       }
+       if(k<i)
+               write(1,&bin[k+1],i-k-1);
+       else {
+               write(1,&bin[k+1],LBIN-k-1);
+               write(1,bin,i);
+       }
+       fexit();
+errcom:
+       fprintf(stderr, "usage: tail [+\b_[n][lbc][rf]] [file]\n");
+       exit(2);
+}
+
+fexit()
+{      register int n;
+       if (!follow || piped) exit(0);
+       for (;;)
+       {       sleep(1);
+               while ((n = read (0, bin, BUFSIZ)) > 0)
+                       write (1, bin, n);
+       }
+}