Mods to tar (--fast-read) to cause it to stop looking for exact-matching

file specifications when they've been extracted (enabling you to get a file
fast if it occurs somewhere close to the front).
Submitted by:	Marc van Kempen <wmbfmk@urc.tue.nl>

gnu/usr.bin/tar/list.c

@@ -95,6 +95,11 @@ read_and (do_something)
     {
       prev_status = status;
       status = read_header ();
+	/* check if the namelist got emptied during the course of reading */
+	/* the tape, if so stop by setting status to EOF */
+      if ((namelist == NULL) && nlpsfreed) { 
+	  status = EOF;
+      }
       switch (status)
 	{
 

gnu/usr.bin/tar/tar.1

@@ -3,7 +3,7 @@
 .\"
 .\"	Written by John F. Woods <jfw@jfwhome.funhouse.com>
 .\"
-.\"	$Id: tar.1,v 1.1 1995/01/26 00:14:11 jkh Exp $
+.\"	$Id: tar.1,v 1.2 1995/01/31 04:36:48 jkh Exp $
 .\"
 .Dd 6 August 1994
 .Os FreeBSD
@@ -158,6 +158,9 @@ on a remote machine.
 .It Fl -new-volume-script Ar file
 Run a script at the end of each archive volume (implies
 .Fl M ) .
+.It Fl -fast-read
+Stop after all non-wildcard extraction targets have been found
+in the archive.
 .It Fl G
 .It Fl -incremental
 Create/list/extract old GNU-format incremental backup.

gnu/usr.bin/tar/tar.c

@@ -84,6 +84,7 @@ void name_add ();
 void name_init ();
 void options ();
 char *un_quote_string ();
+int nlpsfreed = 0;
 
 #ifndef S_ISLNK
 #define lstat stat
@@ -182,6 +183,7 @@ struct option long_options[] =
   {"atime-preserve", 0, &f_atime_preserve, 1},
 
   {"unlink", 0, &f_unlink, 1},
+  {"fast-read", 0, &f_fast_read, 1},
 
   {0, 0, 0, 0}
 };
@@ -760,6 +762,7 @@ Other options:\n\
 --block-compress	block the output of compression program for tapes\n\
 -[0-7][lmh]		specify drive and density\n\
 --unlink		unlink files before creating them\n\
+--fast-read 		stop after desired names in archive have been found\n\
 ", stdout);
 }
 
@@ -1123,6 +1126,7 @@ name_match (p)
      register char *p;
 {
   register struct name *nlp;
+  struct name *tmpnlp;
   register int len;
 
 again:
@@ -1174,7 +1178,36 @@ name_match (p)
 	    }
 	  if (nlp->change_dir && chdir (nlp->change_dir))
 	    msg_perror ("Can't change to directory %s", nlp->change_dir);
+	  if (f_fast_read) {
+	      if (strcmp(p, nlp->name) == 0) {
+		  /* remove the current entry, since we found a match */
+		  /* use brute force, this code is a mess anyway */
+		  if (namelist->next == NULL) { 
+		      /* the list contains one element */
+		      free(namelist);
+		      namelist = NULL;
+		  } else {
+		      if (nlp == namelist) { 
+			  /* the first element is the one */
+			  tmpnlp = namelist->next;
+			  free(namelist);
+			  namelist = tmpnlp;
+		      } else {
+			  tmpnlp = namelist;
+			  while (tmpnlp->next != nlp) {
+			      tmpnlp = tmpnlp->next;
+			  }
+			  tmpnlp->next = nlp->next;
+			  free(nlp);
+		      }
+		  }
+		  /* set a boolean to decide wether we started with a  */
+		  /* non-empty  namelist, that was emptied */
+		  nlpsfreed = 1;	
+	      }
+	  } 
 	  return 1;		/* We got a match */
+	      
 	}
     }
 

gnu/usr.bin/tar/tar.h

@@ -232,6 +232,7 @@ TAR_EXTERN int f_force_local;	/* --force-local */
 TAR_EXTERN int f_atime_preserve;/* --atime-preserve */
 TAR_EXTERN int f_compress_block; /* --compress-block */
 TAR_EXTERN int f_unlink;	/* --unlink */
+TAR_EXTERN int f_fast_read;	/* --fast-read */
 
 /*
  * We default to Unix Standard format rather than 4.2BSD tar format.
@@ -274,6 +275,10 @@ TAR_EXTERN char *gnu_dumpfile;
  */
 TAR_EXTERN char read_error_flag;
 
+/*
+ * global boolean, see name_match in tar.c
+ */
+extern int	nlpsfreed;
 
 /*
  * Declarations of functions available to the world.