Index: savecore.c
===================================================================
RCS file: /home/ncvs/src/sbin/savecore/savecore.c,v
retrieving revision 1.36
diff -u -r1.36 savecore.c
--- savecore.c	2000/10/17 22:43:41	1.36
+++ savecore.c	2001/02/13 12:33:27
@@ -346,8 +346,8 @@
 void
 save_core()
 {
-	register FILE *fp;
-	register int bounds, ifd, nr, nw;
+	FILE *fp;
+	int bounds, ifd, nr, nw, he, hs;
 	char path[MAXPATHLEN];
 	mode_t oumask;
 
@@ -405,7 +405,39 @@
 				syslog(LOG_ERR, "%s: %m", ddname);
 			goto err2;
 		}
-		nw = fwrite(buf, 1, nr, fp);
+		for (nw = 0; nw < nr; nw = he) {
+			/* find a contiguous block of zeroes */
+			for (hs = nw; hs < nr; hs += PAGE_SIZE) {
+				for (he = hs; he < nr && buf[he] == 0; ++he)
+					/* nothing */ ;
+				
+				/* round down to a block boundary */
+				he &= ~PAGE_MASK;
+				
+				/* if we're still > hs, we've found a hole */
+				if (he > hs)
+					break;
+			}
+
+			/*
+			 * 1) Don't go beyond the end of the buffer.
+			 * 2) If the end of the buffer is less than
+			 *    BLOCKSIZE bytes away, we're at the end
+			 *    of the file, so just grab what's left.
+			 */
+			if (hs + PAGE_SIZE > nr)
+				hs = he = nr;
+			
+			/* nw <= hs <= nr */
+			if (hs > nw)
+				if (fwrite(buf + nw, hs - nw, 1, fp) != 1)
+					break;
+			
+			/* hs <= he <= nr */
+			if (he > hs)
+				if (fseek(fp, he - hs, SEEK_CUR) == -1)
+					break;
+		}
 		if (nw != nr) {
 			syslog(LOG_ERR, "%s: %m", path);
 err2:			syslog(LOG_WARNING,
@@ -457,7 +489,7 @@
 int
 verify_dev(name, dev)
 	char *name;
-	register dev_t dev;
+	dev_t dev;
 {
 	struct stat sb;
 
@@ -477,7 +509,7 @@
  */
 void
 find_dev(dev)
-	register dev_t dev;
+	dev_t dev;
 {
 	struct dirent *ent;
 	char *dn, *dnp;
@@ -551,7 +583,7 @@
 int
 check_space()
 {
-	register FILE *fp;
+	FILE *fp;
 	const char *tkernel;
 	off_t minfree, spacefree, totfree, kernelsize, needed;
 	struct stat st;