diff --git a/usr.bin/bsdiff/bsdiff/bsdiff.c b/usr.bin/bsdiff/bsdiff/bsdiff.c
index a4813253b23e..06a8812308c8 100644
--- a/usr.bin/bsdiff/bsdiff/bsdiff.c
+++ b/usr.bin/bsdiff/bsdiff/bsdiff.c
@@ -1,337 +1,336 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
  * Copyright 2003-2005 Colin Percival
  * All rights reserved
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted providing that the following conditions 
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include <sys/types.h>
 
 #include <bzlib.h>
 #include <err.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/mman.h>
 
 #ifndef O_BINARY
 #define O_BINARY 0
 #endif
 
 #include "divsufsort64.h"
 #define saidx_t saidx64_t
 #define divsufsort divsufsort64
 
 #define MIN(x,y) (((x)<(y)) ? (x) : (y))
 
 static off_t matchlen(u_char *old,off_t oldsize,u_char *new,off_t newsize)
 {
 	off_t i;
 
 	for(i=0;(i<oldsize)&&(i<newsize);i++)
 		if(old[i]!=new[i]) break;
 
 	return i;
 }
 
 static off_t search(off_t *I,u_char *old,off_t oldsize,
 		u_char *new,off_t newsize,off_t st,off_t en,off_t *pos)
 {
 	off_t x,y;
 
 	if(en-st<2) {
 		x=matchlen(old+I[st],oldsize-I[st],new,newsize);
 		y=matchlen(old+I[en],oldsize-I[en],new,newsize);
 
 		if(x>y) {
 			*pos=I[st];
 			return x;
 		} else {
 			*pos=I[en];
 			return y;
 		}
 	}
 
 	x=st+(en-st)/2;
 	if(memcmp(old+I[x],new,MIN(oldsize-I[x],newsize))<0) {
 		return search(I,old,oldsize,new,newsize,x,en,pos);
 	} else {
 		return search(I,old,oldsize,new,newsize,st,x,pos);
 	};
 }
 
 static void offtout(off_t x,u_char *buf)
 {
 	off_t y;
 
 	if(x<0) y=-x; else y=x;
 
 		buf[0]=y%256;y-=buf[0];
 	y=y/256;buf[1]=y%256;y-=buf[1];
 	y=y/256;buf[2]=y%256;y-=buf[2];
 	y=y/256;buf[3]=y%256;y-=buf[3];
 	y=y/256;buf[4]=y%256;y-=buf[4];
 	y=y/256;buf[5]=y%256;y-=buf[5];
 	y=y/256;buf[6]=y%256;y-=buf[6];
 	y=y/256;buf[7]=y%256;
 
 	if(x<0) buf[7]|=0x80;
 }
 
 static void
 usage(void)
 {
 
 	fprintf(stderr, "usage: bsdiff oldfile newfile patchfile\n");
 	exit(1);
 }
 
 int main(int argc,char *argv[])
 {
 	int fd;
 	u_char *old,*new;
-	off_t oldsize,newsize;
+	off_t oldsize,newsize,xnewsize;
 	saidx_t *I;
 	off_t scan,pos,len;
 	off_t lastscan,lastpos,lastoffset;
 	off_t oldscore,scsc;
 	off_t s,Sf,lenf,Sb,lenb;
 	off_t overlap,Ss,lens;
 	off_t i;
 	off_t dblen,eblen;
 	u_char *db,*eb;
 	u_char buf[8];
 	u_char header[32];
 	FILE * pf;
 	BZFILE * pfbz2;
 	int bz2err;
 
 	if (argc != 4)
 		usage();
 
 	/* Allocate oldsize+1 bytes instead of oldsize bytes to ensure
 		that we never try to malloc(0) and get a NULL pointer */
 	if(((fd=open(argv[1],O_RDONLY|O_BINARY,0))<0) ||
 	    ((oldsize=lseek(fd,0,SEEK_END))==-1))
 		err(1, "%s", argv[1]);
 
 	if (oldsize > SSIZE_MAX ||
 	    (uintmax_t)oldsize >= SIZE_T_MAX / sizeof(off_t) ||
 	    oldsize == OFF_MAX) {
 		errno = EFBIG;
 		err(1, "%s", argv[1]);
 	}
 
-	if (((old=malloc(oldsize+1))==NULL) ||
-		(lseek(fd,0,SEEK_SET)!=0) ||
-		(read(fd,old,oldsize)!=oldsize) ||
-		(close(fd)==-1)) err(1,"%s",argv[1]);
+	old = mmap(NULL, oldsize+1, PROT_READ, MAP_SHARED, fd, 0);
+	if (old == MAP_FAILED || close(fd) == -1)
+		err(1, "%s", argv[1]);
 
 	if(((I=malloc((oldsize+1)*sizeof(saidx_t)))==NULL)) err(1,NULL);
 
 	if(divsufsort(old, I, oldsize)) err(1, "divsufsort");
 
 	/* Allocate newsize+1 bytes instead of newsize bytes to ensure
 		that we never try to malloc(0) and get a NULL pointer */
 	if(((fd=open(argv[2],O_RDONLY|O_BINARY,0))<0) ||
 	    ((newsize=lseek(fd,0,SEEK_END))==-1))
 		err(1, "%s", argv[2]);
 
 	if (newsize > SSIZE_MAX || (uintmax_t)newsize >= SIZE_T_MAX ||
 	    newsize == OFF_MAX) {
 		errno = EFBIG;
 		err(1, "%s", argv[2]);
 	}
 
-	if (((new=malloc(newsize+1))==NULL) ||
-		(lseek(fd,0,SEEK_SET)!=0) ||
-		(read(fd,new,newsize)!=newsize) ||
-		(close(fd)==-1)) err(1,"%s",argv[2]);
+	new = mmap(NULL, newsize+1, PROT_READ, MAP_SHARED, fd, 0);
+	if (new == MAP_FAILED || close(fd) == -1)
+		err(1, "%s", argv[2]);
 
 	if(((db=malloc(newsize+1))==NULL) ||
 		((eb=malloc(newsize+1))==NULL)) err(1,NULL);
 	dblen=0;
 	eblen=0;
 
 	/* Create the patch file */
 	if ((pf = fopen(argv[3], "wb")) == NULL)
 		err(1, "%s", argv[3]);
 
 	/* Header is
 		0	8	 "BSDIFF40"
 		8	8	length of bzip2ed ctrl block
 		16	8	length of bzip2ed diff block
 		24	8	length of new file */
 	/* File is
 		0	32	Header
 		32	??	Bzip2ed ctrl block
 		??	??	Bzip2ed diff block
 		??	??	Bzip2ed extra block */
 	memcpy(header,"BSDIFF40",8);
 	offtout(0, header + 8);
 	offtout(0, header + 16);
 	offtout(newsize, header + 24);
 	if (fwrite(header, 32, 1, pf) != 1)
 		err(1, "fwrite(%s)", argv[3]);
 
 	/* Compute the differences, writing ctrl as we go */
 	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
 		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
 	scan=0;len=0;pos=0;
 	lastscan=0;lastpos=0;lastoffset=0;
 	while(scan<newsize) {
 		oldscore=0;
 
 		for(scsc=scan+=len;scan<newsize;scan++) {
 			len=search(I,old,oldsize,new+scan,newsize-scan,
 					0,oldsize-1,&pos);
 
 			for(;scsc<scan+len;scsc++)
 			if((scsc+lastoffset<oldsize) &&
 				(old[scsc+lastoffset] == new[scsc]))
 				oldscore++;
 
 			if(((len==oldscore) && (len!=0)) || 
 				(len>oldscore+8)) break;
 
 			if((scan+lastoffset<oldsize) &&
 				(old[scan+lastoffset] == new[scan]))
 				oldscore--;
 		}
 
 		if((len!=oldscore) || (scan==newsize)) {
 			s=0;Sf=0;lenf=0;
 			for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
 				if(old[lastpos+i]==new[lastscan+i]) s++;
 				i++;
 				if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; }
 			}
 
 			lenb=0;
 			if(scan<newsize) {
 				s=0;Sb=0;
 				for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
 					if(old[pos-i]==new[scan-i]) s++;
 					if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; }
 				}
 			}
 
 			if(lastscan+lenf>scan-lenb) {
 				overlap=(lastscan+lenf)-(scan-lenb);
 				s=0;Ss=0;lens=0;
 				for(i=0;i<overlap;i++) {
 					if(new[lastscan+lenf-overlap+i]==
 					   old[lastpos+lenf-overlap+i]) s++;
 					if(new[scan-lenb+i]==
 					   old[pos-lenb+i]) s--;
 					if(s>Ss) { Ss=s; lens=i+1; }
 				}
 
 				lenf+=lens-overlap;
 				lenb-=lens;
 			}
 
 			for(i=0;i<lenf;i++)
 				db[dblen+i]=new[lastscan+i]-old[lastpos+i];
 			for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
 				eb[eblen+i]=new[lastscan+lenf+i];
 
 			dblen+=lenf;
 			eblen+=(scan-lenb)-(lastscan+lenf);
 
 			offtout(lenf,buf);
 			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
 			if (bz2err != BZ_OK)
 				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
 
 			offtout((scan-lenb)-(lastscan+lenf),buf);
 			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
 			if (bz2err != BZ_OK)
 				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
 
 			offtout((pos-lenb)-(lastpos+lenf),buf);
 			BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
 			if (bz2err != BZ_OK)
 				errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
 
 			lastscan=scan-lenb;
 			lastpos=pos-lenb;
 			lastoffset=pos-scan;
 		}
 	}
 	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
 	if (bz2err != BZ_OK)
 		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
 
 	/* Compute size of compressed ctrl data */
 	if ((len = ftello(pf)) == -1)
 		err(1, "ftello");
 	offtout(len-32, header + 8);
 
 	/* Write compressed diff data */
 	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
 		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
 	BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
 	if (bz2err != BZ_OK)
 		errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
 	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
 	if (bz2err != BZ_OK)
 		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
 
 	/* Compute size of compressed diff data */
-	if ((newsize = ftello(pf)) == -1)
+	if ((xnewsize = ftello(pf)) == -1)
 		err(1, "ftello");
-	offtout(newsize - len, header + 16);
+	offtout(xnewsize - len, header + 16);
 
 	/* Write compressed extra data */
 	if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
 		errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
 	BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
 	if (bz2err != BZ_OK)
 		errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
 	BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
 	if (bz2err != BZ_OK)
 		errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
 
 	/* Seek to the beginning, write the header, and close the file */
 	if (fseeko(pf, 0, SEEK_SET))
 		err(1, "fseeko");
 	if (fwrite(header, 32, 1, pf) != 1)
 		err(1, "fwrite(%s)", argv[3]);
 	if (fclose(pf))
 		err(1, "fclose");
 
 	/* Free the memory we used */
 	free(db);
 	free(eb);
 	free(I);
-	free(old);
-	free(new);
+	munmap(old, oldsize+1);
+	munmap(new, newsize+1);
 
 	return 0;
 }
diff --git a/usr.bin/bsdiff/bspatch/bspatch.c b/usr.bin/bsdiff/bspatch/bspatch.c
index d7fabddabbfe..ea43d78b12a1 100644
--- a/usr.bin/bsdiff/bspatch/bspatch.c
+++ b/usr.bin/bsdiff/bspatch/bspatch.c
@@ -1,300 +1,302 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
  * Copyright 2003-2005 Colin Percival
  * All rights reserved
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted providing that the following conditions 
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 #ifndef WITHOUT_CAPSICUM
 #include <sys/capsicum.h>
 #endif
 
 #include <bzlib.h>
 #include <err.h>
 #include <fcntl.h>
 #include <libgen.h>
 #include <limits.h>
 #include <stdckdint.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/mman.h>
 
 #ifndef O_BINARY
 #define O_BINARY 0
 #endif
 #define HEADER_SIZE 32
 
 static char *newfile;
 static int dirfd = -1;
 
 static void
 exit_cleanup(void)
 {
 
 	if (dirfd != -1 && newfile != NULL)
 		if (unlinkat(dirfd, newfile, 0))
 			warn("unlinkat");
 }
 
 static inline off_t
 add_off_t(off_t a, off_t b)
 {
 	off_t result;
 
 	if (ckd_add(&result, a, b))
 		errx(1, "Corrupt patch");
 	return result;
 }
 
 static off_t offtin(u_char *buf)
 {
 	off_t y;
 
 	y = buf[7] & 0x7F;
 	y = y * 256; y += buf[6];
 	y = y * 256; y += buf[5];
 	y = y * 256; y += buf[4];
 	y = y * 256; y += buf[3];
 	y = y * 256; y += buf[2];
 	y = y * 256; y += buf[1];
 	y = y * 256; y += buf[0];
 
 	if (buf[7] & 0x80)
 		y = -y;
 
 	return (y);
 }
 
 static void
 usage(void)
 {
 
 	fprintf(stderr, "usage: bspatch oldfile newfile patchfile\n");
 	exit(1);
 }
 
 int main(int argc, char *argv[])
 {
 	FILE *f, *cpf, *dpf, *epf;
 	BZFILE *cpfbz2, *dpfbz2, *epfbz2;
 	char *directory, *namebuf;
 	int cbz2err, dbz2err, ebz2err;
 	int newfd, oldfd;
 	off_t oldsize, newsize;
 	off_t bzctrllen, bzdatalen;
 	u_char header[HEADER_SIZE], buf[8];
 	u_char *old, *new;
 	off_t oldpos, newpos;
 	off_t ctrl[3];
 	off_t i, lenread, offset;
 #ifndef WITHOUT_CAPSICUM
 	cap_rights_t rights_dir, rights_ro, rights_wr;
 #endif
 
 	if (argc != 4)
 		usage();
 
 	/* Open patch file */
 	if ((f = fopen(argv[3], "rb")) == NULL)
 		err(1, "fopen(%s)", argv[3]);
 	/* Open patch file for control block */
 	if ((cpf = fopen(argv[3], "rb")) == NULL)
 		err(1, "fopen(%s)", argv[3]);
 	/* open patch file for diff block */
 	if ((dpf = fopen(argv[3], "rb")) == NULL)
 		err(1, "fopen(%s)", argv[3]);
 	/* open patch file for extra block */
 	if ((epf = fopen(argv[3], "rb")) == NULL)
 		err(1, "fopen(%s)", argv[3]);
 	/* open oldfile */
 	if ((oldfd = open(argv[1], O_RDONLY | O_BINARY, 0)) < 0)
 		err(1, "open(%s)", argv[1]);
 	/* open directory where we'll write newfile */
 	if ((namebuf = strdup(argv[2])) == NULL ||
 	    (directory = dirname(namebuf)) == NULL ||
 	    (dirfd = open(directory, O_DIRECTORY)) < 0)
 		err(1, "open %s", argv[2]);
 	free(namebuf);
 	if ((newfile = basename(argv[2])) == NULL)
 		err(1, "basename");
 	/* open newfile */
 	if ((newfd = openat(dirfd, newfile,
 	    O_CREAT | O_TRUNC | O_WRONLY | O_BINARY, 0666)) < 0)
 		err(1, "open(%s)", argv[2]);
 	atexit(exit_cleanup);
 
 #ifndef WITHOUT_CAPSICUM
 	if (cap_enter() < 0)
 		err(1, "failed to enter security sandbox");
 
-	cap_rights_init(&rights_ro, CAP_READ, CAP_FSTAT, CAP_SEEK);
+	cap_rights_init(&rights_ro, CAP_READ, CAP_FSTAT, CAP_SEEK, CAP_MMAP_R);
 	cap_rights_init(&rights_wr, CAP_WRITE);
 	cap_rights_init(&rights_dir, CAP_UNLINKAT);
 
 	if (cap_rights_limit(fileno(f), &rights_ro) < 0 ||
 	    cap_rights_limit(fileno(cpf), &rights_ro) < 0 ||
 	    cap_rights_limit(fileno(dpf), &rights_ro) < 0 ||
 	    cap_rights_limit(fileno(epf), &rights_ro) < 0 ||
 	    cap_rights_limit(oldfd, &rights_ro) < 0 ||
 	    cap_rights_limit(newfd, &rights_wr) < 0 ||
 	    cap_rights_limit(dirfd, &rights_dir) < 0)
 		err(1, "cap_rights_limit() failed, could not restrict"
 		    " capabilities");
 #endif
 
 	/*
 	File format:
 		0	8	"BSDIFF40"
 		8	8	X
 		16	8	Y
 		24	8	sizeof(newfile)
 		32	X	bzip2(control block)
 		32+X	Y	bzip2(diff block)
 		32+X+Y	???	bzip2(extra block)
 	with control block a set of triples (x,y,z) meaning "add x bytes
 	from oldfile to x bytes from the diff block; copy y bytes from the
 	extra block; seek forwards in oldfile by z bytes".
 	*/
 
 	/* Read header */
 	if (fread(header, 1, HEADER_SIZE, f) < HEADER_SIZE) {
 		if (feof(f))
 			errx(1, "Corrupt patch");
 		err(1, "fread(%s)", argv[3]);
 	}
 
 	/* Check for appropriate magic */
 	if (memcmp(header, "BSDIFF40", 8) != 0)
 		errx(1, "Corrupt patch");
 
 	/* Read lengths from header */
 	bzctrllen = offtin(header + 8);
 	bzdatalen = offtin(header + 16);
 	newsize = offtin(header + 24);
 	if (bzctrllen < 0 || bzctrllen > OFF_MAX - HEADER_SIZE ||
 	    bzdatalen < 0 || bzctrllen + HEADER_SIZE > OFF_MAX - bzdatalen ||
 	    newsize < 0 || newsize > SSIZE_MAX)
 		errx(1, "Corrupt patch");
 
 	/* Close patch file and re-open it via libbzip2 at the right places */
 	if (fclose(f))
 		err(1, "fclose(%s)", argv[3]);
 	offset = HEADER_SIZE;
 	if (fseeko(cpf, offset, SEEK_SET))
 		err(1, "fseeko(%s, %jd)", argv[3], (intmax_t)offset);
 	if ((cpfbz2 = BZ2_bzReadOpen(&cbz2err, cpf, 0, 0, NULL, 0)) == NULL)
 		errx(1, "BZ2_bzReadOpen, bz2err = %d", cbz2err);
 	offset = add_off_t(offset, bzctrllen);
 	if (fseeko(dpf, offset, SEEK_SET))
 		err(1, "fseeko(%s, %jd)", argv[3], (intmax_t)offset);
 	if ((dpfbz2 = BZ2_bzReadOpen(&dbz2err, dpf, 0, 0, NULL, 0)) == NULL)
 		errx(1, "BZ2_bzReadOpen, bz2err = %d", dbz2err);
 	offset = add_off_t(offset, bzdatalen);
 	if (fseeko(epf, offset, SEEK_SET))
 		err(1, "fseeko(%s, %jd)", argv[3], (intmax_t)offset);
 	if ((epfbz2 = BZ2_bzReadOpen(&ebz2err, epf, 0, 0, NULL, 0)) == NULL)
 		errx(1, "BZ2_bzReadOpen, bz2err = %d", ebz2err);
 
 	if ((oldsize = lseek(oldfd, 0, SEEK_END)) == -1 ||
-	    oldsize > SSIZE_MAX ||
-	    (old = malloc(oldsize)) == NULL ||
-	    lseek(oldfd, 0, SEEK_SET) != 0 ||
-	    read(oldfd, old, oldsize) != oldsize ||
-	    close(oldfd) == -1)
+	    oldsize > SSIZE_MAX)
 		err(1, "%s", argv[1]);
+
+	old = mmap(NULL, oldsize+1, PROT_READ, MAP_SHARED, oldfd, 0);
+	if (old == MAP_FAILED || close(oldfd) != 0)
+		err(1, "%s", argv[1]);
+
 	if ((new = malloc(newsize)) == NULL)
 		err(1, NULL);
 
 	oldpos = 0;
 	newpos = 0;
 	while (newpos < newsize) {
 		/* Read control data */
 		for (i = 0; i <= 2; i++) {
 			lenread = BZ2_bzRead(&cbz2err, cpfbz2, buf, 8);
 			if ((lenread < 8) || ((cbz2err != BZ_OK) &&
 			    (cbz2err != BZ_STREAM_END)))
 				errx(1, "Corrupt patch");
 			ctrl[i] = offtin(buf);
 		}
 
 		/* Sanity-check */
 		if (ctrl[0] < 0 || ctrl[0] > INT_MAX ||
 		    ctrl[1] < 0 || ctrl[1] > INT_MAX)
 			errx(1, "Corrupt patch");
 
 		/* Sanity-check */
 		if (add_off_t(newpos, ctrl[0]) > newsize)
 			errx(1, "Corrupt patch");
 
 		/* Read diff string */
 		lenread = BZ2_bzRead(&dbz2err, dpfbz2, new + newpos, ctrl[0]);
 		if ((lenread < ctrl[0]) ||
 		    ((dbz2err != BZ_OK) && (dbz2err != BZ_STREAM_END)))
 			errx(1, "Corrupt patch");
 
 		/* Add old data to diff string */
 		for (i = 0; i < ctrl[0]; i++)
 			if (add_off_t(oldpos, i) < oldsize)
 				new[newpos + i] += old[oldpos + i];
 
 		/* Adjust pointers */
 		newpos = add_off_t(newpos, ctrl[0]);
 		oldpos = add_off_t(oldpos, ctrl[0]);
 
 		/* Sanity-check */
 		if (add_off_t(newpos, ctrl[1]) > newsize)
 			errx(1, "Corrupt patch");
 
 		/* Read extra string */
 		lenread = BZ2_bzRead(&ebz2err, epfbz2, new + newpos, ctrl[1]);
 		if ((lenread < ctrl[1]) ||
 		    ((ebz2err != BZ_OK) && (ebz2err != BZ_STREAM_END)))
 			errx(1, "Corrupt patch");
 
 		/* Adjust pointers */
 		newpos = add_off_t(newpos, ctrl[1]);
 		oldpos = add_off_t(oldpos, ctrl[2]);
 	}
 
 	/* Clean up the bzip2 reads */
 	BZ2_bzReadClose(&cbz2err, cpfbz2);
 	BZ2_bzReadClose(&dbz2err, dpfbz2);
 	BZ2_bzReadClose(&ebz2err, epfbz2);
 	if (fclose(cpf) || fclose(dpf) || fclose(epf))
 		err(1, "fclose(%s)", argv[3]);
 
 	/* Write the new file */
 	if (write(newfd, new, newsize) != newsize || close(newfd) == -1)
 		err(1, "%s", argv[2]);
 	/* Disable atexit cleanup */
 	newfile = NULL;
 
 	free(new);
-	free(old);
+	munmap(old, oldsize+1);
 
 	return (0);
 }