From 60babcd97b871c8f037b426beb57f21d20d57a9e Mon Sep 17 00:00:00 2001
From: Shunqian Zheng <zhengsq@rock-chips.com>
Date: Thu, 6 Jan 2022 15:06:44 +0800
Subject: [PATCH] bspatch: adaption to embedded system

Use mmap to avoid large memory allocation.
Support read old file from block device(e.g. /dev/mmcblkMpN), which
requires an extra old-file-size argument.

Signed-off-by: Shunqian Zheng <zhengsq@rock-chips.com>
---
 bspatch.c | 50 +++++++++++++++++++++++++++++++++++---------------
 1 file changed, 35 insertions(+), 15 deletions(-)

diff --git a/bspatch.c b/bspatch.c
index de47d2a..0c6952c 100644
--- a/bspatch.c
+++ b/bspatch.c
@@ -36,6 +36,8 @@ __FBSDID("$FreeBSD: src/usr.bin/bsdiff/bspatch/bspatch.c,v 1.1 2005/08/06 01:59:
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
 
 static off_t offtin(u_char *buf)
 {
@@ -69,8 +71,25 @@ int main(int argc,char * argv[])
 	off_t ctrl[3];
 	off_t lenread;
 	off_t i;
-
-	if(argc!=4) errx(1,"usage: %s oldfile newfile patchfile\n",argv[0]);
+	struct stat old_stat;
+
+	if(argc!=4 && argc!=5) errx(1,"usage: %s oldfile newfile patchfile\n"
+		"             or\n"
+		"                %s /dev/mmcblkMpN newfile patchfile oldsize\n", argv[0]);
+
+	oldsize = 0;
+	stat(argv[1], &old_stat);
+	if (old_stat.st_mode & S_IFBLK && argc == 5) {
+		oldsize = atoi(argv[4]);
+	} else if (old_stat.st_mode & S_IFREG && argc == 4) {
+		if(((fd=open(argv[1],O_RDONLY,0))<0) ||
+		   ((oldsize=lseek(fd,0,SEEK_END))<=0) ||
+		   (close(fd)==-1))
+			 err(1,"file %s size err!",argv[1]);
+	} else {
+		errx(1, "oldfile shall be regular file or block device,\n"
+			"         for block device, the oldfile_size arg is needed\n");
+	}
 
 	/* Open patch file */
 	if ((f = fopen(argv[3], "r")) == NULL)
@@ -105,7 +124,7 @@ int main(int argc,char * argv[])
 	bzctrllen=offtin(header+8);
 	bzdatalen=offtin(header+16);
 	newsize=offtin(header+24);
-	if((bzctrllen<0) || (bzdatalen<0) || (newsize<0))
+	if((bzctrllen<0) || (bzdatalen<0) || (newsize<=0))
 		errx(1,"Corrupt patch\n");
 
 	/* Close patch file and re-open it via libbzip2 at the right places */
@@ -133,13 +152,19 @@ int main(int argc,char * argv[])
 	if ((epfbz2 = BZ2_bzReadOpen(&ebz2err, epf, 0, 0, NULL, 0)) == NULL)
 		errx(1, "BZ2_bzReadOpen, bz2err = %d", ebz2err);
 
+	//if oldfile is a block device, get oldsize from arg
 	if(((fd=open(argv[1],O_RDONLY,0))<0) ||
-		((oldsize=lseek(fd,0,SEEK_END))==-1) ||
-		((old=malloc(oldsize+1))==NULL) ||
-		(lseek(fd,0,SEEK_SET)!=0) ||
-		(read(fd,old,oldsize)!=oldsize) ||
+		((old=mmap(NULL,oldsize,PROT_READ,MAP_SHARED|MAP_POPULATE,fd,0))==MAP_FAILED) ||
 		(close(fd)==-1)) err(1,"%s",argv[1]);
-	if((new=malloc(newsize+1))==NULL) err(1,NULL);
+
+	/* mmap the new file */
+	if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_RDWR,0666))<0) ||
+		(lseek(fd,newsize-1,SEEK_SET)!=(newsize-1)) ||
+		(write(fd, "E", 1) != 1) ||
+		(lseek(fd,0,SEEK_SET)!=0) ||
+		((new=mmap(NULL,newsize,PROT_READ | PROT_WRITE,MAP_SHARED,fd,0))==MAP_FAILED) ||
+		(close(fd)==-1))
+		err(1,"%s",argv[2]);
 
 	oldpos=0;newpos=0;
 	while(newpos<newsize) {
@@ -193,13 +218,8 @@ int main(int argc,char * argv[])
 	if (fclose(cpf) || fclose(dpf) || fclose(epf))
 		err(1, "fclose(%s)", argv[3]);
 
-	/* Write the new file */
-	if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_WRONLY,0666))<0) ||
-		(write(fd,new,newsize)!=newsize) || (close(fd)==-1))
-		err(1,"%s",argv[2]);
-
-	free(new);
-	free(old);
+	munmap(new, newsize);
+	munmap(old, oldsize);
 
 	return 0;
 }
-- 
2.25.1