[BusyBox] Re: DD fix problem

[Gennady Feldman]

Hello Kent.

    Thanks for reporting this. I missed that part, good catch. Here is my second
attempt at fixing dd.
Changes:
- Added ibs variable to hold the read-in value.
- Fixed up the code to limit upper blocksize limit for each read upto the BUFSIZ

G.F.

kent robotti wrote:

> I have this problem when using a bs of M with
> your patched dd.
>
> dd if=/dev/zero of=fooboo bs=1M count=1
> -1+1 records in
> 0+0 records out
>
> I had to apply your patch to the latest cvs dd by hand.
> [clipped]
-------------- next part --------------
diff -u usage.orig usage.c
--- usage.orig	Mon Nov 27 15:24:07 2000
+++ usage.c	Mon Nov 27 15:25:47 2000
@@ -160,7 +160,7 @@
 
 #if defined BB_DD
 const char dd_usage[] =
-	"dd [if=FILE] [of=FILE] [bs=N] [count=N] [skip=N] [seek=N]\n"
+	"dd [if=FILE] [of=FILE] [bs=N] [count=N] [skip=N] [seek=N] [conv=notrunc|sync]\n"
 #ifndef BB_FEATURE_TRIVIAL_HELP
 	"\nCopy a file, converting and formatting according to options\n\n"
 	"\tif=FILE\tread from FILE instead of stdin\n"
@@ -170,6 +170,7 @@
 	"\tskip=N\tskip N input blocks\n"
 	"\tseek=N\tskip N output blocks\n"
 	"\tconv=notrunc\t dont truncate of at end of write\n"
+	"\tconv=sync\t pad the last block with zeros until blocksize\n"
 	"\n"
 	"Numbers may be suffixed by w (x2), k (x1024), b (x512), or M (x1024^2)\n"
 #endif
diff -u dd.orig dd.c
--- dd.orig	Mon Nov 27 15:24:12 2000
+++ dd.c	Tue Nov 28 11:44:54 2000
@@ -49,14 +49,15 @@
 	int inCc = 0;
 	int outCc;
 	int trunc=TRUE;
-	long blockSize = 512;
+	int sync=FALSE;
+	long blockSize = 512,ibs;
 	uintmax_t skipBlocks = 0;
 	uintmax_t seekBlocks = 0;
 	uintmax_t count = (uintmax_t) - 1;
 	uintmax_t inTotal = 0;
 	uintmax_t outTotal = 0;
 	uintmax_t totalSize;
-	uintmax_t readSize;
+
 	unsigned char buf[BUFSIZ];
 	char *keyword = NULL;
 
@@ -98,6 +99,8 @@
 			keyword = (strchr(*argv, '=') + 1);
                 	if (strcmp(keyword, "notrunc") == 0) 
 				trunc=FALSE;
+			if (strcmp(keyword, "sync") == 0) 
+				sync=TRUE;
 		} else {
 			goto usage;
 		}
@@ -137,13 +140,24 @@
 	lseek(inFd, (off_t) (skipBlocks * blockSize), SEEK_SET);
 	lseek(outFd, (off_t) (seekBlocks * blockSize), SEEK_SET);
 	totalSize=count*blockSize;
-	while ((readSize = totalSize - inTotal) > 0) {
-		if (readSize > BUFSIZ)
-			readSize=BUFSIZ;
-		inCc = fullRead(inFd, buf, readSize);
+
+	ibs=blockSize;
+	if (ibs > BUFSIZ)
+		ibs=BUFSIZ;
+			
+	while (totalSize > outTotal) {
+		inCc = fullRead(inFd, buf, ibs);
 		inTotal += inCc;
-		if ((outCc = fullWrite(outFd, buf, inCc)) < 1)
+		if ( (sync==TRUE) && (inCc>0) )
+			while (inCc<ibs)
+				buf[inCc++]='\0';
+
+		if ((outCc = fullWrite(outFd, buf, inCc)) < 1){
+			if (outCc < 0 ){
+				perror("Error during write");
+			}
 			break;
+		}
 		outTotal += outCc;
         }
 	if (trunc == TRUE) {