3 files changed, 130 insertions(+), 4 deletions(-)

A ipsdiff.c
R ips.c => ipspatch.c
M mkfile

@@ 0,0 1,121 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+
+#define PUT2(p, u) (p)[0] = (u)>>8, (p)[1] = (u)
+#define PUT3(p, u) (p)[0] = (u)>>16, (p)[1] = (u)>>8, (p)[2] = (u)
+
+Biobuf *ips;
+typedef struct Bin Bin;
+struct Bin{
+	int fd;
+	long dot;
+	long n, off;
+	uchar data[0xFFFF];
+};
+
+static Bin base, modded;
+static int dump = 0;
+
+static long
+slurp(Bin *b)
+{
+	long n;
+
+	n = readn(b->fd, b->data + b->off, sizeof b->data - b->off);
+	if(n < 0)
+		sysfatal("read: %r");
+	b->n = b->off + n;
+	return n;
+}
+
+static void
+emit(u32int off, uchar *data, u16int size)
+{
+	uchar buf[3 + 2];
+
+	if(size == 0)
+		return;
+	PUT3(buf, off);
+	PUT2(buf+3, size);
+	if(dump)
+		fprint(2, "%ud %ud\n", off, size);
+	if(Bwrite(ips, buf, sizeof buf) != sizeof buf)
+		sysfatal("Bwrite: %r");
+	if(Bwrite(ips, data, size) != size)
+		sysfatal("Bwrite: %r");
+}
+
+static void
+diff(Bin *a, Bin *b)
+{
+	uchar *ap, *bp;
+	uchar *ac, *bc;
+	uchar *ae, *be;
+	int x;
+
+	ap = a->data;
+	bp = b->data;
+	ae = a->data + a->n;
+	be = b->data + b->n;
+
+	if(a->n != b->n)
+		sysfatal("desync: %ld %ld", a->n, a->n);
+
+	while(ap < ae && bp < be){
+		if(*ap == *bp){
+			ap++;
+			bp++;
+			continue;
+		}
+		// FIXME: better way of expanding diff context
+		x = 32;
+		for(ac = ap, bc = bp; ac < ae && bc < be; ac++, bc++){
+			if(--x <= 0 && *ac == *bc)
+				break;
+		}
+		emit(a->dot + (ap - a->data), bp, bc - bp);
+		ap = ac;
+		bp = bc;
+	}
+	a->dot += a->n;
+	b->dot += b->n;
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s base modified >patch.ips", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char **argv)
+{
+	ARGBEGIN{
+	case 'd':
+		dump++;
+		break;
+	default:
+		usage();
+	}ARGEND;
+	if(argc < 2)
+		usage();
+
+	ips = Bfdopen(1, OWRITE);
+	if(ips == nil)
+		sysfatal("Bfdopen: %r");
+	Bwrite(ips, "PATCH", 5);
+
+	base.fd = open(argv[0], OREAD);
+	modded.fd = open(argv[1], OREAD);
+	if(base.fd < 0 || modded.fd < 0)
+		sysfatal("open: %r");
+
+	while(slurp(&base) != 0 && slurp(&modded) != 0)
+		diff(&base, &modded);
+
+	Bwrite(ips, "EOF", 3);
+	Bflush(ips);
+	exits(nil);
+}

@@ 12,6 12,7 @@ enum{
 
 static uchar section[Hdrsz + 0xFFFF + RLEsz];
 static Biobuf *ips;
+static int dump = 0;
 
 static int
 readsect(u32int *off, u16int *sz)


@@ 37,6 38,7 @@ readsect(u32int *off, u16int *sz)
 		*sz = count;
 	} else if(Bread(ips, section + Hdrsz, *sz) != *sz)
 		sysfatal("short read of data: %r");
+	//fprint(2, "%ud %ud\n", *off, *sz);
 	return 1;
 }
 


@@ 57,6 59,9 @@ main(int argc, char **argv)
 	u16int sz;
 
 	ARGBEGIN{
+	case 'd':
+		dump++;
+		break;
 	default:
 		usage();
 	}ARGEND;

@@ 1,8 1,8 @@
 </$objtype/mkfile
 
 BIN=$home/bin/$objtype
-TARG=ips
-OFILES=\
-	ips.$O\
+TARG=\
+	ipsdiff\
+	ipspatch\
 
-</sys/src/cmd/mkone
+</sys/src/cmd/mkmany