code: plan9front

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git/rebase: allow rebase without a clean tree

Here, patch grows a dry run option (-n), which allows
git/import to bail out early if it would patch files
that are dirty in tree.

Once git/import refuses to patch dirty files, git/rebase
can skip checking if the whole tree is clean, which is
both convenient and much faster on large trees.

--- a/sys/man/1/patch

+++ b/sys/man/1/patch

@@ -28,6 +28,9 @@

 Reverse direction of the patch. Additions become removals,

 and the new and old file names are swapped.

 .TP

+.B -n

+Print the files that would be modified by this patch, but do not apply it.

+.TP

 .BI -p \ nstrip

 Remove the prefix containing

 .I nstrip

--- a/sys/src/cmd/git/import

+++ b/sys/src/cmd/git/import

@@ -76,8 +76,16 @@

 	# force re-reading env

 	rc -c '

-		echo applying $msg | sed 1q

 		date=`{seconds $date}

+		files=`$nl{patch -np1 < $diffpath}

+		if(! git/walk -q $files){

+			>[1=2] {

+				echo patch would clobber files:

+				git/walk $files

+				exit clobber

+			}

+		}

+		echo applying $msg | sed 1q

 		if(! files=`$nl{patch -p1 < $diffpath})

 			die ''patch failed''

 		for(f in $files){

@@ -111,6 +119,6 @@

 	if(test -d $p && test -f $p/header && test -f $p/body)

 		{{cat $p/header; echo; cat $p/body} | apply} || die $status

 	if not

-		apply < $p || die $status

+		apply < $p

 }

 exit ''

--- a/sys/src/cmd/git/rebase

+++ b/sys/src/cmd/git/rebase

@@ -7,8 +7,6 @@

 eval `''{aux/getflags $*} || exec aux/usage

 tmp=_rebase.working

-if(! git/walk -q)

-	die dirty working tree

 if(~ $#abort 1){

 	if(! test -f .git/rebase.todo)

 		die no rebase to abort

--- a/sys/src/cmd/patch.c

+++ b/sys/src/cmd/patch.c

@@ -52,6 +52,7 @@

 void	(*addold)(Hunk*, char*);

 Fchg	*changed;

 int	nchanged;

+int	dryrun;

 char*

 readline(Biobuf *f, int *lnum)

@@ -392,21 +393,22 @@

 	char *tmp;

 	int fd;

-	if(strcmp(new, "/dev/null") == 0){

-		if(len != 0)

-			sysfatal("diff modifies removed file");

-		if(remove(old) == -1)

-			sysfatal("removeold %s: %r", old);

+	if(strcmp(new, "/dev/null") == 0 && len != 0){

+		sysfatal("diff modifies removed file");

 		return;

 	}

-	if(mkpath(new) == -1)

-		sysfatal("mkpath %s: %r", new);

-	if((tmp = smprint("%s.tmp%d", new, getpid())) == nil)

-		sysfatal("smprint: %r");

-	if((fd = create(tmp, OWRITE, 0666)) == -1)

-		sysfatal("open %s: %r", tmp);

-	if(write(fd, o, len) != len)

-		sysfatal("write %s: %r", tmp);

+	tmp = nil;

+	if(!dryrun){

+		if(mkpath(new) == -1)

+			sysfatal("mkpath %s: %r", new);

+		if((tmp = smprint("%s.tmp%d", new, getpid())) == nil)

+			sysfatal("smprint: %r");

+		if((fd = create(tmp, OWRITE, 0666)) == -1)

+			sysfatal("open %s: %r", tmp);

+		if(write(fd, o, len) != len)

+			sysfatal("write %s: %r", tmp);

+		close(fd);

+	}

 	if((changed = realloc(changed, (nchanged+1)*sizeof(Fchg))) == nil)

 		sysfatal("realloc: %r");

 	if((changed[nchanged].new = strdup(new)) == nil)

@@ -415,7 +417,6 @@

 		sysfatal("strdup: %r");

 	changed[nchanged].tmp = tmp;

 	nchanged++;

-	close(fd);

 }

 void

@@ -429,7 +430,14 @@

 		if(!ok){

 			if(remove(c->tmp) == -1)

 				fprint(2, "remove %s: %r\n", c->tmp);

-		}else{

+			goto Free;

+		}

+		if(!dryrun){

+			if(strcmp(c->new, "/dev/null") == 0){

+				if(remove(c->old) == -1)

+					sysfatal("remove %s: %r", c->old);

+				goto Print;

+			}

 			if((fd = open(c->tmp, ORDWR)) == -1)

 				sysfatal("open %s: %r", c->tmp);

 			if(strcmp(c->old, c->new) == 0 && remove(c->old) == -1)

@@ -438,11 +446,13 @@

 				sysfatal("create %s: %r", c->new);

 			if(close(fd) == -1)

 				sysfatal("close %s: %r", c->tmp);

-			if(strcmp(c->new, "/dev/null") == 0)

-				print("%s\n", c->old);

-			else

-				print("%s\n", c->new);

 		}

+Print:

+		if(strcmp(c->new, "/dev/null") == 0)

+			print("%s\n", c->old);

+		else

+			print("%s\n", c->new);

+Free:

 		free(c->tmp);

 		free(c->old);

 		free(c->new);

@@ -560,16 +570,18 @@

 	for(i = 0; i < p->nhunk; i++){

 		h = &p->hunk[i];

 		if(curfile == nil || strcmp(curfile, h->newpath) != 0){

-			if(slurp(&f, h->oldpath) == -1)

+			if(!dryrun && slurp(&f, h->oldpath) == -1)

 				sysfatal("slurp %s: %r", h->oldpath);

 			curfile = h->newpath;

 			e = f.buf;

 		}

-		s = e;

-		e = search(&f, h, fname);

-		o = append(o, &osz, s, e);

-		o = append(o, &osz, h->new, h->new + h->newlen);

-		e += h->oldlen;

+		if(!dryrun){

+			s = e;

+			e = search(&f, h, fname);

+			o = append(o, &osz, s, e);

+			o = append(o, &osz, h->new, h->new + h->newlen);

+			e += h->oldlen;

+		}

 		if(i+1 == p->nhunk || strcmp(curfile, p->hunk[i+1].newpath) != 0){

 			o = append(o, &osz, e, f.buf + f.len);

 			blat(h->oldpath, h->newpath, o, osz);

@@ -601,7 +613,7 @@

 void

 usage(void)

 {

-	fprint(2, "usage: %s [-R] [-p nstrip] [patch...]\n", argv0);

+	fprint(2, "usage: %s [-nR] [-p nstrip] [patch...]\n", argv0);

 	exits("usage");

 }

@@ -615,6 +627,9 @@

 	ARGBEGIN{

 	case 'p':

 		strip = atoi(EARGF(usage()));

+		break;

+	case 'n':

+		dryrun++;

 		break;

 	case 'R':

 		reverse++;