acme: apply nemos acmediskread patch (from sources)

pread does not guarantee that it would read all the data asked for.
But acme usage of disk assumes that. This issues as many reads as
needed to make acme work when read returns less data than it wanted.

1 files changed, 11 insertions, 1 deletions

diff --git a/sys/src/cmd/acme/disk.c b/sys/src/cmd/acme/disk.c
index 4c22d0a8c..9b76a5582 100644
--- a/sys/src/cmd/acme/disk.c
+++ b/sys/src/cmd/acme/disk.c
@@ -120,10 +120,20 @@ diskwrite(Disk *d, Block **bp, Rune *r, uint n)
 void
 diskread(Disk *d, Block *b, Rune *r, uint n)
 {
+	int tot, nr;
+	char *p;
+
 	if(n > b->n)
 		error("internal error: diskread");
 
 	ntosize(b->n, nil);
-	if(pread(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
+	n *= sizeof(Rune);
+	p = (char*)r;
+	for(tot = 0; tot < n; tot += nr){
+		nr = pread(d->fd, p+tot, n-tot, b->addr+tot);
+		if(nr <= 0)
+			error("read error from temp file");
+	}
+	if(tot != n)
 		error("read error from temp file");
 }