ed: Detect correctly end of file in gettxt()

The function gettxt() is basically a repeat loop where it loops
until it arrives to the end of the file when it doesn't find  a
newline, but the condition to detect the end of file was wrong
and it looped forever in a file without newline.

ed.c

@@ -244,6 +244,7 @@ gettxt(int line)
 		return addchar('\0', &text);
 
 repeat:
+	chksignals();
 	if (!csize || off < lasto || off - lasto >= csize) {
 		block = off & ~(CACHESIZ-1);
 		if (lseek(scratch, block, SEEK_SET) < 0 ||
@@ -257,7 +258,7 @@ repeat:
 		++off;
 		addchar(*p, &text);
 	}
-	if (csize && p == buf + csize)
+	if (csize == CACHESIZ && p == buf + csize)
 		goto repeat;
 
 	addchar('\n', &text);

tests/0007-ed.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+set -e
+
+tmp=tmp.$$
+
+trap 'rm -f $tmp' EXIT
+trap 'rm -f $tmp; kill -KILL $$' HUP INT TERM
+
+printf 'something important' > $tmp
+ed $tmp <<EOF 2>/dev/null | grep something | diff -w $tmp -
+1p
+EOF