MFC r313948: bsdgrep: fix EOF handling with --mmap

Rework part of the loop in grep_fgetln to return the rest of the line
and ensure that we still advance the buffer by the length of the rest
of the line.

PR:		165471
Approved by:	emaste (mentor)

1 files changed, 11 insertions, 5 deletions

diff --git a/usr.bin/grep/file.c b/usr.bin/grep/file.c
index 81f227d..34831f1 100644
--- a/usr.bin/grep/file.c
+++ b/usr.bin/grep/file.c
@@ -219,12 +219,18 @@ grep_fgetln(struct file *f, size_t *lenp)
 		if (bufrem == 0)
 			/* EOF: return partial line */
 			break;
-		if ((p = memchr(bufpos, '\n', bufrem)) == NULL)
+		if ((p = memchr(bufpos, '\n', bufrem)) == NULL &&
+		    filebehave != FILE_MMAP)
 			continue;
-		/* got it: finish up the line (like code above) */
-		++p;
-		diff = p - bufpos;
-		len += diff;
+		if (p == NULL) {
+			/* mmap EOF: return partial line, consume buffer */
+			diff = len;
+		} else {
+			/* got it: finish up the line (like code above) */
+			++p;
+			diff = p - bufpos;
+			len += diff;
+		}
 		if (grep_lnbufgrow(len))
 		    goto error;
 		memcpy(lnbuf + off, bufpos, diff);