Deal with files that lack a final newline before EOF (you naughty

emacs users!).  In most cases this just means checking for EOF in
addition to '\n'.  However, we need to tread carefully in readhash().
There we return 0 on EOF iff it is the first char in a "line".

Additionally, if the -b or -w flags were specified and the last
character in one file was '\n' but the other file is missing '\n',
pretend that we didn't see the newline in the one file.  This is
consistent with GNU diff.  For the non-{b,w} case, print
"\ No newline at end of file" when we see EOF before a newline in
one file where the other file has one.  Again, this is for consistency
with GNU diff and patch(1) in -current knows how to interpret this
message.

OK tedu@ and otto@

1 files changed, 42 insertions, 24 deletions

diff --git a/usr.bin/diff/diffreg.c b/usr.bin/diff/diffreg.c
index 9ca4cbcec89..f2bad0095e8 100644
--- a/usr.bin/diff/diffreg.c
+++ b/usr.bin/diff/diffreg.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: diffreg.c,v 1.33 2003/07/15 23:17:56 millert Exp $	*/
+/*	$OpenBSD: diffreg.c,v 1.34 2003/07/16 21:39:06 millert Exp $	*/
 
 /*
  * Copyright (C) Caldera International Inc.  2001-2002.
@@ -65,7 +65,7 @@
  */
 
 #ifndef lint
-static const char rcsid[] = "$OpenBSD: diffreg.c,v 1.33 2003/07/15 23:17:56 millert Exp $";
+static const char rcsid[] = "$OpenBSD: diffreg.c,v 1.34 2003/07/16 21:39:06 millert Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -705,6 +705,15 @@ check(char *file1, FILE *f1, char *file2, FILE *f2)
 			for (;;) {
 				c = getc(f1);
 				d = getc(f2);
+				/*
+				 * GNU diff ignores a missing newline
+				 * in one file if bflag || wflag.
+				 */
+				if ((bflag || wflag) &&
+				    ((c == EOF && d == '\n') ||
+				    (c == '\n' && d == EOF))) {
+					break;
+				}
 				ctold++;
 				ctnew++;
 				if (bflag && isspace(c) && isspace(d)) {
@@ -731,13 +740,13 @@ check(char *file1, FILE *f1, char *file2, FILE *f2)
 				if (chrtran[c] != chrtran[d]) {
 					jackpot++;
 					J[i] = 0;
-					if (c != '\n')
+					if (c != '\n' && c != EOF)
 						ctold += skipline(f1);
-					if (d != '\n')
+					if (d != '\n' && c != EOF)
 						ctnew += skipline(f2);
 					break;
 				}
-				if (c == '\n')
+				if (c == '\n' || c == EOF)
 					break;
 			}
 		} else {
@@ -747,13 +756,13 @@ check(char *file1, FILE *f1, char *file2, FILE *f2)
 				if ((c = getc(f1)) != (d = getc(f2))) {
 					/* jackpot++; */
 					J[i] = 0;
-					if (c != '\n')
+					if (c != '\n' && c != EOF)
 						ctold += skipline(f1);
-					if (d != '\n')
+					if (d != '\n' && c != EOF)
 						ctnew += skipline(f2);
 					break;
 				}
-				if (c == '\n')
+				if (c == '\n' || c == EOF)
 					break;
 			}
 		}
@@ -820,9 +829,8 @@ skipline(FILE *f)
 {
 	int i, c;
 
-	for (i = 1; (c = getc(f)) != '\n'; i++)
-		if (c < 0)
-			return (i);
+	for (i = 1; (c = getc(f)) != '\n' && c != EOF; i++)
+		continue;
 	return (i);
 }
 
@@ -866,8 +874,7 @@ output(char *file1, FILE *f1, char *file2, FILE *f2)
 	if (format == D_IFDEF) {
 		for (;;) {
 #define	c i0
-			c = getc(f1);
-			if (c < 0)
+			if ((c = getc(f1)) == EOF)
 				return;
 			putchar(c);
 		}
@@ -1043,12 +1050,15 @@ fetch(long *f, int a, int b, FILE *lb, char *s, int oldfile)
 			fputs(s, stdout);
 		col = 0;
 		for (j = 0; j < nc; j++) {
-			c = getc(lb);
-			if (c == '\t' && tflag)
-				do
+			if ((c = getc(lb)) == EOF) {
+				puts("\n\\ No newline at end of file");
+				return;
+			}
+			if (c == '\t' && tflag) {
+				do {
 					putchar(' ');
-				while (++col & 7);
-			else {
+				} while (++col & 7);
+			} else {
 				putchar(c);
 				col++;
 			}
@@ -1078,8 +1088,11 @@ readhash(FILE *f)
 	if (!bflag && !wflag) {
 		if (iflag)
 			for (shift = 0; (t = getc(f)) != '\n'; shift += 7) {
-				if (t == -1)
-					return (0);
+				if (t == EOF) {
+					if (shift == 0)
+						return (0);
+					break;
+				}
 				sum += (long)chrtran[t] << (shift
 #ifdef POW2
 				    &= HALFLONG - 1);
@@ -1089,8 +1102,11 @@ readhash(FILE *f)
 			}
 		else
 			for (shift = 0; (t = getc(f)) != '\n'; shift += 7) {
-				if (t == -1)
-					return (0);
+				if (t == EOF) {
+					if (shift == 0)
+						return (0);
+					break;
+				}
 				sum += (long)t << (shift
 #ifdef POW2
 				    &= HALFLONG - 1);
@@ -1101,8 +1117,6 @@ readhash(FILE *f)
 	} else {
 		for (shift = 0;;) {
 			switch (t = getc(f)) {
-			case -1:
-				return (0);
 			case '\t':
 			case ' ':
 				space++;
@@ -1120,6 +1134,10 @@ readhash(FILE *f)
 #endif
 				shift += 7;
 				continue;
+			case EOF:
+				if (shift == 0)
+					return (0);
+				/* FALLTHROUGH */
 			case '\n':
 				break;
 			}