commit - 7a54ad3ae5d25aa5349668c8d3d3fa048a8f0733
commit + 6f26cb2ecbe03d692e63a4f263febfb5a74e4377
blob - 92887ff151b6faa423752b1fa9baa3c123f19726
blob + 51cb9c7966c778bceaaaf06691252cd4887e5e63
--- include/diff/diff_output.h
+++ include/diff/diff_output.h
@@ -26,5 +26,5 @@ int diff_output_unidiff(FILE *dest, const struct diff_
 				 const struct diff_result *result,
 				 unsigned int context_lines);
 int diff_output_info(FILE *dest, const struct diff_input_info *info);
-void diff_output_lines(FILE *dest, const char *prefix,
+int diff_output_lines(FILE *dest, const char *prefix,
 		       struct diff_atom *start_atom, unsigned int count);
blob - e93c1e9cc1701fc9a4f1d457d33924914bb20adf
blob + e9dd89fa1226d66603de9f1e80fd72bca21fefcb
--- lib/diff_output.c
+++ lib/diff_output.c
@@ -15,6 +15,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <errno.h>
 #include <inttypes.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -25,58 +26,67 @@
 #include <diff/diff_main.h>
 #include <diff/diff_output.h>
 
-static char
-get_atom_byte(struct diff_atom *atom, off_t off)
+static int
+get_atom_byte(int *ch, struct diff_atom *atom, off_t off)
 {
-	int ch;
 	off_t cur;
 
-	if (atom->at != NULL)
-		return atom->at[off];
+	if (atom->at != NULL) {
+		*ch = atom->at[off];
+		return 0;
+	}
 
 	cur = ftello(atom->d->root->f);
 	if (cur == -1)
-		abort(); /* XXX cannot return error */
+		return errno;
 
 	if (cur != atom->pos + off &&
 	    fseeko(atom->d->root->f, atom->pos + off, SEEK_SET) == -1)
-		abort(); /* XXX cannot return error */
+		return errno;
 
-	ch = fgetc(atom->d->root->f);
-	if (ch == EOF)
-		abort(); /* XXX cannot return error */
+	*ch = fgetc(atom->d->root->f);
+	if (*ch == EOF && ferror(atom->d->root->f))
+		return errno;
 
-	return ch;
+	return 0;
 }
 
-void
+int
 diff_output_lines(FILE *dest, const char *prefix, struct diff_atom *start_atom,
 		  unsigned int count)
 {
 	struct diff_atom *atom;
+	int rc;
 	foreach_diff_atom(atom, start_atom, count) {
 		fprintf(dest, "%s", prefix);
-		int i;
+		int i, ch;
 		unsigned int len = atom->len;
 		if (len) {
-			char ch;
-			ch = get_atom_byte(atom, len - 1);
+			rc = get_atom_byte(&ch, atom, len - 1);
+			if (rc)
+				return rc;
 			if (ch == '\n')
 				len--;
 			if (len) {
-				ch = get_atom_byte(atom, len - 1);
+				rc = get_atom_byte(&ch, atom, len - 1);
+				if (rc)
+					return rc;
 				if (ch == '\r')
 					len--;
 			}
 		}
 
 		for (i = 0; i < len; i++) {
-			char c = get_atom_byte(atom, i);
-			if ((c < 0x20 || c >= 0x7f) && c != '\t')
-				fprintf(dest, "\\x%02x", (unsigned char)c);
+			rc = get_atom_byte(&ch, atom, i);
+			if (rc)
+				return rc;
+			if ((ch < 0x20 || ch >= 0x7f) && ch != '\t')
+				fprintf(dest, "\\x%02x", (unsigned char)ch);
 			else
-				fprintf(dest, "%c", c);
+				fprintf(dest, "%c", ch);
 		}
 		fprintf(dest, "\n");
 	}
+
+	return 0;
 }