Merge branch 'mmap-regexec'

This topic branch fixes a segmentation fault when using `-G` or `-S
--pickaxe-regex` with `git diff` on new-born files that are configured
without user diff drivers, and that hence get mmap()ed into memory.

Signed-off-by: Johannes Schindelin <[email protected]>

diff.c

@@ -2826,6 +2826,15 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
 			s->data = strbuf_detach(&buf, &size);
 			s->size = size;
 			s->should_free = 1;
+		} else {
+			/* data must be NUL-terminated so e.g. for regexec() */
+			char *data = xmalloc(s->size + 1);
+			memcpy(data, s->data, s->size);
+			data[s->size] = '\0';
+			munmap(s->data, s->size);
+			s->should_munmap = 0;
+			s->data = data;
+			s->should_free = 1;
 		}
 	}
 	else {

diffcore-pickaxe.c

@@ -49,6 +49,8 @@ static int diff_grep(mmfile_t *one, mmfile_t *two,
 	xpparam_t xpp;
 	xdemitconf_t xecfg;
 
+	assert(!one || one->ptr[one->size] == '\0');
+	assert(!two || two->ptr[two->size] == '\0');
 	if (!one)
 		return !regexec(regexp, two->ptr, 1, &regmatch, 0);
 	if (!two)

t/t4059-diff-pickaxe.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+#
+# Copyright (c) 2016 Johannes Schindelin
+#
+
+test_description='Pickaxe options'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	test_commit initial &&
+	printf "%04096d" 0 >4096-zeroes.txt &&
+	git add 4096-zeroes.txt &&
+	test_tick &&
+	git commit -m "A 4k file"
+'
+test_expect_success '-G matches' '
+	git diff --name-only -G "^0{4096}$" HEAD^ >out &&
+	test 4096-zeroes.txt = "$(cat out)"
+'
+
+test_done