diff: let "git diff -O" read orderfile from any file and fail properly
The -O flag really shouldn't silently fail to do anything when given
a path that it can't read from.
However, it should be able to read from un-mmappable files, such as:
* pipes/fifos
* /dev/null: It's a character device (at least on Linux)
* ANY empty file:
Quoting Linux mmap(2), "SUSv3 specifies that mmap() should fail if
length is 0. However, in kernels before 2.6.12, mmap() succeeded in
this case: no mapping was created and the call returned addr. Since
kernel 2.6.12, mmap() fails with the error EINVAL for this case."
We especially want "-O/dev/null" to work, since we will be documenting
it as the way to cancel "diff.orderfile" when we add that.
(Note: "-O/dev/null" did have the right effect, since the existing error
handling essentially worked out to "silently ignore the orderfile". But
this was probably more coincidence than anything else.)
So, lets toss all of that logic to get the file mmapped and just use
strbuf_read_file() instead, which gives us decent error handling
practically for free.
Signed-off-by: Samuel Bronson <naesten@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diffcore-order.c b/diffcore-order.c
index 23e9385..a63f332 100644
--- a/diffcore-order.c
+++ b/diffcore-order.c
@@ -10,28 +10,21 @@
static void prepare_order(const char *orderfile)
{
- int fd, cnt, pass;
+ int cnt, pass;
+ struct strbuf sb = STRBUF_INIT;
void *map;
char *cp, *endp;
- struct stat st;
- size_t sz;
+ ssize_t sz;
if (order)
return;
- fd = open(orderfile, O_RDONLY);
- if (fd < 0)
- return;
- if (fstat(fd, &st)) {
- close(fd);
- return;
- }
- sz = xsize_t(st.st_size);
- map = mmap(NULL, sz, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
- close(fd);
- if (map == MAP_FAILED)
- return;
+ sz = strbuf_read_file(&sb, orderfile, 0);
+ if (sz < 0)
+ die_errno(_("failed to read orderfile '%s'"), orderfile);
+ map = strbuf_detach(&sb, NULL);
endp = (char *) map + sz;
+
for (pass = 0; pass < 2; pass++) {
cnt = 0;
cp = map;
