read_info_alternates: warn on non-trivial errors

When we fail to open $GIT_DIR/info/alternates, we silently
assume there are no alternates. This is the right thing to
do for ENOENT, but not for other errors.

A hard error is probably overkill here. If we fail to read
an alternates file then either we'll complete our operation
anyway, or we'll fail to find some needed object. Either
way, a warning is good idea. And we already have a helper
function to handle this pattern; let's just call
warn_on_fopen_error().

Note that technically the errno from strbuf_read_file()
might be from a read() error, not open(). But since read()
would never return ENOENT or ENOTDIR, and since it produces
a generic "unable to access" error, it's suitable for
handling errors from either.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/sha1_file.c b/sha1_file.c
index a913865df8e448ad42f4acc9a03158cba08d9add..d65ca432459e7be287ec6ed85125a9afa6b74de1 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -456,6 +456,7 @@ static void read_info_alternates(const char * relative_base, int depth)
 
        path = xstrfmt("%s/info/alternates", relative_base);
        if (strbuf_read_file(&buf, path, 1024) < 0) {
+               warn_on_fopen_errors(path);
                free(path);
                return;
        }