checkout-index: simplify locking logic

`newfd` starts out negative. If we then take the lock, `newfd` will
become non-negative. We later check for exactly that property before
calling `write_locked_index()`. That is, we are simply using `newfd` as
a boolean to keep track of whether we took the lock or not. (We always
use `newfd` and `lock_file` together, so they really are mirroring each
other.)

Drop `newfd` and check with `is_lock_file_locked()` instead. While at
it, move the `static struct lock_file` into `cmd_checkout_index()` and
make it non-static. It is only used in this function, and after
076aa2cbd (tempfile: auto-allocate tempfiles on heap, 2017-09-05), we
can have lockfiles on the stack.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/checkout-index.c b/builtin/checkout-index.c
index 39c8be05dc4beda2f0cd179e5c5f495ce079f8d9..b0e78b819db3138f1c5ac4fe4b5d850ab306b470 100644 (file)
--- a/builtin/checkout-index.c
+++ b/builtin/checkout-index.c
@@ -129,8 +129,6 @@ static const char * const builtin_checkout_index_usage[] = {
        NULL
 };
 
-static struct lock_file lock_file;
-
 static int option_parse_stage(const struct option *opt,
                              const char *arg, int unset)
 {
@@ -150,7 +148,7 @@ static int option_parse_stage(const struct option *opt,
 int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 {
        int i;
-       int newfd = -1;
+       struct lock_file lock_file = LOCK_INIT;
        int all = 0;
        int read_from_stdin = 0;
        int prefix_length;
@@ -206,7 +204,7 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
        if (index_opt && !state.base_dir_len && !to_tempfile) {
                state.refresh_cache = 1;
                state.istate = &the_index;
-               newfd = hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+               hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
        }
 
        /* Check out named files first */
@@ -251,7 +249,7 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
        if (all)
                checkout_all(prefix, prefix_length);
 
-       if (0 <= newfd &&
+       if (is_lock_file_locked(&lock_file) &&
            write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
                die("Unable to write new index file");
        return 0;