worktree: use xsize_t to access file size

To read the "gitdir" file into memory, we stat the file and
allocate a buffer. But we store the size in an "int", which
may be truncated. We should use a size_t and xsize_t(),
which will detect truncation.

An overflow is unlikely for a "gitdir" file, but it's a good
practice to model.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/worktree.c b/builtin/worktree.c
index de26849..2f4a4ef 100644 (file)
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -38,7 +38,8 @@ static int prune_worktree(const char *id, struct strbuf *reason)
 {
        struct stat st;
        char *path;
-       int fd, len;
+       int fd;
+       size_t len;
 
        if (!is_directory(git_path("worktrees/%s", id))) {
                strbuf_addf(reason, _("Removing worktrees/%s: not a valid directory"), id);
@@ -56,7 +57,7 @@ static int prune_worktree(const char *id, struct strbuf *reason)
                            id, strerror(errno));
                return 1;
        }
-       len = st.st_size;
+       len = xsize_t(st.st_size);
        path = xmallocz(len);
        read_in_full(fd, path, len);
        close(fd);