mmap: set FD_CLOEXEC for file descriptors we keep open for mmap()

I do not have any proof that this matters to any existing
problems I am seeing, but I do not think of any reason not to do
this.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/sha1_file.c b/sha1_file.c
index 84037fe98fa6ea0e4f1127c165786df51a34c5dd..d9622d95e7e3d7b91982ae60dbc36a7996856682 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -540,6 +540,7 @@ static void open_packed_git(struct packed_git *p)
        struct pack_header hdr;
        unsigned char sha1[20];
        unsigned char *idx_sha1;
+       long fd_flag;
 
        p->pack_fd = open(p->pack_name, O_RDONLY);
        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
@@ -553,6 +554,16 @@ static void open_packed_git(struct packed_git *p)
        } else if (p->pack_size != st.st_size)
                die("packfile %s size changed", p->pack_name);
 
+       /* We leave these file descriptors open with sliding mmap;
+        * there is no point keeping them open across exec(), though.
+        */
+       fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
+       if (fd_flag < 0)
+               die("cannot determine file descriptor flags");
+       fd_flag |= FD_CLOEXEC;
+       if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
+               die("cannot set FD_CLOEXEC");
+
        /* Verify we recognize this pack file format. */
        read_or_die(p->pack_fd, &hdr, sizeof(hdr));
        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))