[PATCH 09/20] tempfile: handle NULL tempfile pointers gracefully
- From
Jeff King <peff@peff.net>
- Date
- Sep 5, 2017, 12:14 UTC
- Message-ID
- <20170905121440.hxbyspsruzrwigtq@sigill.intra.peff.net>
- In-Reply-To
- <20170905121353.62zg3mtextmq5zrs@sigill.intra.peff.net>
The tempfile functions all take pointers to tempfile objects, but do not check whether the argument is NULL. This isn't a big deal in practice, since the lifetime of any tempfile object is defined to last for the whole program. So even if we try to call delete_tempfile() on an already-deleted tempfile, our "active" check will tell us that it's a noop.
In preparation for transitioning to a new system that loosens the "tempfile objects can never be freed" rule, let's tighten up our active checks:
1. A NULL pointer is now defined as "inactive" (so it will
BUG for most functions, but works as a silent noop for
things like delete_tempfile). 2. Functions should always do the "active" check before
looking at any of the struct fields.Signed-off-by: Jeff King <peff@peff.net> --- tempfile.c | 12 +++++++----- tempfile.h | 2 +- 2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/tempfile.c b/tempfile.c index 964c66d504..861f817133 100644 --- a/tempfile.c +++ b/tempfile.c @@ -236,13 +236,15 @@ FILE *get_tempfile_fp(struct tempfile *tempfile) int close_tempfile_gently(struct tempfile *tempfile) { - int fd = tempfile->fd; - FILE *fp = tempfile->fp; + int fd; + FILE *fp; int err; - if (fd < 0) + if (!is_tempfile_active(tempfile) || tempfile->fd < 0) return 0; + fd = tempfile->fd; + fp = tempfile->fp; tempfile->fd = -1; if (fp) { tempfile->fp = NULL; @@ -262,10 +264,10 @@ int close_tempfile_gently(struct tempfile *tempfile) int reopen_tempfile(struct tempfile *tempfile) { - if (0 <= tempfile->fd) - die("BUG: reopen_tempfile called for an open object"); if (!is_tempfile_active(tempfile)) die("BUG: reopen_tempfile called for an inactive object"); + if (0 <= tempfile->fd) + die("BUG: reopen_tempfile called for an open object"); tempfile->fd = open(tempfile->filename.buf, O_WRONLY); return tempfile->fd; } diff --git a/tempfile.h b/tempfile.h index d854dcdd3e..d30663182d 100644 --- a/tempfile.h +++ b/tempfile.h @@ -211,7 +211,7 @@ extern FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode); static inline int is_tempfile_active(struct tempfile *tempfile) { - return tempfile->active; + return tempfile && tempfile->active; } /*
-- 2.14.1.721.gc5bc1565f1