@matheusbsbs / matheus-bagliano / commits / f5b4dc7668

tempfile: handle NULL tempfile pointers gracefully

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> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Sep 5, 2017 at 08:14 UTC f5b4dc7668b6c8d71432af9f9ddad6f7c62d284e

2 files changed +8 -6

tempfile.c

+7 -5

@@ -236,13 +236,15 @@ FILE *get_tempfile_fp(struct tempfile *tempfile)

236

237 int close_tempfile_gently(struct tempfile *tempfile)

238 {

239 - int fd = tempfile->fd;

240 - FILE *fp = tempfile->fp;

239 + int fd;

240 + FILE *fp;

241 int err;

242

243 - if (fd < 0)

243 + if (!is_tempfile_active(tempfile) || tempfile->fd < 0)

244 return 0;

245

246 + fd = tempfile->fd;

247 + fp = tempfile->fp;

248 tempfile->fd = -1;

249 if (fp) {

250 tempfile->fp = NULL;

@@ -262,10 +264,10 @@ int close_tempfile_gently(struct tempfile *tempfile)

264

265 int reopen_tempfile(struct tempfile *tempfile)

266 {

265 - if (0 <= tempfile->fd)

266 - die("BUG: reopen_tempfile called for an open object");

267 if (!is_tempfile_active(tempfile))

268 die("BUG: reopen_tempfile called for an inactive object");

269 + if (0 <= tempfile->fd)

270 + die("BUG: reopen_tempfile called for an open object");

271 tempfile->fd = open(tempfile->filename.buf, O_WRONLY);

272 return tempfile->fd;

273 }

tempfile.h

+1 -1

@@ -211,7 +211,7 @@ extern FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode);

211

212 static inline int is_tempfile_active(struct tempfile *tempfile)

213 {

214 - return tempfile->active;

214 + return tempfile && tempfile->active;

215 }

216

217 /*