Re: [Libguestfs] [PATCH 1/2] lib: Add CLEANUP_FREE macro which automatically calls 'free' when leaving scope.

From: "Richard W.M. Jones" <rjones(a)redhat.com&gt; Use the macro like this to create temporary variables which are automatically cleaned up when the scope is exited: { CLEANUP_FREE (char *, foo, strdup (bar)); /* char *foo = strdup (bar) */ ... // no need to call free (foo)! } On GCC and LLVM, this is implemented using __attribute__((cleanup(...))). On other compilers, we fall back to a less efficient implementation which saves up the memory allocations and frees them all when the handle is closed. --- configure.ac | 35 +++++++++++++++++++++++++++++++++++ src/alloc.c | 19 +++++++++++++++++++ src/guestfs-internal.h | 33 +++++++++++++++++++++++++++++++++ src/handle.c | 15 +++++++++++++++ 4 files changed, 102 insertions(+)

+#ifndef HAVE_ATTRIBUTE_CLEANUP +void +guestfs___defer_free (guestfs_h *g, void (*freefn) (void *), void *data) +{ + struct deferred_free *p = safe_malloc (g, sizeof *p); + + p->freefn = freefn; + p->data = data; + p->next = g->deferred_frees; + g->deferred_frees = p; +} +#endif

guestfs_close (guestfs_h *g) { struct qemu_param *qp, *qp_next; +#ifndef HAVE_ATTRIBUTE_CLEANUP + struct deferred_free *dfp, *dfp_next; +#endif guestfs_h **gg; if (g->state == NO_HANDLE) { @@ -324,6 +327,18 @@ guestfs_close (guestfs_h *g) while (g->error_cb_stack) guestfs_pop_error_handler (g); +#ifndef HAVE_ATTRIBUTE_CLEANUP + /* For compilers that don't support __attribute__((cleanup(...))), + * free any temporary data that we allocated in CLEANUP_* macros + * here. + */ + for (dfp = g->deferred_frees; dfp; dfp = dfp_next) { + dfp->freefn (&dfp->data); + dfp_next = dfp->next; + free (dfp); + } +#endif +