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author | Ian Jackson <ian.jackson@eu.citrix.com> | 2012-06-28 18:43:25 +0100 |
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committer | Ian Jackson <ian.jackson@eu.citrix.com> | 2012-06-28 18:43:25 +0100 |
commit | 27e1ccd1db641b4f57c8249a6e4d7492140dd285 (patch) | |
tree | d7b36cf04a52d929987f26afba33a5dbf8598995 /tools/libxl/libxl_aoutils.c | |
parent | 145511d2ce456a6590f28e14e32b7c4cce1c4c69 (diff) | |
download | xen-27e1ccd1db641b4f57c8249a6e4d7492140dd285.tar.gz xen-27e1ccd1db641b4f57c8249a6e4d7492140dd285.tar.bz2 xen-27e1ccd1db641b4f57c8249a6e4d7492140dd285.zip |
libxl: Do not pass NULL as gc_opt; introduce NOGC
In 25182:6c3345d7e9d9 the practice of passing NULL to gc-using memory
allocation functions was introduced. However, the arrangements there
were not correct as committed, because the error handling and logging
depends on getting a ctx from the gc - so an allocation error would in
fact result in libxl dereferencing NULL.
Instead, provide a special dummy gc in the ctx, called `nogc_gc'. It
is marked out specially by having alloc_maxsize==-1, which is
otherwise invalid.
Functions which need to actually look into the gc use the new test
function gc_is_real (whose purpose is mainly clarity of the code) to
check whether the gc is the dummy one, and do nothing if it is. And
we provide a helper macro NOGC which uses the in-scope real gc to find
the ctx and hence the dummy gc (and which replaces the previous
#define NOGC NULL).
Change all callers which pass 0 or NULL to an allocation function to
use NOGC or &ctx->nogc_gc, as applicable in the context.
We add a comment near the definition of LIBXL_INIT_GC pointing out
that it isn't any more the only place a libxl__gc struct is
initialised, for the benefit of anyone changing the contents of gc's
in the future.
Also, actually document that libxl__ptr_add is legal with ptr==NULL,
and change a couple of calls not to check for NULL argument.
Reported-by: Bamvor Jian Zhang <bjzhang@suse.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Bamvor Jian Zhang <bjzhang@suse.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Diffstat (limited to 'tools/libxl/libxl_aoutils.c')
-rw-r--r-- | tools/libxl/libxl_aoutils.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/tools/libxl/libxl_aoutils.c b/tools/libxl/libxl_aoutils.c index 7f8d6d3bf6..99972a23b0 100644 --- a/tools/libxl/libxl_aoutils.c +++ b/tools/libxl/libxl_aoutils.c @@ -77,6 +77,7 @@ static void datacopier_check_state(libxl__egc *egc, libxl__datacopier_state *dc) void libxl__datacopier_prefixdata(libxl__egc *egc, libxl__datacopier_state *dc, const void *data, size_t len) { + EGC_GC; libxl__datacopier_buf *buf; /* * It is safe for this to be called immediately after _start, as @@ -88,7 +89,7 @@ void libxl__datacopier_prefixdata(libxl__egc *egc, libxl__datacopier_state *dc, assert(len < dc->maxsz - dc->used); - buf = libxl__zalloc(0, sizeof(*buf) - sizeof(buf->buf) + len); + buf = libxl__zalloc(NOGC, sizeof(*buf) - sizeof(buf->buf) + len); buf->used = len; memcpy(buf->buf, data, len); |