diff-delta: set size out-parameter to 0 for NULL delta
When we cannot generate a delta, we return NULL but leave delta_size untouched. This is generally OK, as callers rely on NULL to decide if the output is usable or not. But it can confuse compilers; in particular, gcc 9.2.1 with "-flto -O3" complains in fast-import's store_object() that delta_len may be used uninitialized. Let's change the diff-delta code to set the size explicitly to 0 for a NULL return. That silences the compiler and makes it easier to reason about the result. Reported-by: Stephan Beyer <s-beyer@gmx.net> Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jeff King committed
Sep 5, 2019 at 18:53 UTC
e4b369069e4a7630233a045784d0b1e2425b0a05
1 file changed
+2
diff-delta.c
+2
@@ -326,6 +326,8 @@ create_delta(const struct delta_index *index,
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const unsigned char *ref_data, *ref_top, *data, *top;
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unsigned char *out;
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+ *delta_size = 0;
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+
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if (!trg_buf || !trg_size)
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return NULL;
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