67 lines
2.0 KiB
Diff
67 lines
2.0 KiB
Diff
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Make sure that statements such as:
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strcpy (dst, "/gnu/store/…");
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do not result in chunked /gnu/store strings that are undetectable by
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Guix's GC and its grafting code. See <http://bugs.gnu.org/24703>.
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--- gcc-5.3.0/gcc/builtins.c 2016-10-18 10:50:46.080616285 +0200
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+++ gcc-5.3.0/gcc/builtins.c 2016-11-09 15:26:43.693042737 +0100
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@@ -3192,6 +3192,42 @@ determine_block_size (tree len, rtx len_
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GET_MODE_MASK (GET_MODE (len_rtx)));
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}
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+/* Return true if STR contains the string "/gnu/store". */
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+
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+static bool
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+store_reference_p (tree str)
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+{
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+ if (TREE_CODE (str) == ADDR_EXPR)
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+ str = TREE_OPERAND (str, 0);
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+
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+ if (TREE_CODE (str) != STRING_CST)
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+ return false;
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+
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+ int len;
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+ const char *store;
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+
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+ store = getenv ("NIX_STORE") ? getenv ("NIX_STORE") : "/gnu/store";
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+ len = strlen (store);
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+
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+ /* Size of the hash part of store file names, including leading slash and
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+ trailing hyphen. */
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+ const int hash_len = 34;
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+
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+ if (TREE_STRING_LENGTH (str) < len + hash_len)
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+ return false;
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+
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+ /* We cannot use 'strstr' because 'TREE_STRING_POINTER' returns a string
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+ that is not necessarily NUL-terminated. */
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+
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+ for (int i = 0; i < TREE_STRING_LENGTH (str) - (len + hash_len); i++)
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+ {
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+ if (strncmp (TREE_STRING_POINTER (str) + i, store, len) == 0)
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+ return true;
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+ }
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+
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+ return false;
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+}
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+
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/* Helper function to do the actual work for expand_builtin_memcpy. */
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static rtx
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@@ -3207,6 +3243,13 @@ expand_builtin_memcpy_args (tree dest, t
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unsigned HOST_WIDE_INT max_size;
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unsigned HOST_WIDE_INT probable_max_size;
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+ /* Do not emit block moves, which translate to the 'movabs' instruction on
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+ x86_64, when SRC refers to store items. That way, store references
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+ remain visible to the Guix GC and grafting code. See
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+ <http://bugs.gnu.org/24703>. */
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+ if (store_reference_p (src))
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+ return NULL_RTX;
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+
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/* If DEST is not a pointer type, call the normal function. */
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if (dest_align == 0)
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return NULL_RTX;
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