55 lines
1.3 KiB
C
55 lines
1.3 KiB
C
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/* Code to byte-swap static constructor/destructor tables on
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broken a.out little-endian targets. The startup code should call
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__fix_ctors just before calling main. It is safe to use on non-broken
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or big-endian targets. */
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extern long __CTOR_LIST__[];
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extern long __DTOR_LIST__[];
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static void
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byte_swap (long *entry)
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{
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unsigned char *p = (unsigned char *)entry;
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unsigned char tmp;
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tmp = p[0];
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p[0] = p[3];
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p[3] = tmp;
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tmp = p[1];
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p[1] = p[2];
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p[2] = tmp;
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}
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static void
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fix_table (long *table)
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{
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long len = table[0];
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/* The heuristic for deciding if a table is broken is to examine
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the word at the start of the table, which contains the number
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of function pointers immediately following. If the low word
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is zero, and the high word is non-zero, it's very likely that
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it is byte-swapped. This test will fail if the program has
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an exact multiple of 64K static constructors or destructors, a very
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unlikely situation. */
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if ((len & 0xffff) == 0 && (len & 0xffff0000) != 0)
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{
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/* The table looks broken. Byte-swap all the words in the table, up
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to a NULL entry, which marks the end of the table. */
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do
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{
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byte_swap (table);
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table++;
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}
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while (*table);
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}
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}
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void
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__fix_ctors (void)
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{
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fix_table (__CTOR_LIST__);
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fix_table (__DTOR_LIST__);
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}
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