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Alter glibc override to work with RTL_DEEPBIND
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When using dlopen with RTL_DEEPBIND the LD_PRELOAD used
by the majority of allocators does not work as both libc
and snmallocs allocators can be called by various dso.

This patch uses GLIBC's __malloc_hook to override the allocator
as well as LD_PRELOAD.  This means that all libraries will
call snmalloc when performing allocation.
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mjp41 committed Feb 27, 2023
1 parent b357165 commit 53b88f9
Showing 1 changed file with 18 additions and 0 deletions.
18 changes: 18 additions & 0 deletions src/snmalloc/override/malloc.cc
Original file line number Diff line number Diff line change
Expand Up @@ -227,4 +227,22 @@ extern "C"
return SNMALLOC_NAME_MANGLE(memalign)(
OS_PAGE_SIZE, (size + OS_PAGE_SIZE - 1) & ~(OS_PAGE_SIZE - 1));
}

#if __has_include(<features.h>)
# include <features.h>
#endif
#if defined(__GLIBC__) && !defined(SNMALLOC_PASS_THROUGH)
// glibc uses these hooks to replace malloc.
// This is required when RTL_DEEPBIND is used and the library is
// LD_PRELOADed.
// See https://github.com/microsoft/snmalloc/issues/595
SNMALLOC_EXPORT void (*SNMALLOC_NAME_MANGLE(__free_hook))(void* ptr) =
&SNMALLOC_NAME_MANGLE(free);
SNMALLOC_EXPORT void* (*SNMALLOC_NAME_MANGLE(__malloc_hook))(size_t size) =
&SNMALLOC_NAME_MANGLE(malloc);
SNMALLOC_EXPORT void* (*SNMALLOC_NAME_MANGLE(__realloc_hook))(
void* ptr, size_t size) = &SNMALLOC_NAME_MANGLE(realloc);
SNMALLOC_EXPORT void* (*SNMALLOC_NAME_MANGLE(__memalign_hook))(
size_t alignment, size_t size) = &SNMALLOC_NAME_MANGLE(memalign);
#endif
}

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