LAPACKE: add runtime allocator override (LAPACKE_set_alloc)

Route the LAPACKE_malloc / LAPACKE_free defaults through function
pointers so the LAPACKE test suite can inject allocation failures at
run time, mirroring LAPACKE_set_nancheck. Compile-time macro overrides
are unaffected.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

LAPACKE/include/lapacke.h

@@ -39,11 +39,24 @@
 extern "C" {
 #endif /* __cplusplus */
 
+/* All LAPACKE-internal allocations (workspaces, row-major transposition
+ * buffers) go through a replaceable allocator. Defining the LAPACKE_malloc /
+ * LAPACKE_free macros at compile time replaces the allocator entirely. */
+
+/** \brief Allocate through the installed allocator (malloc by default). */
+void *LAPACKE_malloc_proxy(size_t size);
+/** \brief Release through the installed deallocator (free by default). */
+void LAPACKE_free_proxy(void *ptr);
+/** \brief Install a custom allocator: malloc_fn / free_fn must form a
+ *  matching pair; NULL restores the defaults. Mutates global state and is
+ *  not thread-safe. */
+void LAPACKE_set_alloc(void *(*malloc_fn)(size_t), void (*free_fn)(void *));
+
 #ifndef LAPACKE_malloc
-#define LAPACKE_malloc( size ) malloc( size )
+#define LAPACKE_malloc(size) LAPACKE_malloc_proxy(size)
 #endif
 #ifndef LAPACKE_free
-#define LAPACKE_free( p )      free( p )
+#define LAPACKE_free(p) LAPACKE_free_proxy(p)
 #endif
 
 #define LAPACK_C2INT( x ) (lapack_int)(*((float*)&x ))

LAPACKE/src/CMakeLists.txt

@@ -1208,6 +1208,7 @@ lapacke_dtzrzf_work.c
 )
 
 set(COMMON_SOURCES
+lapacke_alloc.c
 lapacke_nancheck.c
 )
 set(SOURCES

LAPACKE/src/Makefile

@@ -43,6 +43,7 @@ include $(TOPSRCDIR)/make.inc
 
 OBJ = \
 lapacke_ilaver.o \
+lapacke_alloc.o \
 lapacke_nancheck.o
 
 OBJ_C = \

LAPACKE/src/lapacke_alloc.c

@@ -0,0 +1,61 @@
+/*****************************************************************************
+ * Replaceable allocator for LAPACKE-internal allocations.
+ *
+ * The LAPACKE_malloc / LAPACKE_free macros default to the functions below,
+ * which forward to a run-time replaceable allocator (malloc / free until
+ * changed via LAPACKE_set_alloc). Like the nancheck flag, the allocator is
+ * shared between all APIs, so this file must be compiled exactly once,
+ * without an API suffix.
+ *****************************************************************************/
+
+#include <stdlib.h>
+
+#include "lapacke.h"
+
+static void *(*lapacke_malloc_fn)(size_t) = malloc;
+static void (*lapacke_free_fn)(void *) = free;
+
+/**
+ * \brief Allocate memory through the installed allocator.
+ *
+ * Default of the LAPACKE_malloc macro.
+ *
+ * \param[in] size Allocation size in bytes.
+ * \return The allocation, or NULL on failure.
+ */
+void *LAPACKE_malloc_proxy(size_t size)
+{
+    return lapacke_malloc_fn(size);
+}
+
+/**
+ * \brief Release memory through the installed deallocator.
+ *
+ * Default of the LAPACKE_free macro.
+ *
+ * \param[in] ptr Allocation obtained through LAPACKE_malloc_proxy.
+ */
+void LAPACKE_free_proxy(void *ptr)
+{
+    lapacke_free_fn(ptr);
+}
+
+/**
+ * \brief Install a custom allocator for LAPACKE-internal allocations.
+ *
+ * Subsequent LAPACKE-internal allocations (workspaces, row-major
+ * transposition buffers) are made with malloc_fn and released with
+ * free_fn. The two must form a matching pair: memory allocated with
+ * malloc_fn is released through free_fn, so pairing an allocator with an
+ * incompatible deallocator is undefined behavior. The setter mutates
+ * global state shared by all threads and is not thread-safe; call it
+ * during setup, like LAPACKE_set_nancheck.
+ *
+ * \param[in] malloc_fn Replacement for malloc; NULL restores malloc.
+ * \param[in] free_fn   Replacement for free; NULL restores free.
+ */
+void LAPACKE_set_alloc(void *(*malloc_fn)(size_t), void (*free_fn)(void *))
+{
+    lapacke_malloc_fn = (malloc_fn != NULL) ? malloc_fn : malloc;
+    lapacke_free_fn = (free_fn != NULL) ? free_fn : free;
+}