fix: code quality improvements across C codebase

- Replace sprintf with snprintf (1024-byte errbuf) in hmmmm.c, base_device.c,
  compose_device.c, config.c
- Fix WRITE_MEM macro: use smartAddrWriteHandlers for write ident (was
  incorrectly reading from smartAddrReadHandlers)
- Replace alloca with malloc+free in dispatchMemAccessNotifications
- Guard closeBaseDevice against NULL lib/partial initialization
- Simplify intercept context storage to single contiguous allocation
- Add NULL checks after calloc in config handler with proper cleanup
- Guard find_device_by_id against zero-length path

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

devices/avr_generic/inc/instr.h

@@ -0,0 +1,105 @@
+#ifndef __INSTR_H__
+#define __INSTR_H__
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "mem.h"
+
+
+#ifndef OPCODE_WORDSIZE
+    #error OPCODE_WORDSIZE must be provided
+//     #define OPCODE_WORDSIZE 1
+#endif
+#if OPCODE_WORDSIZE == 1
+    typedef uint8_t opcode_t;
+#elif OPCODE_WORDSIZE == 2
+    typedef uint16_t opcode_t;
+#elif OPCODE_WORDSIZE == 3
+    typedef uint32_t opcode_t;
+#elif OPCODE_WORDSIZE == 4
+    typedef uint32_t opcode_t;
+#else
+    #error OPCODE_WORDSIZE must be one of 1,2,3,
+#endif
+
+
+#ifndef PC_WORDSIZE
+    #error PC_WORDSIZE must be provided
+//     #define PC_WORDSIZE 1
+#endif
+#if PC_WORDSIZE == 1
+    typedef uint8_t prog_counter_t;
+#elif PC_WORDSIZE == 2
+    typedef uint16_t prog_counter_t;
+#elif PC_WORDSIZE == 3
+    typedef uint32_t prog_counter_t;
+#elif PC_WORDSIZE == 4
+    typedef uint32_t prog_counter_t;
+#else
+    #error PC_WORDSIZE must be one of 1,2,3,4
+#endif
+
+typedef uint8_t (*instr_h_func)(prog_counter_t*, device_mem_t*);
+
+typedef struct 
+{
+    instr_h_func h;
+    opcode_t base;
+    opcode_t argsMask;
+    uint8_t opcodeLen;
+
+} instruction_metadata_t;
+
+instr_h_func* genInstrArray(char* errbuf);
+void setOpcodeSizes(uint8_t* opcodeSizes);
+opcode_t extractOpcode(device_mem_t* devMem, prog_counter_t programCounter);
+
+
+
+
+#define AVRe 1
+#define AVRxm 2
+#define AVRxt 3
+#define AVRrc 4
+
+#ifndef ARCH
+#define ARCH AVRe
+#endif
+
+
+
+#define READ_MEM(__tgt, __mem, __segno, __addr, __cell_t) \
+{\
+    uint64_t __globalAddr = __mem->memsegShifts[__segno] + __addr; \
+    if (__mem->smartAddrReadHandlers[__globalAddr].func != NULL) \
+    { \
+        __tgt = *(__cell_t*)__mem->smartAddrReadHandlers[__globalAddr].func(__mem->smartAddrReadHandlers[__globalAddr].ident, __addr, __mem->rawCells + __mem->memsegShifts[__segno]); \
+    } \
+    else \
+    { \
+        __tgt = ((__cell_t*)__mem->cells[__segno])[__addr]; \
+    } \
+    __mem->memreadCellAddrs[__mem->memreadLen] = __globalAddr; \
+    __mem->memreadLen += 1; \
+}
+
+#define WRITE_MEM(__mem, __segno, __addr, __cell_t, __val) \
+{ \
+    uint64_t __globalAddr = __mem->memsegShifts[__segno] + __addr; \
+    if (__mem->smartAddrWriteHandlers[__globalAddr].func != NULL) \
+    { \
+        __cell_t __dat = (__cell_t)(__val); \
+        __mem->smartAddrWriteHandlers[__globalAddr].func(__mem->smartAddrWriteHandlers[__globalAddr].ident, __addr, __mem->rawCells + __mem->memsegShifts[__segno], (void*)&__dat); \
+    } \
+    else \
+    { \
+        ((__cell_t*)__mem->cells[__segno])[__addr] = (__cell_t)(__val); \
+    } \
+    __mem->memwriteCellAddrs[__mem->memwriteLen] = __globalAddr; \
+    __mem->memwriteLen += 1; \
+}
+
+
+
+#endif // ifndef __INSTR_H__