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fmc.c
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fmc.c
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/*
* fmc.c
*
* 'Find Memory Corruption' related main file
*
* Author: rp <[email protected]>
*
*/
#include "fmc.h"
#include <string.h>
typedef struct __fmc_mem_table {
int64_t allocated_addr;
struct __fmc_mem_table *prev;
struct __fmc_mem_table *next;
} fmc_mem_table_t;
static fmc_mem_table_t *fmc_allocation_table_head;
/**
* fmc_init()
*
* initialize the backend for future debugging
*
**/
void
fmc_init()
{
fmc_allocation_table_head = NULL;
fmc_dbg("allocation table has been initialized");
}
/**
* fmc_deinit()
*
* Deinitialize the backend for future debugging
*
**/
void
fmc_deinit()
{
fmc_mem_table_t *iterator = NULL;
char *hdr_func, *ftr_func;
int32_t hdr_lineno, ftr_lineno;
int32_t posn = 0;
size_t orig_size;
void *ptr;
if (NULL == fmc_allocation_table_head)
return;
fmc_err("===================== ERROR =====================");
fmc_err("allocation table is not empty!!");
fmc_err("Leaked memory addresses are:");
iterator = fmc_allocation_table_head;
while (iterator) {
ptr = (void *)iterator->allocated_addr;
posn = 0;
orig_size = *(size_t *)(ptr + posn); posn += sizeof(size_t);
// extract the header
hdr_lineno = *(int32_t *)(ptr + posn); posn += FMC_LINENUM_SIZE;
hdr_func = (char *)(ptr + posn); posn += FMC_FUNCNAME_SIZE;
posn += FMC_SIGNATURE_SIZE; // add the header signature size
posn += orig_size; // add the original size
posn += FMC_SIGNATURE_SIZE; // add the footer signature size
// extract the header
ftr_func = (char *)(ptr + posn); posn += FMC_FUNCNAME_SIZE;
ftr_lineno = *(int32_t *)(ptr + posn); posn += FMC_LINENUM_SIZE;
fmc_err("%p --> HDR[%s:%ld] - FTR[%s:%d]", ptr,
hdr_func, hdr_lineno, ftr_func, ftr_lineno);
iterator = iterator->next;
}
fmc_err("");
}
/**
* fmc_add_new_elem
*
* allocate a new element to be put in the table
*
**/
static void
fmc_add_new_elem(void *ptr)
{
fmc_mem_table_t *new_elem = (fmc_mem_table_t *)calloc(1, sizeof(fmc_mem_table_t));;
new_elem->allocated_addr = (int64_t)ptr;
if (NULL == fmc_allocation_table_head) {
fmc_allocation_table_head = new_elem;
} else {
new_elem->prev = fmc_allocation_table_head;
fmc_allocation_table_head->next = new_elem;
}
}
/**
* fmc_find_elem
*
* find an element in the table
*
**/
static fmc_mem_table_t*
fmc_find_elem(void *ptr)
{
fmc_mem_table_t *iterator = fmc_allocation_table_head;
while (iterator) {
if (iterator->allocated_addr == (int64_t)ptr) break;
iterator = iterator->next;
}
return iterator;
}
/**
* fmc_del_elem
*
* delete an element from the table
*
**/
static void
fmc_del_elem(void *ptr)
{
fmc_mem_table_t *elem = fmc_find_elem(ptr);
if (elem == fmc_allocation_table_head) fmc_allocation_table_head = NULL;
if (NULL != elem->prev) elem->prev->next = elem->next;
if (NULL != elem->next) elem->next->prev = elem->prev;
free(elem);
}
/**
* fmc_alloc()
*
* allocate memory for the user with additional debug information
*
* fname - file name for this invocation.
* func - name of the function where this was invoked
* line_no - line number of the function where this was invoked
* size - size to be allocated
*
* The final outcome is:
* ---------------------------------------------------------------------------------------------------
* | ORIGINAL SIZE | LINENO | FUNC_NAME | SIGNATURE | <USER MEMORY> | SIGNATURE | FUNC_NAME | LINENO |
* ---------------------------------------------------------------------------------------------------
**/
void*
fmc_alloc(const char *fname, const char *func, int32_t line_no, size_t original_size)
{
size_t new_size = sizeof(size_t) + FMC_HEADER_SIZE + original_size + FMC_FOOTER_SIZE;
char *buf = calloc(new_size, sizeof(char));
int32_t posn = 0;
/*
* Fill up the HEADER with:
* -----------------------------------------------------------------------
* | ORIGINAL SIZE | LINENO | FUNC_NAME | SIGNATURE | user area.....
* -----------------------------------------------------------------------
*/
*((size_t *)(buf + posn)) = original_size; posn += sizeof(size_t);
*((int32_t *)(buf + posn)) = line_no; posn += FMC_LINENUM_SIZE;
snprintf((char*)buf + posn, (size_t)FMC_FUNCNAME_SIZE, "%s", func); posn += FMC_FUNCNAME_SIZE;
snprintf((char*)buf + posn, (size_t)FMC_SIGNATURE_SIZE, "%s", FMC_SIGNATURE); posn += FMC_SIGNATURE_SIZE;
// add up the original size
posn += original_size;
/*
* Fill up the FOOTER with:
* ---------------------------------------------------
* ...user area| SIGNATURE | FUNC_NAME | LINENO |
* ---------------------------------------------------
*/
snprintf((char*)buf + posn, (size_t)FMC_SIGNATURE_SIZE, "%s", FMC_SIGNATURE); posn += FMC_SIGNATURE_SIZE;
snprintf((char*)buf + posn, (size_t)FMC_FUNCNAME_SIZE, "%s", func); posn += FMC_FUNCNAME_SIZE;
*((int32_t *)(buf + posn)) = line_no;
fmc_add_new_elem(buf);
fmc_dbg("allocated memory[%p] for a call from [%s:%d]", buf, func, line_no);
return (buf + sizeof(size_t) + FMC_HEADER_SIZE);
}
/**
* fmc_check_memory
*
* check for memory corruption
**/
static void
fmc_check_memory(void *ptr, const char *fname, const char *func, int32_t line_no)
{
int32_t posn = 0;
size_t orig_size;
char *hdr_sign, *ftr_sign;
char *hdr_func, *ftr_func;
int32_t hdr_lineno, ftr_lineno;
// extract the original size
orig_size = *(size_t *)(ptr + posn); posn += sizeof(size_t);
// extract the header
hdr_lineno = *(int32_t *)(ptr + posn); posn += FMC_LINENUM_SIZE;
hdr_func = (char *)(ptr + posn); posn += FMC_FUNCNAME_SIZE;
hdr_sign = (char *)(ptr + posn); posn += FMC_SIGNATURE_SIZE;
// add the original size
posn += orig_size;
// extract the header
ftr_sign = (char *)(ptr + posn); posn += FMC_SIGNATURE_SIZE;
ftr_func = (char *)(ptr + posn); posn += FMC_FUNCNAME_SIZE;
ftr_lineno = *(int32_t *)(ptr + posn); posn += FMC_LINENUM_SIZE;
// Check SIGNATUREs
if (memcmp((const void*)hdr_sign, FMC_SIGNATURE, FMC_SIGNATURE_SIZE)) {
fmc_err("===================== ERROR =====================");
fmc_err("Underflow error on memory allocated by [%s:%d] & freed at [%s:%d]",
ftr_func, ftr_lineno, func, line_no);
fmc_fatal();
}
if (memcmp((const void*)ftr_sign, FMC_SIGNATURE, FMC_SIGNATURE_SIZE)) {
fmc_err("===================== ERROR =====================");
fmc_err("Overflow error on memory allocated by [%s:%d] & freed at [%s:%d]",
hdr_func, hdr_lineno, func, line_no);
fmc_fatal();
}
// Check the rest
if (memcmp((const void*)hdr_func, (const void*)ftr_func, FMC_FUNCNAME_SIZE)) {
fmc_err("===================== ERROR =====================");
fmc_err("Memory corruption at function name on memory allocated by [%s:%d] & freed at [%s:%d]",
hdr_func, hdr_lineno, func, line_no);
fmc_err("Memory corruption at function name on memory allocated by [%s:%d] & freed at [%s:%d]",
ftr_func, ftr_lineno, func, line_no);
fmc_fatal();
}
if (hdr_lineno != ftr_lineno) {
fmc_err("===================== ERROR =====================");
fmc_err("Memory corruption at line number on memory allocated by [%s:%d] & freed at [%s:%d]",
hdr_func, hdr_lineno, func, line_no);
fmc_err("Memory corruption at line number on memory allocated by [%s:%d] & freed at [%s:%d]",
ftr_func, ftr_lineno, func, line_no);
fmc_fatal();
}
fmc_dbg("All looks well with %p by [%s:%d]", ptr, hdr_func, hdr_lineno);
}
/**
* fmc_free()
*
* frees the memory provided to the user through this framework
*
* fname - file name for this invocation.
* func - name of the function where this was invoked
* line_no - line number of the function where this was invoked
* ptr - pointer to be freed
*
**/
void
fmc_free(const char *fname, const char *func, int32_t line_no, void *ptr)
{
char *our_ptr = (char *)ptr - (FMC_HEADER_SIZE + sizeof(size_t));
fmc_check_memory(our_ptr, fname, func, line_no);
fmc_del_elem(our_ptr);
fmc_dbg("freeing up memory[%p] for a call from [%s:%d]", our_ptr, func, line_no);
}