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malloc_wrapper.c
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malloc_wrapper.c
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#include <unistd.h>
#include <dlfcn.h>
#include <execinfo.h>
#include <stdbool.h>
#include <string.h>
#define MALLOC_FUNCTION_NAME "malloc"
#define MAIN "main"
#define CALLED_BY "Called by: "
#define NEWLINE "\n"
#define LAST_TRACE 1
#define NB_STACKTRACE_REQUESTED 2
#define NB_START_NAMES 2
#ifndef MALLOC_LIMIT
# define MALLOC_LIMIT 1
#endif
#ifndef BIN_NAME
# define BIN_NAME UNKNOW
#endif
static void print_stacktrace(char * const * const calledby)
{
if (calledby != NULL && calledby[LAST_TRACE] != NULL)
{
write(STDERR_FILENO, CALLED_BY, sizeof(CALLED_BY));
write(STDERR_FILENO, calledby[LAST_TRACE], strlen(calledby[LAST_TRACE]));
write(STDERR_FILENO, NEWLINE, sizeof(NEWLINE));
}
}
static bool has_the_program_started(char * const * const calledby)
{
static const char *stacktrace_start_names[NB_START_NAMES] = {BIN_NAME, MAIN};
if (calledby != NULL && calledby[LAST_TRACE] != NULL)
{
for (int i = 0; i < NB_START_NAMES; ++i)
{
if (strstr(calledby[LAST_TRACE], stacktrace_start_names[i]) != NULL)
return true;
}
}
return false;
}
void *malloc(size_t size)
{
static unsigned int counter = 0;
static bool backtrace_function_need_allocation = false;
static bool start_counter = false;
static void *(*real_malloc)(size_t) = NULL;
void *called_functions_address[NB_STACKTRACE_REQUESTED] = {NULL, NULL};
char **calledby;
if (real_malloc == NULL)
real_malloc = dlsym(RTLD_NEXT, MALLOC_FUNCTION_NAME);
if (backtrace_function_need_allocation == true)
return real_malloc(size);
if (backtrace_function_need_allocation == false)
{
backtrace_function_need_allocation = true;
backtrace(called_functions_address, NB_STACKTRACE_REQUESTED);
calledby = backtrace_symbols(called_functions_address, NB_STACKTRACE_REQUESTED);
backtrace_function_need_allocation = false;
if (start_counter == false)
{
if (has_the_program_started(calledby) == true)
start_counter = true;
else
return real_malloc(size);
}
}
++counter;
if (counter <= MALLOC_LIMIT)
return real_malloc(size);
print_stacktrace(calledby);
return NULL;
}