LM_FindSegment
Searches for a memory segment that a given address is within and populates the segment_out parameter with the result.
Signature
LM_API lm_bool_t LM_CALL
LM_FindSegment(lm_address_t address,
lm_segment_t *segment_out);
Parameters
The address to search for.
A pointer to an lm_segment_t structure to populate with information about the segment that contains the specified address.
Return Value
Returns LM_TRUE if the specified address is found within a segment, or LM_FALSE otherwise.
Segment Structure
The lm_segment_t structure contains information about a memory segment:
typedef struct lm_segment_t {
lm_address_t base; // Base address of the segment
lm_address_t end; // End address of the segment
lm_size_t size; // Size of the segment in bytes
lm_prot_t prot; // Memory protection flags
} lm_segment_t;
Memory Protection Flags
The prot field can be a combination of the following flags:
LM_PROT_NONE - No protectionLM_PROT_R - Read permissionLM_PROT_W - Write permissionLM_PROT_X - Execute permissionLM_PROT_XR - Execute and read permissionsLM_PROT_XW - Execute and write permissionsLM_PROT_RW - Read and write permissionsLM_PROT_XRW - Execute, read, and write permissions
Example
#include <libmem/libmem.h>
#include <stdio.h>
int main()
{
lm_segment_t segment;
lm_address_t addr = 0x12345678; // Address to search for
if (LM_FindSegment(addr, &segment)) {
printf("Found segment containing address 0x%lx:\n", addr);
printf(" Base: 0x%lx\n", segment.base);
printf(" End: 0x%lx\n", segment.end);
printf(" Size: %zu bytes\n", segment.size);
printf(" Prot: 0x%x\n", segment.prot);
// Check permissions
if (segment.prot & LM_PROT_R) printf(" - Readable\n");
if (segment.prot & LM_PROT_W) printf(" - Writable\n");
if (segment.prot & LM_PROT_X) printf(" - Executable\n");
} else {
printf("Address 0x%lx not found in any segment\n", addr);
}
return 0;
}
Example: Find Segment of a Function
#include <libmem/libmem.h>
#include <stdio.h>
void my_function()
{
printf("Hello from my_function!\n");
}
int main()
{
lm_segment_t segment;
lm_address_t func_addr = (lm_address_t)my_function;
if (LM_FindSegment(func_addr, &segment)) {
printf("Function at 0x%lx is in segment:\n", func_addr);
printf(" Range: 0x%lx - 0x%lx\n", segment.base, segment.end);
printf(" Size: %zu bytes\n", segment.size);
// Verify it's executable
if (segment.prot & LM_PROT_X) {
printf(" Segment is executable (as expected)\n");
}
}
return 0;
}
Example: Validate Memory Access
#include <libmem/libmem.h>
#include <stdio.h>
lm_bool_t can_read_address(lm_address_t addr)
{
lm_segment_t segment;
if (LM_FindSegment(addr, &segment)) {
return (segment.prot & LM_PROT_R) ? LM_TRUE : LM_FALSE;
}
return LM_FALSE;
}
lm_bool_t can_write_address(lm_address_t addr)
{
lm_segment_t segment;
if (LM_FindSegment(addr, &segment)) {
return (segment.prot & LM_PROT_W) ? LM_TRUE : LM_FALSE;
}
return LM_FALSE;
}
int main()
{
lm_address_t addr = 0x400000;
printf("Checking address 0x%lx:\n", addr);
printf(" Can read: %s\n", can_read_address(addr) ? "yes" : "no");
printf(" Can write: %s\n", can_write_address(addr) ? "yes" : "no");
return 0;
}
LM_FindSegmentEx
Searches for a memory segment that a given address is within in a specified process and populates the segment_out parameter with the result.
Signature
LM_API lm_bool_t LM_CALL
LM_FindSegmentEx(const lm_process_t *process,
lm_address_t address,
lm_segment_t *segment_out);
Parameters
process
const lm_process_t *
required
A pointer to a structure containing information about the process whose memory segments will be searched.
The address to search for.
A pointer to an lm_segment_t structure to populate with information about the segment that contains the specified address.
Return Value
Returns LM_TRUE if the specified address is found within a segment, or LM_FALSE otherwise.
Example
#include <libmem/libmem.h>
#include <stdio.h>
int main()
{
lm_process_t process;
lm_module_t module;
lm_segment_t segment;
// Find a process
if (!LM_FindProcess("target.exe", &process)) {
printf("Failed to find process\n");
return 1;
}
// Find a module in the process
if (!LM_FindModuleEx(&process, "game.dll", &module)) {
printf("Failed to find module\n");
return 1;
}
// Find the segment containing the module's base address
if (LM_FindSegmentEx(&process, module.base, &segment)) {
printf("Module '%s' base address 0x%lx is in segment:\n",
module.name, module.base);
printf(" Segment base: 0x%lx\n", segment.base);
printf(" Segment end: 0x%lx\n", segment.end);
printf(" Segment size: %zu bytes\n", segment.size);
printf(" Protection: 0x%x\n", segment.prot);
} else {
printf("Address not found in any segment\n");
}
return 0;
}
Example: Check Remote Address Permissions
#include <libmem/libmem.h>
#include <stdio.h>
lm_bool_t is_address_writable(const lm_process_t *process, lm_address_t addr)
{
lm_segment_t segment;
if (LM_FindSegmentEx(process, addr, &segment)) {
return (segment.prot & LM_PROT_W) ? LM_TRUE : LM_FALSE;
}
return LM_FALSE;
}
int main()
{
lm_process_t process;
lm_address_t target_addr = 0x10000000;
if (LM_FindProcess("game.exe", &process)) {
if (is_address_writable(&process, target_addr)) {
printf("Address 0x%lx is writable in %s\n",
target_addr, process.name);
// Safe to write to this address
} else {
printf("Address 0x%lx is not writable in %s\n",
target_addr, process.name);
}
}
return 0;
}
Example: Find Segment Before Memory Operation
#include <libmem/libmem.h>
#include <stdio.h>
int main()
{
lm_process_t process;
lm_segment_t segment;
lm_address_t addr = 0x400000;
lm_byte_t data[] = {0x90, 0x90, 0x90, 0x90}; // NOP instructions
if (!LM_FindProcess("target.exe", &process)) {
printf("Failed to find process\n");
return 1;
}
// Check if address exists and get its permissions
if (!LM_FindSegmentEx(&process, addr, &segment)) {
printf("Address 0x%lx not found in process memory\n", addr);
return 1;
}
// Verify the segment is writable
if (!(segment.prot & LM_PROT_W)) {
printf("Segment is not writable, changing protection...\n");
lm_prot_t old_prot;
if (!LM_ProtMemoryEx(&process, addr, sizeof(data),
LM_PROT_XRW, &old_prot)) {
printf("Failed to change memory protection\n");
return 1;
}
}
// Now safe to write
lm_size_t written = LM_WriteMemoryEx(&process, addr, data, sizeof(data));
printf("Wrote %zu bytes to 0x%lx\n", written, addr);
return 0;
}
See Also