Code: C To List All Processes

This code was written by a friend of mine, IceDane, and posted online in 2005. Though it was released in 2005, it still works to list all running processes on a Windows XP machine. It is untested on Vista at the time of writing.

#include <windows.h>
#include <stdio.h>
#include <tlhelp32.h>

int main(int argc, char **argv)
{
// Handle for the process snap.
HANDLE hProcessSnap;

// A struct containing info on the process snape.
// This is where we get the name and PID of the process
PROCESSENTRY32 peStruct;

// Take a snapshot of all processes running.
hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);

// Let's make sure that the snapshot is valid, and the function didn't fail.
if(hProcessSnap == INVALID_HANDLE_VALUE)
{
printf("\n\nError creating snapshot of processes.\n\n");

return 0;
}

// We need to set the size of the struct before we use it.
peStruct.dwSize = sizeof(PROCESSENTRY32);

// Get info about the first process and make sure it won't F*** up.
if(Process32First(hProcessSnap, &peStruct) == FALSE)
{
printf("\n\nError calling Process32First.\n\n");

CloseHandle(hProcessSnap);

return 0;
}

// Open a file for writing.
FILE *out = fopen("processlisting.txt", "w+");

// Print the 'title'.
fprintf(out, "%17s - PID\n", "Process name");
fprintf(out, "--------------------------------\n");

// Loop through the process list, outputting name and PID of each process to the file each turn.
// We use do-while loop to ensure that the first process also gets printed.
do
{
fprintf(out, "%17s - %d\n", peStruct.szExeFile, peStruct.th32ProcessID);
}
while(Process32Next(hProcessSnap, &peStruct));

// Close file and the handle.
fclose(out);
CloseHandle(hProcessSnap);

printf("\n\nProcess list stored in processlisting.txt\n\n");

return 0;
}

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