/*
   readmem.c
   dumps the virtual memory of a linux process using ptrace+/dev/pid/mem 
   (c) 2007 Y. Guillot
   distributed under the terms of the WtfPLv2
*/

// define this to dump to separate files (gcc -DSEPARATE_DUMP_FILES)
//#define SEPARATE_DUMP_FILES

#ifdef TARGET_64
// for 64bit target (see /proc/cpuinfo addr size virtual)
 #define MEM_MAX (1ULL << 48)
#else
 #define MEM_MAX (1ULL << 32)
#endif

#define _LARGEFILE64_SOURCE
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/ptrace.h>

int main(int argc, char **argv)
{
	if (argc < 2) {
		printf("usage: readmem <pid>\n");
		exit(1);
	}

	char buf[128];
	int pid = atoi(argv[1]);
	snprintf(buf, sizeof(buf), "/proc/%d/mem", pid);
	int fd = open(buf, O_RDONLY);
	if (fd == -1) {
		fprintf(stderr, "open failed: %m\n");
		exit(1);
	}

	int fdo = -1;
#ifndef SEPARATE_DUMP_FILES
	snprintf(buf, sizeof(buf), "memdump_%d", pid);
	fdo = open(buf, O_WRONLY | O_CREAT, 0644);
	if (fdo == -1) {
		fprintf(stderr, "open2 failed: %m\n");
		close(fd);
		exit(1);
	}
#endif
	
	long ptret = ptrace(PTRACE_ATTACH, pid, 0, 0);
	if (ptret == -1) {
		fprintf(stderr, "ptrace failed: %s\n", strerror(errno));
		close(fdo);
		close(fd);
		exit(1);
	}

	unsigned char page[4096];
	unsigned long long offset = 0;
#ifdef SEPARATE_DUMP_FILES
	unsigned long long  lastoff = -1;
#endif
	
	while (offset < MEM_MAX) {
		lseek64(fd, offset, SEEK_SET);
		
		ssize_t ret;
		ret = read(fd, page, sizeof(page));

		if (ret >= 0)
			fprintf(stderr, "got page at %llx\n", offset);
		else if (!(offset & 0xfffffff))
			fprintf(stderr, "fail %llx\r", offset);
		
		if (ret > 0) {
#ifdef SEPARATE_DUMP_FILES
			if (offset != lastoff + sizeof(page)) {
				if (fdo != -1)
					close(fdo);
				snprintf(buf, sizeof(buf), "memdump_%d_%08llx", pid, offset);
				fdo = open(buf, O_WRONLY | O_CREAT, 0644);
				if (fdo == -1) {
					fprintf(stderr, "open failed: %m\n");
					ptrace(PTRACE_DETACH, pid, 0, 0);
					close(fd);
					exit(1);
				}
			}
			lastoff = offset;
#endif
			write(fdo, page, sizeof(page));
		}
		
		offset += sizeof(page);
	}

	ptrace(PTRACE_DETACH, pid, 0, 0);
	close(fdo);
	close(fd);
	return 0;
}