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Vdso.C
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Vdso.C
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#include "Vdso.h"
#include "Common.h"
#include "MemoryMappings.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <vector>
#include <unistd.h>
using std::vector;
VdsoBinary::VdsoBinary ()
: outFile(NULL)
{
const MemoryMappings allMappings(getpid());
const MemoryMappings::Mapping* vdsoMemory = allMappings.Find("[vdso]");
if (!vdsoMemory)
{
printf("no vdso found in mappings\n");
return;
}
const unsigned int startAddress = vdsoMemory->start;
const unsigned int endAddress = vdsoMemory->end;
const int size = endAddress - startAddress;
if (size <= 0 || size > 100000)
{
printf("invalid VDSO size %d\n", size);
return;
}
char memPath[] = "/proc/self/mem";
const int memFd = open(memPath, O_RDONLY);
if (!memFd)
{
printf("failed to open %s: %s (%d)\n", memPath, strerror(errno), errno);
return;
}
const off64_t seekResult = lseek64(memFd, startAddress, SEEK_SET);
if (seekResult == -1)
{
printf("seeking to 0x%x in %s failed: %s (%d)\n", startAddress, memPath, strerror(errno), errno);
close(memFd);
return;
}
vector<char> data;
data.resize(size+1);
errno = 0;
const int bytesRead = read(memFd, &(data[0]), size);
if (bytesRead != size)
{
printf("reading from %s failed: read %d bytes, expected %d bytes; error: %s (%d)\n",
memPath, bytesRead, size, strerror(errno), errno);
close(memFd);
return;
}
close(memFd);
static const char pathTemplate[] = "/tmp/extracted-vdso.bin.XXXXXX";
vector<char> tempName;
tempName.resize(sizeof(pathTemplate));
memcpy(&(tempName[0]), pathTemplate, sizeof(pathTemplate));
const int tempFd = mkstemp(&(tempName[0]));
this->outFile = fdopen(tempFd, "w");
if (!this->outFile)
{
printf("opening temp fd %d (for file '%s') failed: %s (%d)\n", tempFd, &(tempName[0]), strerror(errno), errno);
close(tempFd);
return;
}
const int bytesWritten = fwrite(&(data[0]), 1, size, this->outFile);
if (bytesWritten != size)
{
printf("writing to %s failed: wrote %d bytes of %d bytes; error: %s (%d)\n",
&(tempName[0]), bytesWritten, size, strerror(errno), errno);
return;
}
this->path = string(&(tempName[0]));
DEBUG("VDSO path: %s", this->path.c_str());
}
VdsoBinary::~VdsoBinary ()
{
if (this->outFile)
{
fclose(this->outFile);
this->outFile = NULL;
}
if (!this->path.empty())
{
unlink(this->path.c_str());
}
}
string VdsoBinary::Path () const
{
return this->path;
}