Final code at end of debugging:
bool testFileCopyWithSharedMem(const string &srcFileName, const string &destFileName)
{
bool isCopyOk = false;
string diffCmd = "diff " + srcFileName + " " + destFileName;
int retval = system(diffCmd.c_str());
cout << "system(" << diffCmd << ") returned: " << retval << endl;
if( retval == 0 )
{
isCopyOk = true;
}
return isCopyOk;
}
int doFileCopyWithSharedMem(const string &srcFileName, const string &destFileName, size_t sharedMemSize)
{
//int retval = 0;
//Map SourceFile
errno = 0;
int srcfd = open(srcFileName.c_str(), O_RDONLY);
if (srcfd < 0) {
const char * causeOfError = strerror(errno);
cout << "open() returned:" << causeOfError << " at:" << __LINE__ << " in:" <<__FUNCTION__ << endl;
cout << "open(" << srcFileName << ") returned: " << srcfd << endl;
return -1;
}
struct stat sb;
fstat(srcfd,&sb);
long pageSize;
//pageSize = sb.st_size;
pageSize = sysconf(_SC_PAGESIZE);
errno = 0;
char *srcFilePtr = 0;
srcFilePtr = (char *) mmap(0, pageSize, PROT_READ, MAP_SHARED, srcfd, 0);
if (srcFilePtr == MAP_FAILED)
{
const char * causeOfError = strerror(errno);
cout << "mmap() returned:" << causeOfError << " at:" << __LINE__ << " in:" <<__FUNCTION__ << endl;
return -1;
}
//Map Dest File
errno = 0;
int destfd = open(destFileName.c_str(), O_RDWR|O_CREAT|O_TRUNC, 0600 );
if (destfd < 0) {
const char * causeOfError = strerror(errno);
cout << "creat() returned:" << causeOfError << " at:" << __LINE__ << " in:" <<__FUNCTION__ << endl;
cout << "creat(" << destFileName << ") returned: " << destfd << endl;
return -1;
}
errno = 0;
char *destFilePtr = 0;
destFilePtr = (char *) mmap(0, pageSize, PROT_WRITE|PROT_READ, MAP_SHARED, destfd, 0);
if (destFilePtr == MAP_FAILED) {
const char * causeOfError = strerror(errno);
cout << "mmap() returned:" << causeOfError << " at:" << __LINE__ << " in:" <<__FUNCTION__ << endl;
return -1;
}
ftruncate(destfd, sb.st_size);
cout<< "PID:" << getpid() <
//cout << srcFilePtr << destFilePtr <
system("cat /proc/self/maps");
memcpy(destFilePtr, srcFilePtr, sb.st_size);
//msync(destFilePtr, pageSize,MS_SYNC);
munmap(srcFilePtr, pageSize);
munmap(destFilePtr, pageSize);
close(srcfd);
close(destfd);
return 0;
}
---------------------------------------------------------------------------- Time required: Debugging 1 AM to 5:40 AM. 20 Minutes to note down these points in the blog. 2 hrs to massage it into shape.
Interesting Links:
DevShed : development tutorials: http://www.devshed.com/ Gentoo Bug Reporting Guide: http://www.gentoo.org/doc/en/bugzilla-howto.xml C sample source on Gnu/Linux : http://www.c.happycodings.com/Gnu-Linux/index.html Mmap() security bug with Null Pointers: http://blog.ksplice.com/2010/03/null-pointers-part-i/ Wiki on Chromium multi-process debugging with gdb: http://code.google.com/p/chromium/wiki/LinuxDebugging BugReport: http://www.mail-archive.com/ubuntu-bugs@lists.ubuntu.com/msg2333427.html
mmap is not the territory Part 1 : http://techtalkies.blogspot.com/2010/09/mmap-is-not-territory-or-mapfail-sigbus.html
bool testFileCopyWithSharedMem(const string &srcFileName, const string &destFileName)
{
bool isCopyOk = false;
string diffCmd = "diff " + srcFileName + " " + destFileName;
int retval = system(diffCmd.c_str());
cout << "system(" << diffCmd << ") returned: " << retval << endl;
if( retval == 0 )
{
isCopyOk = true;
}
return isCopyOk;
}
int doFileCopyWithSharedMem(const string &srcFileName, const string &destFileName, size_t sharedMemSize)
{
//int retval = 0;
//Map SourceFile
errno = 0;
int srcfd = open(srcFileName.c_str(), O_RDONLY);
if (srcfd < 0) {
const char * causeOfError = strerror(errno);
cout << "open() returned:" << causeOfError << " at:" << __LINE__ << " in:" <<__FUNCTION__ << endl;
cout << "open(" << srcFileName << ") returned: " << srcfd << endl;
return -1;
}
struct stat sb;
fstat(srcfd,&sb);
long pageSize;
//pageSize = sb.st_size;
pageSize = sysconf(_SC_PAGESIZE);
errno = 0;
char *srcFilePtr = 0;
srcFilePtr = (char *) mmap(0, pageSize, PROT_READ, MAP_SHARED, srcfd, 0);
if (srcFilePtr == MAP_FAILED)
{
const char * causeOfError = strerror(errno);
cout << "mmap() returned:" << causeOfError << " at:" << __LINE__ << " in:" <<__FUNCTION__ << endl;
return -1;
}
//Map Dest File
errno = 0;
int destfd = open(destFileName.c_str(), O_RDWR|O_CREAT|O_TRUNC, 0600 );
if (destfd < 0) {
const char * causeOfError = strerror(errno);
cout << "creat() returned:" << causeOfError << " at:" << __LINE__ << " in:" <<__FUNCTION__ << endl;
cout << "creat(" << destFileName << ") returned: " << destfd << endl;
return -1;
}
errno = 0;
char *destFilePtr = 0;
destFilePtr = (char *) mmap(0, pageSize, PROT_WRITE|PROT_READ, MAP_SHARED, destfd, 0);
if (destFilePtr == MAP_FAILED) {
const char * causeOfError = strerror(errno);
cout << "mmap() returned:" << causeOfError << " at:" << __LINE__ << " in:" <<__FUNCTION__ << endl;
return -1;
}
ftruncate(destfd, sb.st_size);
cout<< "PID:" << getpid() <
//cout << srcFilePtr << destFilePtr <
system("cat /proc/self/maps");
memcpy(destFilePtr, srcFilePtr, sb.st_size);
//msync(destFilePtr, pageSize,MS_SYNC);
munmap(srcFilePtr, pageSize);
munmap(destFilePtr, pageSize);
close(srcfd);
close(destfd);
return 0;
}
---------------------------------------------------------------------------- Time required: Debugging 1 AM to 5:40 AM. 20 Minutes to note down these points in the blog. 2 hrs to massage it into shape.
Interesting Links:
DevShed : development tutorials: http://www.devshed.com/ Gentoo Bug Reporting Guide: http://www.gentoo.org/doc/en/bugzilla-howto.xml C sample source on Gnu/Linux : http://www.c.happycodings.com/Gnu-Linux/index.html Mmap() security bug with Null Pointers: http://blog.ksplice.com/2010/03/null-pointers-part-i/ Wiki on Chromium multi-process debugging with gdb: http://code.google.com/p/chromium/wiki/LinuxDebugging BugReport: http://www.mail-archive.com/ubuntu-bugs@lists.ubuntu.com/msg2333427.html
mmap is not the territory Part 1 : http://techtalkies.blogspot.com/2010/09/mmap-is-not-territory-or-mapfail-sigbus.html
