I've been trying to change the active partition of an LTO8 tape in Windows (7 & Server 2012 R2) using the following code snippet (which gcc compiles without any warnings):
DWORD partition= 2;
if(SetTapePosition(hTape, TAPE_LOGICAL_BLOCK, partition, 0, 0, FALSE) != NO_ERROR)
<irrelevant error code here>
which returns without any errors. But it doesn't change the partition. I can use the same function and handle to seek to various blocks within the first (default) partition, so I don't think that's the problem.
The tape is definitely partitioned, and I have no problem changing to the second partition under linux using the mt command.
Turns out the issue is with Quantum's device driver; if I force load HP's device driver, I can change the active partition without any issue.
Related
I'm writing a windows (MS) application to get the name of the process of the active window.
On a desktop PC running 32-bit Windows XP Professional the application runs as expected. But on a laptop machine with a 64-bit Windows 7 Professional OS the does not work as expected. For certain processes an invalid handle is returned. I get the same results on an ultrabook running Windows 8.1 64-bit.
The relevant code snippet is as follows:
DWORD dwThreadID, dwProcessID;
GUITHREADINFO gti;
HANDLE hProcess;
char szProcessFileName[MAX_PATH] = {0};
gti.cbSize = sizeof(GUITHREADINFO);
GetGUIThreadInfo(0, >i);
dwThreadID = GetWindowThreadProcessId(gti.hwndActive, &dwProcessID);
hProcess = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, FALSE, dwProcessID);
// Get the name of the process (no error checking for brevity)
GetModuleFileNameEx(hProcess, NULL, szProcessFileName, MAX_PATH);
When the application runs in the non-Windows XP OSes, as stated above, for certain processes OpenProcess and GetModuleFileNameEx fail. GetModuleFileNameEx typically fails with ERROR_PARTIAL_COPY (error code: 299) or ERROR_INVALID_PARAMETER (error code: 87) whereas OpenProcess fails with ERROR_INVALID_HANDLE (error code: 6)
Not sure what's going on. Any help is greatly appreciated. I wonder if it has to do with user permissions.
The source code is compiled as a 32-bit application on a 64-bit machine running Windows 7 Pro x64.
It's a bit of a long read but try... this for starters.
If you are running on XP or above, the recommended workaround to get at the 64-bit process image path from a 32-bit process, is to use the newer GetProcessImageFileName which gets the path (via ProcessImageFileName (27) process information class of NtQueryInformationProcess). The wow64 layer does not do much this time because it is just a unicode string. However this function has a downside – the path returned is of the form /Device/HarddiskVolumeX instead of DOS style drive letter based paths.
Note how the one error was trying to tell you that only 32-bits of a 64-bit address was copied into your pointer. The article describes it better than I can.
my program get events from remote systems, every event contains an timestamp.
I want to log this events to syslog using the event timestamp instead of systemtime.
Is there any way to send a custom header to syslog deamon ?
I'm using rsyslog on debian
EDIT:
The "events" are generated by some "bare-metal" devices.
My application is a gateway between a realtime-ethernet (EthernetPOWERLINK) and a normal network.
I want to save them in micro-second precision, because its important to know in wich sequence they are occoured.
So i need the exact timestamp created by the bare-metal devices.
I'like to put this events into syslog.
I did not found any lib (except syslog.h) to write into syslog).
I really need to build the packages myself and send them to rsyslog deamon ?
No, don't open that can of worms.
If you allow the sender to specify the timestamp, you allow an attacker to spoof the timestamps of events they wish to hide. That kind of defeats the entire purpose (security-wise) of using a separate machine for logging.
What you can do, however, is compare the current time and the timestamp, and include that at the start of every logged message, using something like
struct timespec now;
struct timespec timestamp;
double delta;
int priority = facility | level;
const char *const message;
delta = difftime(timestamp.tv_sec, now.tv_sec)
+ ((double)timestamp.tv_nsec - now.tv_nsec) / 1000000000.0;
syslog(priority, "[%+.0fs] %s\n", delta, message);
On a typically configured Linux machine, that should produce something similar to
Jan 18 08:01:02 hostname service: [-1s] Original message
assuming the message took at least half a second to arrive. If hostname has its clock running fast, the delta would be positive. Normally, the delta is zero. In the case of a very slow network, the delta is negative, since the original event happened in the past relative to the timestamp shown.
If you already have infrastructure in place to monitor the logged messages, you can have a daemon or a cron script read the log files, and generate new log files (not via syslog(), but simply with string and file operations) with the timestamps adjusted by the specified delta. However, that must be done with extreme care, recognizing unacceptable or unexpectedly changing deltas, or maybe flagging them somehow.
If you write your log file monitoring/display widgets, then you can very easily let the user switch between "actual" (syslog) or "derived" (syslog + delta) timestamps, as the delta is trivial to extract from the logged lines if always present; even then, you must be careful to let the user know if a delta is out of bounds or changes unexpectedly, as such a change is most always informative to the user. (If it is not nefarious, it does mean there is something iffy with the machine timekeeping; time should not just jump around. Even NTP adjustments should be quite smooth.)
If you insist on opening that can of worms, just produce your own log files. Many applications do. It's not like syslog() was a magic bullet or a strict requirement for reliable logging, after all.
If your log-receiving application runs as a specific user and group, you can create /var/log/yourlogs/ owned by root user and that group, and save your log files there. Set the directory mode to 02770 (drwxrws--- or u=rwx,g=rwxs,o=), and all files created in that directory will automatically be owned by the same group (that's what the setgid bit, s, does for directories). You just need to make sure your service sets umask to 002 (and uses 0666 or 0660 mode flags when creating log files), so that they stay group-readable and group-writable.
Log rotation (archiving and/or deleting old log files, mailing logs) is usually a separate service, provided by the logrotate package, and configured by dropping a service-specific configuration file in /etc/logrotate.d/ at installation time. In other words, even if you write your own log files, do not rotate them; use the existing service for this. It makes life much easier for your users, us system administrators. (Note: Setting umask 002 at the start of the log rotate scripts is very useful in the above directory case; created files will then be group-writable. umask 022 will make them group-read-only.)
Ok've solved this, by enabling networking support (TCP) and micro seconds timer in rsyslog configuration.
Accroding to RFC 5424 my application build raw syslog messages and sends them via TCP (port 514) to the deamon.
Thanks to Nominal Animal, but i've no choice...
You can write a raw log message to the /dev/log file. This is a Unix domain socket from where the syslog server reads the messages, as they are written with the syslog() function.
I'm not sure about portability since the message format written by syslog() does not seem to follow the RFC 5424. I can only share my findings with busybox and its syslogd and nc utilities.
syslog() function writes messages as datagrams in the form <PRI>Mon DD HH:MM:SS message, where PRI is a priority, i.e. a decimal number computed as facility | severity, followed by a timestamp and a message.
With nc -u local:/dev/log, you can write UDP datagrams to the domain socket directly. For example, writing <84>Apr 3 07:27:20 hello world results in a Apr 3 07:27:20 hostname authpriv.warn hello world line in /var/log/messages.
Then you are free to extend the timestamp with the microseconds precision. Anyway, you need to make sure your syslog server implementation accepts such form. In case of busybox, I had to modify the source code.
Note: Busybox needs to be configured with enabled CONFIG_NC_EXTRA, CONFIG_NC_110_COMPAT and CONFIG_FEATURE_UNIX_LOCAL options to allow for opening /dev/log with nc.
I am using OpenSearchServer v1.2.4 rc3.
In the first few days it's working fine.
But when its Index size reached 1.0GB I got this error
"Error (java.lang.NullPointerException)"
when I start my crawler. The crawler works fine for some time and then stops with this error
"Error (java.lang.NullPointerException)".
What's wrong?
Depending of the size of your index, a memory parameter must be added. By default, OpenSearchServer is setup to run on small server with the default RAM value provided by the Java Virtual Machine (from 64MB to 512MB only).
For large indexes, you must set up a higher value. On a Unix/Linux server, just create an /etc/opensearchserver file with the following content:
CATALINA_OPTS="-Xms2G -Xmx2G -server"
export CATALINA_OPTS
On a Windows server, edit the start.bat files. Add the following line just after :okExec
set CATALINA_OPTS="-Xms2G -Xmx2G -server"
Replace 2G (which mean 2 GB) by the size of the memory you want to allocate to OpenSearchServer.
In a 32 bits version, the memory is limited to 2.5GB. You can use more memory with a 64 bits operating system using the following lines (on Unix/Linux):
CATALINA_OPTS="-Xms12G -Xmx12G -d64 -server"
for Window 64bits:
set CATALINA_OPTS="-Xms12G -Xmx12G -d64 -server"
After restarting OpenSearchServer, just check in the Runtime tab panel that you have the correct size of memory available.
Regarding the error details, it is more useful to have the full stack trace. You can find it in the log file (data/logs/oss.log), or in the Runtime/Logs tab panel.
Which one is better in following aspects to get OS name, OS version in windows -
time in getting information
compatibility in all windows OS like xp, vista and higher
systeminfo or wmic command? I wanted to avoid the use of OSVersionInfoEx in C as one has to hardcode the marketing name detection and will add to maintenance work if new flavour of windows gets introduced. Please share your opinion.
GetVersionEx - You can't get any faster than this for getting a basic os version number. But you are right, you won't be able to map newer versions of the OS to the correct string. Have you considered just doing this:
OSVERSIONINFOEX version = {};
char szOS[MAX_OS_LENGTH];
version.dwOSVersionInfoSize = sizeof(version);
GetVersionEx((OSVERSIONINFO*)&version);
if (MyFunctionToMapVersionToString(&version, szOS) == false)
{
sprintf(szOS, "Microsoft Windows %d.%d", version.dwMajorVersion, version.dwMinorVersion);
}
WMI - A bit more code to write. But you could likely just do this at app startup (or when it's needed) and cache the result if the information is needed again. It's not like the operating system product name will change after the app has queried for it once. :) As to backwards compatibility, I'm sure it work fine on older operating systems... but you are going to test it before shipping it to the customer, right?
If you want an undocumented way, there is a registry key that has exactly what you want in it:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion ("ProductName")
I would like to know which entry under /dev a file is in. For example, if /dev/sdc1 is mounted under /media/disk, and I ask for /media/disk/foo.txt, I would like to get /dev/sdc as response.
Using stat system call on that file I will get its partition major and minor numbers (8 and 33, for sdc1). Now I need to get the "root" device (sdc) or its major/minor from that. Is there any syscall or library function I could use to link a partition to its main device? Or even better, to get that device directly from the file?
brw-rw---- 1 root floppy 8, 32 2011-04-01 20:00 /dev/sdc
brw-rw---- 1 root floppy 8, 33 2011-04-01 20:00 /dev/sdc1
Thanks in advance!
The quick and dirty version: df $file | awk 'NR == 2 {print $1}'.
Programmatically... well, there's a reason I started with the quick and dirty version. There's no portable way to programmatically get the list of mounted filesystems. (getmntent() gets fstab entries, which is not the same thing.) Moreover, you can't even parse the output of mount(8) reliably; on different Unixes, the mountpoint may be the first or the last item. The most portable way to do this ends up being... parsing df output (And even that is iffy, as you noticed with the partition number.). So you're right back to the quick and dirty shell solution anyway, unless you want to traverse /dev and look for block devices with matching major(st_rdev) (major() being from sys/types.h).
If you restrict this to Linux, you can use /proc/mounts to get the list of mounted filesystems. Other specific Unixes can similarly be optimized: for example, on OS X and I think FreeBSD, you can use sysctl() on the vfs tree to get mountpoints. At worst you can find and use the appropriate header file to decipher whatever the mount table file is (and yes, even that varies: on Solaris it's /etc/mnttab, on many other systems it's /etc/mtab, some systems put it in /var/run instead of /etc, and on many Linuxes it's either nonexistent or a symlink to /proc/mounts). And its format is different on pretty much every Unix-like OS.
The information you want exists in sysfs which exposes the linux device tree. This models the relationships between the devices on the system and since you are trying to determine a parent disk device from a partition, this is the place to look. I don't know if there are any hard and fast rules you can rely on to stop your code breaking with future versions of the kernel, but the kernel developers do try to maintain sysfs as a stable interface.
If you look at /sys/dev/block/<major>:<minor>, you'll see it is a symlink with the tail components being block/<disk-device-name>/<partition-device-name>. If you were to perform a readlink(2) system call on that, you could parse the link destination to get the disk device name. In shell (since it's easier to express this way, but doing it in C will be pretty easy):
$ echo $(basename $(dirname $(readlink /sys/dev/block/8:33)))
sdc
Alternatively, you could take advantage of the nesting of partition directories in the disk directories (again in shell, but from C, its an open(2), read(2), and close(2)):
$ cat /sys/dev/block/8:33/../dev
8:32
That assumes your starting major:minor is actually for a partition, not some other sort of non-nested device.
What you looking for is impossible - there is no 1:1 connection between a block device file and the partition it is describing.
Consider:
You can create multiple block device files with different names (but the same major and minor numbers) and they are indistinguishable (N:1)
You can use a block device file as an argument to mount to mount a partition and then delete the block device file leaving the partition mounted. (0:1)
So there is no way to do what you want except in a few specific and narrow cases.
Major number will tell you which device it is: 3 - IDE on 1st controller, 22 - IDE on 2nd controller and 8 for SCSI.
Minor number will tell you partition number and - for IDE devices - if it's primary or secondary drive. This calculation is different for IDE and SCSI.
For IDE it is: x*64 + p, x is drive number on the controller (0 or 1) and p is partition
For SCSI it is: y*16 + p, where y is drive number and p is partition
Not a syscall, but:
df -h /path/to/my/file
From https://unix.stackexchange.com/questions/128471/determine-what-device-a-directory-is-located-on
So you could look at df's source code and see what it does.
I realize this post is old, but this question was the 2nd result in my search and no one has mentioned df -h