Programming :: Subsequent Calls To Realloc Cause Memory Dump?
Feb 17, 2010
I'm trying to write a C program that extends an array to any user inputed size.
Code:
if (arraysize == 0) {
arraysize = (int) pos + 1;
a = (int *) calloc (arraysize,sizeof(int));
for (i = 0 ; i < arraysize ; i++ )
a[i] = -1;
code....
The program dumps with that sequence of inputs everytime, but might dump an input before or after if different positions are requested. Interestingly, when I tested pos = 2000..2008, I got no dumps. So is realloc somehow trying to extend the array into bad space?
I have a string problem with a function I am writing and I cant figure it out. I am trying to write unit test which will verify it works as expected. As I need to make use of it elsewhere and obviously robust and correct enough that I can rely on it. Okay first of all I define the following structure
I am trying to port some "C" code from Solaris to Linux. I have a Dell PowerEdge R610 with an Intel Xeon E5504 quad core processor running Red Hat Linux Enterprise 5.3. I am compiling in 64 bit mode. I have managed to get the code compiled and linked, but when I attempt to execute it, I get a core dump in one of the C library calls (like strcpy or printf.)
I have a static library that contains our own code that makes the call to the C library. If I move the library method into the source file with the main method and rename it to be certain that I am executing my method instead of the method in our library, the call succeeds. Eventually another static library call is made that results in a core dump in the shared object. I compile my library code into a static library with gcc as:
I wrote a test program for learning usage of realloc() and I thin I did everything right but I get this error exactly with my 4th time that while tries to reallocate memory in MakeDSt function for DSt->SArray:
In one of our core dump we have the followings in the core back trace:
#0 0xb77bf947 in raise () from /lib/tls/libc.so.6 #1 0xb77c10c9 in abort () from /lib/tls/libc.so.6 #2 0xb77f56ba in __fsetlocking () from /lib/tls/libc.so.6 #3 0xb77fcf7f in mallopt () from /lib/tls/libc.so.6 #4 0xb77fd022 in free () from /lib/tls/libc.so.6
It occurred in a memory block free operation. From our analysis, there seems no issue relate the the memory block it self. The memory pointer pointed to the right memory block to be freed and the contents of the memory seems right (not corrupted), in one world, there is nothing obviously wrong. Does any one have any ideas what could be wrong when seeing about?
What is the real difference between system calls and normal function calls. Ultimately function calls too would be passed to kernel for some or the other work.
I have used Dump Command to dump the application files. For Full backup the level 0 is working fine. For incremental backup I used the level 1 or 2 it is getting the error as
DUMP: Only level 0 dumps are allowed on a subdirectory DUMP: The ENTIRE dump is aborted.
The code I used =============================== #!/bin/bash #Full Day Backup Script #application folders backup #test is the username now=$(date +"%d-%m-%Y") [Code]...
I want to generate core dump files from my program when it crashes. Its a pretty big process and has about 10-11 threads in it.I have followed the documentation to enable core dump by setting ulimit to unlimited etc. I quickly tried "A demo program creating a core dump" from the following webpage, which succeeds in Segfault and dumping a core file in the directory that I configured.However, I tried running my original program and caused it to crash. I did this by making calls to kill(), raise() or the same null pointer access as shown in the webpage above. In each case, my program crashed but did not generate a core dump file. Am I missing something?My program is in C++ and my environment is Redhat 9.0 (kernel 2.4.20)
Going through the "Why do I NOT get a core dump?" section on the same webpage as above, I can see two potential problems. One - there are issues with the suid/sgid (bullet # 6). I am not able to change any settings with suid because my system does not contain either /proc/sys/fs/suid_dumpable or /proc/sys/kernel/suid_dumpableTwo, my program has threads in it and the bullet # 8 is the problem.
is there a way to get GDB to dump memory map so I can see if certain parts of the memory is executable or not (i.e : if heap/stack is executable). Do you know of a way to do this within GDB session? Just didn't use gdb, and did instead: cat /proc/$PID/maps
Somehow zypper is running at 100% cpu and won't die with command line kill, the system monitor kill, terminate or anything. I set it's priority to the lowest it will go, tried to stop it then kill it, nothing works as it simply is not responding to anything and it has been running now for 47 hours.
Is there a way to simply dump a process out of memory without requiring it to respond to a signal? because signals are doing nothing.
I have got a script with an outer and inner loop. The inner loop issues loads of echo's which need to be redirected to a log file determined by the outer loop. The obvious solution is to redirect every echo to >$LOG and set LOG in the outer loop.
Code:
for f in $FILES ; do LOG=<logfile> for l in $LINES ; do
[code]....
it is possible to map stdout to $LOG in the outer loop without having to redirect every subsequent individual command output?
I am new to C and linux. My code below does arbitary writes but I cant figure out where or how it does it.
I am calling the insertNode() function with seq = 'MISSISSPPI$' and alphabets = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ$'
Code:
Weird behaviour I should mention is that when I check for NULL pointer in node->child[index], the unassigned values are not null anymore, they point to arbitary memory.
I have a process which runs for a while and then due to some unknown reason ends abruptly without giving a core. I tried looking in the logs and after watching for a pattern am still not 100% sure of the reason. So I was wondering if there is a way to catch the signal which ends the process and print some values in the handler function. I have called the handler for SIGTERM and SIGABRT functions but none of these are getting triggered. I looked online and did not find any other option. Can you please suggest if tehre is any other signal that can be caught for this unknown abrupt termination.
I am developing an application whose executable is generated inside a certain folder hierarchy (say: /DevPath/MyProject/bin). My source code is located in a different branch of this hierarchy (say: /DevPath/MyProject/src). When my app crashes, its core files are stored in /DevPath/MyProject. I'm developing the app on a pc, but running it on a separate platform in which i can only execute it. Folder hierarchy is the same as above on both computers. Usually, when a new executable version is ready, we update both the executable and the source code on the target platform, transferring all the new /DevPath/MyProject folder on it. But sometimes it can really be a bother, so we update only the executable.
1)In the case we only update the executable, keeping an old source code version, and the app generates a core file, can i trust the backtrace produced by gdb in this case? I.e., does gdb need the latest source code files or it just needs the debugging information?
2) (More radical question ) Do i really need to keep the source code on the target platform for core dump analysis or i just need the executable?
To analyse a coredump, I need to specify program name/path in GDB/KDevelop. Since the program name along with arguments is also within a core dump, I wonder if it doesn't keep the proper path of program that crashed and so asks for it?
I have a problem in making multiple calls using PJSIP. I registered different accounts that implements IAccount and added that in the CallManager. When i try to make the calls from the same CallManager, I could able to make the first call. When second call is made the first call got cut and it is alerting and the same for the thrid call..Could anyone help me in this regard.
Note: Calls has to be made from different numbers to different destinations. Is it possible to make multiple outbound calls simultaneously from the same instance of CallManager?
Is that possible that SHM shared memory is counted as cache memory on Linux with kernel 2.6.18?If find it really odd since this memory is not file backed, but I have a piece of code that loads data using shm_open+mmap, and it generates an amount of cache memory in /proc/meminfo that corresponds exactly to the amount of shared memory (I load that data from a file but I am using posix_fadvise(fd,0,0,POSIX_FADV_DONTNEED) to ensure this file is not cached and I made sure that it is working as expected). As far as I know SHM memory was not tagged as cache memory with kernel 2.6.9.If it is the case it is really unfortunate since normally cache memory can be considered to be part of the "available" memory since it can be flushed promptly but this is clearly not the case with SHM memory... Is there an easy way to get the total amount of used SHM memory on a system?
We recently ported an application over from IRIX to Linux, specifically SUSE Enterprise 11 and gcc (glibc 2.9). On IRIX there was a library trace utility call 'par' that allowed me to execute a C program and trace all the library calls it made, tracking how much time was spent in each call. I have been trying to find something similar for SUSE. I have found the ?trace programs (strace, ltrace, and ktrace) none of which is default installed on SUSE 11.Does any one have a suggestion on which ?trace to install and use or is there something else out there better?
I know there is a way to call winapi in runtime in windows. I want to ask how can I call a system call in gcc in runtime (when I don't know what it can be)? I don't mean syscall that I think is for calling only system calls and not library functions.
Is there a way to hook calls to new/malloc, delete/free in C++? I tried the following methods: LD_PRELOAD -> fails for malloc, because dlsym seems to depend on malloc -Wl,--wrap,malloc -> doesn't work for 'new' gcc hooks -> doesn't work always, e.g. for uclibc there are no hooks Are there any other methods I could try?
I'm trying to produce a alphabetic, non-repetitive list of all System service calls in all c files located in a folder. Here's what I got so far. grep -ow '[A-Za-z]*SYS[$][A-Za-z]*' *.c | sort Which produces all system service calls in alphabetic order I just need to find out how to make it non-repetitive.
How does a C program start in linux? Is main() the first function called in the a c application by kernel. I understand it is the first called function written by the application programmer, but the question is to understand the what all kernel does and what all functions it calls before calling main()
