malloc - Page 3 - Developer IT

is there a flag "M_FAST" in FreeBSD kernel for Malloc Call ?

- by KaluSingh Gabbar

if you know there is one, can you let me know what its for ? if not please say so : ) thanks. Signature : void * malloc(unsigned long size, struct malloc_type type, int flags); for example. other flags are... M_ZERO Causes the allocated memory to be set to all zeros. M_WAITOK Indicates that it is OK to wait for resources. If the request cannot be immediately fulfilled, the current process is put to sleep to wait for resources to be released by other processes. The malloc(), realloc(), and reallocf() functions cannot return NULL if M_WAITOK is specified.** This is the root of my confusion EDIT: The clarification for M_FAST is made in my answer below.

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Memory allocated with malloc does not persist outside function scope?

- by PM

Hi, I'm a bit new to C's malloc function, but from what I know it should store the value in the heap, so you can reference it with a pointer from outside the original scope. I created a test program that is supposed to do this but I keep getting the value 0, after running the program. What am I doing wrong? int f1(int * b) { b = malloc(sizeof(int)); *b = 5; } int main() { int * a; f1(a); printf("%d\n", a); return 0; }

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enabling guard malloc for Iphone device or for store kit api?

- by Nareshkumar

I am using store kit api for an application on iphone. I would like to know if it is possible to enable Malloc Guard while running on the device and see if there are any memory leaks. Could someone let me know if it is possible?

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Why exactly should I not call free() on variables not allocated by malloc()?

- by ultrajohn

I read somewhere that it is disastrous to use free to get rid of an object not created by calling malloc, is this true? why?

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how to find out the page size of a processor using C program and malloc?

- by cforfun

is it possible to find out the page size of a processor using C program and malloc? and not by using sysconf() call?

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How I return the size of the pointer that I have allocate with malloc?

- by drigoSkalWalker

See this example! int main( int argc, char ** argv ) { int *ptr = malloc(100 * sizeof (int)); printf("sizeof(array) is %d bytes\n", sizeof(ptr)); } The printf function return only 4 bytes! What is wrong? Thanks so much!!!

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Strange errors in Visual C++ :: 'malloc' : function does not take 1 arguments

- by pecker

Error 38 error C2660: 'malloc' : function does not take 1 arguments C:\VolumeRenderer\render.cpp 296 1 VolumeRenderer Error 39 error C2660: 'malloc' : function does not take 1 arguments C:\VolumeRenderer\render.cpp 412 1 VolumeRenderer Error 40 error C2660: 'malloc' : function does not take 1 arguments C:\VolumeRenderer\render.cpp 414 1 VolumeRenderer Error 41 error C2660: 'read_den' : function does not take 4 arguments C:\VolumeRenderer\render.cpp 506 1 VolumeRenderer My all malloc sections are like this: /* allocate space for the raw data */ density_size = BRAIN_XLEN * BRAIN_YLEN * BRAIN_ZLEN; density = (unsigned char*)malloc(density_size); if (density == NULL) { fprintf(stderr, "out of memory\n"); exit(1); } regarding read_den (last error) unsigned char *read_den(char *filename,int *xptr,int *yptr,int *zptr)// function prototype src_volume = read_den(src_file, &src_xlen, &src_ylen, &src_zlen);// fucntion call Is it my code or the errors that are absurd. How to rectify them?

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pointer being freed was not allocated. Complex malloc history help

- by Martin KS

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Malloc to a CGPoint Pointer throwing EXC_BAD_ACCESS when accessing

- by kdbdallas

I am trying to use a snippet of code from a Apple programming guide, and I am getting a EXC_BAD_ACCESS when trying to pass a pointer to a function, right after doing a malloc. (For Reference: iPhone Application Programming Guide: Event Handling - Listing 3-6) The code in question is really simple: CFMutableDictionaryRef touchBeginPoints; UITouch *touch; .... CGPoint *point = (CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch); if (point == NULL) { point = (CGPoint *)malloc(sizeof(CGPoint)); CFDictionarySetValue(touchBeginPoints, touch, point); } Now when the program goes into the if statement it assigns the 'output' of malloc into the point variable/pointer. Then when it tries to pass point into the CFDictionarySetValue function it crashes the application with: Program received signal: “EXC_BAD_ACCESS”. Someone suggested not doing the malloc and pass the point var/pointer as: &point, however that still gave me a EXC_BAD_ACCESS. What I am (and it looks like Apple) doing wrong??? Thanks in advance.

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Writing to pointer out of bounds after malloc() not causing error

- by marr

Hi, when I try the code below it works fine. Am I missing something? main() { int *p; p=malloc(sizeof(int)); printf("size of p=%d\n",sizeof(p)); p[500]=999999; printf("p[0]=%d",p[500]); return 0; } I tried it with malloc(0*sizeof(int)) or anything but it works just fine. The program only crashes when I don't use malloc at all. So even if I allocate 0 memory for the array p, it still stores values properly. So why am I even bothering with malloc then?

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incompatible declaration in built in function malloc and incompatible types in assignment error in

- by mekasperasky

char char* c[30]; c = (char*) malloc(30*sizeof(char) ); How does this give an incompatible declaration in built in function warning and and incompatible types in assignment error in the line where i have declared malloc . According to the syntax of malloc , i shouldnt have any error

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malloc in kernel

- by yoavstr

when i try to malloc at kernel mod i get screamed by the compiler : res=(ListNode*)malloc(sizeof(ListNode)); and the compiler is screaming : /root/ex3/ex3mod.c:491: error: implicit declaration of function ‘malloc’ what should i do ?

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Why malloc memory in a function and free it outside is a bad idea?

- by skydoor

if this is a bad idea, how to allocate memory in the function?

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Allocating memory inside a function and returning it back

- by user2651062

I want to pass a pointer to my function and allocate the memory to which this pointer points. I've read in other posts that I should pass a double pointer to this function and I did so, but I keep getting segmentation fault: #include <iostream> #include <stdlib.h> using namespace std; void allocate(unsigned char** t) { *t=(unsigned char*)malloc(3*sizeof(unsigned char)); if(*t == NULL) cout<<"Allcoation failed"<<endl; else for(int m=0;m<3;m++) *(t[m])=0; } int main() { unsigned char* t; allocate(&t); cout<<t[0]<<" "<<t[1]<<endl; return 0; } the result is always this: Segmentation fault (core dumped) I don't think that there's anything missing from this code. What could be wrong?

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Boost::Mutex & Malloc

- by M. Tibbits

Hi all, I'm trying to use a faster memory allocator in C++. I can't use Hoard due to licensing / cost. I was using NEDMalloc in a single threaded setting and got excellent performance, but I'm wondering if I should switch to something else -- as I understand things, NEDMalloc is just a replacement for C-based malloc() & free(), not the C++-based new & delete operators (which I use extensively). The problem is that I now need to be thread-safe, so I'm trying to malloc an object which is reference counted (to prevent excess copying), but which also contains a mutex pointer. That way, if you're about to delete the last copy, you first need to lock the pointer, then free the object, and lastly unlock & free the mutex. However, using malloc to create a boost::mutex appears impossible because I can't initialize the private object as calling the constructor directly ist verboten. So I'm left with this odd situation, where I'm using new to allocate the lock and nedmalloc to allocate everything else. But when I allocate a large amount of memory, I run into allocation errors (which disappear when I switch to malloc instead of nedmalloc ~ but the performance is terrible). My guess is that this is due to fragmentation in the memory and an inability of nedmalloc and new to place nice side by side. There has to be a better solution. What would you suggest?

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p=malloc()!=null.......

- by gcc

char *p,*p1,*p2,*p3,*p4; for(;;) { if((p=malloc(10))!=NULL && (p1=malloc(20))!=NULL ......) break; } Writing if(........) is too boring and long, are there any ways to make it simpler?

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Threads are blocked in malloc and free, virtual size

- by Albert Wang

Hi, I'm running a 64-bit multi-threaded program on the windows server 2003 server (X64), It run into a case that some of the threads seem to be blocked in the malloc or free function forever. The stack trace is like follows: ntdll.dll!NtWaitForSingleObject() + 0xa bytes ntdll.dll!RtlpWaitOnCriticalSection() - 0x1aa bytes ntdll.dll!RtlEnterCriticalSection() + 0xb040 bytes ntdll.dll!RtlpDebugPageHeapAllocate() + 0x2f6 bytes ntdll.dll!RtlDebugAllocateHeap() + 0x40 bytes ntdll.dll!RtlAllocateHeapSlowly() + 0x5e898 bytes ntdll.dll!RtlAllocateHeap() - 0x1711a bytes MyProg.exe!malloc(unsigned __int64 size=0) Line 168 C MyProg.exe!operator new(unsigned __int64 size=1) Line 59 + 0x5 bytes C++ ntdll.dll!NtWaitForSingleObject() ntdll.dll!RtlpWaitOnCriticalSection() ntdll.dll!RtlEnterCriticalSection() ntdll.dll!RtlpDebugPageHeapFree() ntdll.dll!RtlDebugFreeHeap() ntdll.dll!RtlFreeHeapSlowly() ntdll.dll!RtlFreeHeap() MyProg.exe!free(void * pBlock=0x000000007e8e4fe0) C BTW, the param values passed to the new operator is not correct here maybe due to optimization. Also, at the same time, I found in the process Explorer, the virtual size of this program is 10GB, but the private bytes and working set is very small (<2GB). We did have some threads using virtualalloc but in a way that commit the memory in the call, and these threads are not blocked. m_pBuf = VirtualAlloc(NULL, m_size, MEM_COMMIT, PAGE_READWRITE); ...... VirtualFree(m_pBuf, 0, MEM_RELEASE); This looks strange to me, seems a lot of virtual space is reserved but not committed, and malloc/free is blocked by lock. I'm guessing if there's any corruptions in the memory/object, so plan to turn on gflag with pageheap to troubleshoot this. Does anyone has similar experience on this before? Could you share with me so I may get more hints? Thanks a lot!

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Fault address when malloc/free pthread_t across threads

- by scleung

Fault address occurred when i malloc pthread_t to save a newly created thread id and free it in another thread. Codes as follows: typedef struct _TaskInfo { // int dummy_int; pthread_t tid; } TaskInfo; void* dummy_task(void* pArg) { free(pArg); return NULL; } void create_task() { TaskInfo *pInfo; pthread_attr_t attr; // set detached state stuff ... pInfo = (TaskInfo*) malloc(sizeof(TaskInfo)); pthread_create(&pInfo->tid, &attr, dummy_task, pInfo); // destroy pthread attribute stuff ... } int main() { int i; while(i < 10000) { create_task(); ++i; } return 0; } When I uncomment the member dummy_int of TaskInfo it sometimes ran successfully, but sometimes failed. My platform is VMWare + Ubuntu 9.10 + ndk r3 Thanks!

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C release dynamically allocated memory

- by user1152463

I have defined function, which returns multidimensional array. allocation for rows arr = (char **)malloc(size); allocation for columns (in loop) arr[i] = (char *)malloc(v); and returning type is char** Everything works fine, except freeing the memory. If I call free(arr[i]) and/or free(arr) on array returned by function, it crashes. Thanks for help EDIT:: allocating fuction pole = malloc(zaznamov); char ulica[52], t[52], datum[10]; float dan; int i = 0, v; *max = 0; while (!is_eof(f)) { get_record(t, ulica, &dan, datum, f); v = strlen(ulica) - 1; pole[i] = malloc(v); strcpy(pole[i], ulica); pole[i][v] = '\0'; if (v > *max) { *max = v; } i++; } return pole;` part of main where i am calling function pole = function(); releasing memory int i; for (i = 0; i < zaznamov; i++) { free(pole[i]); pole[i] = NULL; } free(pole); pole = NULL;

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c struct pointer issues

- by clear2k

I'm trying to cast a struct into another struct but I'm having incompatible pointer issues within the cast and the malloc under some_func (structs layout are the same) struct stu1 **some_func(struct stu1 *my_struct) { my_struct = (struct stu1 **)malloc(sizeof(struct stu1 *)*total_size); for(i=0;i<20;i++){ my_struct[i] = (struct stu1 *)malloc(sizeof(struct stu1)); printf("%s",my_struct[i++]->a); } } int main() { struct stu1 **my_struct; struct stu2 **my_struct2; struct stu3 **my_struct3; my_struct = some_func(my_struct); my_struct2 = (struct stu2**)some_func((struct stu1*)my_struct2); my_struct3 = (struct stu3**)some_func((struct stu1*)my_struct3); }

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Strcpy and malloc issues

- by mrblippy

Hi, i am having trouble getting a method relating to a linked list working, i get the errors: assignment makes pointer from integer without a cast and passing argument 1 of âstrcpyâ makes pointer from integer without a cast. i have tried to include all the relevant code, but let me know if you need more info. thanks. struct unit { char code[5]; char *name; node_ptr students; }; typedef struct node *node_ptr; struct node { int student_id; char *studentname; node_ptr next; }; void enrol_student(struct unit u[], int n) { int i, p; int student_id = 0; char code_to_enrol[7]; char buffer[100]; node_ptr studentslist; scanf("%s\n", code_to_enrol); for(i=0; i <= n; i++) { studentslist = u[i].students; if(strcmp(u[i].code ,code_to_enrol)<=0) { scanf("enter student details %d %s\n", &studentID, buffer); p = (char *) malloc (strlen(buffer)+1); strcpy(p, buffer); insert_in_order(student_id, buffer, studentslist); } } } void insert_in_order(int n, char *i, node_ptr list) { node_ptr before = list; node_ptr students = (node_ptr) malloc(sizeof(struct node)); students->ID = n; students->name = *i; while(before->next && (before->next->ID < n)) { before = before->next; } students->next = before->next; before->next = students; }

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malloc works, cudaHostAlloc segfaults?

- by Mikhail

I am new to CUDA and I want to use cudaHostAlloc. I was able to isolate my problem to this following code. Using malloc for host allocation works, using cudaHostAlloc results in a segfault, possibly because the area allocated is invalid? When I dump the pointer in both cases it is not null, so cudaHostAlloc returns something... works in_h = (int*) malloc(length*sizeof(int)); //works for (int i = 0;i<length;i++) in_h[i]=2; doesn't work cudaHostAlloc((void**)&in_h,length*sizeof(int),cudaHostAllocDefault); for (int i = 0;i<length;i++) in_h[i]=2; //segfaults Standalone Code #include <stdio.h> void checkDevice() { cudaDeviceProp info; int deviceName; cudaGetDevice(&deviceName); cudaGetDeviceProperties(&info,deviceName); if (!info.deviceOverlap) { printf("Compute device can't use streams and should be discared."); exit(EXIT_FAILURE); } } int main() { checkDevice(); int *in_h; const int length = 10000; cudaHostAlloc((void**)&in_h,length*sizeof(int),cudaHostAllocDefault); printf("segfault comming %d\n",in_h); for (int i = 0;i<length;i++) { in_h[i]=2; } free(in_h); return EXIT_SUCCESS; } ~ Invocation [id129]$ nvcc fun.cu [id129]$ ./a.out segfault comming 327641824 Segmentation fault (core dumped) Details Program is run in interactive mode on a cluster. I was told that an invocation of the program from the compute node pushes it to the cluster. Have not had any trouble with other home made toy cuda codes.

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Why doesn't this work?

- by user146780

I'v tried to solve a memory leak in the GLU callback by creating a global variable but now it dos not draw anything: GLdouble *gluptr = NULL; void CALLBACK combineCallback(GLdouble coords[3], GLdouble *vertex_data[4], GLfloat weight[4], GLdouble **dataOut) { GLdouble *vertex; if(gluptr == NULL) { gluptr = (GLdouble *) malloc(6 * sizeof(GLdouble)); } vertex = (GLdouble*)gluptr; vertex[0] = coords[0]; vertex[1] = coords[1]; vertex[2] = coords[2]; for (int i = 3; i < 6; i++) { vertex[i] = weight[0] * vertex_data[0][i] + weight[1] * vertex_data[0][i] + weight[2] * vertex_data[0][i] + weight[3] * vertex_data[0][i]; } *dataOut = vertex; } basically instead of doing malloc each time in the loop (thus the memory leak) im using a global pointer, but this doesn't work (drawing to the screen). Why would using malloc to a pointer created in the function work any different than a global variable? Thanks

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How to debug macruby?

- by Dan

Hi, I've encountered an inconsistent bug with MacRuby and have no idea how to go about debugging this. If anyone could help would be great. I don't know if this is due to my own code or is it a bug in the MacRuby framework. I have a feeling it's my own code, something about over-retaining a piece of memory and hence the garbage collection failed. This is the error from Xcode. Thanks. CSV Wizard(30245,0x7fff704f7ca0) malloc: resurrection error for object 0x20199da20 while assigning {conservative-block}[196608](0x302360060)[117616] = Array[64](0x20199da20) garbage pointer stored into reachable memory, break on auto_zone_resurrection_error to debug CSV Wizard(30245,0x103781000) malloc: garbage block 0x20199da20(Array[64]) was over-retained during finalization, refcount = 1 This could be an unbalanced CFRetain(), or CFRetain() balanced with -release. Break on auto_zone_resurrection_error() to debug. CSV Wizard(30245,0x103781000) malloc: fatal resurrection error for garbage block 0x20199da20(Array[64]): over-retained during finalization, refcount = 1

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Getting exc_bad_access error only when mallocguard is enabled

- by Nareshkumar

I have an app for iPhone in development which works properly when the Malloc guard is not enabled. However when i try to enable the malloc guard i get the following error after the app is loaded. #0 0x95f65684 in objc_msgSend () #1 0x30506515 in NSPopAutoreleasePool () #2 0x30901697 in _UIApplicationHandleEvent () #3 0x32046375 in PurpleEventCallback () #4 0x30245560 in CFRunLoopRunSpecific () #5 0x30244628 in CFRunLoopRunInMode () #6 0x308f930d in -[UIApplication _run] () #7 0x309021ee in UIApplicationMain () Now my problem is that i am not able to debug the exact location where its getting the error.. have tried malloc_error_break but didnt work out. Is it that malloc guard enabling auto releases some of the objects based on allocation??

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Search found 756 results on 31 pages for 'malloc'.

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- by KaluSingh Gabbar

- by PM

- by Nareshkumar

- by ultrajohn

- by cforfun

- by drigoSkalWalker

- by pecker

- by Martin KS

- by kdbdallas

- by marr

- by mekasperasky

- by yoavstr

- by skydoor

- by user2651062

- by M. Tibbits

- by gcc

- by Albert Wang

- by scleung

- by user1152463

- by clear2k

- by mrblippy

- by Mikhail

- by user146780

- by Dan

- by Nareshkumar

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