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seg fault with a linked list in another linked list

4 New Member
hi there
i have a linked list content another linked list. which is something like:
Expand|Select|Wrap|Line Numbers
  1. struct nodebranch{
  2.     unsigned int offset;
  3.     unsigned char data[130];
  4.     struct nodebranch *next;
  5. };
  6.  
  7. struct node{
  8.     unsigned int id;
  9.     struct nodebranch *branch;
  10.     struct node *next;
  11. };
  12.  
what i need to do is, search the list, find the node with same id, and insert the packet into the branch of that id with sorted order.

so i have a function called insertToList(st ruct node **msgBuffer, L2_IDU l2idu)
and a function insertToBranch( struct nodebranch **bufferNode, L2_IDU l2idu)

the insertToBranch will be called in insertToList. insertToList basiclly check if the id match node, if yes, call insertToBranch( ), not, add node and call insertToBranch( )

here is how i call insertToBranch( ) from inserToList()
Expand|Select|Wrap|Line Numbers
  1. /*case 1, there s a node in the list have same id */
  2.         if(currentList != NULL && preList!=NULL){
  3.  
  4.             /* insert the packet into the node */
  5.             insertToBranch(&(currentList->branch), l2idu);
  6.             }
  7.  
and it worked all fine untill when i get into isertToBranch() , when i trying to point a current pointer to the node. part of the code is
Expand|Select|Wrap|Line Numbers
  1. void insertToBranch(struct nodebranch **bufferNode, L2_IDU l2idu){
  2.  
  3.     printf("in the insertToBranch function\n");
  4.     int offset;                         /* the offset of incoming packet l2idu*/
  5.     int i;                             /* counter i */
  6.     int length;                         /* totle length of the packet */
  7.     int lastPacketDataLength = 0;         /* the data length of the last packet(where MP=0)*/
  8.     struct nodebranch * newNode;      /* newNode to add into branch */
  9.     struct nodebranch * pre;         /* a linked list point one node before current*/
  10.     struct nodebranch * current;      
  11.  
  12.     /* current point to bufferNode */
  13.     current = *bufferNode;
  14.  
  15.  
i think there s something wrong with the pointer reference been carried to the insertToBranch( ). but not sure. i know it looks very messy. shoot me questions if u dont get it. and sorry i cant give all the code since they r HUGE.
ps. yes, i have to use linked list of linked list, since i need carefully watch the memory for my program.

cheers
dave
Nov 2 '06 #1
3 1519
nbras
4 New Member
hi!
could you upload your file or send it to my e-mail alnbras@gmail.c om

I can't understand your code completely...

I hope I can help u
Nov 2 '06 #2
idshiy
4 New Member
is there any space i can upload my files here? i have about eight files for this project, so i dont know if i should upload them all.
Nov 3 '06 #3
idshiy
4 New Member
but here is the file i have problem with.
Expand|Select|Wrap|Line Numbers
  1.  
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <unistd.h>
  5.  
  6. #include "bool.h"
  7. #include "layer2.h"
  8. #include "layer3.h"
  9.  
  10. /* The Layer 3 PDU length is the MTU of Layer 3. */
  11. /* (even though we can't really put all that into one packet) */
  12. #define L3_PDU_MAXLENGTH    L3_MTU
  13.  
  14. /* the fill in for other headers which need to be set to zero*/
  15. #define ZERO 0x00;
  16.  
  17. /* a global varible for identification */
  18. static int identificator = 0;
  19.  
  20.  
  21. /* the branch linked list */
  22. struct nodebranch{
  23.     unsigned int offset;
  24.     unsigned char data[130];
  25.     struct nodebranch *next;
  26. };
  27.  
  28. struct node{
  29.     unsigned int id;
  30.     struct nodebranch *branch;
  31.     struct node *next;
  32. };
  33.  
  34. /* the linked list we use to store different msgs before send them*/
  35. static void insertToList(struct node **msgBuffer, L2_IDU l2idu);
  36. static void insertToBranch(struct nodebranch **bufferNode, L2_IDU l2idu);
  37. static int countLength(struct nodebranch **branch);
  38.  
  39. /* the function to check if all the packets have been stored, if is
  40.  * sort and send the msg and return a 1, else return 0
  41.  */
  42. void StoreAndSendMessage(struct nodebranch * branch, int branchLength, int lastPacketDataLength);
  43.  
  44. void checkAndSend(struct nodebranch **branch, L2_IDU l2idu); 
  45.  
  46. //void insert( NodePtr *sPtr, char value);
  47. //void delete( NodePtr *sPtr, char value);
  48.  
  49. /* the packet is a Layer 3 protocol data unit */
  50. typedef unsigned char L3_PDU[L3_PDU_MAXLENGTH];
  51.  
  52. int L3_connected=FALSE;
  53.  
  54. /* the function that Layer 2 calls */
  55. static void L3_receiveL2_IDU(L2_IDU l2idu);
  56.  
  57. /* the pointer to a function, to call when giving a DU to Layer 4 */
  58. static void (* receiveL3_IDU)(L3_IDU l3idu);  
  59.  
  60. /**
  61.  * Place your function header and description here.
  62.  *  - describe how you implemented the reassembly
  63.  *  - describe any data structures you used
  64.  *  - etc.
  65.  */
  66. static void L3_receiveL2_IDU(L2_IDU l2idu)
  67. {
  68.     /* the linked list of linked list which store all the packets
  69.      * before sending them
  70.      */
  71.     printf("show something before the seg fault!!\n");
  72.     struct node *msgBuffer = NULL;
  73.  
  74.     insertToList(&msgBuffer, l2idu);
  75. }
  76.  
  77. void insertToList(struct node **Buffer, L2_IDU l2idu){
  78.  
  79.     int id;                            /* identification */        
  80.     /* check if the linked list already have node with the same
  81.      * identificaton
  82.      */
  83.     struct node *currentList;            /*currentListList pointer*/
  84.     struct node *new;                /*use to add new node*/
  85.     struct node *preList;                /*point to one before msgBuffer*/
  86.  
  87.     /*allocate memory to new*/
  88.     new = malloc(sizeof(struct node));
  89.  
  90.     /* get id */
  91.     id = ((l2idu.data[4]<<8) | l2idu.data[5]);
  92.  
  93.     /* if there s space, insert packet*/
  94.     if(new != NULL){
  95.  
  96.         preList = NULL;
  97.         currentList = *Buffer;
  98.  
  99.         /* loop to the last node in the list or the node which got
  100.          * the same id no. with the packet*/
  101.         while(currentList != NULL && currentList->id != id){
  102.             preList = currentList;
  103.             currentList = currentList->next;
  104.         }
  105.         /*case 1, there s a node in the list have same id */
  106.         if(currentList != NULL && preList!=NULL){
  107.  
  108.             /* insert the packet into the node */
  109.             insertToBranch(&(currentList->branch), l2idu);
  110.             printf("out of insertToBranch function01");
  111.  
  112.         }
  113.         /* otherwise, the list comes to the end, and we ll add the packet
  114.          * on the end of the list*/
  115.         else{    
  116.             new->id = id;
  117.             insertToBranch(&(currentList->branch), l2idu);
  118.             printf("out of insertToBranch function02");
  119.             new->next = NULL; /*node doesnt link to other node*/
  120.  
  121.             /* case 3, empty list */
  122.             if (preList == NULL){
  123.                 new->next = *Buffer;
  124.                 *Buffer = new;
  125.                 /* point currentList to new */
  126.                 currentList = new;
  127.             }
  128.             /* case 2, no id in the list, add to the end of list */
  129.             else {
  130.                 preList->next = new;
  131.                 new->next = currentList;
  132.                 /* point currentList to new */
  133.                 currentList = new;
  134.             }
  135.         }
  136.     } 
  137.     else {
  138.         printf("%c not inserted. No memory available.\n", id );
  139.     }
  140.  
  141.     /* after insert the packet, we need to check if the branch which 
  142.      * just insert the packet has a MF set to true. if its true, means
  143.      * there s chance the whole msg has been recieved. if its so, store 
  144.      * and send the msg, and clear the branch free the memory. 
  145.      */
  146.      checkAndSend(&currentList->branch, l2idu);
  147.  
  148.      if(currentList->branch == NULL){
  149.          preList->next = currentList->next;
  150.          free(currentList);
  151.      }    
  152. }
  153.  
  154.  
  155.  
  156. /*insert the packet into the node with same id, along
  157.  * with data, a offset and a counter will be saved as well
  158.  * for later use. after the packet has been saved onto branch,
  159.  * check if all the packets has been recieved, by check if 
  160.  * the count equl to the offset/16. sort and send them and 
  161.  * make branch to NULL and free the memory.
  162.  * the packet with MF = 0 (the last packet) will be inserted
  163.  * on the end of the list while others will be inserted in the
  164.  * front. 
  165.  */
  166. void insertToBranch(struct nodebranch **bufferNode, L2_IDU l2idu){
  167.  
  168.     printf("in the insertToBranch function\n");
  169.     int offset;                         /* the offset of incoming packet l2idu*/
  170.     int i;                             /* counter i */
  171.     int length;                         /* totle length of the packet */
  172.     int lastPacketDataLength = 0;         /* the data length of the last packet(where MP=0)*/
  173.     struct nodebranch * newNode;      /* newNode to add into branch */
  174.     struct nodebranch * pre;         /* a linked list point one node before current*/
  175.     struct nodebranch * current;      
  176.  
  177.     /* current point to bufferNode */
  178.     current = *bufferNode;
  179.  
  180.     /* get the offset, while the MF is 1, need to change that bit 
  181.      * into 0 1st. 
  182.      */
  183.  
  184.     printf("the current is pointed to *bufferNode\n");
  185.     if( (l2idu.data[6] ^ (1<<5)) > l2idu.data[6]){
  186.         offset = ((l2idu.data[6]<<8) | l2idu.data[7]);
  187.         printf("the offset is : %d \n", offset);
  188.     }
  189.     else {
  190.         offset = ( ( (l2idu.data[6] ^ (1<<5)) <<8) | l2idu.data[7]);
  191.         printf("the offset is : %d \n", offset);
  192.     }
  193.  
  194.     /* get totle length of the packet */
  195.     length = ((l2idu.data[2]<<8) | l2idu.data[3]);
  196.  
  197.     /* asign memory to the new node */
  198.     newNode = malloc(sizeof(struct nodebranch));
  199.  
  200.     /*if the MF = 0, the bufferNode->MF will be set to TRUE 
  201.      */
  202.     if((l2idu.data[6] ^ (1<<5)) > l2idu.data[6]) {
  203.  
  204.         /* the data length of packet which have MF=0 */
  205.         lastPacketDataLength = length - 20;
  206.     }
  207.     /* for all the packets, will be inserted into a sorted list */
  208.     /* loop to get the sorted position of the packet */
  209.     while(current != NULL && offset > current->offset){
  210.         pre = current;
  211.         current = current->next;
  212.     }
  213.  
  214.     /* put packet into a new node */    
  215.     newNode->offset = offset;
  216.     for(i=0; i<(length-20); i++){
  217.         newNode->data[i] = l2idu.data[20+i];
  218.     }
  219.  
  220.     /* for empty list */
  221.     if(pre == NULL){
  222.         newNode->next = *bufferNode;
  223.         *bufferNode = newNode;
  224.     }
  225.     /* if list s not empty, insert new node */
  226.     else{
  227.         pre->next = newNode;
  228.         newNode->next = current;
  229.     }
  230. }
  231.  
  232.  
  233.  
  234. void checkAndSend(struct nodebranch **branch, L2_IDU l2idu){
  235.  
  236.     int i;
  237.     int count = 0;
  238.     int branchLength;
  239.     int lastPacketLength;
  240.     int lastPacketOffset;
  241.     struct nodebranch *pre;
  242.     struct nodebranch *currentCheck;
  243.     L3_IDU l3idu;
  244.  
  245.     /* point current to branch*/
  246.     /*********************************************************************/
  247.     /*THIS IS THE PART CAUSE SEG FAULT(I THINK) */
  248.     currentCheck = *branch;
  249.     /*********************************************************************/
  250.  
  251.     /* check the length of the branch */
  252.     branchLength = countLength(&*branch);
  253.  
  254.     /* get the last node(MF = 0)'s offset */
  255.     while(currentCheck->next != NULL){
  256.         pre = currentCheck;
  257.         currentCheck = currentCheck->next;
  258.     }
  259.     lastPacketOffset = currentCheck->offset;
  260.  
  261.     lastPacketLength = countLength(&currentCheck);
  262.  
  263.     /*compare the banch length with lastPackOffset/16 see if all the packets has been
  264.      * received */
  265.      if(branchLength == lastPacketOffset/16){
  266.  
  267.          /* store the msg into l3idu */
  268.          l3idu.length = (branchLength - 1)*128 + lastPacketLength;
  269.  
  270.          /*store the data, since they already been sorted in order, so just go node 
  271.           * by node, and store them into l3idu. */
  272.          while(currentCheck->next != NULL){
  273.  
  274.              for(i=0; i<128; i++){
  275.                  l3idu.data[i + (count*128)] = currentCheck->data[i];
  276.              }
  277.              pre->next = currentCheck;
  278.              currentCheck = currentCheck->next;
  279.              free(pre);
  280.              count++;
  281.          }
  282.          /* it come to the last node, which have MF=0 and data length from 1 to 130*/
  283.          for(i=0; i<lastPacketLength; i++){
  284.              l3idu.data[i + (count * 128)] = currentCheck->data[i];
  285.          }
  286.          free(currentCheck);
  287.  
  288.          receiveL3_IDU(l3idu);
  289.      }
  290. }
  291.  
  292.  
  293.  
  294. int countLength(struct nodebranch **branch){
  295.  
  296.     int counter = 0;
  297.     struct nodebranch * countlength = *branch;
  298.  
  299.     while(countlength != NULL){
  300.         counter++ ; 
  301.         countlength = countlength->next;
  302.     }    
  303.     return counter;
  304. }     
  305.  
  306.  
  307. /*******************************************************************************
  308. YOU DON'T NEED TO MODIFY ANY CODE BENEATH THIS POINT
  309. The following code will not be read during marking.
  310. *******************************************************************************/
  311.  
  312. void L3_callback(void (*func)(L3_IDU l3idu))
  313. {
  314.     receiveL3_IDU = func;
  315. }
  316.  
  317. void L3_connectToPeerDevice(const char *hostname, int port)
  318. {
  319.     /* establish connection to vhub, etc. */
  320.     L2_connectToPeerDevice(hostname, port);
  321.  
  322.     /* since Layer 1 terminates if can't connect, then assume connected */
  323.     L3_connected=TRUE;
  324.  
  325.     /* set the call back function for receiving bytes from Layer 2 */
  326.     L2_callback(L3_receiveL2_IDU);
  327.  
  328. }
  329.  
  330. void L3_disconnectFromPeerDevice(void)
  331. {
  332.     L2_disconnectFromPeerDevice();
  333.  
  334.     /* since Layer 1 terminates if can't disconnect, then assume disconnected */
  335.     L3_connected=FALSE;
  336. }
  337.  
  338.  
  339.  
have a look into function insertToList and insertToBranch, i think the line cause seg fault is in insertToBranch.

thanks
Nov 3 '06 #4

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marktang
by: marktang | last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...
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11142
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...
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10745
jinu1996
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
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10848
by: Hystou | last post by:
Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
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10417
tracyyun
by: tracyyun | last post by:
Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
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9575
agi2029
by: agi2029 | last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...
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7972
isladogs
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...
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4614
by: 6302768590 | last post by:
Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
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4221
muto222
by: muto222 | last post by:
How can i add a mobile payment intergratation into php mysql website.

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