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Top Forums Programming how to avoid the segfault from Address 0x1cd00000103 out of bounds Post 302277358 by cdbug on Friday 16th of January 2009 04:38:00 AM
Old 01-16-2009
They are pointers. This is sure. But there is some mistakes in the code I gave before. The assignment should use * before the pointers. I am sorry for carelessness when posted. But when checking with 'while ( *( tr->root->is_done ) )', the same segfault happen. And corresponding pinter address still be 'out of bounds". In my code, such statements exist.

This is a package coded by a previous member. He habits to use such structure for varialbes which control execution. A large package means that it is not easy to change all the strutures of this kind.

What's more, I think this is really a topic worth discusssion.



Quote:
Originally Posted by otheus
"out of bounds" means "invalid memory address". You avoid it by properly mallocing memory before using it.

I hate to say this, but you seem very confused about pointers. I think you need to read a very concise summary on C pointers.

In the code you provide, you are trying to assign values to the address...
Code:
node->des = 0;

You should instead be doing:
Code:
*(node->des) = 0;
 
This correction is good. I losed stars when posted.

And your loop should be:
Code:
while ( *(  tr->root->is_done ) ) {
... 
}
 
At this situation, segfaults still happen

Also, root itself is a pointer. So you first need to allocate it:
Code:
tr->root = malloc(sizeof(struct node_t));
tr->root->hood = malloc(sizeof(double*));

"tr" is also a pointer, and this needs to be allocated too, but I have no idea what kind of structure it is.


Also, this structure is very unusual. I cannot imagine why you want every element to be a pointer to something!
 

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MALLOC_GET_STATE(3)					     Linux Programmer's Manual					       MALLOC_GET_STATE(3)

NAME
malloc_get_state, malloc_set_state - record and restore state of malloc implementation SYNOPSIS
#include <malloc.h> void* malloc_get_state(void); int malloc_set_state(void *state); DESCRIPTION
The malloc_get_state() function records the current state of all malloc(3) internal bookkeeping variables (but not the actual contents of the heap or the state of malloc_hook(3) functions pointers). The state is recorded in a system-dependent opaque data structure dynamically allocated via malloc(3), and a pointer to that data structure is returned as the function result. (It is the caller's responsibility to free(3) this memory.) The malloc_set_state() function restores the state of all malloc(3) internal bookkeeping variables to the values recorded in the opaque data structure pointed to by state. RETURN VALUE
On success, malloc_get_state() returns a pointer to a newly allocated opaque data structure. On error (for example, memory could not be allocated for the data structure), malloc_get_state() returns NULL. On success, malloc_set_state() returns 0. If the implementation detects that state does not point to a correctly formed data structure, malloc_set_state() returns -1. If the implementation detects that the version of the data structure referred to by state is a more recent version than this implementation knows about, malloc_set_state() returns -2. CONFORMING TO
These functions are GNU extensions. NOTES
These functions are useful when using this malloc(3) implementation as part of a shared library, and the heap contents are saved/restored via some other method. This technique is used by GNU Emacs to implement its "dumping" function. Hook function pointers are never saved or restored by these functions, with two exceptions: if malloc checking (see mallopt(3)) was in use when malloc_get_state() was called, then malloc_set_state() resets malloc checking hooks if possible; if malloc checking was not in use in the recorded state, but the caller has requested malloc checking, then the hooks are reset to 0. SEE ALSO
malloc(3), mallopt(3) GNU
2014-06-13 MALLOC_GET_STATE(3)
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