Where do malloc() and free() store allocated sizes and addresses?

by

There are lots of ways in which malloc/free can store the size of the memory area. For example, it might be stored just before the area returned by malloc. Or it might be stored in a lookup table elsewhere. Or it might be stored implicitly: some areas might be reserved for specific sizes of allocations.

To find out how the C library in Linux (glibc) does this, get the source code from http://ftp.gnu.org/gnu/glibc/ and look at the malloc/malloc.c file. There is some documentation at the top, and it refers to A Memory Allocator by Doug Lea.

More Related Contents:

  1. How do free and malloc work in C?
  2. Setting variable to NULL after free
  3. How much memory would be freed if pointer is changed in C?
  4. What is a contiguous memory block?
  5. Why would you ever want to allocate memory on the heap rather than the stack? [duplicate]
  6. If free() knows the length of my array, why can’t I ask for it in my own code?
  7. Why exactly should I not call free() on variables not allocated by malloc()?
  8. How to avoid long chain of free’s (or deletes) after every error check in C?
  9. What happens to memory after free()?
  10. How to check heap size for a process on Linux
  11. String literals: Where do they go?
  12. Getting a stack overflow exception when declaring a large array
  13. Determine size of dynamically allocated memory in C
  14. Difference between static memory allocation and dynamic memory allocation
  15. Does stack grow upward or downward?
  16. “register” keyword in C?
  17. Arrays, heap and stack and value types
  18. Pointer address in a C multidimensional array
  19. Obtaining peak bandwidth on Haswell in the L1 cache: only getting 62%
  20. Measuring Cache Latencies
  21. malloc(sizeof(int)) vs malloc(sizeof(int *)) vs (int *)malloc(sizeof(int))
  22. Why do I get different results when I dereference a pointer after freeing it?
  23. Memory usage of current process in C
  24. Malloc vs custom allocator: Malloc has a lot of overhead. Why?
  25. Determining Stack Space with Visual Studio
  26. Resizing an array with C
  27. Size of stack and heap memory [duplicate]
  28. Is freeing allocated memory needed when exiting a program in C
  29. Is free() zeroing out memory?
  30. Struct varies in memory size?

Leave a Comment