Gdb dump memory in specific region, save formatted output into a file

Question

I have a buggy (memory leaked) software. As an evidence, I have 1GB of core.dump file. Heap size is 900MB, so obviously, something allocates, but does not free the memory. So, I have a memory region to examine like this. ``` (gdb) x/50000s 0x200000000 ``` However, this is hard to guess only with naked eyes, which object or struct is not freed. My idea to trace is, "Save gdb formatted output into a file, and run a pattern match to see which magic string comes up the most." So, here is my question: How can I save output of following command into a textfile, so that I can write an analyzer? ``` (gdb) x/10000000s 0x20000000 <-- I need this output into a file ```

Accepted Answer

You could use the "dump" function of gdb, see: https://sourceware.org/gdb/onlinedocs/gdb/Dump_002fRestore-Files.html

For your example:

```
dump binary memory result.bin 0x200000000 0x20000c350
```

This will give you a plain binary dump int file `result.bin`. You can also use the following to dump it in hex format:

```
dump ihex memory result.bin 0x200000000 0x20000c350
```

Using the dump command is much clearer than using the gdb logging hack (which even did not work for me somehow).

Gdb dump memory in specific region, save formatted output into a file

Solution

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