[Feature] Support pvPortRealloc #1315

[skb666]

Description

This PR introduces a new API pvPortRealloc to FreeRTOS, providing dynamic memory reallocation similar to the standard C library's realloc. With configSUPPORT_HEAP_REALLOC enabled, applications can now resize heap-allocated memory blocks at runtime, either shrinking, expanding in place, or reallocating with data migration when needed.

Key Changes:

• Added the pvPortRealloc API in portable/MemMang/heap_4.c and heap_5.c.
• Added the configuration macro configSUPPORT_HEAP_REALLOC (default 0, must be 1 to enable realloc support).
• Updated FreeRTOSConfig.h and checked for correct configuration use.
• Critical sections and heap integrity checks are enforced throughout realloc logic.
• Follows realloc semantics:
  • NULL pointer behaves like malloc.
  • Size 0 behaves like free.
  • Tries in-place expand or shrink when possible; otherwise allocates a new block, copies data, and frees the old one.

Test Steps

1. Enable configSUPPORT_HEAP_REALLOC and ensure dynamic allocation is also enabled.
2. Build with either heap_4.c or heap_5.c.
3. Call pvPortRealloc to:
   • Expand, shrink, and reduce memory blocks.
   • Pass NULL as input.
   • Pass size 0.
   • Test fragmentation and edge cases (failing allocation, invalid pointers).
4. Validate heap stats and application logic remain correct.

Checklist:

• I have tested my changes. No regression in existing tests.
• I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

#1315

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[AniruddhaKanhere]

Hello @skb666,

Thank you for taking the time to contribute to the FreeRTOS-kernel.

I have some comments/questions about your PR. Can you please take a look and let me know what you think?

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[hoxi]

This will have to move down to line 472. We can get a pvPortRealloc(NULL, size) as first call; before the heap is initialized.

[hoxi]

This will have to move down to line 507. We can get a pvPortRealloc(NULL, size) as first call; before the heap is initialized.