usr: libc: Add realloc()

Implement realloc() to resize allocated memory from malloc()

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 22 insertions, 0 deletions

diff --git a/lib/libc/include/stdlib.h b/lib/libc/include/stdlib.h
index 97c777b..b1de3f3 100644
--- a/lib/libc/include/stdlib.h
+++ b/lib/libc/include/stdlib.h
@@ -86,6 +86,7 @@ __dead void _Exit(int status);
 #endif
 
 void *malloc(size_t size);
+void *realloc(void *ptr, size_t size);
 void free(void *ptr);
 
 void srand(unsigned int r);
diff --git a/lib/libc/src/stdlib/malloc.c b/lib/libc/src/stdlib/malloc.c
index 1c9e8ca..4f25c24 100644
--- a/lib/libc/src/stdlib/malloc.c
+++ b/lib/libc/src/stdlib/malloc.c
@@ -36,6 +36,7 @@
 #include <stdatomic.h>
 #include <stdio.h>
 #include <stdbool.h>
+#include <string.h>
 
 #define HEAP_SIZE   0x1001A8
 #define HEAP_MAGIC  0x05306A    /* "OSMORA" :~) */
@@ -163,6 +164,26 @@ malloc(size_t size)
     return PTR_OFFSET(next_block, sizeof(*next_block));
 }
 
+void *
+realloc(void *ptr, size_t size)
+{
+    struct mem_block *blk;
+    void *new_buf;
+
+    blk = PTR_NOFFSET(ptr, sizeof(*blk));
+    if (blk->magic != HEAP_MAGIC) {
+        __heap_abort("realloc: bad realloc block detected\n");
+    }
+    if (!blk->allocated) {
+        __heap_abort("realloc: bad realloc\n");
+    }
+
+    new_buf = malloc(size);
+    memcpy(new_buf, ptr, blk->size);
+    free(ptr);
+    return new_buf;
+}
+
 void
 free(void *ptr)
 {