Document the mallinfo struct, add missing attributes.

Change-Id: Ia97acce1f6a83bd8b3ba8dd20efd962bc96f35a9

2 files changed, 24 insertions, 18 deletions

diff --git a/libc/include/malloc.h b/libc/include/malloc.h
index ec21926c9..8875e542d 100644
--- a/libc/include/malloc.h
+++ b/libc/include/malloc.h
@@ -27,30 +27,30 @@
 
 __BEGIN_DECLS
 
-extern __mallocfunc void*  malloc(size_t);
-extern __mallocfunc void*  calloc(size_t, size_t);
-extern void*  realloc(void *, size_t);
-extern void   free(void *);
+extern void* malloc(size_t byte_count) __mallocfunc __wur;
+extern void* calloc(size_t item_count, size_t item_size) __mallocfunc __wur;
+extern void* realloc(void* p, size_t byte_count) __wur;
+extern void free(void* p);
 
-extern void*  memalign(size_t  alignment, size_t  bytesize);
-extern size_t malloc_usable_size(void*);
+extern void* memalign(size_t alignment, size_t byte_count) __mallocfunc __wur;
+extern size_t malloc_usable_size(void* p);
 
-extern void*  valloc(size_t  bytesize);
-extern void*  pvalloc(size_t bytesize);
+extern void* valloc(size_t byte_count) __mallocfunc __wur;
+extern void* pvalloc(size_t byte_count) __mallocfunc __wur;
 
 #ifndef STRUCT_MALLINFO_DECLARED
 #define STRUCT_MALLINFO_DECLARED 1
 struct mallinfo {
-  size_t arena;
-  size_t ordblks;
-  size_t smblks;
-  size_t hblks;
-  size_t hblkhd;
-  size_t usmblks;
-  size_t fsmblks;
-  size_t uordblks;
-  size_t fordblks;
-  size_t keepcost;
+  size_t arena;    /* Total number of non-mmapped bytes currently allocated from OS. */
+  size_t ordblks;  /* Number of free chunks. */
+  size_t smblks;   /* (Unused.) */
+  size_t hblks;    /* (Unused.) */
+  size_t hblkhd;   /* Total number of bytes in mmapped regions. */
+  size_t usmblks;  /* Maximum total allocated space; greater than total if trimming has occurred. */
+  size_t fsmblks;  /* (Unused.) */
+  size_t uordblks; /* Total allocated space (normal or mmapped.) */
+  size_t fordblks; /* Total free space. */
+  size_t keepcost; /* Upper bound on number of bytes releasable by malloc_trim. */
 };
 #endif  /* STRUCT_MALLINFO_DECLARED */
 
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index 937abe0c0..aa65b546c 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -321,6 +321,12 @@
 #define __always_inline
 #endif
 
+#if __GNUC_PREREQ__(3, 4)
+#define __wur __attribute__((__warn_unused_result__))
+#else
+#define __wur
+#endif
+
 /*
  * Macros for manipulating "link sets".  Link sets are arrays of pointers
  * to objects, which are gathered up by the linker.