[libc] Expand usage of libc null checks. (#116262)

Fixes #111546

---------

Co-authored-by: alyyelashram <150528548+alyyelashram@users.noreply.github.com>

Author: AlyElashram

libc/src/string/memccpy.cpp

@@ -10,13 +10,18 @@
 
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include <stddef.h> // For size_t.
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(void *, memccpy,
                    (void *__restrict dest, const void *__restrict src, int c,
                     size_t count)) {
+  if (count) {
+    LIBC_CRASH_ON_NULLPTR(dest);
+    LIBC_CRASH_ON_NULLPTR(src);
+  }
   unsigned char end = static_cast<unsigned char>(c);
   const unsigned char *uc_src = static_cast<const unsigned char *>(src);
   unsigned char *uc_dest = static_cast<unsigned char *>(dest);

libc/src/string/memchr.cpp

@@ -8,6 +8,7 @@
 
 #include "src/string/memchr.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/string/string_utils.h"
 
 #include "src/__support/common.h"
@@ -17,6 +18,8 @@ namespace LIBC_NAMESPACE_DECL {
 
 // TODO: Look at performance benefits of comparing words.
 LLVM_LIBC_FUNCTION(void *, memchr, (const void *src, int c, size_t n)) {
+  if (n)
+    LIBC_CRASH_ON_NULLPTR(src);
   return internal::find_first_character(
       reinterpret_cast<const unsigned char *>(src),
       static_cast<unsigned char>(c), n);

libc/src/string/memcmp.cpp

@@ -8,6 +8,7 @@
 
 #include "src/string/memcmp.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/string/memory_utils/inline_memcmp.h"
 
 #include <stddef.h> // size_t
@@ -16,6 +17,10 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, memcmp,
                    (const void *lhs, const void *rhs, size_t count)) {
+  if (count) {
+    LIBC_CRASH_ON_NULLPTR(lhs);
+    LIBC_CRASH_ON_NULLPTR(rhs);
+  }
   return inline_memcmp(lhs, rhs, count);
 }
 

libc/src/string/memcpy.cpp

@@ -9,13 +9,18 @@
 #include "src/string/memcpy.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/string/memory_utils/inline_memcpy.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(void *, memcpy,
                    (void *__restrict dst, const void *__restrict src,
                     size_t size)) {
+  if (size) {
+    LIBC_CRASH_ON_NULLPTR(dst);
+    LIBC_CRASH_ON_NULLPTR(src);
+  }
   inline_memcpy(dst, src, size);
   return dst;
 }

libc/src/string/memmove.cpp

@@ -8,6 +8,7 @@
 
 #include "src/string/memmove.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/string/memory_utils/inline_memcpy.h"
 #include "src/string/memory_utils/inline_memmove.h"
 #include <stddef.h> // size_t
@@ -16,6 +17,10 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(void *, memmove,
                    (void *dst, const void *src, size_t count)) {
+  if (count) {
+    LIBC_CRASH_ON_NULLPTR(dst);
+    LIBC_CRASH_ON_NULLPTR(src);
+  }
   // Memmove may handle some small sizes as efficiently as inline_memcpy.
   // For these sizes we may not do is_disjoint check.
   // This both avoids additional code for the most frequent smaller sizes

libc/src/string/mempcpy.cpp

@@ -8,6 +8,7 @@
 
 #include "src/string/mempcpy.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/string/memory_utils/inline_memcpy.h"
 
 #include "src/__support/common.h"
@@ -18,6 +19,10 @@ namespace LIBC_NAMESPACE_DECL {
 LLVM_LIBC_FUNCTION(void *, mempcpy,
                    (void *__restrict dst, const void *__restrict src,
                     size_t count)) {
+  if (count) {
+    LIBC_CRASH_ON_NULLPTR(dst);
+    LIBC_CRASH_ON_NULLPTR(src);
+  }
   inline_memcpy(dst, src, count);
   return reinterpret_cast<char *>(dst) + count;
 }

libc/src/string/memrchr.cpp

@@ -9,11 +9,16 @@
 #include "src/string/memrchr.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include <stddef.h>
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(void *, memrchr, (const void *src, int c, size_t n)) {
+
+  if (n)
+    LIBC_CRASH_ON_NULLPTR(src);
+
   const unsigned char *str = reinterpret_cast<const unsigned char *>(src);
   const unsigned char ch = static_cast<unsigned char>(c);
   for (; n != 0; --n) {

libc/src/string/memset.cpp

@@ -9,11 +9,15 @@
 #include "src/string/memset.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/string/memory_utils/inline_memset.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(void *, memset, (void *dst, int value, size_t count)) {
+  if (count)
+    LIBC_CRASH_ON_NULLPTR(dst);
+
   inline_memset(dst, static_cast<uint8_t>(value), count);
   return dst;
 }

libc/src/string/stpncpy.cpp

@@ -8,6 +8,7 @@
 
 #include "src/string/stpncpy.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/string/memory_utils/inline_bzero.h"
 
 #include "src/__support/common.h"
@@ -17,6 +18,10 @@ namespace LIBC_NAMESPACE_DECL {
 LLVM_LIBC_FUNCTION(char *, stpncpy,
                    (char *__restrict dest, const char *__restrict src,
                     size_t n)) {
+  if (n) {
+    LIBC_CRASH_ON_NULLPTR(dest);
+    LIBC_CRASH_ON_NULLPTR(src);
+  }
   size_t i;
   // Copy up until \0 is found.
   for (i = 0; i < n && src[i] != '\0'; ++i)

libc/src/string/strcasestr.cpp

@@ -11,6 +11,7 @@
 #include "src/__support/common.h"
 #include "src/__support/ctype_utils.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/string/memory_utils/inline_strstr.h"
 
 namespace LIBC_NAMESPACE_DECL {
@@ -23,6 +24,9 @@ LLVM_LIBC_FUNCTION(char *, strcasestr,
     return LIBC_NAMESPACE::internal::tolower(a) -
            LIBC_NAMESPACE::internal::tolower(b);
   };
+
+  LIBC_CRASH_ON_NULLPTR(haystack);
+  LIBC_CRASH_ON_NULLPTR(needle);
   return inline_strstr(haystack, needle, case_cmp);
 }