string-util: rework memory_erase() to not use GCC optimize attribute (#3812)

[elogind.git] / src / basic / string-util.c

diff --git a/src/basic/string-util.c b/src/basic/string-util.c
index 293a15f9c041cf59f5354829cfdc86b0b0622a20..5d4510e1b3bc457103da44e9128cc240588fdc53 100644 (file)
--- a/src/basic/string-util.c
+++ b/src/basic/string-util.c
@@ -22,6 +22,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "alloc-util.h"
 #include "gunicode.h"
@@ -323,6 +324,14 @@ char ascii_tolower(char x) {
         return x;
 }
 
+char ascii_toupper(char x) {
+
+        if (x >= 'a' && x <= 'z')
+                return x - 'a' + 'A';
+
+        return x;
+}
+
 char *ascii_strlower(char *t) {
         char *p;
 
@@ -334,6 +343,17 @@ char *ascii_strlower(char *t) {
         return t;
 }
 
+char *ascii_strupper(char *t) {
+        char *p;
+
+        assert(t);
+
+        for (p = t; *p; p++)
+                *p = ascii_toupper(*p);
+
+        return t;
+}
+
 char *ascii_strlower_n(char *t, size_t n) {
         size_t i;
 
@@ -803,25 +823,20 @@ int free_and_strdup(char **p, const char *s) {
         return 1;
 }
 
-#pragma GCC push_options
-#pragma GCC optimize("O0")
+/*
+ * Pointer to memset is volatile so that compiler must de-reference
+ * the pointer and can't assume that it points to any function in
+ * particular (such as memset, which it then might further "optimize")
+ * This approach is inspired by openssl's crypto/mem_clr.c.
+ */
+typedef void *(*memset_t)(void *,int,size_t);
 
-void* memory_erase(void *p, size_t l) {
-        volatile uint8_t* x = (volatile uint8_t*) p;
+static volatile memset_t memset_func = memset;
 
-        /* This basically does what memset() does, but hopefully isn't
-         * optimized away by the compiler. One of those days, when
-         * glibc learns memset_s() we should replace this call by
-         * memset_s(), but until then this has to do. */
-
-        for (; l > 0; l--)
-                *(x++) = 'x';
-
-        return p;
+void* memory_erase(void *p, size_t l) {
+        return memset_func(p, 'x', l);
 }
 
-#pragma GCC pop_options
-
 char* string_erase(char *x) {
 
         if (!x)