osdep: Create qemu_getauxval and qemu_init_auxval

Abstract away dependence on a system implementation of getauxval.

Signed-off-by: Richard Henderson <rth@twiddle.net>

2 files changed, 75 insertions, 0 deletions

diff --git a/util/Makefile.objs b/util/Makefile.objs
index 2bb13a2a59..af3e5cb157 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -12,3 +12,4 @@ util-obj-y += qemu-option.o qemu-progress.o
 util-obj-y += hexdump.o
 util-obj-y += crc32c.o
 util-obj-y += throttle.o
+util-obj-y += getauxval.o
diff --git a/util/getauxval.c b/util/getauxval.c
new file mode 100644
index 0000000000..476c883b32
--- /dev/null
+++ b/util/getauxval.c
@@ -0,0 +1,74 @@
+/*
+ * QEMU access to the auxiliary vector
+ *
+ * Copyright (C) 2013 Red Hat, Inc
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu-common.h"
+#include "qemu/osdep.h"
+
+#ifdef CONFIG_GETAUXVAL
+/* Don't inline this in qemu/osdep.h, because pulling in <sys/auxv.h> for
+   the system declaration of getauxval pulls in the system <elf.h>, which
+   conflicts with qemu's version.  */
+
+#include <sys/auxv.h>
+
+unsigned long qemu_getauxval(unsigned long key)
+{
+    return getauxval(key);
+}
+#elif defined(__linux__)
+#include "elf.h"
+
+/* Our elf.h doesn't contain Elf32_auxv_t and Elf64_auxv_t, which is ok because
+   that just makes it easier to define it properly for the host here.  */
+typedef struct {
+    unsigned long a_type;
+    unsigned long a_val;
+} ElfW_auxv_t;
+
+static const ElfW_auxv_t *auxv;
+
+void qemu_init_auxval(char **envp)
+{
+    /* The auxiliary vector is located just beyond the initial environment.  */
+    while (*envp++ != NULL) {
+        continue;
+    }
+    auxv = (const ElfW_auxv_t *)envp;
+}
+
+unsigned long qemu_getauxval(unsigned long type)
+{
+    /* If we were able to find the auxiliary vector, use it.  */
+    if (auxv) {
+        const ElfW_auxv_t *a;
+        for (a = auxv; a->a_type != 0; a++) {
+            if (a->a_type == type) {
+                return a->a_val;
+            }
+        }
+    }
+
+    return 0;
+}
+#endif