Add getauxval.c back

qemu/util/getauxval.c

@@ -0,0 +1,109 @@
+/*
+ * 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;
+
+static const ElfW_auxv_t *qemu_init_auxval(void)
+{
+    ElfW_auxv_t *a;
+    ssize_t size = 512, r, ofs;
+    int fd;
+
+    /* Allocate some initial storage.  Make sure the first entry is set
+       to end-of-list, so that we've got a valid list in case of error.  */
+    auxv = a = g_malloc(size);
+    a[0].a_type = 0;
+    a[0].a_val = 0;
+
+    fd = open("/proc/self/auxv", O_RDONLY);
+    if (fd < 0) {
+        return a;
+    }
+
+    /* Read the first SIZE bytes.  Hopefully, this covers everything.  */
+    r = read(fd, a, size);
+
+    if (r == size) {
+        /* Continue to expand until we do get a partial read.  */
+        do {
+            ofs = size;
+            size *= 2;
+            auxv = a = g_realloc(a, size);
+            r = read(fd, (char *)a + ofs, ofs);
+        } while (r == ofs);
+}
+
+    close(fd);
+    return a;
+}
+
+unsigned long qemu_getauxval(unsigned long type)
+{
+    const ElfW_auxv_t *a = auxv;
+
+    if (unlikely(a == NULL)) {
+        a = qemu_init_auxval();
+    }
+
+    for (; a->a_type != 0; a++) {
+        if (a->a_type == type) {
+            return a->a_val;
+        }
+    }
+
+    return 0;
+}
+
+#else
+
+unsigned long qemu_getauxval(unsigned long type)
+{
+    return 0;
+}
+
+#endif