Add support for older versions of Android

Based on:
- dl_iterate_phdr() patch by Jeff Muizelaar.
- maps_next() improvement from AOSP: 7d46a21.
- unwi_unwind_method and x86_local_resume() from AOSP: 1c82a52.

1 files changed, 95 insertions, 0 deletions

diff --git a/src/dl-iterate-phdr.c b/src/dl-iterate-phdr.c
new file mode 100644
index 00000000..65e3a007
--- /dev/null
+++ b/src/dl-iterate-phdr.c
@@ -0,0 +1,95 @@
+/* libunwind - a platform-independent unwind library
+   Copyright (C) 2003-2005 Hewlett-Packard Co
+	Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
+
+This file is part of libunwind.
+
+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.  */
+
+#if defined(__ANDROID__) && __ANDROID_API__ < 21
+
+#include <dlfcn.h>
+#include <link.h>
+
+#include "libunwind_i.h"
+#include "os-linux.h"
+
+#ifndef IS_ELF
+/* Copied from NDK header. */
+#define IS_ELF(ehdr) ((ehdr).e_ident[EI_MAG0] == ELFMAG0 && \
+                      (ehdr).e_ident[EI_MAG1] == ELFMAG1 && \
+                      (ehdr).e_ident[EI_MAG2] == ELFMAG2 && \
+                      (ehdr).e_ident[EI_MAG3] == ELFMAG3)
+#endif
+
+typedef int (*unw_iterate_phdr_impl) (int (*callback) (
+                                        struct dl_phdr_info *info,
+                                        size_t size, void *data),
+                                      void *data);
+
+HIDDEN int
+dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info, size_t size, void *data),
+                 void *data)
+{
+  static int initialized = 0;
+  static unw_iterate_phdr_impl libc_impl;
+  int rc = 0;
+  struct map_iterator mi;
+  unsigned long start, end, offset, flags;
+
+  if (!initialized)
+    {
+      libc_impl = dlsym (RTLD_NEXT, "dl_iterate_phdr");
+      initialized = 1;
+    }
+
+  if (libc_impl != NULL)
+    return libc_impl (callback, data);
+
+  if (maps_init (&mi, getpid()) < 0)
+    return -1;
+
+  while (maps_next (&mi, &start, &end, &offset, &flags))
+    {
+      Elf_W(Ehdr) *ehdr = (Elf_W(Ehdr) *) start;
+      Dl_info canonical_info;
+
+      if (mi.path[0] != '\0' && (flags & PROT_EXEC) != 0 && IS_ELF (*ehdr)
+          && dladdr (ehdr, &canonical_info) == 0
+          && ehdr == canonical_info.dli_fbase)
+        {
+          struct dl_phdr_info info;
+          Elf_W(Phdr) *phdr = (Elf_W(Phdr) *) (start + ehdr->e_phoff);
+
+          info.dlpi_addr = start;
+          info.dlpi_name = canonical_info.dli_fname;
+          info.dlpi_phdr = phdr;
+          info.dlpi_phnum = ehdr->e_phnum;
+
+          rc = callback (&info, sizeof (info), data);
+        }
+    }
+
+  maps_close (&mi);
+
+  return rc;
+}
+
+#endif