Promote nameless lambda used by dl_iterate_phdr to named function.

[saugustine]

Summary

This cleans up control flow inside findUnwindSections, and will make
it easier to replace this code in a following patch. Also, expose the
data structure to allow use by a future replacment function.

[mstorsjo]

LGTM (but I didn't have the possibility to test it right now, but it seems right).

[mstorsjo]

Got to test this now as well, and it works fine for windows at least. Thanks!

libunwind/src/AddressSpace.hpp

LocalAddressSpace::getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
   }
 
   if (encoding & DW_EH_PE_indirect)
     result = getP(result);
 
   return result;
 }
 
-inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
-                                                  UnwindInfoSections &info) {
 #ifdef __APPLE__
-  dyld_unwind_sections dyldInfo;
-  if (_dyld_find_unwind_sections((void *)targetAddr, &dyldInfo)) {
-    info.dso_base                      = (uintptr_t)dyldInfo.mh;
- #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
-    info.dwarf_section                 = (uintptr_t)dyldInfo.dwarf_section;
-    info.dwarf_section_length          = dyldInfo.dwarf_section_length;
- #endif
-    info.compact_unwind_section        = (uintptr_t)dyldInfo.compact_unwind_section;
-    info.compact_unwind_section_length = dyldInfo.compact_unwind_section_length;
-    return true;
-  }
 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
-  // Bare metal is statically linked, so no need to ask the dynamic loader
-  info.dwarf_section_length = (uintptr_t)(&__eh_frame_end - &__eh_frame_start);
-  info.dwarf_section =        (uintptr_t)(&__eh_frame_start);
-  _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: section %p length %p",
-                             (void *)info.dwarf_section, (void *)info.dwarf_section_length);
-#if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
-  info.dwarf_index_section =        (uintptr_t)(&__eh_frame_hdr_start);
-  info.dwarf_index_section_length = (uintptr_t)(&__eh_frame_hdr_end - &__eh_frame_hdr_start);
-  _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: index section %p length %p",
-                             (void *)info.dwarf_index_section, (void *)info.dwarf_index_section_length);
-#endif
-  if (info.dwarf_section_length)
-    return true;
 #elif defined(_LIBUNWIND_ARM_EHABI) && defined(_LIBUNWIND_IS_BAREMETAL)
-  // Bare metal is statically linked, so no need to ask the dynamic loader
-  info.arm_section =        (uintptr_t)(&__exidx_start);
-  info.arm_section_length = (uintptr_t)(&__exidx_end - &__exidx_start);
-  _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: section %p length %p",
-                             (void *)info.arm_section, (void *)info.arm_section_length);
-  if (info.arm_section && info.arm_section_length)
-    return true;
 #elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_WIN32)
-  HMODULE mods[1024];
-  HANDLE process = GetCurrentProcess();
-  DWORD needed;
-
-  if (!EnumProcessModules(process, mods, sizeof(mods), &needed)) {
-    DWORD err = GetLastError();
-    _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: EnumProcessModules failed, "
-                               "returned error %d", (int)err);
-    return false;
-  }
-
-  for (unsigned i = 0; i < (needed / sizeof(HMODULE)); i++) {
-    PIMAGE_DOS_HEADER pidh = (PIMAGE_DOS_HEADER)mods[i];
-    PIMAGE_NT_HEADERS pinh = (PIMAGE_NT_HEADERS)((BYTE *)pidh + pidh->e_lfanew);
-    PIMAGE_FILE_HEADER pifh = (PIMAGE_FILE_HEADER)&pinh->FileHeader;
-    PIMAGE_SECTION_HEADER pish = IMAGE_FIRST_SECTION(pinh);
-    bool found_obj = false;
-    bool found_hdr = false;
-
-    info.dso_base = (uintptr_t)mods[i];
-    for (unsigned j = 0; j < pifh->NumberOfSections; j++, pish++) {
-      uintptr_t begin = pish->VirtualAddress + (uintptr_t)mods[i];
-      uintptr_t end = begin + pish->Misc.VirtualSize;
-      if (!strncmp((const char *)pish->Name, ".text",
-                   IMAGE_SIZEOF_SHORT_NAME)) {
-        if (targetAddr >= begin && targetAddr < end)
-          found_obj = true;
-      } else if (!strncmp((const char *)pish->Name, ".eh_frame",
-                          IMAGE_SIZEOF_SHORT_NAME)) {
-        info.dwarf_section = begin;
-        info.dwarf_section_length = pish->Misc.VirtualSize;
-        found_hdr = true;
-      }
-      if (found_obj && found_hdr)
-        return true;
-    }
-  }
-  return false;
 #elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
-  // Don't even bother, since Windows has functions that do all this stuff
-  // for us.
-  (void)targetAddr;
-  (void)info;
-  return true;
 #elif defined(_LIBUNWIND_ARM_EHABI) && defined(__BIONIC__)
-  // For ARM EHABI, Bionic didn't implement dl_iterate_phdr until API 21. After
-  // API 21, dl_iterate_phdr exists, but dl_unwind_find_exidx is much faster.
-  int length = 0;
-  info.arm_section =
-      (uintptr_t)dl_unwind_find_exidx((_Unwind_Ptr)targetAddr, &length);
-  info.arm_section_length = (uintptr_t)length * sizeof(EHABIIndexEntry);
-  if (info.arm_section && info.arm_section_length)
-    return true;
+// Code inside findUnwindSections handles all these cases.
+//
+// Although the above ifdef chain is ugly, there doesn't seem to be a cleaner
+// way to handle it. The generalized boolean expression is:
+//
+//  A OR (B AND C) OR (D AND C) OR (B AND E) OR (F AND E) OR (D AND G)
+//
+// Running it through various boolean expression simplifiers gives expressions
+// that don't help at all.
 #elif defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
-  struct dl_iterate_cb_data {
-    LocalAddressSpace *addressSpace;
-    UnwindInfoSections *sects;
-    uintptr_t targetAddr;
-  };
+
+struct _LIBUNWIND_HIDDEN dl_iterate_cb_data {
 
-  dl_iterate_cb_data cb_data = {this, &info, targetAddr};
-  int found = dl_iterate_phdr(
-      [](struct dl_phdr_info *pinfo, size_t, void *data) -> int {
-        auto cbdata = static_cast<dl_iterate_cb_data *>(data);
-        bool found_obj = false;
-        bool found_hdr = false;
+int findUnwindSectionsByPhdr(struct dl_phdr_info *pinfo, size_t, void *data) {
 
-        assert(cbdata);
-        assert(cbdata->sects);
 
-        if (cbdata->targetAddr < pinfo->dlpi_addr) {
-          return false;
-        }
 
 #if !defined(Elf_Half)
-        typedef ElfW(Half) Elf_Half;
 #endif
 #if !defined(Elf_Phdr)
-        typedef ElfW(Phdr) Elf_Phdr;
 #endif
 #if !defined(Elf_Addr)
-        typedef ElfW(Addr) Elf_Addr;
 #endif
 
-        Elf_Addr image_base = pinfo->dlpi_addr;
 
 #if defined(__ANDROID__) && __ANDROID_API__ < 18
-        if (image_base == 0) {
-          // Normally, an image base of 0 indicates a non-PIE executable. On
-          // versions of Android prior to API 18, the dynamic linker reported a
-          // dlpi_addr of 0 for PIE executables. Compute the true image base
-          // using the PT_PHDR segment.
-          // See https://github.com/android/ndk/issues/505.
-          for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
-            const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
-            if (phdr->p_type == PT_PHDR) {
-              image_base = reinterpret_cast<Elf_Addr>(pinfo->dlpi_phdr) -
-                  phdr->p_vaddr;
-              break;
-            }
-          }
-        }
 #endif
 
  #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
   #if !defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
    #error "_LIBUNWIND_SUPPORT_DWARF_UNWIND requires _LIBUNWIND_SUPPORT_DWARF_INDEX on this platform."
   #endif
-        size_t object_length;
 
-        for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
-          const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
-          if (phdr->p_type == PT_LOAD) {
-            uintptr_t begin = image_base + phdr->p_vaddr;
-            uintptr_t end = begin + phdr->p_memsz;
-            if (cbdata->targetAddr >= begin && cbdata->targetAddr < end) {
-              cbdata->sects->dso_base = begin;
-              object_length = phdr->p_memsz;
-              found_obj = true;
-            }
-          } else if (phdr->p_type == PT_GNU_EH_FRAME) {
-            EHHeaderParser<LocalAddressSpace>::EHHeaderInfo hdrInfo;
-            uintptr_t eh_frame_hdr_start = image_base + phdr->p_vaddr;
-            cbdata->sects->dwarf_index_section = eh_frame_hdr_start;
-            cbdata->sects->dwarf_index_section_length = phdr->p_memsz;
-            found_hdr = EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
-                *cbdata->addressSpace, eh_frame_hdr_start, phdr->p_memsz,
-                hdrInfo);
-            if (found_hdr)
-              cbdata->sects->dwarf_section = hdrInfo.eh_frame_ptr;
-          }
-        }
 
-        if (found_obj && found_hdr) {
-          cbdata->sects->dwarf_section_length = object_length;
-          return true;
-        } else {
-          return false;
-        }
  #else // defined(_LIBUNWIND_ARM_EHABI)
-        for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
-          const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
-          if (phdr->p_type == PT_LOAD) {
-            uintptr_t begin = image_base + phdr->p_vaddr;
-            uintptr_t end = begin + phdr->p_memsz;
-            if (cbdata->targetAddr >= begin && cbdata->targetAddr < end)
-              found_obj = true;
-          } else if (phdr->p_type == PT_ARM_EXIDX) {
-            uintptr_t exidx_start = image_base + phdr->p_vaddr;
-            cbdata->sects->arm_section = exidx_start;
-            cbdata->sects->arm_section_length = phdr->p_memsz;
-            found_hdr = true;
-          }
-        }
-        return found_obj && found_hdr;
  #endif
-      },
-      &cb_data);
+}
+#endif  // defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
+
+
+inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
+                                                  UnwindInfoSections &info) {
+#ifdef __APPLE__
+  dyld_unwind_sections dyldInfo;
+  if (_dyld_find_unwind_sections((void *)targetAddr, &dyldInfo)) {
+    info.dso_base                      = (uintptr_t)dyldInfo.mh;
+ #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
+    info.dwarf_section                 = (uintptr_t)dyldInfo.dwarf_section;
+    info.dwarf_section_length          = dyldInfo.dwarf_section_length;
+ #endif
+    info.compact_unwind_section        = (uintptr_t)dyldInfo.compact_unwind_section;
+    info.compact_unwind_section_length = dyldInfo.compact_unwind_section_length;
+    return true;
+  }
+#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
+  // Bare metal is statically linked, so no need to ask the dynamic loader
+  info.dwarf_section_length = (uintptr_t)(&__eh_frame_end - &__eh_frame_start);
+  info.dwarf_section =        (uintptr_t)(&__eh_frame_start);
+  _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: section %p length %p",
+                             (void *)info.dwarf_section, (void *)info.dwarf_section_length);
+#if defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
+  info.dwarf_index_section =        (uintptr_t)(&__eh_frame_hdr_start);
+  info.dwarf_index_section_length = (uintptr_t)(&__eh_frame_hdr_end - &__eh_frame_hdr_start);
+  _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: index section %p length %p",
+                             (void *)info.dwarf_index_section, (void *)info.dwarf_index_section_length);
+#endif
+  if (info.dwarf_section_length)
+    return true;
+#elif defined(_LIBUNWIND_ARM_EHABI) && defined(_LIBUNWIND_IS_BAREMETAL)
+  // Bare metal is statically linked, so no need to ask the dynamic loader
+  info.arm_section =        (uintptr_t)(&__exidx_start);
+  info.arm_section_length = (uintptr_t)(&__exidx_end - &__exidx_start);
+  _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: section %p length %p",
+                             (void *)info.arm_section, (void *)info.arm_section_length);
+  if (info.arm_section && info.arm_section_length)
+    return true;
+#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_WIN32)
+  HMODULE mods[1024];
+  HANDLE process = GetCurrentProcess();
+  DWORD needed;
+
+  if (!EnumProcessModules(process, mods, sizeof(mods), &needed)) {
+    DWORD err = GetLastError();
+    _LIBUNWIND_TRACE_UNWINDING("findUnwindSections: EnumProcessModules failed, "
+                               "returned error %d", (int)err);
+    return false;
+  }
+
+  for (unsigned i = 0; i < (needed / sizeof(HMODULE)); i++) {
+    PIMAGE_DOS_HEADER pidh = (PIMAGE_DOS_HEADER)mods[i];
+    PIMAGE_NT_HEADERS pinh = (PIMAGE_NT_HEADERS)((BYTE *)pidh + pidh->e_lfanew);
+    PIMAGE_FILE_HEADER pifh = (PIMAGE_FILE_HEADER)&pinh->FileHeader;
+    PIMAGE_SECTION_HEADER pish = IMAGE_FIRST_SECTION(pinh);
+    bool found_obj = false;
+    bool found_hdr = false;
+
+    info.dso_base = (uintptr_t)mods[i];
+    for (unsigned j = 0; j < pifh->NumberOfSections; j++, pish++) {
+      uintptr_t begin = pish->VirtualAddress + (uintptr_t)mods[i];
+      uintptr_t end = begin + pish->Misc.VirtualSize;
+      if (!strncmp((const char *)pish->Name, ".text",
+                   IMAGE_SIZEOF_SHORT_NAME)) {
+        if (targetAddr >= begin && targetAddr < end)
+          found_obj = true;
+      } else if (!strncmp((const char *)pish->Name, ".eh_frame",
+                          IMAGE_SIZEOF_SHORT_NAME)) {
+        info.dwarf_section = begin;
+        info.dwarf_section_length = pish->Misc.VirtualSize;
+        found_hdr = true;
+      }
+      if (found_obj && found_hdr)
+        return true;
+    }
+  }
+  return false;
+#elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
+  // Don't even bother, since Windows has functions that do all this stuff
+  // for us.
+  (void)targetAddr;
+  (void)info;
+  return true;
+#elif defined(_LIBUNWIND_ARM_EHABI) && defined(__BIONIC__)
+  // For ARM EHABI, Bionic didn't implement dl_iterate_phdr until API 21. After
+  // API 21, dl_iterate_phdr exists, but dl_unwind_find_exidx is much faster.
+  int length = 0;
+  info.arm_section =
+      (uintptr_t)dl_unwind_find_exidx((_Unwind_Ptr)targetAddr, &length);
+  info.arm_section_length = (uintptr_t)length * sizeof(EHABIIndexEntry);
+  if (info.arm_section && info.arm_section_length)
+    return true;
+#elif defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
+  dl_iterate_cb_data cb_data = {this, &info, targetAddr};
+  int found = dl_iterate_phdr(findUnwindSectionsByPhdr, &cb_data);
   return static_cast<bool>(found);
 #endif
 
   return false;
 }
 
 
 inline bool LocalAddressSpace::findOtherFDE(pint_t targetAddr, pint_t &fde) {