Refactor .so name detection logic in minidump/linux_dumper.

This is a refactoring of the logic which determines the
module name and path for a given MappingInfo in minidump_writer.cc.
Such logic, which will be soon shared also with the upcoming
microdump_writer.cc, is simply being moved to linux_dumper.cc,
extracting a GetMappingEffectiveNameAndPath method.
No behavioral change is intended.

BUG=chromium:410294
R=thestig@chromium.org

Review URL: https://breakpad.appspot.com/7734002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1392 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/client/linux/minidump_writer/linux_dumper.cc

@@ -184,10 +184,12 @@ bool ElfFileSoNameFromMappedFile(
   // Did not find SONAME
   return false;
 }
-}  // namespace
 
-// static
+// Find the shared object name (SONAME) by examining the ELF information
-bool LinuxDumper::ElfFileSoName(
+// for |mapping|. If the SONAME is found copy it into the passed buffer
+// |soname| and return true. The size of the buffer is |soname_size|.
+// The SONAME will be truncated if it is too long to fit in the buffer.
+bool ElfFileSoName(
     const MappingInfo& mapping, char* soname, size_t soname_size) {
   if (IsMappedFileOpenUnsafe(mapping)) {
     // Not safe
@@ -214,6 +216,44 @@ bool LinuxDumper::ElfFileSoName(
   return ElfFileSoNameFromMappedFile(mapped_file.data(), soname, soname_size);
 }
 
+}  // namespace
+
+
+// static
+void LinuxDumper::GetMappingEffectiveNameAndPath(const MappingInfo& mapping,
+                                                 char* file_path,
+                                                 size_t file_path_size,
+                                                 char* file_name,
+                                                 size_t file_name_size) {
+  my_strlcpy(file_path, mapping.name, file_path_size);
+
+  // If an executable is mapped from a non-zero offset, this is likely because
+  // the executable was loaded directly from inside an archive file (e.g., an
+  // apk on Android). We try to find the name of the shared object (SONAME) by
+  // looking in the file for ELF sections.
+  bool mapped_from_archive = false;
+  if (mapping.exec && mapping.offset != 0)
+    mapped_from_archive = ElfFileSoName(mapping, file_name, file_name_size);
+
+  if (mapped_from_archive) {
+    // Some tools (e.g., stackwalk) extract the basename from the pathname. In
+    // this case, we append the file_name to the mapped archive path as follows:
+    //   file_name := libname.so
+    //   file_path := /path/to/ARCHIVE.APK/libname.so
+    if (my_strlen(file_path) + 1 + my_strlen(file_name) < file_path_size) {
+      my_strlcat(file_path, "/", file_path_size);
+      my_strlcat(file_path, file_name, file_path_size);
+    }
+  } else {
+    // Common case:
+    //   file_path := /path/to/libname.so
+    //   file_name := libname.so
+    const char* basename = my_strrchr(file_path, '/');
+    basename = basename == NULL ? file_path : (basename + 1);
+    my_strlcpy(file_name, basename, file_name_size);
+  }
+}
+
 bool LinuxDumper::ReadAuxv() {
   char auxv_path[NAME_MAX];
   if (!BuildProcPath(auxv_path, pid_, "auxv")) {

src/client/linux/minidump_writer/linux_dumper.h

@@ -111,19 +111,13 @@ class LinuxDumper {
   virtual bool BuildProcPath(char* path, pid_t pid, const char* node) const = 0;
 
   // Generate a File ID from the .text section of a mapped entry.
-  // If not a member, mapping_id is ignored.
+  // If not a member, mapping_id is ignored. This method can also manipulate the
+  // |mapping|.name to truncate "(deleted)" from the file name if necessary.
   bool ElfFileIdentifierForMapping(const MappingInfo& mapping,
                                    bool member,
                                    unsigned int mapping_id,
                                    uint8_t identifier[sizeof(MDGUID)]);
 
-  // Find the shared object name (SONAME) by examining the ELF information
-  // for |mapping|. If the SONAME is found copy it into the passed buffer
-  // |soname| and return true. The size of the buffer is |soname_size|.
-  // The SONAME will be truncated if it is too long to fit in the buffer.
-  static bool ElfFileSoName(
-      const MappingInfo& mapping, char* soname, size_t soname_size);
-
   uintptr_t crash_address() const { return crash_address_; }
   void set_crash_address(uintptr_t crash_address) {
     crash_address_ = crash_address;
@@ -135,6 +129,17 @@ class LinuxDumper {
   pid_t crash_thread() const { return crash_thread_; }
   void set_crash_thread(pid_t crash_thread) { crash_thread_ = crash_thread; }
 
+  // Extracts the effective path and file name of from |mapping|. In most cases
+  // the effective name/path are just the mapping's path and basename. In some
+  // other cases, however, a library can be mapped from an archive (e.g., when
+  // loading .so libs from an apk on Android) and this method is able to
+  // reconstruct the original file name.
+  static void GetMappingEffectiveNameAndPath(const MappingInfo& mapping,
+                                             char* file_path,
+                                             size_t file_path_size,
+                                             char* file_name,
+                                             size_t file_name_size);
+
  protected:
   bool ReadAuxv();
 

src/client/linux/minidump_writer/minidump_writer.cc

@@ -540,49 +540,9 @@ class MinidumpWriter {
 
     mod.base_of_image = mapping.start_addr;
     mod.size_of_image = mapping.size;
-    const char* filepath_ptr = mapping.name;
-    size_t filepath_len = my_strlen(mapping.name);
-
-    // Figure out file name from path
-    const char* filename_ptr = mapping.name + filepath_len - 1;
-    while (filename_ptr >= mapping.name) {
-      if (*filename_ptr == '/')
-        break;
-      filename_ptr--;
-    }
-    filename_ptr++;
-
-    size_t filename_len = mapping.name + filepath_len - filename_ptr;
-
-    // If an executable is mapped from a non-zero offset, this is likely
-    // because the executable was loaded directly from inside an archive
-    // file. We try to find the name of the shared object (SONAME) by
-    // looking in the file for ELF sections.
-
-    char soname[NAME_MAX];
-    char pathname[NAME_MAX];
-    if (mapping.exec && mapping.offset != 0 &&
-        LinuxDumper::ElfFileSoName(mapping, soname, sizeof(soname))) {
-      filename_ptr = soname;
-      filename_len = my_strlen(soname);
-
-      if (filepath_len + filename_len + 1 < NAME_MAX) {
-        // It doesn't have a real pathname, but tools such as stackwalk
-        // extract the basename, so simulating a pathname is helpful.
-        my_memcpy(pathname, filepath_ptr, filepath_len);
-        pathname[filepath_len] = '/';
-        my_memcpy(pathname + filepath_len + 1, filename_ptr, filename_len);
-        pathname[filepath_len + filename_len + 1] = '\0';
-        filepath_ptr = pathname;
-        filepath_len = filepath_len + filename_len + 1;
-      }
-    }
 
     uint8_t cv_buf[MDCVInfoPDB70_minsize + NAME_MAX];
     uint8_t* cv_ptr = cv_buf;
-    UntypedMDRVA cv(&minidump_writer_);
-    if (!cv.Allocate(MDCVInfoPDB70_minsize + filename_len + 1))
-      return false;
 
     const uint32_t cv_signature = MD_CVINFOPDB70_SIGNATURE;
     my_memcpy(cv_ptr, &cv_signature, sizeof(cv_signature));
@@ -593,20 +553,31 @@ class MinidumpWriter {
       // GUID was provided by caller.
       my_memcpy(signature, identifier, sizeof(MDGUID));
     } else {
+      // Note: ElfFileIdentifierForMapping() can manipulate the |mapping.name|.
       dumper_->ElfFileIdentifierForMapping(mapping, member,
                                            mapping_id, signature);
     }
     my_memset(cv_ptr, 0, sizeof(uint32_t));  // Set age to 0 on Linux.
     cv_ptr += sizeof(uint32_t);
 
+    char file_name[NAME_MAX];
+    char file_path[NAME_MAX];
+    LinuxDumper::GetMappingEffectiveNameAndPath(
+        mapping, file_path, sizeof(file_path), file_name, sizeof(file_name));
+
+    const size_t file_name_len = my_strlen(file_name);
+    UntypedMDRVA cv(&minidump_writer_);
+    if (!cv.Allocate(MDCVInfoPDB70_minsize + file_name_len + 1))
+      return false;
+
     // Write pdb_file_name
-    my_memcpy(cv_ptr, filename_ptr, filename_len + 1);
+    my_memcpy(cv_ptr, file_name, file_name_len + 1);
-    cv.Copy(cv_buf, MDCVInfoPDB70_minsize + filename_len + 1);
+    cv.Copy(cv_buf, MDCVInfoPDB70_minsize + file_name_len + 1);
 
     mod.cv_record = cv.location();
 
     MDLocationDescriptor ld;
-    if (!minidump_writer_.WriteString(filepath_ptr, filepath_len, &ld))
+    if (!minidump_writer_.WriteString(file_path, my_strlen(file_path), &ld))
       return false;
     mod.module_name_rva = ld.rva;
     return true;