minidump-2-core: add more control over filenames

The code has been rewriting the location of the shared lib lookup
completely which breaks normal sysroot usage with gdb.  Split out
the behavior into dedicated flags so people can opt into it.  You
can see examples of -i/-f in the usage() text.

We also change the -S behavior so that it's no longer enabled by
default -- if people want /var/lib/breakpad/, they can pass the -S
flag explicitly.

BUG=chromium:598947

Change-Id: Ic81726c27b4ad6c271c70696f2ac62798f07ccfb
Reviewed-on: https://chromium-review.googlesource.com/402909
Reviewed-by: Mark Mentovai <mark@chromium.org>

1 files changed, 93 insertions, 24 deletions

diff --git a/src/tools/linux/md2core/minidump-2-core.cc b/src/tools/linux/md2core/minidump-2-core.cc
index 1f04ead3..6a9e28eb 100644
--- a/src/tools/linux/md2core/minidump-2-core.cc
+++ b/src/tools/linux/md2core/minidump-2-core.cc
@@ -100,6 +100,8 @@ struct Options {
   string minidump_path;
   bool verbose;
   int out_fd;
+  bool use_filename;
+  bool inc_guid;
   string so_basedir;
 };
 
@@ -110,13 +112,27 @@ Usage(int argc, const char* argv[]) {
           "\n"
           "Convert a minidump file into a core file (often for use by gdb).\n"
           "\n"
+          "The shared library list will by default have filenames as the runtime expects.\n"
+          "There are many flags to control the output names though to make it easier to\n"
+          "integrate with your debug environment (e.g. gdb).\n"
+          " Default:    /lib64/libpthread.so.0\n"
+          " -f:         /lib64/libpthread-2.19.so\n"
+          " -i:         /lib64/<module id>-libpthread.so.0\n"
+          " -f -i:      /lib64/<module id>-libpthread-2.19.so\n"
+          " -S /foo/:   /foo/libpthread.so.0\n"
+          "\n"
           "Options:\n"
           "  -v         Enable verbose output\n"
           "  -o <file>  Write coredump to specified file (otherwise use stdout).\n"
+          "  -f         Use the filename rather than the soname in the sharedlib list.\n"
+          "             The soname is what the runtime system uses, but the filename is\n"
+          "             how it's stored on disk.\n"
+          "  -i         Prefix sharedlib names with ID (when available).  This makes it\n"
+          "             easier to have a single directory full of symbols.\n"
           "  -S <dir>   Set soname base directory.  This will force all debug/symbol\n"
           "             lookups to be done in this directory rather than the filesystem\n"
           "             layout as it exists in the crashing image.  This path should end\n"
-          "             with a slash if it's a directory.\n"
+          "             with a slash if it's a directory.  e.g. /var/lib/breakpad/\n"
           "", basename(argv[0]));
 }
 
@@ -128,8 +144,10 @@ SetupOptions(int argc, const char* argv[], Options* options) {
 
   // Initialize the options struct as needed.
   options->verbose = false;
+  options->use_filename = false;
+  options->inc_guid = false;
 
-  while ((ch = getopt(argc, (char * const *)argv, "ho:S:v")) != -1) {
+  while ((ch = getopt(argc, (char * const *)argv, "fhio:S:v")) != -1) {
     switch (ch) {
       case 'h':
         Usage(argc, argv);
@@ -140,6 +158,12 @@ SetupOptions(int argc, const char* argv[], Options* options) {
         exit(1);
         break;
 
+      case 'f':
+        options->use_filename = true;
+        break;
+      case 'i':
+        options->inc_guid = true;
+        break;
       case 'o':
         output_file = optarg;
         break;
@@ -271,6 +295,7 @@ struct CrashedProcess {
 
     uint32_t permissions;
     uint64_t start_address, end_address, offset;
+    // The name we write out to the core.
     string filename;
     string data;
   };
@@ -306,7 +331,13 @@ struct CrashedProcess {
 
   prpsinfo prps;
 
-  std::map<uintptr_t, string> signatures;
+  // The GUID/filename from MD_MODULE_LIST_STREAM entries.
+  // We gather them for merging later on into the list of maps.
+  struct Signature {
+    char guid[40];
+    string filename;
+  };
+  std::map<uintptr_t, Signature> signatures;
 
   string dynamic_data;
   MDRawDebug debug;
@@ -954,26 +985,19 @@ ParseModuleStream(const Options& options, CrashedProcess* crashinfo,
             record->signature.data4[2], record->signature.data4[3],
             record->signature.data4[4], record->signature.data4[5],
             record->signature.data4[6], record->signature.data4[7]);
-    string filename =
-        full_file.GetAsciiMDString(rawmodule->module_name_rva);
-    size_t slash = filename.find_last_of('/');
-    string basename = slash == string::npos ?
-        filename : filename.substr(slash + 1);
-    if (strcmp(guid, "00000000-0000-0000-0000-000000000000")) {
-      string prefix;
-      if (!options.so_basedir.empty())
-        prefix = options.so_basedir;
-      else
-        prefix = string("/var/lib/breakpad/") + guid + "-" + basename;
-
-      crashinfo->signatures[rawmodule->base_of_image] = prefix + basename;
-    }
+
+    string filename = full_file.GetAsciiMDString(rawmodule->module_name_rva);
+
+    CrashedProcess::Signature signature;
+    strcpy(signature.guid, guid);
+    signature.filename = filename;
+    crashinfo->signatures[rawmodule->base_of_image] = signature;
 
     if (options.verbose) {
-      fprintf(stderr, "0x%08llX-0x%08llX, ChkSum: 0x%08X, GUID: %s, \"%s\"\n",
-              (unsigned long long)rawmodule->base_of_image,
-              (unsigned long long)rawmodule->base_of_image +
-              rawmodule->size_of_image,
+      fprintf(stderr, "0x%" PRIx64 "-0x%" PRIx64 ", ChkSum: 0x%08X, GUID: %s, "
+              " \"%s\"\n",
+              rawmodule->base_of_image,
+              rawmodule->base_of_image + rawmodule->size_of_image,
               rawmodule->checksum, guid, filename.c_str());
     }
   }
@@ -1071,10 +1095,55 @@ AugmentMappings(const Options& options, CrashedProcess* crashinfo,
 
     // Look up signature for this filename. If available, change filename
     // to point to GUID, instead.
-    std::map<uintptr_t, string>::const_iterator guid =
+    std::map<uintptr_t, CrashedProcess::Signature>::const_iterator sig =
       crashinfo->signatures.find((uintptr_t)iter->addr);
-    if (guid != crashinfo->signatures.end()) {
-      filename = guid->second;
+    if (sig != crashinfo->signatures.end()) {
+      // At this point, we have:
+      // old_filename: The path as found via SONAME (e.g. /lib/libpthread.so.0).
+      // sig_filename: The path on disk (e.g. /lib/libpthread-2.19.so).
+      const char* guid = sig->second.guid;
+      string sig_filename = sig->second.filename;
+      string old_filename = filename.empty() ? sig_filename : filename;
+      string new_filename;
+
+      // First set up the leading path.  We assume dirname always ends with a
+      // trailing slash (as needed), so we won't be appending one manually.
+      if (options.so_basedir.empty()) {
+        string dirname;
+        if (options.use_filename) {
+          dirname = sig_filename;
+        } else {
+          dirname = old_filename;
+        }
+        size_t slash = dirname.find_last_of('/');
+        if (slash != string::npos) {
+          new_filename = dirname.substr(0, slash + 1);
+        }
+      } else {
+        new_filename = options.so_basedir;
+      }
+
+      // Insert the module ID if requested.
+      if (options.inc_guid &&
+          strcmp(guid, "00000000-0000-0000-0000-000000000000") != 0) {
+        new_filename += guid;
+        new_filename += "-";
+      }
+
+      // Decide whether we use the filename or the SONAME (where the SONAME tends
+      // to be a symlink to the actual file).
+      string basename = options.use_filename ? sig_filename : old_filename;
+      size_t slash = basename.find_last_of('/');
+      new_filename += basename.substr(slash == string::npos ? 0 : slash + 1);
+
+      if (filename != new_filename) {
+        if (options.verbose) {
+          fprintf(stderr, "0x%" PRIx64": rewriting mapping \"%s\" to \"%s\"\n",
+                  static_cast<uint64_t>(link_map.l_addr),
+                  filename.c_str(), new_filename.c_str());
+        }
+        filename = new_filename;
+      }
     }
 
     if (std::distance(iter, crashinfo->link_map.end()) == 1) {