[Lldb-commits] [lldb] 468ca49 - [lldb] Allow loading of minidumps with no process id

[Pavel Labath via lldb-commits]

Author: Pavel Labath
Date: 2020-01-20T13:08:58+01:00
New Revision: 468ca490c6030462066f8e731902d81bab11c356

URL: https://github.com/llvm/llvm-project/commit/468ca490c6030462066f8e731902d81bab11c356
DIFF: https://github.com/llvm/llvm-project/commit/468ca490c6030462066f8e731902d81bab11c356.diff

LOG: [lldb] Allow loading of minidumps with no process id

Summary:
Normally, on linux we retrieve the process ID from the LinuxProcStatus
stream (which is just the contents of /proc/%d/status pseudo-file).

However, this stream is not strictly required (it's a breakpad
extension), and we are encountering a fair amount of minidumps which do
not have it present. It's not clear whether this is the case with all
these minidumps, but the two known situations where this stream can be
missing are:
- /proc filesystem not mounted (or something to that effect)
- process crashing after exhausting (almost) all file descriptors (so
  the minidump writer may not be able to open the /proc file)

Since this is a corner case which will become less and less relevant
(crashpad-generated minidumps should not suffer from this problem), I
work around this problem by hardcoding the PID to 1 in these cases.
The same thing is done by the gdb plugin when talking to a stub which
does not report a process id (e.g. a hardware probe).

Reviewers: jingham, clayborg

Subscribers: markmentovai, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D70238

Added: 
    lldb/test/Shell/Minidump/no-process-id.yaml

Modified: 
    lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp b/lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp
index 5c090dc6e12f..895ebb11e1f7 100644
--- a/lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp
+++ b/lldb/source/Plugins/Process/minidump/ProcessMinidump.cpp
@@ -226,8 +226,10 @@ Status ProcessMinidump::DoLoadCore() {
 
   llvm::Optional<lldb::pid_t> pid = m_minidump_parser->GetPid();
   if (!pid) {
-    error.SetErrorString("failed to parse PID");
-    return error;
+    GetTarget().GetDebugger().GetAsyncErrorStream()->PutCString(
+        "Unable to retrieve process ID from minidump file, setting process ID "
+        "to 1.\n");
+    pid = 1;
   }
   SetID(pid.getValue());
 

diff  --git a/lldb/test/Shell/Minidump/no-process-id.yaml b/lldb/test/Shell/Minidump/no-process-id.yaml
new file mode 100644
index 000000000000..3dd666a5aa1a
--- /dev/null
+++ b/lldb/test/Shell/Minidump/no-process-id.yaml
@@ -0,0 +1,38 @@
+# RUN: yaml2obj %s > %t
+# RUN: %lldb -c %t -o "thread list" -o "register read" -b 2>&1 | FileCheck %s
+
+# CHECK: (lldb) target create --core
+# CHECK: Unable to retrieve process ID from minidump file, setting process ID to 1.
+# CHECK: Core file {{.*}} was loaded.
+
+# CHECK: (lldb) thread list
+# CHECK: Process 1 stopped
+# CHECK: * thread #1: tid = 16001, 0x0000000000401dc6 a.out
+
+# CHECK: (lldb) register read
+# CHECK: rsp = 0x00007ffceb34a210
+
+--- !minidump
+Streams:
+  - Type:            ThreadList
+    Threads:
+      - Thread Id:       0x00003E81
+        Context:         0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000B0010000000000033000000000000000000000006020100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000010A234EBFC7F000010A234EBFC7F00000000000000000000F09C34EBFC7F0000C0A91ABCE97F00000000000000000000A0163FBCE97F00004602000000000000921C40000000000030A434EBFC7F000000000000000000000000000000000000C61D4000000000007F0300000000000000000000000000000000000000000000801F0000FFFF0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000FFFF00FFFFFFFFFFFFFF00FFFFFFFF25252525252525252525252525252525000000000000000000000000000000000000000000000000000000000000000000FFFF00FFFFFFFFFFFFFF00FFFFFFFF0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000FF00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+        Stack:
+          Start of Memory Range: 0x00007FFCEB34A000
+          Content:         ''
+  - Type:            ModuleList
+    Modules:
+      - Base of Image:   0x0000000000400000
+        Size of Image:   0x00017000
+        Module Name:     'a.out'
+        CodeView Record: ''
+  - Type:            SystemInfo
+    Processor Arch:  AMD64
+    Platform ID:     Linux
+    CSD Version:     'Linux 3.13'
+    CPU:
+      Vendor ID:       GenuineIntel
+      Version Info:    0x00000000
+      Feature Info:    0x00000000
+...