libdwfl: Record dwfl_attach_state error and return it on failure.

When dwfl_attach_state fails functions that need the process state should
return the error that caused the attach to fail. Use this in the backtrace
test to signal any attach failure. This makes sure that architectures that
don't provide unwinder support get properly detected (and the tests SKIPs)
Also don't assert when trying to attach a non-core ELF file, but return an
error to indicate failure.

Signed-off-by: Mark Wielaard <mjw@redhat.com>

diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index c13e01fed456861df3ef838e81549db8dcafb7b6..ac92a219dcb7f25b090745a7ae64e9f77ad5b70f 100644 (file)
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,16 @@
+2014-06-11  Mark Wielaard  <mjw@redhat.com>
+
+       * dwfl_frame.c (__libdwfl_process_free): Reset dwfl->attacherr.
+       (dwfl_attach_state): Set dwfl->attacherr.
+       (dwfl_pid): Check and return dwfl->attacherr if set.
+       (dwfl_getthreads): Likewise.
+       (getthread): Likewise.
+       * libdwflP.h: Add DWFL_E_NO_CORE_FILE.
+       (struct Dwfl): Add attacherr field.
+       * linux-core-attach.c (dwfl_core_file_attach): Set dwfl->attacherr.
+       Don't assert if ELF file is not ET_CORE, just return error.
+       * linux-pid-attach.c (dwfl_linux_proc_attach): Set dwfl->attacherr.
+
 2014-06-10  Mark Wielaard  <mjw@redhat.com>
 
        * argp-std.c (parse_opt): Ignore errors from dwfl_core_file_attach

diff --git a/libdwfl/dwfl_frame.c b/libdwfl/dwfl_frame.c
index fd0b9aeb29a7741340b09228ae52e598941da92c..f6f86c0de6f14b46ede53afdfa551fc705438c30 100644 (file)
--- a/libdwfl/dwfl_frame.c
+++ b/libdwfl/dwfl_frame.c
@@ -1,5 +1,5 @@
 /* Get Dwarf Frame state for target PID or core file.
-   Copyright (C) 2013 Red Hat, Inc.
+   Copyright (C) 2013, 2014 Red Hat, Inc.
    This file is part of elfutils.
 
    This file is free software; you can redistribute it and/or modify
@@ -117,6 +117,7 @@ __libdwfl_process_free (Dwfl_Process *process)
   if (process->ebl_close)
     ebl_closebackend (process->ebl);
   free (process);
+  dwfl->attacherr = DWFL_E_NOERROR;
 }
 
 /* Allocate new Dwfl_Process for DWFL.  */
@@ -134,17 +135,24 @@ bool
 dwfl_attach_state (Dwfl *dwfl, Elf *elf, pid_t pid,
                   const Dwfl_Thread_Callbacks *thread_callbacks, void *arg)
 {
-  if (thread_callbacks == NULL || thread_callbacks->next_thread == NULL
-      || thread_callbacks->set_initial_registers == NULL)
+  if (dwfl->process != NULL)
     {
-      __libdwfl_seterrno (DWFL_E_INVALID_ARGUMENT);
+      __libdwfl_seterrno (DWFL_E_ATTACH_STATE_CONFLICT);
       return false;
     }
-  if (dwfl->process != NULL)
+
+  /* Reset any previous error, we are just going to try again.  */
+  dwfl->attacherr = DWFL_E_NOERROR;
+  if (thread_callbacks == NULL || thread_callbacks->next_thread == NULL
+      || thread_callbacks->set_initial_registers == NULL)
     {
-      __libdwfl_seterrno (DWFL_E_ATTACH_STATE_CONFLICT);
+      dwfl->attacherr = DWFL_E_INVALID_ARGUMENT;
+    fail:
+      dwfl->attacherr = __libdwfl_canon_error (dwfl->attacherr);
+      __libdwfl_seterrno (dwfl->attacherr);
       return false;
     }
+
   Ebl *ebl;
   bool ebl_close;
   if (elf != NULL)
@@ -180,8 +188,8 @@ dwfl_attach_state (Dwfl *dwfl, Elf *elf, pid_t pid,
   if (ebl == NULL)
     {
       /* Not identified EBL from any of the modules.  */
-      __libdwfl_seterrno (DWFL_E_PROCESS_NO_ARCH);
-      return false;
+      dwfl->attacherr = DWFL_E_PROCESS_NO_ARCH;
+      goto fail;
     }
   process_alloc (dwfl);
   Dwfl_Process *process = dwfl->process;
@@ -189,8 +197,8 @@ dwfl_attach_state (Dwfl *dwfl, Elf *elf, pid_t pid,
     {
       if (ebl_close)
        ebl_closebackend (ebl);
-      __libdwfl_seterrno (DWFL_E_NOMEM);
-      return false;
+      dwfl->attacherr = DWFL_E_NOMEM;
+      goto fail;
     }
   process->ebl = ebl;
   process->ebl_close = ebl_close;
@@ -204,6 +212,12 @@ INTDEF(dwfl_attach_state)
 pid_t
 dwfl_pid (Dwfl *dwfl)
 {
+  if (dwfl->attacherr != DWFL_E_NOERROR)
+    {
+      __libdwfl_seterrno (dwfl->attacherr);
+      return -1;
+    }
+
   if (dwfl->process == NULL)
     {
       __libdwfl_seterrno (DWFL_E_NO_ATTACH_STATE);
@@ -238,6 +252,12 @@ int
 dwfl_getthreads (Dwfl *dwfl, int (*callback) (Dwfl_Thread *thread, void *arg),
                 void *arg)
 {
+  if (dwfl->attacherr != DWFL_E_NOERROR)
+    {
+      __libdwfl_seterrno (dwfl->attacherr);
+      return -1;
+    }
+
   Dwfl_Process *process = dwfl->process;
   if (process == NULL)
     {
@@ -309,6 +329,12 @@ getthread (Dwfl *dwfl, pid_t tid,
           int (*callback) (Dwfl_Thread *thread, void *arg),
           void *arg)
 {
+  if (dwfl->attacherr != DWFL_E_NOERROR)
+    {
+      __libdwfl_seterrno (dwfl->attacherr);
+      return -1;
+    }
+
   Dwfl_Process *process = dwfl->process;
   if (process == NULL)
     {

diff --git a/libdwfl/libdwflP.h b/libdwfl/libdwflP.h
index 9b03d8a76fc1a31869e32f7848f3a01ab99432c2..30c0f8a965197251c50a476186a7ba3f5fd49f1b 100644 (file)
--- a/libdwfl/libdwflP.h
+++ b/libdwfl/libdwflP.h
@@ -91,7 +91,8 @@ typedef struct Dwfl_Process Dwfl_Process;
   DWFL_ERROR (ATTACH_STATE_CONFLICT, N_("Dwfl already has attached state"))   \
   DWFL_ERROR (NO_ATTACH_STATE, N_("Dwfl has no attached state"))             \
   DWFL_ERROR (NO_UNWIND, N_("Unwinding not supported for this architecture")) \
-  DWFL_ERROR (INVALID_ARGUMENT, N_("Invalid argument"))
+  DWFL_ERROR (INVALID_ARGUMENT, N_("Invalid argument"))                              \
+  DWFL_ERROR (NO_CORE_FILE, N_("Not an ET_CORE ELF file"))
 
 #define DWFL_ERROR(name, text) DWFL_E_##name,
 typedef enum { DWFL_ERRORS DWFL_E_NUM } Dwfl_Error;
@@ -110,6 +111,7 @@ struct Dwfl
   Dwfl_Module *modulelist;    /* List in order used by full traversals.  */
 
   Dwfl_Process *process;
+  Dwfl_Error attacherr;      /* Previous error attaching process.  */
 
   GElf_Addr offline_next_address;
 

diff --git a/libdwfl/linux-core-attach.c b/libdwfl/linux-core-attach.c
index 1002788e11e50e633c876d4ebe0e65a69da8439a..7ef3f256073fbd961e8e25509c443895e7ff3770 100644 (file)
--- a/libdwfl/linux-core-attach.c
+++ b/libdwfl/linux-core-attach.c
@@ -1,5 +1,5 @@
 /* Get Dwarf Frame state for target core file.
-   Copyright (C) 2013 Red Hat, Inc.
+   Copyright (C) 2013, 2014 Red Hat, Inc.
    This file is part of elfutils.
 
    This file is free software; you can redistribute it and/or modify
@@ -309,33 +309,41 @@ static const Dwfl_Thread_Callbacks core_thread_callbacks =
 int
 dwfl_core_file_attach (Dwfl *dwfl, Elf *core)
 {
+  Dwfl_Error err = DWFL_E_NOERROR;
   Ebl *ebl = ebl_openbackend (core);
   if (ebl == NULL)
     {
-      __libdwfl_seterrno (DWFL_E_LIBEBL);
+      err = DWFL_E_LIBEBL;
+    fail_err:
+      if (dwfl->process == NULL && dwfl->attacherr == DWFL_E_NOERROR)
+       dwfl->attacherr = __libdwfl_canon_error (err);
+      __libdwfl_seterrno (err);
       return -1;
     }
   size_t nregs = ebl_frame_nregs (ebl);
   if (nregs == 0)
     {
-      __libdwfl_seterrno (DWFL_E_NO_UNWIND);
+      err = DWFL_E_NO_UNWIND;
+    fail:
       ebl_closebackend (ebl);
-      return -1;
+      goto fail_err;
     }
   GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (core, &ehdr_mem);
   if (ehdr == NULL)
     {
-      __libdwfl_seterrno (DWFL_E_LIBELF);
-      ebl_closebackend (ebl);
-      return -1;
+      err = DWFL_E_LIBELF;
+      goto fail;
+    }
+  if (ehdr->e_type != ET_CORE)
+    {
+      err = DWFL_E_NO_CORE_FILE;
+      goto fail;
     }
-  assert (ehdr->e_type == ET_CORE);
   size_t phnum;
   if (elf_getphdrnum (core, &phnum) < 0)
     {
-      __libdwfl_seterrno (DWFL_E_LIBELF);
-      ebl_closebackend (ebl);
-      return -1;
+      err = DWFL_E_LIBELF;
+      goto fail;
     }
   pid_t pid = -1;
   Elf_Data *note_data = NULL;
@@ -351,8 +359,8 @@ dwfl_core_file_attach (Dwfl *dwfl, Elf *core)
     }
   if (note_data == NULL)
     {
-      ebl_closebackend (ebl);
-      return DWFL_E_LIBELF;
+      err = DWFL_E_LIBELF;
+      goto fail;
     }
   size_t offset = 0;
   GElf_Nhdr nhdr;
@@ -394,16 +402,14 @@ dwfl_core_file_attach (Dwfl *dwfl, Elf *core)
   if (pid == -1)
     {
       /* No valid NT_PRPSINFO recognized in this CORE.  */
-      __libdwfl_seterrno (DWFL_E_BADELF);
-      ebl_closebackend (ebl);
-      return -1;
+      err = DWFL_E_BADELF;
+      goto fail;
     }
   struct core_arg *core_arg = malloc (sizeof *core_arg);
   if (core_arg == NULL)
     {
-      __libdwfl_seterrno (DWFL_E_NOMEM);
-      ebl_closebackend (ebl);
-      return -1;
+      err = DWFL_E_NOMEM;
+      goto fail;
     }
   core_arg->core = core;
   core_arg->note_data = note_data;

diff --git a/libdwfl/linux-pid-attach.c b/libdwfl/linux-pid-attach.c
index 8aee721169ee052f3a56ee6c27f27d7db6fe56be..d60955e60e2e1f82153e95a4f610c3c122dd87ff 100644 (file)
--- a/libdwfl/linux-pid-attach.c
+++ b/libdwfl/linux-pid-attach.c
@@ -290,13 +290,23 @@ dwfl_linux_proc_attach (Dwfl *dwfl, pid_t pid, bool assume_ptrace_stopped)
 {
   char buffer[36];
   FILE *procfile;
+  int err = 0; /* The errno to return and set for dwfl->attcherr.  */
 
   /* Make sure to report the actual PID (thread group leader) to
      dwfl_attach_state.  */
   snprintf (buffer, sizeof (buffer), "/proc/%ld/status", (long) pid);
   procfile = fopen (buffer, "r");
   if (procfile == NULL)
-    return errno;
+    {
+      err = errno;
+    fail:
+      if (dwfl->process == NULL && dwfl->attacherr == DWFL_E_NOERROR)
+       {
+         errno = err;
+         dwfl->attacherr = __libdwfl_canon_error (DWFL_E_ERRNO);
+       }
+      return err;
+    }
 
   char *line = NULL;
   size_t linelen = 0;
@@ -317,19 +327,26 @@ dwfl_linux_proc_attach (Dwfl *dwfl, pid_t pid, bool assume_ptrace_stopped)
   fclose (procfile);
 
   if (pid == 0)
-    return ESRCH;
+    {
+      err = ESRCH;
+      goto fail;
+    }
 
   char dirname[64];
   int i = snprintf (dirname, sizeof (dirname), "/proc/%ld/task", (long) pid);
   assert (i > 0 && i < (ssize_t) sizeof (dirname) - 1);
   DIR *dir = opendir (dirname);
   if (dir == NULL)
-    return errno;
+    {
+      err = errno;
+      goto fail;
+    }
   struct __libdwfl_pid_arg *pid_arg = malloc (sizeof *pid_arg);
   if (pid_arg == NULL)
     {
       closedir (dir);
-      return ENOMEM;
+      err = ENOMEM;
+      goto fail;
     }
   pid_arg->dir = dir;
   pid_arg->tid_attached = 0;

diff --git a/tests/ChangeLog b/tests/ChangeLog
index bb0ad0d4b34a88cd774301922295413125ae9887..cd8a8e74cb8079bdfefbb9bb5bce91c252d4f319 100644 (file)
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,8 @@
+2014-06-11  Mark Wielaard  <mjw@redhat.com>
+
+       * backtrace.c (main): Check that Dwfl was attached by calling
+       dwfl_pid and printing the error when it is not.
+
 2014-05-18  Mark Wielaard  <mjw@redhat.com>
 
        * testfile-backtrace-demangle.cc (cxxfunc): Make non-static.

diff --git a/tests/backtrace.c b/tests/backtrace.c
index 1a4709b9df1ade126aad14f4694c045835f58c3a..ce0bd17d11444d3f9639daf17e0c1bc907cb2c53 100644 (file)
--- a/tests/backtrace.c
+++ b/tests/backtrace.c
@@ -1,5 +1,5 @@
 /* Test program for unwinding of frames.
-   Copyright (C) 2013 Red Hat, Inc.
+   Copyright (C) 2013, 2014 Red Hat, Inc.
    This file is part of elfutils.
 
    This file is free software; you can redistribute it and/or modify
@@ -459,6 +459,9 @@ main (int argc __attribute__ ((unused)), char **argv)
     };
   (void) argp_parse (&argp, argc, argv, 0, NULL, &dwfl);
   assert (dwfl != NULL);
+  /* We want to make sure the dwfl was properly attached.  */
+  if (dwfl_pid (dwfl) < 0)
+    error (2, 0, "dwfl_pid: %s", dwfl_errmsg (-1));
   dump (dwfl);
   dwfl_end (dwfl);
   return 0;