Access deleted files by /dev/PID/mem.jankratochvil/devmem

libdwfl/
2014-02-22  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Access deleted files by /dev/PID/mem.
	* dwfl_module.c (dwfl_report_module_pid): New function.
	* dwfl_module_getdwarf.c (open_elf): Call __libdw_open_file_at_offset.
	* libdwfl.h (dwfl_report_module_pid): New declaration.
	* libdwflP.h (struct Dwfl_Module): New field pid.
	(INTDECL (dwfl_report_module_pid)): New.
	* linux-proc-maps.c (proc_maps_report): New variable first_high.
	(proc_maps_report) (report): Possibly call dwfl_report_module_pid.

tests/
2014-02-22  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Access deleted files by /dev/PID/mem.
	* Makefile.am (check_PROGRAMS): Add deleted and deleted-lib.so.
	(TESTS, EXTRA_DIST): Add run-deleted.sh.
	(deleted_LDADD, deleted_lib_so_LDFLAGS, deleted_lib_so_CFLAGS): New.
	* deleted-lib.c: New file.
	* deleted.c: New file.
	* run-deleted.sh: New file.

Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com>

5 files changed, 49 insertions, 6 deletions

diff --git a/libdwfl/dwfl_module.c b/libdwfl/dwfl_module.c
index bb167ab2..6787edf0 100644
--- a/libdwfl/dwfl_module.c
+++ b/libdwfl/dwfl_module.c
@@ -175,6 +175,17 @@ dwfl_report_module (Dwfl *dwfl, const char *name,
 }
 INTDEF (dwfl_report_module)
 
+Dwfl_Module *
+dwfl_report_module_pid (Dwfl *dwfl, const char *name, Dwarf_Addr start,
+			Dwarf_Addr end, pid_t pid)
+{
+  assert (pid > 0);
+  Dwfl_Module *mod = dwfl_report_module (dwfl, name, start, end);
+  if (mod != NULL)
+    mod->pid = pid;
+  return mod;
+}
+INTDEF (dwfl_report_module_pid)
 
 /* Finish reporting the current set of modules to the library.
    If REMOVED is not null, it's called for each module that
diff --git a/libdwfl/dwfl_module_getdwarf.c b/libdwfl/dwfl_module_getdwarf.c
index c4bd7395..d667513f 100644
--- a/libdwfl/dwfl_module_getdwarf.c
+++ b/libdwfl/dwfl_module_getdwarf.c
@@ -45,6 +45,16 @@ open_elf (Dwfl_Module *mod, struct dwfl_file *file)
 	 set it with an open failure below.  */
       errno = 0;
 
+      off_t start_offset = 0;
+      size_t maximum_size = ~((size_t) 0);
+      if (mod->pid != 0 && file == &mod->main)
+	{
+	  if (asprintf (&file->name, "/proc/%d/mem", mod->pid) < 0)
+	    return CBFAIL;
+	  start_offset = mod->low_addr;
+	  maximum_size = mod->high_addr - mod->low_addr;
+	}
+
       /* If there was a pre-primed file name left that the callback left
 	 behind, try to open that file name.  */
       if (file->fd < 0 && file->name != NULL)
@@ -53,7 +63,10 @@ open_elf (Dwfl_Module *mod, struct dwfl_file *file)
       if (file->fd < 0)
 	return CBFAIL;
 
-      Dwfl_Error error = __libdw_open_file (&file->fd, &file->elf, true, false);
+      Dwfl_Error error = __libdw_open_file_at_offset (&file->fd, &file->elf,
+						      start_offset,
+						      maximum_size,
+						      true, false);
       if (error != DWFL_E_NOERROR)
 	return error;
     }
diff --git a/libdwfl/libdwfl.h b/libdwfl/libdwfl.h
index 2bb4f455..cedadaef 100644
--- a/libdwfl/libdwfl.h
+++ b/libdwfl/libdwfl.h
@@ -145,6 +145,12 @@ extern int dwfl_report_segment (Dwfl *dwfl, int ndx,
 extern Dwfl_Module *dwfl_report_module (Dwfl *dwfl, const char *name,
 					Dwarf_Addr start, Dwarf_Addr end);
 
+/* Call dwfl_report_module with support of possibly deleted files of running
+   live process with pid PID.  */
+extern Dwfl_Module *dwfl_report_module_pid (Dwfl *dwfl, const char *name,
+					    Dwarf_Addr start, Dwarf_Addr end,
+					    pid_t pid);
+
 /* Report a module to address BASE with start and end addresses computed
    from the ELF program headers in the given file - see the table below.
    FD may be -1 to open FILE_NAME.  On success, FD is consumed by the
diff --git a/libdwfl/libdwflP.h b/libdwfl/libdwflP.h
index 9d7157d6..f9915547 100644
--- a/libdwfl/libdwflP.h
+++ b/libdwfl/libdwflP.h
@@ -158,6 +158,7 @@ struct Dwfl_Module
 
   char *name;			/* Iterator name for this module.  */
   GElf_Addr low_addr, high_addr;
+  pid_t pid;			/* Used for /proc/PID/mem reading.  */
 
   struct dwfl_file main, debug, aux_sym;
   GElf_Addr main_bias;
@@ -709,6 +710,7 @@ INTDECL (dwfl_getthread_frames)
 INTDECL (dwfl_getthreads)
 INTDECL (dwfl_thread_getframes)
 INTDECL (dwfl_frame_pc)
+INTDECL (dwfl_report_module_pid)
 
 /* Leading arguments standard to callbacks passed a Dwfl_Module.  */
 #define MODCB_ARGS(mod)	(mod), &(mod)->userdata, (mod)->name, (mod)->low_addr
diff --git a/libdwfl/linux-proc-maps.c b/libdwfl/linux-proc-maps.c
index cdb6959d..803cbdc0 100644
--- a/libdwfl/linux-proc-maps.c
+++ b/libdwfl/linux-proc-maps.c
@@ -177,14 +177,25 @@ proc_maps_report (Dwfl *dwfl, FILE *f, GElf_Addr sysinfo_ehdr, pid_t pid)
   unsigned int last_dmajor = -1, last_dminor = -1;
   uint64_t last_ino = -1;
   char *last_file = NULL;
-  Dwarf_Addr low = 0, high = 0;
+  Dwarf_Addr low = 0, high = 0, first_high = 0;
 
   inline bool report (void)
     {
       if (last_file != NULL)
 	{
-	  Dwfl_Module *mod = INTUSE(dwfl_report_module) (dwfl, last_file,
-							 low, high);
+	  size_t last_file_len = strlen (last_file);
+	  const char deleted[] = " (deleted)";
+	  const size_t deleted_len = strlen (deleted);
+	  Dwfl_Module *mod;
+	  if (last_file_len > deleted_len
+	      && strcmp (last_file + last_file_len - deleted_len, deleted) == 0)
+	    {
+	      last_file[last_file_len - deleted_len] = 0;
+	      mod = INTUSE(dwfl_report_module_pid) (dwfl, last_file,
+						    low, first_high, pid);
+	    }
+	  else
+	    mod = INTUSE(dwfl_report_module) (dwfl, last_file, low, high);
 	  free (last_file);
 	  last_file = NULL;
 	  if (unlikely (mod == NULL))
@@ -226,7 +237,7 @@ proc_maps_report (Dwfl *dwfl, FILE *f, GElf_Addr sysinfo_ehdr, pid_t pid)
 	    }
 
 	  low = start;
-	  high = end;
+	  high = first_high = end;
 	  if (asprintf (&last_file, "[vdso: %d]", (int) pid) < 0
 	      || report ())
 	    goto bad_report;
@@ -250,7 +261,7 @@ proc_maps_report (Dwfl *dwfl, FILE *f, GElf_Addr sysinfo_ehdr, pid_t pid)
 	  if (report ())
 	    goto bad_report;
 	  low = start;
-	  high = end;
+	  high = first_high = end;
 	  last_file = strdup (file);
 	  last_ino = ino;
 	  last_dmajor = dmajor;