Re: [PATCH] Implement new `info core mappings' command

[Sergio Durigan Junior <sergiodj at redhat dot com>]

Sergio Durigan Junior <sergiodj@redhat.com> writes:

> Hello there,

I have a theory that you only see errors in your patch when it's already
on the mailing list.

> diff --git a/gdb/NEWS b/gdb/NEWS
> index 5cdb63e..6f8feaa 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -3,6 +3,9 @@
>  
>  *** Changes since GDB 7.3.1
>  
> +* GDB has a new `info core mappings' command.  It displays the memory
> +  regions in a corefile, similar to `info pro mappings' command.
                                             ^^^
Typo.

> +static void
> +info_core_cmd (char *args, int from_tty)
> +{
> +  char **argv = NULL;
> +  int mappings_f = 1;
> +  int all = 0;
> +
> +  if (!core_bfd)
> +    error (_("You are not using a corefile at the moment."));
> +
> +  if (args)
> +    {
> +      /* Break up 'args' into an argv array.  */
> +      argv = gdb_buildargv (args);
> +      make_cleanup_freeargv (argv);
> +    }
> +  while (argv != NULL && *argv != NULL)
> +    {
> +      if (strncmp (argv[0], "mappings", strlen (argv[0])) == 0)
> +	{
> +	  mappings_f = 1;
> +	}
> +      else if (strncmp (argv[0], "all", strlen (argv[0])) == 0)
> +	{
> +	  all = 1;
> +	}
> +      argv++;
> +    }
> +
> +  if (mappings_f || all)
> +    print_core_map ();

Forgot to free `argv'.

Please, consider this new patch.

Thanks,

Sergio.

diff --git a/gdb/NEWS b/gdb/NEWS
index 5cdb63e..d04fbe6 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,9 @@
 
 *** Changes since GDB 7.3.1
 
+* GDB has a new `info core mappings' command.  It displays the memory
+  regions in a corefile, similar to `info proc mappings' command.
+
 * GDB has two new commands: "set remote hardware-watchpoint-length-limit"
   and "show remote hardware-watchpoint-length-limit".  These allows to
   set or show the maximum length limit (in bytes) of a remote
diff --git a/gdb/corefile.c b/gdb/corefile.c
index ce3b755..ab3c6bb 100644
--- a/gdb/corefile.c
+++ b/gdb/corefile.c
@@ -24,17 +24,23 @@
 #include <errno.h>
 #include <signal.h>
 #include <fcntl.h>
+#include <ctype.h>
 #include "inferior.h"
 #include "symtab.h"
+#include "gdbarch.h"
+#include "arch-utils.h"
 #include "command.h"
 #include "gdbcmd.h"
 #include "bfd.h"
+#include "elf-bfd.h"
+#include "elf/internal.h"
 #include "target.h"
 #include "gdbcore.h"
 #include "dis-asm.h"
 #include "gdb_stat.h"
 #include "completer.h"
 #include "exceptions.h"
+#include "objfiles.h"
 
 /* Local function declarations.  */
 
@@ -83,6 +89,189 @@ core_file_command (char *filename, int from_tty)
 }
 
 
+/* Helper function for `print_core_map'.  It is used to iterate
+   over the corefile's sections and print proper information about
+   memory-mappings.
+
+   BFD is the bfd used to get the sections.
+   SECT is the current section being "visited".
+   OBJ is not used.  */
+
+static void
+print_proc_map_iter (bfd *bfd, asection *sect, void *obj)
+{
+  /* We're interested in matching sections' names beginning with
+     `load', because they are the sections containing information
+     about the process' memory regions.  */
+  static const char *proc_map_match = "load";
+  int proc_map_match_size = strlen (proc_map_match);
+  /* Flag to indicate whether we have found something.  */
+  int found = 0;
+  /* The section's size.  */
+  bfd_size_type secsize;
+  /* We have to know the bitness of this architecture.  */
+  int bitness;
+  /* We'll use these later.  They are basically used for iterating
+     over every objfile in the system so that we can find needed
+     information about the memory region being examinated.  */
+  struct obj_section *s = NULL;
+  struct objfile *objfile = NULL;
+  /* Fields to be printed for the proc map.  */
+  unsigned long start = 0, end = 0;
+  unsigned int size = 0;
+  char *filename = NULL;
+
+  if (strncmp (proc_map_match, sect->name, proc_map_match_size) != 0)
+    /* This section is not useful.  */
+    return;
+
+  bitness = gdbarch_addr_bit (gdbarch_from_bfd (bfd));
+
+  /* Unfortunately, some sections in the corefile don't have any
+     content inside.  This is bad because we need to print, among
+     other things, its final address in the memory (which is
+     impossible to know if we don't have a size).  That's why we
+     first need to check if the section's got anything inside it.  */
+  secsize = bfd_section_size (bfd, sect);
+
+  if (secsize == 0)
+    {
+      /* Ok, the section is empty.  In this case, we must look inside
+	 ELF's Program Header, because (at least) there we have
+	 information about the section's size.  That's what we're doing
+	 here.  */
+      Elf_Internal_Phdr *p = elf_tdata (bfd)->phdr;
+      if (p != NULL)
+	{
+	  int i;
+	  unsigned int n = elf_elfheader (bfd)->e_phnum;
+	  for (i = 0; i < n; i++, p++)
+	    /* For each entry in the Program Header, we have to
+	       check if the section's initial address is equal to
+	       the entry's virtual address.  If it is, then we
+	       have just found the section's entry in the Program
+	       Header, and can use the entry's information to
+	       complete missing data from the section.  */
+	    if (sect->vma == p->p_vaddr)
+	      {
+		found = 1;
+		break;
+	      }
+	  if (found)
+	    secsize = p->p_memsz;
+	}
+    }
+
+  size = secsize;
+  start = sect->vma;
+  end = (unsigned long) (sect->vma + size);
+
+  /* Now begins a new part of the work.  We still don't have complete
+     information about the memory region.  For example, we still need
+     to know the filename which is represented by the region.  Such
+     info can be gathered from the objfile's data structure, and for
+     that we must iterate over all the objsections and check if the
+     objsection's initial address is inside the section we have at hand.
+     If it is, then we can use this specific objsection to obtain the
+     missing data.  */
+  found = 0;
+  ALL_OBJSECTIONS (objfile, s)
+    if (obj_section_addr (s) >= start
+	&& obj_section_addr (s) <= end)
+      {
+	found = 1;
+	break;
+      }
+
+  if (found)
+    filename = s->objfile->name;
+
+  if (bitness == 32)
+    printf_filtered ("\t%#10lx %#10lx %#10x %7s\n",
+		     start,
+		     end,
+		     (int) size,
+		     filename ? filename : "");
+  else
+    printf_filtered ("  %#18lx %#18lx %#10x %7s\n",
+		     start,
+		     end,
+		     (int) size,
+		     filename ? filename : "");
+}
+
+/* Implements the `info proc map' command when the user has provided
+   a corefile.  */
+
+static void
+print_core_map (void)
+{
+  const char *exe;
+  int bitness;
+
+  gdb_assert (core_bfd != NULL);
+
+  bitness = gdbarch_addr_bit (gdbarch_from_bfd (core_bfd));
+
+  /* Getting the executable name.  */
+  exe = bfd_core_file_failing_command (core_bfd);
+
+  printf_filtered (_("exe = '%s'\n"), exe);
+  printf_filtered (_("Mapped address spaces:\n\n"));
+  if (bitness == 32)
+    printf_filtered ("\t%10s %10s %10s %7s\n",
+		     "Start Addr",
+		     "  End Addr",
+		     "      Size", "objfile");
+  else
+    printf_filtered ("  %18s %18s %10s %7s\n",
+		     "Start Addr",
+		     "  End Addr",
+		     "      Size", "objfile");
+
+  bfd_map_over_sections (core_bfd,
+                         print_proc_map_iter,
+                         NULL);
+}
+
+/* Implement the `info core' command.  */
+
+static void
+info_core_cmd (char *args, int from_tty)
+{
+  char **argv = NULL;
+  int mappings_f = 1;
+  int all = 0;
+  struct cleanup *c;
+
+  if (!core_bfd)
+    error (_("You are not using a corefile at the moment."));
+
+  if (args)
+    {
+      /* Break up 'args' into an argv array.  */
+      argv = gdb_buildargv (args);
+      c = make_cleanup_freeargv (argv);
+    }
+  while (argv != NULL && *argv != NULL)
+    {
+      if (strncmp (argv[0], "mappings", strlen (argv[0])) == 0)
+	{
+	  mappings_f = 1;
+	}
+      else if (strncmp (argv[0], "all", strlen (argv[0])) == 0)
+	{
+	  all = 1;
+	}
+      argv++;
+    }
+
+  if (mappings_f || all)
+    print_core_map ();
+
+  do_cleanups (c);
+}
+
 /* If there are two or more functions that wish to hook into
    exec_file_command, this function will call all of the hook
    functions.  */
@@ -450,6 +639,11 @@ _initialize_core (void)
 {
   struct cmd_list_element *c;
 
+  add_info ("core", info_core_cmd, _("\
+Show information about a corefile.\n\
+Specify any of the following keywords for detailed info:\n\
+  mappings -- list of mapped memory regions."));
+
   c = add_cmd ("core-file", class_files, core_file_command, _("\
 Use FILE as core dump for examining memory and registers.\n\
 No arg means have no core file.  This command has been superseded by the\n\
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index b451a6a..92e06f3 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -17655,6 +17655,13 @@ value; etc.  For more information, see the @samp{proc} man page
 Show all the information about the process described under all of the
 above @code{info proc} subcommands.
 
+@kindex info core
+@cindex core dump file
+@item info core
+@item info core mappings
+@cindex memory address space mappings
+Report the memory address space ranges accessible in the core file.
+
 @ignore
 @comment These sub-options of 'info proc' were not included when
 @comment procfs.c was re-written.  Keep their descriptions around
diff --git a/gdb/testsuite/gdb.base/corefile.exp b/gdb/testsuite/gdb.base/corefile.exp
index 5b0cdf1..190281c 100644
--- a/gdb/testsuite/gdb.base/corefile.exp
+++ b/gdb/testsuite/gdb.base/corefile.exp
@@ -171,6 +171,13 @@ gdb_test_multiple "x/8bd buf2" "$test" {
     }
 }
 
+# Test the `info core mapping' command.
+set ws "\[ \t\]+"
+set test "test info core mapping"
+gdb_test "info core mapping" \
+	".*Mapped address spaces:.*${hex}${ws}${hex}${ws}${hex}.*" \
+	$test
+
 # test reinit_frame_cache
 
 gdb_load ${binfile}