Fix obvious gotcha in string comparison

[deliverable/binutils-gdb.git] / gdb / exec.c

diff --git a/gdb/exec.c b/gdb/exec.c
index 90811c081d3ebcb3fe1868e01cd2ce1ee5710ba7..67ecc6363072cdd7b8b00aaa36085b7c2ccf032f 100644 (file)
--- a/gdb/exec.c
+++ b/gdb/exec.c
@@ -43,6 +43,7 @@
 #include <ctype.h>
 #include <sys/stat.h>
 #include "solist.h"
+#include <algorithm>
 
 void (*deprecated_file_changed_hook) (char *);
 
@@ -135,13 +136,33 @@ exec_file_clear (int from_tty)
     printf_unfiltered (_("No executable file now.\n"));
 }
 
+/* Returns non-zero if exceptions E1 and E2 are equal.  Returns zero
+   otherwise.  */
+
+static int
+exception_print_same (struct gdb_exception e1, struct gdb_exception e2)
+{
+  const char *msg1 = e1.message;
+  const char *msg2 = e2.message;
+
+  if (msg1 == NULL)
+    msg1 = "";
+  if (msg2 == NULL)
+    msg2 = "";
+
+  return (e1.reason == e2.reason
+         && e1.error == e2.error
+         && strcmp (msg1, msg2) == 0);
+}
+
 /* See gdbcore.h.  */
 
 void
-exec_file_locate_attach (int pid, int from_tty)
+exec_file_locate_attach (int pid, int defer_bp_reset, int from_tty)
 {
   char *exec_file, *full_exec_path = NULL;
   struct cleanup *old_chain;
+  struct gdb_exception prev_err = exception_none;
 
   /* Do nothing if we already have an executable filename.  */
   exec_file = (char *) get_exec_file (0);
@@ -151,7 +172,13 @@ exec_file_locate_attach (int pid, int from_tty)
   /* Try to determine a filename from the process itself.  */
   exec_file = target_pid_to_exec_file (pid);
   if (exec_file == NULL)
-    return;
+    {
+      warning (_("No executable has been specified and target does not "
+                "support\n"
+                "determining executable automatically.  "
+                "Try using the \"file\" command."));
+      return;
+    }
 
   /* If gdb_sysroot is not empty and the discovered filename
      is absolute then prefix the filename with gdb_sysroot.  */
@@ -175,9 +202,48 @@ exec_file_locate_attach (int pid, int from_tty)
     }
 
   old_chain = make_cleanup (xfree, full_exec_path);
+  make_cleanup (free_current_contents, &prev_err.message);
+
+  /* exec_file_attach and symbol_file_add_main may throw an error if the file
+     cannot be opened either locally or remotely.
+
+     This happens for example, when the file is first found in the local
+     sysroot (above), and then disappears (a TOCTOU race), or when it doesn't
+     exist in the target filesystem, or when the file does exist, but
+     is not readable.
 
-  exec_file_attach (full_exec_path, from_tty);
-  symbol_file_add_main (full_exec_path, from_tty);
+     Even without a symbol file, the remote-based debugging session should
+     continue normally instead of ending abruptly.  Hence we catch thrown
+     errors/exceptions in the following code.  */
+  TRY
+    {
+      exec_file_attach (full_exec_path, from_tty);
+    }
+  CATCH (err, RETURN_MASK_ERROR)
+    {
+      if (err.message != NULL)
+       warning ("%s", err.message);
+
+      prev_err = err;
+
+      /* Save message so it doesn't get trashed by the catch below.  */
+      prev_err.message = xstrdup (err.message);
+    }
+  END_CATCH
+
+  TRY
+    {
+      if (defer_bp_reset)
+       current_inferior ()->symfile_flags |= SYMFILE_DEFER_BP_RESET;
+      symbol_file_add_main (full_exec_path, from_tty);
+    }
+  CATCH (err, RETURN_MASK_ERROR)
+    {
+      if (!exception_print_same (prev_err, err))
+       warning ("%s", err.message);
+    }
+  END_CATCH
+  current_inferior ()->symfile_flags &= ~SYMFILE_DEFER_BP_RESET;
 
   do_cleanups (old_chain);
 }
@@ -696,8 +762,8 @@ section_table_available_memory (VEC(mem_range_s) *memory,
 
          r = VEC_safe_push (mem_range_s, memory, NULL);
 
-         r->start = max (lo1, lo2);
-         r->length = min (hi1, hi2) - r->start;
+         r->start = std::max (lo1, lo2);
+         r->length = std::min (hi1, hi2) - r->start;
        }
     }
 
@@ -735,7 +801,7 @@ section_table_read_available_memory (gdb_byte *readbuf, ULONGEST offset,
          enum target_xfer_status status;
 
          /* Get the intersection window.  */
-         end = min (offset + len, r->start + r->length);
+         end = std::min<CORE_ADDR> (offset + len, r->start + r->length);
 
          gdb_assert (end - offset <= len);
 
@@ -1013,6 +1079,16 @@ ignore (struct target_ops *ops, struct gdbarch *gdbarch,
   return 0;
 }
 
+/* Implement the to_remove_breakpoint method.  */
+
+static int
+exec_remove_breakpoint (struct target_ops *ops, struct gdbarch *gdbarch,
+                       struct bp_target_info *bp_tgt,
+                       enum remove_bp_reason reason)
+{
+  return 0;
+}
+
 static int
 exec_has_memory (struct target_ops *ops)
 {
@@ -1044,7 +1120,7 @@ Specify the filename of the executable file.";
   exec_ops.to_get_section_table = exec_get_section_table;
   exec_ops.to_files_info = exec_files_info;
   exec_ops.to_insert_breakpoint = ignore;
-  exec_ops.to_remove_breakpoint = ignore;
+  exec_ops.to_remove_breakpoint = exec_remove_breakpoint;
   exec_ops.to_stratum = file_stratum;
   exec_ops.to_has_memory = exec_has_memory;
   exec_ops.to_make_corefile_notes = exec_make_note_section;