Partially available/unavailable data in requested range

In gdb.trace/unavailable.exp, an action is defined to collect
struct_b.struct_a.array[2] and struct_b.struct_a.array[100],

struct StructB
{
  int d, ef;
  StructA struct_a;
  int s:1;
  static StructA static_struct_a;
  const char *string;
};

and the other files are not collected.

When GDB examine traceframe collected by the action, "struct_b" is
unavailable completely, which is wrong.

(gdb) p struct_b
$1 = <unavailable>

When GDB reads 'struct_b', it will request to read memory at struct_b's address
of length LEN.  Since struct_b.d is not collected, no 'M' block
includes the first part of the desired range, so tfile_xfer_partial returns
TARGET_XFER_UNAVAILABLE and GDB thinks the whole requested range is unavailable.

In order to fix this problem, in the iteration to 'M' blocks, we record the
lowest address of blocks within the request range.  If it has, the requested
range isn't unavailable completely.  This applies to ctf too.  With this patch
applied, the result looks good and fails in unavailable.exp is fixed.

(gdb) p struct_b
$1 = {d = <unavailable>, ef = <unavailable>, struct_a = {a = <unavailable>, b = <unavailable>, array = {<unavailable>,
<unavailable>, -1431655766, <unavailable> <repeats 97 times>, -1431655766, <unavailable> <repeats 9899 times>}, ptr = <unavailable>, bitfield = <unavailable>}, s = <unavailable>,   static static_struct_a = {a = <unavailable>, b = <unavailable>, array = {<unavailable> <repeats 10000 times>}, ptr = <unavailable>,
bitfield = <unavailable>}, string = <unavailable>}

gdb:

2014-05-05  Yao Qi  <yao@codesourcery.com>
	    Pedro Alves  <palves@redhat.com>

	* tracefile-tfile.c (tfile_xfer_partial): Record the lowest
	address of blocks that intersects the requested range.  Trim
	LEN up to LOW_ADDR_AVAILABLE if read from executable read-only
	sections.
	* ctf.c (ctf_xfer_partial): Likewise.

gdb/testsuite:

2014-05-05  Yao Qi  <yao@codesourcery.com>

	* gdb.trace/unavailable.exp (gdb_collect_args_test): Save
	traceframes into tfile and ctf trace files.  Read data from
	trace file and test collected data.
	(gdb_collect_locals_test): Likewise.
	(gdb_unavailable_registers_test): Likewise.
	(gdb_unavailable_floats): Likewise.
	(gdb_collect_globals_test): Likewise.
	(top-level): Append "ctf" to trace_file_targets if GDB
	supports.

5 files changed, 183 insertions, 2 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 43aace7..fc8b44a 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,4 +1,13 @@
 2014-05-05  Yao Qi  <yao@codesourcery.com>
+	    Pedro Alves  <palves@redhat.com>
+
+	* tracefile-tfile.c (tfile_xfer_partial): Record the lowest
+	address of blocks that intersects the requested range.  Trim
+	LEN up to LOW_ADDR_AVAILABLE if read from executable read-only
+	sections.
+	* ctf.c (ctf_xfer_partial): Likewise.
+
+2014-05-05  Yao Qi  <yao@codesourcery.com>
 
 	* printcmd.c (display_command): Remove the check to
 	target_has_execution.
diff --git a/gdb/ctf.c b/gdb/ctf.c
index bac7c28..84d0a48 100644
--- a/gdb/ctf.c
+++ b/gdb/ctf.c
@@ -1328,6 +1328,9 @@ ctf_xfer_partial (struct target_ops *ops, enum target_object object,
       struct bt_iter_pos *pos;
       int i = 0;
       enum target_xfer_status res;
+      /* Records the lowest available address of all blocks that
+	 intersects the requested range.  */
+      ULONGEST low_addr_available = 0;
 
       gdb_assert (ctf_iter != NULL);
       /* Save the current position.  */
@@ -1410,6 +1413,10 @@ ctf_xfer_partial (struct target_ops *ops, enum target_object object,
 		}
 	    }
 
+	  if (offset < maddr && maddr < (offset + len))
+	    if (low_addr_available == 0 || low_addr_available > maddr)
+	      low_addr_available = maddr;
+
 	  if (bt_iter_next (bt_ctf_get_iter (ctf_iter)) < 0)
 	    break;
 	}
@@ -1419,7 +1426,9 @@ ctf_xfer_partial (struct target_ops *ops, enum target_object object,
 
       /* Requested memory is unavailable in the context of traceframes,
 	 and this address falls within a read-only section, fallback
-	 to reading from executable.  */
+	 to reading from executable, up to LOW_ADDR_AVAILABLE  */
+      if (offset < low_addr_available)
+	len = min (len, low_addr_available - offset);
       res = exec_read_partial_read_only (readbuf, offset, len, xfered_len);
 
       if (res == TARGET_XFER_OK)
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index bd3829c..311b528 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,17 @@
 2014-05-05  Yao Qi  <yao@codesourcery.com>
 
+	* gdb.trace/unavailable.exp (gdb_collect_args_test): Save
+	traceframes into tfile and ctf trace files.  Read data from
+	trace file and test collected data.
+	(gdb_collect_locals_test): Likewise.
+	(gdb_unavailable_registers_test): Likewise.
+	(gdb_unavailable_floats): Likewise.
+	(gdb_collect_globals_test): Likewise.
+	(top-level): Append "ctf" to trace_file_targets if GDB
+	supports.
+
+2014-05-05  Yao Qi  <yao@codesourcery.com>
+
 	* gdb.trace/unavailable.exp (gdb_collect_args_test): Move some
 	code to ...
 	(gdb_collect_args_test_1): ... it.  New proc.
diff --git a/gdb/testsuite/gdb.trace/unavailable.exp b/gdb/testsuite/gdb.trace/unavailable.exp
index d76b54d..ec5ed26 100644
--- a/gdb/testsuite/gdb.trace/unavailable.exp
+++ b/gdb/testsuite/gdb.trace/unavailable.exp
@@ -188,6 +188,8 @@ proc gdb_collect_args_test_1 {} {
 proc gdb_collect_args_test {} {
     with_test_prefix "unavailable arguments" {
 	global gdb_prompt
+	global testfile srcdir subdir binfile
+	global trace_file_targets
 
 	prepare_for_trace_test
 
@@ -203,6 +205,30 @@ proc gdb_collect_args_test {} {
 	gdb_test "tfind none" \
 	    "#0  end .*" \
 	    "cease trace debugging"
+
+	set tracefile [standard_output_file ${testfile}]
+	gdb_test "tsave ${tracefile}.args.tfile" \
+	    "Trace data saved to file '${tracefile}.args.tfile'\.\\r" \
+	    "tsave ${testfile}.args.tfile"
+	gdb_test "tsave -ctf ${tracefile}.args.ctf" \
+	    "Trace data saved to directory '${tracefile}.args.ctf'\.\\r" \
+	    "save ctf trace file"
+
+	foreach target_name ${trace_file_targets} {
+	    # Restart GDB and read the trace data in ${TARGET_NAME} target.
+	    gdb_exit
+	    gdb_start
+	    gdb_reinitialize_dir $srcdir/$subdir
+	    gdb_file_cmd $binfile
+	    gdb_test "target ${target_name} ${tracefile}.args.${target_name}" ".*" \
+		"change to ${target_name} target"
+
+	    with_test_prefix "${target_name}" {
+		gdb_test "tfind start" "#0  args_test_func .*" \
+		    "tfind test frame"
+		gdb_collect_args_test_1
+	    }
+	}
     }
 }
 
@@ -244,6 +270,8 @@ proc gdb_collect_locals_test_1 { func } {
 proc gdb_collect_locals_test { func msg } {
     with_test_prefix "unavailable locals: $msg" {
 	global gdb_prompt
+	global testfile srcdir subdir binfile
+	global trace_file_targets
 
 	prepare_for_trace_test
 
@@ -261,6 +289,30 @@ proc gdb_collect_locals_test { func msg } {
 	gdb_test "tfind none" \
 	    "#0  end .*" \
 	    "cease trace debugging"
+
+	set tracefile [standard_output_file ${testfile}]
+	gdb_test "tsave ${tracefile}.locals.tfile" \
+	    "Trace data saved to file '${tracefile}.locals.tfile'\.\\r" \
+	    "tsave ${testfile}.locals.tfile"
+	gdb_test "tsave -ctf ${tracefile}.locals.ctf" \
+	    "Trace data saved to directory '${tracefile}.locals.ctf'\.\\r" \
+	    "save ctf trace file"
+
+	foreach target_name ${trace_file_targets} {
+	    # Restart GDB and read the trace data in ${TARGET_NAME} target.
+	    gdb_exit
+	    gdb_start
+	    gdb_reinitialize_dir $srcdir/$subdir
+	    gdb_file_cmd $binfile
+	    gdb_test "target ${target_name} ${tracefile}.locals.${target_name}" ".*" \
+		"change to ${target_name} target"
+
+	    with_test_prefix "${target_name}" {
+		gdb_test "tfind start" "#0  $func .*" \
+		    "tfind test frame"
+		gdb_collect_locals_test_1 $func
+	    }
+	}
     }
 }
 
@@ -302,6 +354,8 @@ proc gdb_unavailable_registers_test_1 { } {
 
 proc gdb_unavailable_registers_test { } {
     with_test_prefix "unavailable registers" {
+	global testfile srcdir subdir binfile
+	global trace_file_targets
 
 	prepare_for_trace_test
 
@@ -318,6 +372,30 @@ proc gdb_unavailable_registers_test { } {
 	gdb_unavailable_registers_test_1
 
 	gdb_test "tfind none" "#0  end .*" "cease trace debugging"
+
+	set tracefile [standard_output_file ${testfile}]
+	gdb_test "tsave ${tracefile}.registers.tfile" \
+	    "Trace data saved to file '${tracefile}.registers.tfile'\.\\r" \
+	    "tsave ${testfile}.registers.tfile"
+	gdb_test "tsave -ctf ${tracefile}.registers.ctf" \
+	    "Trace data saved to directory '${tracefile}.registers.ctf'\.\\r" \
+	    "save ctf trace file"
+
+	foreach target_name ${trace_file_targets} {
+	    # Restart GDB and read the trace data in ${TARGET_NAME} target.
+	    gdb_exit
+	    gdb_start
+	    gdb_reinitialize_dir $srcdir/$subdir
+	    gdb_file_cmd $binfile
+	    gdb_test "target ${target_name} ${tracefile}.registers.${target_name}" ".*" \
+		"change to ${target_name} target"
+
+	    with_test_prefix "${target_name}" {
+		gdb_test "tfind start" "#0  globals_test_func .*" \
+		    "tfind test frame"
+		gdb_unavailable_registers_test_1
+	    }
+	}
     }
 }
 
@@ -340,6 +418,9 @@ proc gdb_unavailable_floats_1 { } {
 
 proc gdb_unavailable_floats { } {
     with_test_prefix "unavailable floats" {
+	global testfile srcdir subdir binfile
+	global trace_file_targets
+
 	prepare_for_trace_test
 
 	# We'll simply re-use the globals_test_function for this test
@@ -355,6 +436,30 @@ proc gdb_unavailable_floats { } {
 	gdb_unavailable_floats_1
 
 	gdb_test "tfind none" "#0  end .*" "cease trace debugging"
+
+	set tracefile [standard_output_file ${testfile}]
+	gdb_test "tsave ${tracefile}.floats.tfile" \
+	    "Trace data saved to file '${tracefile}.floats.tfile'\.\\r" \
+	    "tsave ${testfile}.floats.tfile"
+	gdb_test "tsave -ctf ${tracefile}.floats.ctf" \
+	    "Trace data saved to directory '${tracefile}.floats.ctf'\.\\r" \
+	    "save ctf trace file"
+
+	foreach target_name ${trace_file_targets} {
+	    # Restart GDB and read the trace data in ${TARGET_NAME} target.
+	    gdb_exit
+	    gdb_start
+	    gdb_reinitialize_dir $srcdir/$subdir
+	    gdb_file_cmd $binfile
+	    gdb_test "target ${target_name} ${tracefile}.floats.${target_name}" ".*" \
+		"change to ${target_name} target"
+
+	    with_test_prefix "${target_name}" {
+		gdb_test "tfind start" "#0  globals_test_func .*" \
+		    "tfind test frame"
+		gdb_unavailable_floats_1
+	    }
+	}
     }
 }
 
@@ -551,6 +656,9 @@ proc gdb_collect_globals_test_1 { } {
 
 proc gdb_collect_globals_test { } {
     with_test_prefix "collect globals" {
+	global testfile binfile srcdir subdir
+	global trace_file_targets
+
 	prepare_for_trace_test
 
 	set testline [gdb_get_line_number "set globals_test_func tracepoint here"]
@@ -596,6 +704,31 @@ proc gdb_collect_globals_test { } {
 	gdb_test "tfind none" \
 	    "#0  end .*" \
 	    "cease trace debugging"
+
+	set tracefile [standard_output_file ${testfile}]
+	gdb_test "tsave ${tracefile}.globals.tfile" \
+	    "Trace data saved to file '${tracefile}.globals.tfile'\.\\r" \
+	    "tsave ${testfile}.globals.tfile"
+	gdb_test "tsave -ctf ${tracefile}.globals.ctf" \
+	    "Trace data saved to directory '${tracefile}.globals.ctf'\.\\r" \
+	    "save ctf trace file"
+
+	foreach target_name ${trace_file_targets} {
+	    # Restart GDB and read the trace data in ${TARGET_NAME} target.
+	    gdb_exit
+	    gdb_start
+	    gdb_reinitialize_dir $srcdir/$subdir
+	    gdb_file_cmd $binfile
+	    gdb_test "target ${target_name} ${tracefile}.globals.${target_name}" ".*" \
+		"change to ${target_name} target"
+
+	    with_test_prefix "${target_name}" {
+		gdb_test "tfind start" "#0  globals_test_func .*" \
+		    "tfind test frame"
+		gdb_collect_globals_test_1
+	    }
+	}
+
     }
 }
 
@@ -617,6 +750,15 @@ if { ![gdb_target_supports_trace] } then {
     return 1
 }
 
+set trace_file_targets [list "tfile"]
+gdb_test_multiple "target ctf" "" {
+    -re "Undefined target command: \"ctf\"\.  Try \"help target\"\.\r\n$gdb_prompt $" {
+    }
+    -re "No CTF directory specified.*\r\n$gdb_prompt $" {
+	lappend trace_file_targets "ctf"
+    }
+}
+
 # Body of test encased in a proc so we can return prematurely.
 gdb_trace_collection_test
 
diff --git a/gdb/tracefile-tfile.c b/gdb/tracefile-tfile.c
index efa69b2..37dc691 100644
--- a/gdb/tracefile-tfile.c
+++ b/gdb/tracefile-tfile.c
@@ -853,6 +853,9 @@ tfile_xfer_partial (struct target_ops *ops, enum target_object object,
     {
       int pos = 0;
       enum target_xfer_status res;
+      /* Records the lowest available address of all blocks that
+	 intersects the requested range.  */
+      ULONGEST low_addr_available = 0;
 
       /* Iterate through the traceframe's blocks, looking for
 	 memory.  */
@@ -886,13 +889,19 @@ tfile_xfer_partial (struct target_ops *ops, enum target_object object,
 	      return TARGET_XFER_OK;
 	    }
 
+	  if (offset < maddr && maddr < (offset + len))
+	    if (low_addr_available == 0 || low_addr_available > maddr)
+	      low_addr_available = maddr;
+
 	  /* Skip over this block.  */
 	  pos += (8 + 2 + mlen);
 	}
 
       /* Requested memory is unavailable in the context of traceframes,
 	 and this address falls within a read-only section, fallback
-	 to reading from executable.  */
+	 to reading from executable, up to LOW_ADDR_AVAILABLE.  */
+      if (offset < low_addr_available)
+	len = min (len, low_addr_available - offset);
       res = exec_read_partial_read_only (readbuf, offset, len, xfered_len);
 
       if (res == TARGET_XFER_OK)