[PATCH] Skip argv0-symlink.exp on target argv[0] isn't available

[Yao Qi <yao@codesourcery.com>]

I see the following two fails on arm-none-eabi target, because argv[0]
isn't available.

print argv[0]^M
$1 = 0x1f78 "/dev/null"^M
(gdb) FAIL: gdb.base/argv0-symlink.exp: kept file symbolic link name

print argv[0]^M
$1 = 0x1f78 "/dev/null"^M
(gdb) FAIL: gdb.base/argv0-symlink.exp: kept directory symbolic link name

My first thought is to check [target_info exists noargs], and skip the
test if it returns true.  However, noargs is set in gdbserver board
files, so argv0-symlink.exp will be skipped on gdbserver board file.
The change is too aggressive.

When the program is running with gdbserver, argv[1] to argv[N] aren't
available, but argv[0] is.  Fortunately, argv0-symlink.exp only
requires argv[0].  argv0-symlink.exp can be run with gdbserver board
file, as what we do now.

What we need to check is whether argv[0] is available, so I add a new
proc gdb_has_argv0 to do so by starting a program, and check
argc/argv[0] to see whether argv[0] is available.

Dan fixed the similar problem by checking noargs, which is too strong.
https://sourceware.org/ml/gdb-patches/2010-02/msg00398.html as a
result, the test is skipped on gdbserver.  This patch fixed it too.

Re-run argv0-symlink.exp, scm-value.exp, and py-value.exp on x86-linux
(both native and gdbserver) and arm-none-eabi.  No fail on x86-linux,
and argv0-symlink.exp is skipped on arm-none-eabi target.

gdb/testsuite:

2014-10-16  Yao Qi  <yao@codesourcery.com>

	* gdb.base/argv0-symlink.exp: Skip it if gdb_has_argv0 return
	false.
	* gdb.guile/scm-value.exp (test_value_in_inferior): Don't
	check [target_info exists noargs], check [gdb_has_argv0]
	instead.
	* gdb.python/py-value.exp (test_value_in_inferior): Likewise.
	* lib/gdb.exp (gdb_has_argv0, gdb_has_argv0_1): New
	procedures.
---
 gdb/testsuite/gdb.base/argv0-symlink.exp |  5 ++
 gdb/testsuite/gdb.guile/scm-value.exp    |  5 +-
 gdb/testsuite/gdb.python/py-value.exp    |  5 +-
 gdb/testsuite/lib/gdb.exp                | 79 ++++++++++++++++++++++++++++++++
 4 files changed, 92 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.base/argv0-symlink.exp b/gdb/testsuite/gdb.base/argv0-symlink.exp
index d849b4c..183fd70 100644
--- a/gdb/testsuite/gdb.base/argv0-symlink.exp
+++ b/gdb/testsuite/gdb.base/argv0-symlink.exp
@@ -13,6 +13,11 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+if { ![gdb_has_argv0] } {
+    unsupported "Can't get argv\[0\]."
+    return
+}
+
 standard_testfile
 
 if { [build_executable ${testfile}.exp ${testfile} ${srcfile}] == -1 } {
diff --git a/gdb/testsuite/gdb.guile/scm-value.exp b/gdb/testsuite/gdb.guile/scm-value.exp
index ae80d1b..2b49134 100644
--- a/gdb/testsuite/gdb.guile/scm-value.exp
+++ b/gdb/testsuite/gdb.guile/scm-value.exp
@@ -20,6 +20,8 @@ load_lib gdb-guile.exp
 
 standard_testfile
 
+set has_argv0 [gdb_has_argv0]
+
 # Build inferior to language specification.
 # LANG is one of "c" or "c++".
 proc build_inferior {exefile lang} {
@@ -86,7 +88,8 @@ proc test_value_in_inferior {} {
 	"set arg0"
 
     # Check that the dereferenced value is sane.
-    if { ! [target_info exists noargs] } {
+    global has_argv0
+    if { $has_argv0 } {
 	gdb_test "gu (print arg0)" \
 	    "0x.*$testfile\"" "verify dereferenced value"
     }
diff --git a/gdb/testsuite/gdb.python/py-value.exp b/gdb/testsuite/gdb.python/py-value.exp
index 0d18bef..afa55a5 100644
--- a/gdb/testsuite/gdb.python/py-value.exp
+++ b/gdb/testsuite/gdb.python/py-value.exp
@@ -20,6 +20,8 @@ load_lib gdb-python.exp
 
 standard_testfile
 
+set has_argv0 [gdb_has_argv0]
+
 # Build inferior to language specification.
 # LANG is one of "c" or "c++".
 proc build_inferior {exefile lang} {
@@ -221,7 +223,8 @@ proc test_value_in_inferior {} {
   gdb_py_test_silent_cmd "python arg0 = argv.dereference ()" "dereference value" 1
 
   # Check that the dereferenced value is sane
-  if { ! [target_info exists noargs] } {
+  global has_argv0
+  if { $has_argv0 } {
     gdb_test "python print (arg0)" "0x.*$testfile\"" "verify dereferenced value"
   }
 
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 7b2a402..dd525dc 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -4227,6 +4227,85 @@ gdb_caching_proc gdb_skip_xml_test {
     return $xml_missing
 }
 
+# Return true if argv[0] is available.
+
+gdb_caching_proc gdb_has_argv0 {
+    set result 0
+
+    # Set up, compile, and execute a test program to check whether
+    # argv[0] is available.
+    set src [standard_temp_file has_argv0[pid].c]
+    set exe [standard_temp_file has_argv0[pid].x]
+
+    gdb_produce_source $src {
+	int main (int argc, char **argv) {
+	    return 0;
+	}
+    }
+
+    gdb_compile $src $exe executable {debug}
+
+    # Helper proc.
+    proc gdb_has_argv0_1 { exe } {
+	global srcdir subdir
+	global gdb_prompt hex decimal
+
+	gdb_exit
+	gdb_start
+	gdb_reinitialize_dir $srcdir/$subdir
+	gdb_load "$exe"
+
+	# Set breakpoint on main.
+	send_gdb "break main\n"
+	gdb_expect {
+	    -re "Breakpoint.*${gdb_prompt} $" {
+	    }
+	    -re "${gdb_prompt} $" {
+		return 0
+	    }
+	}
+
+	# Run to main.
+	gdb_run_cmd
+	gdb_expect {
+	    -re "Breakpoint.*${gdb_prompt} $" {
+	    }
+	    -re "${gdb_prompt} $" {
+		return 0
+	    }
+	}
+
+	# Check whether argc is 1.
+	send_gdb "p argc\n"
+	gdb_expect {
+	    -re " = 1\r\n${gdb_prompt} $" {
+
+		send_gdb "p argv\[0\]\n"
+		gdb_expect {
+		    -re " = $hex \".*$exe\"\r\n${gdb_prompt} $" {
+			return 1
+		    }
+		    -re "${gdb_prompt} $" {
+			return 0
+		    }
+		}
+	    }
+	    -re "${gdb_prompt} $" {
+		return 0
+	    }
+	}
+	return 0
+    }
+
+    set result [gdb_has_argv0_1 $exe]
+
+    gdb_exit
+    file delete $src
+    file delete $exe
+
+    return $result
+}
+
 # Note: the procedure gdb_gnu_strip_debug will produce an executable called
 # ${binfile}.dbglnk, which is just like the executable ($binfile) but without
 # the debuginfo. Instead $binfile has a .gnu_debuglink section which contains
-- 
1.9.3