Re: [PATCH] Fix calling gcore when gdb is not in $PATH.

[Luis Machado <lgustavo@codesourcery.com>]

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On 10/11/2013 04:00 PM, Jan Kratochvil wrote:
> On Fri, 11 Oct 2013 20:22:05 +0200, Luis Machado wrote:
>> Hmmm... unless there is some discrepancy between shell interpreters,
>> mine (bash) does the following:
>
> OK, true, it works thanks to the 'which' command there.
>
> But then why you have there the conditional
> 	if test "x$binary_path" = x. ; then
> ?
> You can run the 'which' block every time and it will work.

That's true. Though i've noticed that the following gives an unexpected 
result...

Invocation: sh gcore (with gcore living in ".")
The /usr/bin/gdb binary gets picked up, because "which gcore" returns 
nothing even if gcore lives in ".". *sigh*.

An additional check needs to be done. The attached update patch 
accomplishes this. It seems to cover all the scenarios.

I decided to add a chunk of code to error out in case the correct GDB 
binary is not found.

Thoughts?

Luis

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2013-10-14  Luis Machado  <lgustavo@codesourcery.com>

	* gcore.in: Call GDB using the full path to the gcore script.
	Error out if the GDB binary is not found.

diff --git a/gdb/gcore.in b/gdb/gcore.in
index 9c5b14d..cbc8f06 100644
--- a/gdb/gcore.in
+++ b/gdb/gcore.in
@@ -43,6 +43,40 @@ then
     shift; shift
 fi
 
+# Attempt to fetch the absolute path to the gcore script that was
+# called.
+binary_path=`dirname "$0"`
+
+if test "x$binary_path" = x. ; then
+  # We got "." back as a path.  This means the user executed
+  # the gcore script locally (i.e. ./gcore) or called the
+  # script via a shell interpreter (i.e. sh gcore).
+  binary_basename=`basename "$0"`
+
+  # If the gcore script was called like "sh gcore" and the script
+  # lives in the current directory, "which" will not give us "gcore".
+  # So first we check if the script is in the current directory
+  # before using the output "which".
+  if test -f "$binary_basename" ; then
+    # We have a local gcore script in ".".  This covers the case of
+    # doing "./gcore" or "sh gcore".
+    binary_path="."
+  else
+    # The gcore script was not found in ".", which means the script
+    # was called from somewhere else in $PATH.  Extract the correct
+    # path now.
+    binary_path_from_env=`which "$0"`
+    binary_path=`dirname "$binary_path_from_env"`
+  fi
+fi
+
+# Check if the GDB binary is in the expected path.  If not, just
+# quit with a message.
+if [ ! -f "$binary_path"/@GDB_TRANSFORM_NAME@ ]; then
+  echo "gcore: GDB binary (${binary_path}/@GDB_TRANSFORM_NAME@) not found"
+  exit 1
+fi
+
 # Initialise return code.
 rc=0
 
@@ -51,7 +85,7 @@ for pid in $*
 do
 	# `</dev/null' to avoid touching interactive terminal if it is
 	# available but not accessible as GDB would get stopped on SIGTTIN.
-	@GDB_TRANSFORM_NAME@ </dev/null --nx --batch \
+	$binary_path/@GDB_TRANSFORM_NAME@ </dev/null --nx --batch \
 	    -ex "set pagination off" -ex "set height 0" -ex "set width 0" \
 	    -ex "attach $pid" -ex "gcore $name.$pid" -ex detach -ex quit