src/gdb ChangeLog breakpoint.c c-lang.c corefi ...

[palves at sourceware dot org]

CVSROOT:	/cvs/src
Module name:	src
Changes by:	palves@sourceware.org	2013-10-09 17:00:00

Modified files:
	gdb            : ChangeLog breakpoint.c c-lang.c corefile.c 
	                 gdbcore.h target.c target.h valprint.c 
	gdb/testsuite  : ChangeLog 
	gdb/testsuite/gdb.python: py-prettyprint.exp 

Log message:
	Stop using errno values around target_xfer interfaces and memory errors.
	
	target_read_memory & friends build on top of target_read (thus on top
	of the target_xfer machinery), but turn all errors to EIO, an errno
	value.  I think we'd better convert all these to return a
	target_xfer_error too, like target_xfer_partial in a previous patch.
	The patch starts by doing that.
	
	(The patch does not add a enum target_xfer_error value for '0'/no
	error, and likewise does not change the return type of several of
	these functions to enum target_xfer_error, because different functions
	return '0' with different semantics.)
	
	I audited the tree for memory_error calls, EIO checks, places where
	GDB hardcodes 'errno = EIO', and also for strerror calls.  What I
	found is that nowadays there's really no need to handle random errno
	values, other than the EIOs gdb itself hardcodes.  No doubt errno
	values would appear in common code back in the day when
	target_xfer_memory was the main interface to access memory, but
	nowadays, any errno value that deprecated interface could return is
	just absorved by default_xfer_partial:
	
	else if (xfered == 0 && errno == 0)
	/* "deprecated_xfer_memory" uses 0, cross checked against
	ERRNO as one indication of an error.  */
	return 0;
	else
	return -1;
	
	There are two places in the code that check for EIO and print "out of
	bounds", and defer to strerror for other errors.  That's
	c-lang.c:c_get_string, and valprint.c.:val_print_string.  AFAICT, the
	strerror branch can never be reached nowadays, as the only error
	possible to get at those points is EIO, given that it's GDB itself
	that set that errno value (in target_read_memory, etc.).
	
	breakpoint.c:insert_bp_location always prints the error val as if an
	errno, returned by target_insert_breakpoint, with strerr.  Now the
	error here is either always EIO for mem-break.c targets (again
	hardcoded by the target_read_memory/target_write_memory functions), so
	this always prints "Input/output error" or similar (depending on
	host), or, for remote targets (and probably others), this gem:
	
	Error accessing memory address 0x80200400: Unknown error -1.
	
	This patch makes these 3 places print the exact same error
	memory_error prints.  This changes output, but I think this is better,
	for making memory error output consistent with other commands, and, it
	means we have a central place to tweak for memory errors.
	
	E.g., this changes:
	
	Cannot insert breakpoint 1.
	Error accessing memory address 0x5fc660: Input/output error.
	
	to:
	
	Cannot insert breakpoint 1.
	Cannot access memory at address 0x5fc660
	
	Which I find pretty much acceptable.
	
	Surprisingly, only py-prettyprint.exp had a regression, for needing an
	adjustment.  I also grepped the testsuite for the old errors, and
	found no other hits.
	
	Now that errno values aren't used anywhere in any of these memory
	access related routines, I made memory_error itself take a
	target_xfer_error instead of an errno.  The new
	target_xfer_memory_error function added recently is no longer
	necessary, and is thus removed.
	
	Tested on x86_64 Fedora 17, native and gdbserver.
	
	gdb/
	2013-10-09  Pedro Alves  <palves@redhat.com>
	
	* breakpoint.c (insert_bp_location): Use memory_error_message to
	build the memory error string.
	* c-lang.c: Include "gdbcore.h".
	(c_get_string): Use memory_error to throw error.
	(target_xfer_memory_error): Delete.
	(memory_error_message): New, factored out from
	target_xfer_memory_error.
	(memory_error): Change parameter type to target_xfer_error.
	Rewrite.
	(read_memory): Use memory_error instead of
	target_xfer_memory_error.
	* gdbcore.h: Include "target.h".
	(memory_error): Change parameter type to target_xfer_error.
	(memory_error_message): Declare function.
	* target.c (target_read_memory, target_read_stack)
	(target_write_memory, target_write_raw_memory): Return
	TARGET_XFER_E_IO on error.  Adjust comments.
	(get_target_memory): Pass TARGET_XFER_E_IO to memory_error,
	instead of EIO.
	* target.h (target_read, target_insert_breakpoint)
	(target_remove_breakpoint): Adjust comments.
	* valprint.c (partial_memory_read): Rename parameter, and adjust
	comment.
	(val_print_string): Use memory_error_message to build the memory
	error string.
	
	gdb/testsuite/
	2013-10-09  Pedro Alves  <palves@redhat.com>
	
	* gdb.python/py-prettyprint.exp (run_lang_tests): Adjust expected
	output.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/ChangeLog.diff?cvsroot=src&r1=1.16088&r2=1.16089
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/breakpoint.c.diff?cvsroot=src&r1=1.780&r2=1.781
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/c-lang.c.diff?cvsroot=src&r1=1.108&r2=1.109
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/corefile.c.diff?cvsroot=src&r1=1.75&r2=1.76
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/gdbcore.h.diff?cvsroot=src&r1=1.46&r2=1.47
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/target.c.diff?cvsroot=src&r1=1.349&r2=1.350
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/target.h.diff?cvsroot=src&r1=1.273&r2=1.274
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/valprint.c.diff?cvsroot=src&r1=1.140&r2=1.141
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/ChangeLog.diff?cvsroot=src&r1=1.3829&r2=1.3830
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/gdb.python/py-prettyprint.exp.diff?cvsroot=src&r1=1.30&r2=1.31