Re: [PATCH v4 2/9] Explicit locations: introduce new struct event_location-based API

Doug Evans
2015-05-17T20:54:51Z

Keith Seitz <keiths@redhat.com> writes:
> This patch introduces the new breakpoint/"linespec" API based on
> a new struct event_location. This API currently only supports
> traditional linespecs, maintaining the status quo of the code base.
> Future patches will add additional functionality for other location
> types such as address locations.

Hi. Just a couple of nits and a couple of questions.
I wrote down a question for myself below.
I haven't read the entire series yet.

>
> gdb/ChangeLog:
>
> * Makefile.in (SFILES): Add location.c.
> (HFILES_NO_SRCDIR): Add location.h.
> (COMMON_OBS): Add location.o.
> * linespec.c (linespec_lex_to_end): New function.
> * linespec.c (linespec_lex_to_end): Declare.

typo: linespec.h

> * location.c: New file.
> * location.h: New file.
>...
>
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 95104ef..0a51564 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -851,7 +851,7 @@ SFILES = ada-exp.y ada-lang.c ada-typeprint.c ada-valprint.c ada-tasks.c \
> inline-frame.c \
> interps.c \
> jv-exp.y jv-lang.c jv-valprint.c jv-typeprint.c jv-varobj.c \
> - language.c linespec.c minidebug.c \
> + language.c linespec.c location.c minidebug.c \
> m2-exp.y m2-lang.c m2-typeprint.c m2-valprint.c \
> macrotab.c macroexp.c macrocmd.c macroscope.c main.c maint.c \
> mdebugread.c memattr.c mem-break.c minsyms.c mipsread.c memory-map.c \
> @@ -937,7 +937,7 @@ mi/mi-out.h mi/mi-main.h mi/mi-common.h mi/mi-cmds.h linux-nat.h \
> complaints.h gdb_proc_service.h gdb_regex.h xtensa-tdep.h inf-loop.h \
> common/gdb_wait.h common/gdb_assert.h solib.h ppc-tdep.h cp-support.h glibc-tdep.h \
> interps.h auxv.h gdbcmd.h tramp-frame.h mipsnbsd-tdep.h \
> -amd64-linux-tdep.h linespec.h i387-tdep.h mn10300-tdep.h \
> +amd64-linux-tdep.h linespec.h location.h i387-tdep.h mn10300-tdep.h \
> sparc64-tdep.h monitor.h ppcobsd-tdep.h srec.h \
> coff-pe-read.h parser-defs.h gdb_ptrace.h mips-linux-tdep.h \
> m68k-tdep.h spu-tdep.h jv-lang.h environ.h amd64-tdep.h \
> @@ -1021,7 +1021,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
> source.o value.o eval.o valops.o valarith.o valprint.o printcmd.o \
> block.o symtab.o psymtab.o symfile.o symfile-debug.o symmisc.o \
> linespec.o dictionary.o \
> - infcall.o \
> + location.o infcall.o \
> infcmd.o infrun.o \
> expprint.o environ.o stack.o thread.o \
> exceptions.o \
> diff --git a/gdb/linespec.c b/gdb/linespec.c
> index d2089b5..a480be1 100644
> --- a/gdb/linespec.c
> +++ b/gdb/linespec.c
> @@ -2435,6 +2435,61 @@ linespec_parser_delete (void *arg)
> linespec_state_destructor (PARSER_STATE (parser));
> }
>
> +/* See description in linespec.h. */
> +
> +void
> +linespec_lex_to_end (char **stringp)
> +{
> + linespec_parser parser;
> + struct cleanup *cleanup;
> + linespec_token token;
> + volatile struct gdb_exception e;
> + const char *orig;
> +
> + if (stringp == NULL || *stringp == NULL)
> + return;
> +
> + linespec_parser_new (&parser, 0, current_language, NULL, 0, NULL);
> + cleanup = make_cleanup (linespec_parser_delete, &parser);
> + parser.lexer.saved_arg = *stringp;
> + PARSER_STREAM (&parser) = orig = *stringp;
> +
> + TRY
> + {
> + do
> + {
> + /* Stop before any comma tokens; we need it to keep it
> + as the next token in the string. */
> + token = linespec_lexer_peek_token (&parser);
> + if (token.type == LSTOKEN_COMMA)
> + break;
> +
> + /* For addresses advance the parser stream past
> + any parsed input and stop lexing. */
> + if (token.type == LSTOKEN_STRING
> + && *LS_TOKEN_STOKEN (token).ptr == '*')
> + {
> + const char *arg;
> +
> + arg = *stringp;
> + (void) linespec_expression_to_pc (&arg);
> + PARSER_STREAM (&parser) = arg;
> + break;
> + }
> +
> + token = linespec_lexer_consume_token (&parser);
> + }
> + while (token.type != LSTOKEN_EOI && token.type != LSTOKEN_KEYWORD);
> + }
> + CATCH (e, RETURN_MASK_ERROR)
> + {

I'm guessing I'm missing something here.
Is the intent to ignore errors here?

> + }
> + END_CATCH
> +
> + *stringp += PARSER_STREAM (&parser) - orig;
> + do_cleanups (cleanup);
> +}
> +
> /* See linespec.h. */
>
> void
> diff --git a/gdb/linespec.h b/gdb/linespec.h
> index 7e66024..77ec46d 100644
> --- a/gdb/linespec.h
> +++ b/gdb/linespec.h
> @@ -156,4 +156,9 @@ extern struct symtabs_and_lines decode_line_with_last_displayed (char *, int);
> the keyword. If not, return NULL. */
>
> extern const char *linespec_lexer_lex_keyword (const char *p);
> +
> +/* Find the end of the (first) linespec pointed to by *STRINGP.
> + STRINGP will be advanced to this point. */
> +
> +extern void linespec_lex_to_end (char **stringp);
> #endif /* defined (LINESPEC_H) */
> diff --git a/gdb/location.c b/gdb/location.c
> new file mode 100644
> index 0000000..39e09c1
> --- /dev/null
> +++ b/gdb/location.c
> @@ -0,0 +1,234 @@
> +/* Data structures and API for event locations in GDB.
> + Copyright (C) 2013-2015 Free Software Foundation, Inc.
> +
> + This file is part of GDB.
> +
> + This program is free software; you can redistribute it and/or modify
> + it under the terms of the GNU General Public License as published by
> + the Free Software Foundation; either version 3 of the License, or
> + (at your option) any later version.
> +
> + This program is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + GNU General Public License for more details.
> +
> + You should have received a copy of the GNU General Public License
> + along with this program. If not, see <http://www.gnu.org/licenses/>. */
> +
> +#include "defs.h"
> +#include "gdb_assert.h"
> +#include "location.h"
> +#include "symtab.h"
> +#include "language.h"
> +#include "linespec.h"
> +#include "cli/cli-utils.h"
> +#include "probe.h"
> +
> +#include <ctype.h>
> +#include <string.h>
> +
> +/* An event location used to set a stop event in the inferior.
> + This structure is an amalgam of the various ways
> + to specify where a stop event should be set. */
> +
> +struct event_location
> +{
> + /* The type of this breakpoint specification. */
> + enum event_location_type type;
> +#define EL_TYPE(PTR) (PTR)->type
> +
> + union
> + {
> + /* A generic "this is a string specification" for a location.
> + This representation is used by both "normal" linespecs and
> + probes. */
> + char *addr_string;
> +#define EL_LINESPEC(PTR) ((PTR)->u.addr_string)
> + } u;
> +
> + /* Cached string representation of this location. This is used, e.g., to
> + save stop event locations to file. Malloc'd. */
> + char *as_string;
> +#define EL_STRING(PTR) ((PTR)->as_string)
> +};
> +
> +/* See description in location.h. */
> +
> +enum event_location_type
> +event_location_type (const struct event_location *location)
> +{
> + return EL_TYPE (location);
> +}
> +
> +/* See description in location.h. */
> +
> +struct event_location *
> +new_linespec_location (char **linespec)
> +{
> + struct event_location *location;
> +
> + location = XCNEW (struct event_location);
> + EL_TYPE (location) = LINESPEC_LOCATION;
> + if (*linespec != NULL)
> + {
> + char *p;
> + char *orig = *linespec;
> +
> + linespec_lex_to_end (linespec);
> + p = remove_trailing_whitespace (orig, *linespec);
> + if ((p - orig) > 0)
> + EL_LINESPEC (location) = savestring (orig, p - orig);
> + }
> + return location;
> +}
> +
> +/* See description in location.h. */
> +
> +const char *
> +get_linespec_location (const struct event_location *location)
> +{
> + gdb_assert (EL_TYPE (location) == LINESPEC_LOCATION);
> + return EL_LINESPEC (location);
> +}
> +
> +/* See description in location.h. */
> +
> +struct event_location *
> +copy_event_location (const struct event_location *src)
> +{
> + struct event_location *dst;
> +
> + dst = XCNEW (struct event_location);
> + EL_TYPE (dst) = EL_TYPE (src);
> + if (EL_STRING (src) != NULL)
> + EL_STRING (dst) = xstrdup (EL_STRING (src));
> +
> + switch (EL_TYPE (src))
> + {
> + case LINESPEC_LOCATION:
> + if (EL_LINESPEC (src) != NULL)
> + EL_LINESPEC (dst) = xstrdup (EL_LINESPEC (src));
> + break;
> +
> + default:
> + gdb_assert_not_reached ("unknown event location type");
> + }
> +
> + return dst;
> +}
> +
> +/* A cleanup function for struct event_location. */
> +
> +static void
> +delete_event_location_cleanup (void *data)
> +{
> + struct event_location *location = (struct event_location *) data;
> +
> + delete_event_location (location);
> +}
> +
> +/* See description in location.h. */
> +
> +struct cleanup *
> +make_cleanup_delete_event_location (struct event_location *location)
> +{
> + return make_cleanup (delete_event_location_cleanup, location);
> +}
> +
> +/* See description in location.h. */
> +
> +void
> +delete_event_location (struct event_location *location)
> +{
> + if (location != NULL)
> + {
> + xfree (EL_STRING (location));
> +
> + switch (EL_TYPE (location))
> + {
> + case LINESPEC_LOCATION:
> + xfree (EL_LINESPEC (location));
> + break;
> +
> + default:
> + gdb_assert_not_reached ("unknown event location type");
> + }
> +
> + xfree (location);
> + }
> +}
> +
> +/* See description in location.h. */
> +
> +char *
> +event_location_to_string_const (const struct event_location *location)
> +{
> + char *result = NULL;
> +
> + if (EL_STRING (location) != NULL)
> + return xstrdup (EL_STRING (location));
> +
> + switch (EL_TYPE (location))
> + {
> + case LINESPEC_LOCATION:
> + if (EL_LINESPEC (location) != NULL)
> + result = xstrdup (EL_LINESPEC (location));
> + break;
> +
> + default:
> + gdb_assert_not_reached ("unknown event location type");
> + }
> +
> + return result;
> +}
> +
> +/* See description in location.h. */
> +
> +const char *
> +event_location_to_string (struct event_location *location)
> +{
> + /* Cache a copy of the string representation. */
> + if (EL_STRING (location) == NULL)
> + EL_STRING (location) = event_location_to_string_const (location);
> +
> + return EL_STRING (location);
> +}
> +
> +/* See description in location.h. */
> +
> +struct event_location *
> +string_to_event_location (char **stringp,
> + const struct language_defn *language)
> +{
> + struct event_location *location;
> +
> + location = new_linespec_location (stringp);
> + return location;
> +}
> +
> +/* See description in location.h. */
> +
> +int
> +event_location_empty_p (const struct event_location *location)
> +{
> + switch (EL_TYPE (location))
> + {
> + case LINESPEC_LOCATION:
> + /* Linespecs are never "empty." (NULL is a valid linespec) */
> + return 0;
> +
> + default:
> + gdb_assert_not_reached ("unknown event location type");
> + }
> +}
> +
> +/* See description in location.h. */
> +
> +void
> +set_event_location_string (struct event_location *location,
> + const char *string)
> +{
> + xfree (EL_STRING (location));
> + EL_STRING (location) = string == NULL ? NULL : xstrdup (string);
> +}
> diff --git a/gdb/location.h b/gdb/location.h
> new file mode 100644
> index 0000000..992f21e
> --- /dev/null
> +++ b/gdb/location.h
> @@ -0,0 +1,113 @@
> +/* Data structures and API for event locations in GDB.
> + Copyright (C) 2013-2015 Free Software Foundation, Inc.
> +
> + This file is part of GDB.
> +
> + This program is free software; you can redistribute it and/or modify
> + it under the terms of the GNU General Public License as published by
> + the Free Software Foundation; either version 3 of the License, or
> + (at your option) any later version.
> +
> + This program is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + GNU General Public License for more details.
> +
> + You should have received a copy of the GNU General Public License
> + along with this program. If not, see <http://www.gnu.org/licenses/>. */
> +
> +#ifndef LOCATIONS_H
> +#define LOCATIONS_H 1
> +
> +struct language_defn;
> +struct event_location;
> +
> +/* An enumeration of the various ways to specify a stop event
> + location (used with create_breakpoint). */
> +
> +enum event_location_type
> +{
> + /* A traditional linespec. */
> + LINESPEC_LOCATION
> +};
> +
> +/* Return the type of the given event location. */
> +
> +extern enum event_location_type
> + event_location_type (const struct event_location *);
> +
> +/* Return a string representation of the LOCATION.
> + This function may return NULL for unspecified linespecs,
> + e.g, LOCATION_LINESPEC and addr_string is NULL.
> +
> + The result is cached in LOCATION. */
> +
> +extern const char *
> + event_location_to_string (struct event_location *location);
> +
> +/* A const version of event_location_to_string that will not cache
> + the resulting string representation. The result is malloc'd
> + and must be freed by the caller. */
> +
> +extern char *
> + event_location_to_string_const (const struct event_location *location);

Note to self: Do we need both non-const and const versions?
[e.g., treat cached value as mutable in c++ sense?]

> +
> +/* Create a new linespec location. The return result is malloc'd
> + and should be freed with delete_event_location. */
> +
> +extern struct event_location *
> + new_linespec_location (char **linespec);
> +
> +/* Return the linespec location (a string) of the given event_location
> + (which must be of type LINESPEC_LOCATION). */
> +
> +extern const char *
> + get_linespec_location (const struct event_location *location);
> +
> +/* Free an event location and any associated data. */
> +
> +extern void delete_event_location (struct event_location *location);
> +
> +/* Make a cleanup to free LOCATION. */
> +
> +extern struct cleanup *
> + make_cleanup_delete_event_location (struct event_location *location);
> +
> +/* Return a copy of the given SRC location. */
> +
> +extern struct event_location *
> + copy_event_location (const struct event_location *src);
> +
> +/* Allocate and "copy" the opaque struct event_location. This is used
> + when decoding locations which must parse their inputs. The return result
> + should be freed. */
> +
> +extern struct event_location *
> + copy_event_location_tmp (const struct event_location *src);

This function doesn't exist in this patch.

> +
> +/* Attempt to convert the input string in *ARGP into an event location.
> + ARGP is advanced past any processed input. Returns a event_location

nit: an event_location

> + (malloc'd) if an event location was successfully found in *ARGP,
> + NULL otherwise.
> +
> + This function may call error() if *ARGP looks like properly formed,
> + but invalid, input, e.g., if it is called with missing argument parameters
> + or invalid options.
> +
> + The return result must be freed with delete_event_location. */
> +
> +extern struct event_location *
> + string_to_event_location (char **argp,
> + const struct language_defn *langauge);
> +
> +/* A convenience function for testing for unset locations. */
> +
> +extern int event_location_empty_p (const struct event_location *location);
> +
> +/* Set the location's string representation. If STRING is NULL, clear
> + the string representation. */
> +
> +extern void
> + set_event_location_string (struct event_location *location,
> + const char *string);
> +#endif /* LOCATIONS_H */