Don't throw Scheme exceptions with live std::vector objects
A complication with the Guile code is that we have two types of
exceptions to consider: GDB/C++ exceptions, and Guile/SJLJ exceptions.
Because Guile exceptions are SJLJ based, we must make sure to not have
live local variables of types with non-trivial dtors when a Guile
exception is thrown, because the dtors won't be run when a Guile
exceptions is thrown.
gdbscm_parse_function_args currently violates this:
void
gdbscm_parse_function_args (const char *func_name,
int beginning_arg_pos,
const SCM *keywords,
const char *format, ...)
{
...
/* Keep track of malloc'd strings. We need to free them upon error. */
std::vector<char *> allocated_strings;
...
for (char *ptr : allocated_strings)
xfree (ptr);
gdbscm_throw (status); /// dtor of "allocated_strings" is not run!
}
This commit fixes the above making using of gdbscm_wrap.
It would be nice if we had a way to make it impossible to write such
code. PR guile/23429 has an idea for that, if someone's interested.
gdb/ChangeLog:
2018-08-21 Pedro Alves <palves@redhat.com>
* guile/scm-utils.c (gdbscm_parse_function_args_1): New, factored
out from gdbscm_parse_function_args.
(gdbscm_parse_function_args): Rework to use gdbscm_wrap and
gdbscm_parse_function_args_1.
This commit is contained in:
Pedro Alves
parent
ae19acf320
commit
4895f384b4
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@ -1,3 +1,10 @@
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2018-08-21 Pedro Alves <palves@redhat.com>
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* guile/scm-utils.c (gdbscm_parse_function_args_1): New, factored
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out from gdbscm_parse_function_args.
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(gdbscm_parse_function_args): Rework to use gdbscm_wrap and
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gdbscm_parse_function_args_1.
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2018-08-21 Simon Marchi <simon.marchi@ericsson.com>
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PR gdb/17816
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@ -306,80 +306,18 @@ lookup_keyword (const SCM *keyword_list, SCM keyword)
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return -1;
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}
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/* Utility to parse required, optional, and keyword arguments to Scheme
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functions. Modelled on PyArg_ParseTupleAndKeywords, but no attempt is made
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at similarity or functionality.
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There is no result, if there's an error a Scheme exception is thrown.
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Guile provides scm_c_bind_keyword_arguments, and feel free to use it.
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This is for times when we want a bit more parsing.
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/* Helper for gdbscm_parse_function_args that does most of the work,
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in a separate function wrapped with gdbscm_wrap so that we can use
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non-trivial-dtor objects here. The result is #f upon success or a
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<gdb:exception> object otherwise. */
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BEGINNING_ARG_POS is the position of the first argument passed to this
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routine. It should be one of the SCM_ARGn values. It could be > SCM_ARG1
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if the caller chooses not to parse one or more required arguments.
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KEYWORDS may be NULL if there are no keywords.
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FORMAT:
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s - string -> char *, malloc'd
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t - boolean (gdb uses "t", for biT?) -> int
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i - int
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u - unsigned int
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l - long
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n - unsigned long
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L - longest
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U - unsigned longest
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O - random scheme object
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| - indicates the next set is for optional arguments
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# - indicates the next set is for keyword arguments (must follow |)
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. - indicates "rest" arguments are present, this character must appear last
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FORMAT must match the definition from scm_c_{make,define}_gsubr.
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Required and optional arguments appear in order in the format string.
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Afterwards, keyword-based arguments are processed. There must be as many
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remaining characters in the format string as their are keywords.
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Except for "|#.", the number of characters in the format string must match
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#required + #optional + #keywords.
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The function is required to be defined in a compatible manner:
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#required-args and #optional-arguments must match, and rest-arguments
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must be specified if keyword args are desired, and/or regular "rest" args.
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Example: For this function,
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scm_c_define_gsubr ("execute", 2, 3, 1, foo);
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the format string + keyword list could be any of:
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1) "ss|ttt#tt", { "key1", "key2", NULL }
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2) "ss|ttt.", { NULL }
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3) "ss|ttt#t.", { "key1", NULL }
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For required and optional args pass the SCM of the argument, and a
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pointer to the value to hold the parsed result (type depends on format
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char). After that pass the SCM containing the "rest" arguments followed
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by pointers to values to hold parsed keyword arguments, and if specified
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a pointer to hold the remaining contents of "rest".
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For keyword arguments pass two pointers: the first is a pointer to an int
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that will contain the position of the argument in the arg list, and the
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second will contain result of processing the argument. The int pointed
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to by the first value should be initialized to -1. It can then be used
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to tell whether the keyword was present.
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If both keyword and rest arguments are present, the caller must pass a
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pointer to contain the new value of rest (after keyword args have been
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removed).
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There's currently no way, that I know of, to specify default values for
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optional arguments in C-provided functions. At the moment they're a
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work-in-progress. The caller should test SCM_UNBNDP for each optional
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argument. Unbound optional arguments are ignored. */
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void
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gdbscm_parse_function_args (const char *func_name,
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int beginning_arg_pos,
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const SCM *keywords,
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const char *format, ...)
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static SCM
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gdbscm_parse_function_args_1 (const char *func_name,
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int beginning_arg_pos,
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const SCM *keywords,
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const char *format, va_list args)
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{
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va_list args;
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const char *p;
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int i, have_rest, num_keywords, position;
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int have_optional = 0;
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@ -391,8 +329,6 @@ gdbscm_parse_function_args (const char *func_name,
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have_rest = validate_arg_format (format);
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num_keywords = count_keywords (keywords);
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va_start (args, format);
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p = format;
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position = beginning_arg_pos;
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@ -511,15 +447,100 @@ gdbscm_parse_function_args (const char *func_name,
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}
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}
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va_end (args);
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return;
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/* Return anything not-an-exception. */
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return SCM_BOOL_F;
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fail:
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va_end (args);
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for (char *ptr : allocated_strings)
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xfree (ptr);
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gdbscm_throw (status);
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/* Return the exception, which gdbscm_wrap takes care of
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throwing. */
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return status;
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}
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/* Utility to parse required, optional, and keyword arguments to Scheme
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functions. Modelled on PyArg_ParseTupleAndKeywords, but no attempt is made
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at similarity or functionality.
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There is no result, if there's an error a Scheme exception is thrown.
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Guile provides scm_c_bind_keyword_arguments, and feel free to use it.
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This is for times when we want a bit more parsing.
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BEGINNING_ARG_POS is the position of the first argument passed to this
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routine. It should be one of the SCM_ARGn values. It could be > SCM_ARG1
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if the caller chooses not to parse one or more required arguments.
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KEYWORDS may be NULL if there are no keywords.
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FORMAT:
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s - string -> char *, malloc'd
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t - boolean (gdb uses "t", for biT?) -> int
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i - int
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u - unsigned int
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l - long
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n - unsigned long
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L - longest
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U - unsigned longest
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O - random scheme object
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| - indicates the next set is for optional arguments
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# - indicates the next set is for keyword arguments (must follow |)
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. - indicates "rest" arguments are present, this character must appear last
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FORMAT must match the definition from scm_c_{make,define}_gsubr.
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Required and optional arguments appear in order in the format string.
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Afterwards, keyword-based arguments are processed. There must be as many
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remaining characters in the format string as their are keywords.
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Except for "|#.", the number of characters in the format string must match
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#required + #optional + #keywords.
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The function is required to be defined in a compatible manner:
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#required-args and #optional-arguments must match, and rest-arguments
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must be specified if keyword args are desired, and/or regular "rest" args.
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Example: For this function,
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scm_c_define_gsubr ("execute", 2, 3, 1, foo);
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the format string + keyword list could be any of:
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1) "ss|ttt#tt", { "key1", "key2", NULL }
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2) "ss|ttt.", { NULL }
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3) "ss|ttt#t.", { "key1", NULL }
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For required and optional args pass the SCM of the argument, and a
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pointer to the value to hold the parsed result (type depends on format
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char). After that pass the SCM containing the "rest" arguments followed
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by pointers to values to hold parsed keyword arguments, and if specified
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a pointer to hold the remaining contents of "rest".
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For keyword arguments pass two pointers: the first is a pointer to an int
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that will contain the position of the argument in the arg list, and the
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second will contain result of processing the argument. The int pointed
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to by the first value should be initialized to -1. It can then be used
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to tell whether the keyword was present.
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If both keyword and rest arguments are present, the caller must pass a
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pointer to contain the new value of rest (after keyword args have been
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removed).
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There's currently no way, that I know of, to specify default values for
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optional arguments in C-provided functions. At the moment they're a
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work-in-progress. The caller should test SCM_UNBNDP for each optional
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argument. Unbound optional arguments are ignored. */
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void
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gdbscm_parse_function_args (const char *func_name,
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int beginning_arg_pos,
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const SCM *keywords,
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const char *format, ...)
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{
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va_list args;
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va_start (args, format);
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gdbscm_wrap (gdbscm_parse_function_args_1, func_name,
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beginning_arg_pos, keywords, format, args);
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va_end (args);
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}
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/* Return longest L as a scheme object. */
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