On Wed, Aug 02, 2017 at 12:36:43PM +0700, Nikolay Marchuk wrote:
> This change introduces new filtering architecture primitives: filter,
> filter_action and bool_expression. Filtering is now done after decoding of
> syscall and tcp->qual_flg stores filtering results.
> 
> * basic_actions.c: New file.
> * basic_filters.c (number_isset): Return bool.
> (add_number_to_set): Make static.
> (qualify_syscall_number): Rename to parse_syscall_number.
> (qualify_syscall_regex): Rename to parse_syscall_regex.
> (qualify_syscall_class): Rename to parse_syscall_class.
> (qualify_syscall_name): Rename to parse_syscall_name.
> (qualify_syscall): Rename to parse_syscall, use renamed functions.
> (qualify_syscall_tokens): Rename to parse_syscall_set, make static,
> remove "name" argument (assume "system call").
> (qualify_tokens): Rename to parse_set.
> (parse_syscall_filter, parse_fd_filter, run_syscall_filter,
> run_fd_filter, free_syscall_filter, free_fd_filter): New functions.
> * defs.h (struct inject_opts): Add init flag.
> (QUAL_READ, QUAL_WRITE): Change description.
> (dump_read, dump_write): Add macros for checking QUAL_READ/QUAL_WRITE.
> (read_set, write_set): Remove global set variables.
> (qualify, qual_flags): Remove old declarations ...
> (filter_syscall, parse_qualify_filter, filtering_parsing_finish):
>  ... and add new declarations.
> * filter.c: New file.
> * filter.h: Change declarations.
> * filter_action.c: New file.
> * filter_expression.c: Likewise.
> * filter_qualify.c (read_set, write_set, abbrev_set, inject_set, raw_set,
> trace_set, verbose_set): Remove set variables.
> (parse_inject_expression): Remove function.
> (parse_inject_common_args): New function.
> (qualify_read): Rename to parse_read.
> (qualify_write): Rename to parse_write.
> (qualify_signals): Use parse_set function.
> (qualify_trace): Rename to parse_trace.
> (qualify_abbrev): Rename to parse_abbrev.
> (qualify_verbose): Rename to parse_verbose.
> (qualify_raw): Rename to parse_raw.
> (qualify_inject_common): Rename to parse_inject_common, use new filters.
> (qualify_fault): Rename to parse_fault.
> (qualify_inject): Rename to parse_inject.
> (qualify): Rename to parse_qualify_filter.
> (qual_flags): Remove function.
> * Makefile.am (strace_SOURCES): Add new files.
> * strace.c (init): Use new filtering for -e option.
> (trace_syscall): Add filtering after syscall decoding.
> * syscall.c (decode_socket_subcall): Remove qual_flags from decoder.
> (decode_ipc_subcall): Likewise.
> (decode_mips_subcall): Likewise.
> (get_scno): Likewise.
> (inject_vec, tamper_with_syscall_entering): Remove inject_vec support code.
> (dumpio): Check new macros instead of global sets.
> ---
>  Makefile.am         |   4 +
>  basic_actions.c     | 147 +++++++++++++++++++++++++++++++++
>  basic_filters.c     |  99 +++++++++++++++++-----
>  defs.h              |  14 ++--
>  filter.c            | 145 ++++++++++++++++++++++++++++++++
>  filter.h            |  37 +++++++--
>  filter_action.c     | 221 +++++++++++++++++++++++++++++++++++++++++++++++++
>  filter_expression.c | 214 +++++++++++++++++++++++++++++++++++++++++++++++
>  filter_qualify.c    | 233 
> +++++++++++++++++++++++-----------------------------
>  strace.c            |  18 ++--
>  syscall.c           |  24 ++----
>  11 files changed, 969 insertions(+), 187 deletions(-)
>  create mode 100644 basic_actions.c
>  create mode 100644 filter.c
>  create mode 100644 filter_action.c
>  create mode 100644 filter_expression.c
> 
> diff --git a/Makefile.am b/Makefile.am
> index 12a7ac4..0cc698a 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -86,6 +86,7 @@ strace_SOURCES =    \
>       affinity.c      \
>       aio.c           \
>       alpha.c         \
> +     basic_actions.c \
>       basic_filters.c \
>       bind.c          \
>       bjm.c           \
> @@ -131,7 +132,10 @@ strace_SOURCES = \
>       fetch_struct_statfs.c \
>       file_handle.c   \
>       file_ioctl.c    \
> +     filter_action.c \
> +     filter_expression.c \
>       filter_qualify.c \
> +     filter.c        \
>       filter.h        \
>       flock.c         \
>       flock.h         \
> diff --git a/basic_actions.c b/basic_actions.c
> new file mode 100644
> index 0000000..5a1ebf8
> --- /dev/null
> +++ b/basic_actions.c
> @@ -0,0 +1,147 @@
> +/*
> + * Copyright (c) 2017 Nikolay Marchuk <marchuk.nikola...@gmail.com>
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + *    notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + *    notice, this list of conditions and the following disclaimer in the
> + *    documentation and/or other materials provided with the distribution.
> + * 3. The name of the author may not be used to endorse or promote products
> + *    derived from this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
> + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
> + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
> + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
> + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
> + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include "defs.h"
> +#include "filter.h"
> +
> +bool
> +is_traced(struct tcb *tcp)
> +{
> +     return (tcp->qual_flg & QUAL_TRACE);
> +}
> +
> +bool
> +not_injected(struct tcb *tcp)
> +{
> +     return !(tcp->qual_flg & QUAL_INJECT);
> +}
> +
> +void *
> +parse_null(const char *str)
> +{
> +     return NULL;
> +}
> +
> +void
> +free_null(void *_priv_data)
> +{
> +     return;
> +}
> +
> +void
> +apply_trace(struct tcb *tcp, void *_priv_data)
> +{
> +     if (!tracing_paths || pathtrace_match(tcp))
> +             tcp->qual_flg |= QUAL_TRACE;
> +}
> +
> +void
> +apply_inject(struct tcb *tcp, void *_priv_data)
> +{
> +     struct inject_opts *opts = _priv_data;
> +
> +     tcp->qual_flg |= QUAL_INJECT;
> +     if (!tcp->inject_vec[current_personality])
> +             tcp->inject_vec[current_personality] =
> +                     xcalloc(nsyscalls, sizeof(struct inject_opts));
> +     if (scno_in_range(tcp->scno)
> +         && !tcp->inject_vec[current_personality][tcp->scno].init)
> +             tcp->inject_vec[current_personality][tcp->scno] = *opts;
> +}
> +
> +static void *
> +parse_inject_common(const char *str, bool fault_tokens_only,
> +                 const char *description)
> +{
> +     struct inject_opts *opts = xmalloc(sizeof(struct inject_opts));
> +     char *buf = str ? xstrdup(str) : NULL;
> +
> +     parse_inject_common_args(buf, opts, ";", fault_tokens_only);
> +     if (!opts->init)
> +             error_msg_and_die("invalid %s '%s'", description, str);
> +     free(buf);
> +     return opts;
> +}
> +
> +void *
> +parse_inject(const char *str)
> +{
> +     return parse_inject_common(str, false, "inject argument");
> +}
> +
> +void free_inject(void *_priv_data)
> +{
> +     free(_priv_data);
> +}
> +
> +void
> +apply_fault(struct tcb *tcp, void *_priv_data)
> +{
> +     apply_inject(tcp, _priv_data);
> +}
> +
> +void *
> +parse_fault(const char *str)
> +{
> +     return parse_inject_common(str, true, "fault argument");
> +}
> +
> +void
> +free_fault(void *_priv_data)
> +{
> +     free_inject(_priv_data);
> +}
> +
> +void
> +apply_read(struct tcb *tcp, void *_priv_data)
> +{
> +     tcp->qual_flg |= QUAL_READ;
> +}
> +
> +void
> +apply_write(struct tcb *tcp, void *_priv_data)
> +{
> +     tcp->qual_flg |= QUAL_WRITE;
> +}
> +
> +void
> +apply_raw(struct tcb *tcp, void *_priv_data)
> +{
> +     tcp->qual_flg |= QUAL_RAW;
> +}
> +
> +void
> +apply_abbrev(struct tcb *tcp, void *_priv_data)
> +{
> +     tcp->qual_flg |= QUAL_ABBREV;
> +}
> +
> +void
> +apply_verbose(struct tcb *tcp, void *_priv_data)
> +{
> +     tcp->qual_flg |= QUAL_VERBOSE;
> +}
> diff --git a/basic_filters.c b/basic_filters.c
> index 316b733..85eb58b 100644
> --- a/basic_filters.c
> +++ b/basic_filters.c
> @@ -48,7 +48,8 @@ number_setbit(const unsigned int i, number_slot_t *const 
> vec)
>  static bool
>  number_isset(const unsigned int i, const number_slot_t *const vec)
>  {
> -     return vec[i / BITS_PER_SLOT] & ((number_slot_t) 1 << (i % 
> BITS_PER_SLOT));
> +     return (vec[i / BITS_PER_SLOT]
> +            & ((number_slot_t) 1 << (i % BITS_PER_SLOT))) ? true : false;
>  }
>  
>  static void
> @@ -62,7 +63,7 @@ reallocate_number_set(struct number_set *const set, const 
> unsigned int new_nslot
>       set->nslots = new_nslots;
>  }
>  
> -void
> +static void
>  add_number_to_set(const unsigned int number, struct number_set *const set)
>  {
>       reallocate_number_set(set, number / BITS_PER_SLOT + 1);
> @@ -77,7 +78,7 @@ is_number_in_set(const unsigned int number, const struct 
> number_set *const set)
>  }
>  
>  static bool
> -qualify_syscall_number(const char *s, struct number_set *set)
> +parse_syscall_number(const char *s, struct number_set *set)
>  {
>       int n = string_to_uint(s);
>       if (n < 0)
> @@ -108,7 +109,7 @@ regerror_msg_and_die(int errcode, const regex_t *preg,
>  }
>  
>  static bool
> -qualify_syscall_regex(const char *s, struct number_set *set)
> +parse_syscall_regex(const char *s, struct number_set *set)
>  {
>       regex_t preg;
>       int rc;
> @@ -180,7 +181,7 @@ lookup_class(const char *s)
>  }
>  
>  static bool
> -qualify_syscall_class(const char *s, struct number_set *set)
> +parse_syscall_class(const char *s, struct number_set *set)
>  {
>       const unsigned int n = lookup_class(s);
>       if (!n)
> @@ -203,7 +204,7 @@ qualify_syscall_class(const char *s, struct number_set 
> *set)
>  }
>  
>  static bool
> -qualify_syscall_name(const char *s, struct number_set *set)
> +parse_syscall_name(const char *s, struct number_set *set)
>  {
>       unsigned int p;
>       bool found = false;
> @@ -225,7 +226,7 @@ qualify_syscall_name(const char *s, struct number_set 
> *set)
>  }
>  
>  static bool
> -qualify_syscall(const char *token, struct number_set *set)
> +parse_syscall(const char *token, struct number_set *set)
>  {
>       bool ignore_fail = false;
>  
> @@ -234,11 +235,11 @@ qualify_syscall(const char *token, struct number_set 
> *set)
>               ignore_fail = true;
>       }
>       if (*token >= '0' && *token <= '9')
> -             return qualify_syscall_number(token, set) || ignore_fail;
> +             return parse_syscall_number(token, set) || ignore_fail;
>       if (*token == '/')
> -             return qualify_syscall_regex(token + 1, set) || ignore_fail;
> -     return qualify_syscall_class(token, set)
> -            || qualify_syscall_name(token, set)
> +             return parse_syscall_regex(token + 1, set) || ignore_fail;
> +     return parse_syscall_class(token, set)
> +            || parse_syscall_name(token, set)
>              || ignore_fail;
>  }
>  
> @@ -247,8 +248,7 @@ qualify_syscall(const char *token, struct number_set *set)
>   * according to STR specification.
>   */
>  void
> -qualify_syscall_tokens(const char *const str, struct number_set *const set,
> -                    const char *const name)
> +parse_syscall_set(const char *const str, struct number_set *const set)
>  {
>       /* Clear all sets. */
>       unsigned int p;
> @@ -286,10 +286,10 @@ handle_inversion:
>  
>       /*
>        * Split the string into comma separated tokens.
> -      * For each token, call qualify_syscall that will take care
> +      * For each token, call parse_syscall that will take care
>        * if adding appropriate syscall numbers to sets.
>        * The absence of tokens or a negative return code
> -      * from qualify_syscall is a fatal error.
> +      * from parse_syscall is a fatal error.
>        */
>       char *copy = xstrdup(s);
>       char *saveptr = NULL;
> @@ -298,24 +298,54 @@ handle_inversion:
>  
>       for (token = strtok_r(copy, ",", &saveptr); token;
>            token = strtok_r(NULL, ",", &saveptr)) {
> -             done = qualify_syscall(token, set);
> +             done = parse_syscall(token, set);
>               if (!done) {
> -                     error_msg_and_die("invalid %s '%s'", name, token);
> +                     error_msg_and_die("invalid system call '%s'", token);
>               }
>       }
>  
>       free(copy);
>  
>       if (!done) {
> -             error_msg_and_die("invalid %s '%s'", name, str);
> +             error_msg_and_die("invalid system call '%s'", str);
> +     }
> +}
> +
> +void *
> +parse_syscall_filter(const char *str)
> +{
> +     struct number_set *set = xcalloc(SUPPORTED_PERSONALITIES,
> +                                      sizeof(struct number_set));
> +
> +     parse_syscall_set(str, set);
> +     return set;
> +}
> +
> +bool
> +run_syscall_filter(struct tcb *tcp, void *_priv_data)
> +{
> +     struct number_set *set = _priv_data;
> +
> +     return is_number_in_set(tcp->scno, &set[current_personality]);
> +}
> +
> +void
> +free_syscall_filter(void *_priv_data)
> +{
> +     struct number_set *set = _priv_data;
> +     unsigned int p;
> +
> +     for (p = 0; p < SUPPORTED_PERSONALITIES; ++p) {
> +             free(set[p].vec);
>       }
> +     free(set);
>  }
>  
>  /*
>   * Add numbers to SET according to STR specification.
>   */
>  void
> -qualify_tokens(const char *const str, struct number_set *const set,
> +parse_set(const char *const str, struct number_set *const set,
>              string_to_uint_func func, const char *const name)
>  {
>       /* Clear the set. */
> @@ -373,3 +403,34 @@ handle_inversion:
>               error_msg_and_die("invalid %s '%s'", name, str);
>       }
>  }
> +
> +void *
> +parse_fd_filter(const char *str)
> +{
> +     struct number_set *set = xmalloc(sizeof(struct number_set));
> +
> +     memset(set, 0, sizeof(struct number_set));
The pair of xmalloc and memset calls can be replaced with xcalloc(1, sizeof()).

> +     parse_set(str, set, string_to_uint, "descriptor");
> +     return set;
> +}
> +
> +bool
> +run_fd_filter(struct tcb *tcp, void *_priv_data)
> +{
> +     int fd = tcp->u_arg[0];
> +     struct number_set *set = _priv_data;
> +
> +     if (fd < 0)
> +             return false;
> +     return is_number_in_set(fd, set);
> +}
> +
> +void
> +free_fd_filter(void *_priv_data)
> +{
> +     struct number_set *set = _priv_data;
> +
> +     free(set->vec);
> +     free(set);
> +     return;
> +}
> diff --git a/defs.h b/defs.h
> index a45d37b..491664a 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -197,6 +197,7 @@ struct inject_opts {
>       uint16_t step;
>       uint16_t signo;
>       int rval;
> +     bool init;
>  };
>  
>  #define MAX_ERRNO_VALUE                      4095
> @@ -266,8 +267,8 @@ struct tcb {
>  #define QUAL_RAW     0x008   /* print all args in hex for this syscall */
>  #define QUAL_INJECT  0x010   /* tamper with this system call on purpose */
>  #define QUAL_SIGNAL  0x100   /* report events with this signal */
> -#define QUAL_READ    0x200   /* dump data read from this file descriptor */
> -#define QUAL_WRITE   0x400   /* dump data written to this file descriptor */
> +#define QUAL_READ    0x200   /* dump data read in this syscall */
> +#define QUAL_WRITE   0x400   /* dump data written in this syscall */
>  
>  #define DEFAULT_QUAL_FLAGS (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE)
>  
> @@ -276,6 +277,8 @@ struct tcb {
>  #define syserror(tcp)        ((tcp)->u_error != 0)
>  #define verbose(tcp) ((tcp)->qual_flg & QUAL_VERBOSE)
>  #define abbrev(tcp)  ((tcp)->qual_flg & QUAL_ABBREV)
> +#define dump_read(tcp)       ((tcp)->qual_flg & QUAL_READ)
> +#define dump_write(tcp)      ((tcp)->qual_flg & QUAL_WRITE)
>  #define filtered(tcp)        ((tcp)->flags & TCB_FILTERED)
>  #define hide_log(tcp)        ((tcp)->flags & TCB_HIDE_LOG)
>  
> @@ -674,13 +677,12 @@ print_struct_statfs64(struct tcb *, kernel_ulong_t 
> addr, kernel_ulong_t size);
>  extern void print_ifindex(unsigned int);
>  
>  struct number_set;
> -extern struct number_set read_set;
> -extern struct number_set write_set;
>  extern struct number_set signal_set;
>  
>  extern bool is_number_in_set(unsigned int number, const struct number_set *);
> -extern void qualify(const char *);
> -extern unsigned int qual_flags(const unsigned int);
> +extern void filtering_parsing_finish(void);
> +extern void filter_syscall(struct tcb *);
> +extern void parse_qualify_filter(const char *);
>  
>  #define DECL_IOCTL(name)                                             \
>  extern int                                                           \
> diff --git a/filter.c b/filter.c
> new file mode 100644
> index 0000000..590228f
> --- /dev/null
> +++ b/filter.c
> @@ -0,0 +1,145 @@
> +/*
> + * Copyright (c) 2017 Nikolay Marchuk <marchuk.nikola...@gmail.com>
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + *    notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + *    notice, this list of conditions and the following disclaimer in the
> + *    documentation and/or other materials provided with the distribution.
> + * 3. The name of the author may not be used to endorse or promote products
> + *    derived from this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
> + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
> + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
> + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
> + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
> + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include "defs.h"
> +#include "filter.h"
> +
> +#define DECL_FILTER(name)                                            \
> +extern void *                                                                
> \
> +parse_ ## name ## _filter(const char *);                             \
> +extern bool                                                          \
> +run_ ## name ## _filter(struct tcb *, void *);                               
> \
> +extern void                                                          \
> +free_ ## name ## _filter(void *)                                     \
> +/* End of DECL_FILTER definition. */
> +
> +DECL_FILTER(syscall);
> +DECL_FILTER(fd);
> +#undef DECL_FILTER
> +
> +#define FILTER_TYPE(name)                                            \
> +{#name, parse_ ## name ## _filter, run_ ## name ## _filter,          \
> +     free_ ## name ## _filter}
Please, either add /* End of ... */ comment, or indent this definition.

> +
> +static const struct filter_type {
> +     const char *name;
> +     void *(*parse_filter)(const char *);
> +     bool (*run_filter)(struct tcb *, void *);
> +     void (*free_priv_data)(void *);
> +} filter_types[] = {
> +     FILTER_TYPE(syscall),
> +     FILTER_TYPE(fd),
> +};
> +#undef FILTER_TYPE
> +
> +struct filter {
> +     const struct filter_type *type;
> +     void *_priv_data;
> +};
> +
> +static const struct filter_type *
> +lookup_filter_type(const char *str)
> +{
> +     unsigned int i;
> +
> +     for (i = 0; i < ARRAY_SIZE(filter_types); i++) {
> +             if (!strcmp(filter_types[i].name, str))
> +                     return &filter_types[i];
> +     }
> +     return NULL;
> +}
> +
> +struct filter *
> +add_filter_to_array(struct filter **filters, unsigned int *nfilters,
> +                 const char *name)
> +{
> +     const struct filter_type *type = lookup_filter_type(name);
> +     struct filter *filter;
> +
> +     if (!type)
> +             error_msg_and_die("invalid filter '%s'", name);
> +     *filters = xreallocarray(*filters, ++(*nfilters),
> +                              sizeof(struct filter));
> +     filter = &((*filters)[*nfilters - 1]);
> +     filter->type = type;
> +     return filter;
> +}
> +
> +void
> +parse_filter(struct filter *filter, const char *str)
> +{
> +     filter->_priv_data = filter->type->parse_filter(str);
> +}
> +
> +static bool
> +run_filter(struct tcb *tcp, struct filter *filter)
> +{
> +     return filter->type->run_filter(tcp, filter->_priv_data);
> +}
> +
> +void
> +run_filters(struct tcb *tcp, struct filter *filters, unsigned int nfilters,
> +         bool *variables_buf)
> +{
> +     unsigned int i;
> +
> +     for (i = 0; i < nfilters; ++i)
> +             variables_buf[i] = run_filter(tcp, &filters[i]);
> +}
> +
> +void
> +free_filter(struct filter *filter)
> +{
> +     if (!filter)
> +             return;
> +     filter->type->free_priv_data(filter->_priv_data);
> +}
> +
> +void *
> +get_filter_priv_data(struct filter *filter)
> +{
> +     return filter ? filter->_priv_data : NULL;
> +}
> +
> +void
> +set_filter_priv_data(struct filter *filter, void *_priv_data)
> +{
> +     if (filter)
> +             filter->_priv_data = _priv_data;
> +}
> +
> +void
> +set_filters_qualify_mode(struct filter **filters, unsigned int *nfilters)
> +{
> +     unsigned int i;
> +
> +     for (i = 0; i < *nfilters - 1; ++i)
> +             free_filter(*filters + i);
> +     (*filters)[0] = (*filters)[*nfilters - 1];
> +     *filters = xreallocarray(*filters, 1, sizeof(struct filter));
> +     *nfilters = 1;
> +}
> diff --git a/filter.h b/filter.h
> index a798199..4085d45 100644
> --- a/filter.h
> +++ b/filter.h
> @@ -28,11 +28,38 @@
>  # define STRACE_FILTER_H
>  # include "defs.h"
>  
> +struct filter;
> +
> +struct filter_action;
> +
> +struct bool_expression;
> +
>  typedef int (*string_to_uint_func)(const char *);
> +void parse_set(const char *const, struct number_set *const,
> +            string_to_uint_func, const char *const);
> +void parse_inject_common_args(char *, struct inject_opts *, const char 
> *delim,
> +                           const bool fault_tokens_only);
> +
> +/* filter api */
> +struct filter* add_filter_to_array(struct filter **, unsigned int *nfilters,
> +                                const char *name);
> +void parse_filter(struct filter *, const char *str);
> +void run_filters(struct tcb *, struct filter *, unsigned int, bool *);
> +void free_filter(struct filter *);
> +void *get_filter_priv_data(struct filter *);
> +void set_filter_priv_data(struct filter *, void *);
> +void set_filters_qualify_mode(struct filter **, unsigned int *nfilters);
> +
> +/* filter action api */
> +struct filter *create_filter(struct filter_action *, const char *name);
> +struct filter_action *find_or_add_action(const char *);
> +void *get_filter_action_priv_data(struct filter_action *);
> +void set_filter_action_priv_data(struct filter_action *, void *);
> +void set_qualify_mode(struct filter_action *);
> +
> +/* filter expression api */
> +struct bool_expression *create_expression();
> +bool run_expression(struct bool_expression *, bool *, unsigned int);
> +void set_expression_qualify_mode(struct bool_expression *);
>  
> -void add_number_to_set(const unsigned int, struct number_set *const);
> -void qualify_tokens(const char *const, struct number_set *const,
> -                    string_to_uint_func, const char *const);
> -void qualify_syscall_tokens(const char *const, struct number_set *const,
> -                            const char *const);
>  #endif
> diff --git a/filter_action.c b/filter_action.c
> new file mode 100644
> index 0000000..f8bca97
> --- /dev/null
> +++ b/filter_action.c
> @@ -0,0 +1,221 @@
> +/*
> + * Copyright (c) 2017 Nikolay Marchuk <marchuk.nikola...@gmail.com>
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + *    notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + *    notice, this list of conditions and the following disclaimer in the
> + *    documentation and/or other materials provided with the distribution.
> + * 3. The name of the author may not be used to endorse or promote products
> + *    derived from this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
> + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
> + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
> + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
> + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
> + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include "defs.h"
> +#include "filter.h"
> +
> +#define DECL_FILTER_ACTION(name)                                     \
> +extern void                                                          \
> +apply_ ## name(struct tcb *, void *)                                 \
> +/* End of DECL_FILTER_ACTION definition. */
> +
> +DECL_FILTER_ACTION(trace);
> +DECL_FILTER_ACTION(inject);
> +DECL_FILTER_ACTION(fault);
> +DECL_FILTER_ACTION(read);
> +DECL_FILTER_ACTION(write);
> +DECL_FILTER_ACTION(raw);
> +DECL_FILTER_ACTION(abbrev);
> +DECL_FILTER_ACTION(verbose);
> +#undef DECL_FILTER_ACTION
> +
> +extern bool is_traced(struct tcb *);
> +extern bool not_injected(struct tcb *);
> +
> +#define DECL_FILTER_ACTION_PARSER(name)                                      
> \
> +extern void *                                                                
> \
> +parse_ ## name(const char *);                                                
> \
> +extern void                                                          \
> +free_ ## name(void *)                                                        
> \
> +/* End of DECL_FILTER_ACTION_PARSER definition. */
> +
> +DECL_FILTER_ACTION_PARSER(null);
> +DECL_FILTER_ACTION_PARSER(inject);
> +DECL_FILTER_ACTION_PARSER(fault);
> +#undef DECL_FILTER_ACTION_PARSER
> +
> +#define FILTER_ACTION_TYPE(NAME, PRIORITY, PARSER, PREFILTER)                
> \
> +{#NAME, PRIORITY, parse_ ## PARSER, free_ ## PARSER, PREFILTER, apply_ ## 
> NAME}
> +
> +static const struct filter_action_type {
> +     const char *name;
> +     unsigned int priority;
> +     void * (*parse_args)(const char *);
> +     void (*free_priv_data)(void *);
> +     bool (*prefilter)(struct tcb *);
> +     void (*apply)(struct tcb *, void *);
> +} action_types[] = {
> +     FILTER_ACTION_TYPE(trace,       2,      null,   NULL),
> +     FILTER_ACTION_TYPE(inject,      2,      inject, not_injected),
> +     FILTER_ACTION_TYPE(fault,       2,      fault,  not_injected),
> +     FILTER_ACTION_TYPE(read,        1,      null,   is_traced),
> +     FILTER_ACTION_TYPE(write,       1,      null,   is_traced),
> +     FILTER_ACTION_TYPE(raw,         1,      null,   is_traced),
> +     FILTER_ACTION_TYPE(abbrev,      1,      null,   is_traced),
> +     FILTER_ACTION_TYPE(verbose,     1,      null,   is_traced),
> +};
> +#undef FILTER_ACTION_TYPE
> +
> +struct filter_action {
> +     /* Used to correct order of actions with same priority. */
"with the same"

> +     unsigned int id;
> +     const struct filter_action_type *type;
> +     struct bool_expression *expr;
> +     unsigned int nfilters;
> +     struct filter *filters;
> +     void *_priv_data;
> +};
> +
> +static struct filter_action *filter_actions;
> +static unsigned int nfilter_actions;
> +
> +static bool *variables_buf;
> +
> +/* Compares actions priority. If actions have same priority, uses LIFO order 
> */
"action priorities", "actions' priorities", or "priorities of actions"

"have the same"

> +static int
> +compare_action_priority(const void *a, const void *b)
> +{
> +     const struct filter_action *action_a = a;
> +     const struct filter_action *action_b = b;
> +     unsigned int priority_a = action_a->type->priority;
> +     unsigned int priority_b = action_b->type->priority;
> +
> +     if (priority_a != priority_b) {
> +             return (priority_a > priority_b) ? -1 : 1;
> +     } else {
> +             return (action_a->id > action_b->id) ? -1 : 1;
> +     }
> +}
> +
> +void
> +filtering_parsing_finish(void)
> +{
> +     unsigned int maxfilters = 0;
> +     unsigned int i;
> +
> +     /* Sort actions by priority */
> +     qsort(filter_actions, nfilter_actions, sizeof(struct filter_action),
> +           &compare_action_priority);
> +
> +     /* Allocate variables_buf sufficient for any action */
> +     for (i = 0; i < nfilter_actions; ++i) {
> +             if (filter_actions[i].nfilters > maxfilters)
> +                     maxfilters = filter_actions[i].nfilters;
> +     }
> +     variables_buf = xcalloc(maxfilters, sizeof(bool));
> +}
> +
> +static const struct filter_action_type *
> +lookup_filter_action_type(const char *str)
> +{
> +     unsigned int i;
> +
> +     for (i = 0; i < ARRAY_SIZE(action_types); ++i) {
> +             if (!strcmp(action_types[i].name, str))
> +                     return &action_types[i];
> +     }
> +     return NULL;
> +}
> +
> +static struct filter_action *
> +add_action(const struct filter_action_type *type)
> +{
> +     struct filter_action *action;
> +
> +     filter_actions = xreallocarray(filter_actions, ++nfilter_actions,
> +                                    sizeof(struct filter_action));
> +     action = &filter_actions[nfilter_actions - 1];
> +     memset(action, 0, sizeof(*action));
> +     action->id = nfilter_actions - 1;
> +     action->type = type;
> +     action->expr = create_expression();
> +     return action;
> +}
> +
> +struct filter_action *
> +find_or_add_action(const char *name)
> +{
> +     const struct filter_action_type *type = lookup_filter_action_type(name);
> +     unsigned int i;
> +
> +     if (!type)
> +             error_msg_and_die("invalid filter action '%s'", name);
> +     /* If action takes arguments, add new action */
> +     if (type->parse_args != &parse_null)
> +             return add_action(type);
On a side note, this doesn't really helps in case of multiple actions
affecting the same syscall, as in strace -e trace=write -e 'fault(syscall
write;error=1;when=2+2)' -e 'fault(syscall write;error=2;when=2+3)' ls

> +
> +     for (i = 0; i < nfilter_actions; ++i) {
> +             if (filter_actions[i].type == type)
> +                     return &filter_actions[i];
> +     }
> +     return add_action(type);
> +}
> +
> +static void
> +run_filter_action(struct tcb *tcp, struct filter_action *action)
> +{
> +     if (action->type->prefilter && !action->type->prefilter(tcp))
> +             return;
> +     run_filters(tcp, action->filters, action->nfilters, variables_buf);
> +     if (run_expression(action->expr, variables_buf, action->nfilters))
> +             action->type->apply(tcp, action->_priv_data);
> +}
> +
> +struct filter *
> +create_filter(struct filter_action *action, const char *name)
> +{
> +     return add_filter_to_array(&action->filters, &action->nfilters, name);
> +}
> +
> +void
> +set_qualify_mode(struct filter_action *action)
> +{
> +     set_filters_qualify_mode(&action->filters, &action->nfilters);
> +     set_expression_qualify_mode(action->expr);
> +}
> +
> +void
> +filter_syscall(struct tcb *tcp)
> +{
> +     unsigned int i;
> +
> +     for (i = 0; i < nfilter_actions; ++i)
> +             run_filter_action(tcp, &filter_actions[i]);
> +}
> +
> +void *
> +get_filter_action_priv_data(struct filter_action *action)
> +{
> +     return action ? action->_priv_data : NULL;
> +}
> +
> +void
> +set_filter_action_priv_data(struct filter_action *action, void *_priv_data)
> +{
> +     if (action)
> +             action->_priv_data = _priv_data;
> +}
> diff --git a/filter_expression.c b/filter_expression.c
> new file mode 100644
> index 0000000..5dc5e41
> --- /dev/null
> +++ b/filter_expression.c
> @@ -0,0 +1,214 @@
> +/*
> + * Copyright (c) 2017 Nikolay Marchuk <marchuk.nikola...@gmail.com>
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + *    notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + *    notice, this list of conditions and the following disclaimer in the
> + *    documentation and/or other materials provided with the distribution.
> + * 3. The name of the author may not be used to endorse or promote products
> + *    derived from this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
> + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
> + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
> + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
> + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
> + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include "defs.h"
> +
> +struct expression_token {
> +     enum token_type {
> +             TOK_VARIABLE,
> +             TOK_OPERATOR
> +     } type;
> +     union token_data {
> +             unsigned int variable_id;
> +             enum operator_type {
> +                     OP_NOT,
> +                     OP_AND,
> +                     OP_OR
> +             } operator_id;
> +     } data;
> +};
> +
> +struct bool_expression {
> +     unsigned int ntokens;
> +     struct expression_token *tokens;
> +};
> +
> +struct bool_expression *
> +create_expression(void)
> +{
> +     struct bool_expression *expr = xmalloc(sizeof(struct bool_expression));
> +
> +     memset(expr, 0, sizeof(struct bool_expression));
xmalloc+memset can be replaced with xcalloc call.

> +     return expr;
> +}
> +
> +static void
> +reallocate_expression(struct bool_expression *const expr,
> +                   const unsigned int new_ntokens)
> +{
> +     if (new_ntokens <= expr->ntokens)
> +             return;
> +     expr->tokens = xreallocarray(expr->tokens, new_ntokens,
> +                                  sizeof(*expr->tokens));
> +     memset(expr->tokens + expr->ntokens, 0,
> +            sizeof(*expr->tokens) * (new_ntokens - expr->ntokens));
> +     expr->ntokens = new_ntokens;
> +}
> +
> +void
> +set_expression_qualify_mode(struct bool_expression *expr)
> +{
> +     if (!expr)
> +             error_msg_and_die("invalid expression");
Why reallocate_expression doesn't have the same check?

> +     reallocate_expression(expr, 1);
> +     expr->tokens[0].type = TOK_VARIABLE;
> +     expr->tokens[0].data.variable_id = 0;
> +}
> +
> +/* Print full diagnostics for corrupted expression */
> +static void
> +handle_corrupted_expression(struct bool_expression *expr, bool *stack,
> +                         unsigned int stack_size, unsigned int current_pos,
> +                         bool *variables, unsigned int variables_num)
> +{
> +     char *buf, *pos;
> +     unsigned int buf_size;
> +     unsigned int i;
> +
> +     error_msg("corrupted filter expression:");
> +
> +     /* Print expression. */
> +     buf_size = sizeof("expression (ntokens = ):")
> +                 + 3 * sizeof(unsigned int)
> +                 + (sizeof("op_") + 3 * sizeof(int)) * expr->ntokens;
> +     buf = xcalloc(buf_size, sizeof(char));
There's no need to use calloc if your string is going to be
\0-terminated anyway.

> +     pos = buf;
> +     pos += sprintf(pos, "expression (ntokens = %u):", expr->ntokens);
snprintf is always better. Return code should be checked as well.

Usually, some helper function is defined, like

        int
        printf_append(char **ptr, char *end, const char *fmt, ...)
                ATTRIBUTE_PRINTF(..)
        {
                int ret;
                va_list args;

                va_start(args, fmt)
                ret = vsnprintf(*ptr, end - *ptr, fmt, args);
                va_end(args);

                if (ret < 0)
                        return ret;

                *ptr += MIN(ret, end - *ptr);

                return ret;
        }

which allows sleeping well even without checking the return code of
any of consecutive printf_append calls, especially when you're sure that
buffer is big enough.

> +     for (i = 0; i < expr->ntokens; ++i) {
> +             switch (expr->tokens[i].type) {
> +             case TOK_VARIABLE:
> +                     pos += sprintf(pos, "v_%u",
> +                                    expr->tokens[i].data.variable_id);
> +                     break;
> +             case TOK_OPERATOR:
> +                     switch (expr->tokens[i].data.operator_id) {
> +                     case OP_NOT:
> +                             pos += sprintf(pos, "not");
> +                             break;
> +                     case OP_AND:
> +                             pos += sprintf(pos, "and");
> +                             break;
> +                     case OP_OR:
> +                             pos += sprintf(pos, "or");
> +                     default:
> +                             pos += sprintf(pos, "op_%d",
> +                                           expr->tokens[i].data.operator_id);
> +                     }
> +             default:
> +                     pos += sprintf(pos, "?_%d", expr->tokens[i].type);
> +             }
> +     }
> +     error_msg("%s\n", buf);
> +     free(buf);
> +
> +     /* Print variables. */
> +     buf_size = sizeof("variables (nvariables = ):") + 3 * sizeof(int)
> +                 + sizeof("false") * variables_num;
> +     buf = xcalloc(buf_size, sizeof(char));
> +     pos = buf;
> +     pos += sprintf(pos, "variables (nvariables = %u):", variables_num);
> +     for (i = 0; i < variables_num; ++i)
> +             pos += sprintf(pos, variables[i] ? " true" : " false");
> +     error_msg("%s\n", buf);
> +     free(buf);
> +
> +     error_msg("current position: %u\n", current_pos);
> +
> +     /* Print current stack state. */
> +     buf_size = sizeof("stack (stack_size = ):") + 3 * sizeof(int);
> +     buf = xcalloc(buf_size, sizeof(char));
> +     pos = buf;
> +     pos += sprintf(pos, "stack (stack_size = %u):", stack_size);
> +     for (i = 0; i < stack_size; ++i)
> +             pos += sprintf(pos, stack[i] ? " true" : " false");
> +     error_msg_and_die("%s\n", buf);
error_* functions terminate their output with newline already, no need
to pass it explicitly here (I assume it is used in previous calls in
order to produce empty lines).

> +}
Actually, this is far more comprehensive that I expected, thanks.

> +
> +#define MAX_STACK_SIZE 32
> +
> +bool
> +run_expression(struct bool_expression *expr, bool *variables,
> +            unsigned int variables_num)
> +{
> +     bool stack[MAX_STACK_SIZE];
> +     unsigned int stack_size = 0;
> +     unsigned int i;
> +
> +     for (i = 0; i < expr->ntokens; ++i) {
> +             struct expression_token *tok = &expr->tokens[i];
> +
> +             switch (tok->type) {
> +             case TOK_VARIABLE:
> +                     if (stack_size == MAX_STACK_SIZE)
> +                             error_msg_and_die("stack overflow");
> +
> +                     if (tok->data.variable_id >= variables_num)
> +                             handle_corrupted_expression(expr, stack,
> +                                                         stack_size, i,
> +                                                         variables,
> +                                                         variables_num);
> +                     stack[stack_size++] = variables[tok->data.variable_id];
> +                     break;
> +             case TOK_OPERATOR:
> +                     switch (tok->data.operator_id) {
> +                     case OP_NOT:
> +                             if (stack_size == 0)
> +                                     handle_corrupted_expression(expr, stack,
> +                                                             stack_size, i,
> +                                                             variables,
> +                                                             variables_num);
> +                             stack[stack_size - 1] = !stack[stack_size - 1];
> +                             break;
> +                     case OP_AND:
> +                             if (stack_size < 2)
> +                                     handle_corrupted_expression(expr, stack,
> +                                                             stack_size, i,
> +                                                             variables,
> +                                                             variables_num);
> +                             stack[stack_size - 2] = stack[stack_size - 2]
> +                                                  && stack[stack_size - 1];
> +                             --stack_size;
> +                             break;
> +                     case OP_OR:
> +                             if (stack_size < 2)
> +                                     handle_corrupted_expression(expr, stack,
> +                                                             stack_size, i,
> +                                                             variables,
> +                                                             variables_num);
> +                             stack[stack_size - 2] = stack[stack_size - 2]
> +                                                  || stack[stack_size - 1];
> +                             --stack_size;
> +                             break;
> +                     }
> +             }
> +     }
> +
> +     if (stack_size != 1)
> +             handle_corrupted_expression(expr, stack, stack_size, i,
> +                                         variables, variables_num);
> +     return stack[0];
> +}
> diff --git a/filter_qualify.c b/filter_qualify.c
> index 32db332..105afdf 100644
> --- a/filter_qualify.c
> +++ b/filter_qualify.c
> @@ -38,16 +38,8 @@ struct number_set {
>       bool not;
>  };
>  
> -struct number_set read_set;
> -struct number_set write_set;
>  struct number_set signal_set;
>  
> -static struct number_set abbrev_set[SUPPORTED_PERSONALITIES];
> -static struct number_set inject_set[SUPPORTED_PERSONALITIES];
> -static struct number_set raw_set[SUPPORTED_PERSONALITIES];
> -static struct number_set trace_set[SUPPORTED_PERSONALITIES];
> -static struct number_set verbose_set[SUPPORTED_PERSONALITIES];
> -
>  static int
>  find_errno_by_name(const char *name)
>  {
> @@ -156,174 +148,168 @@ parse_inject_token(const char *const token, struct 
> inject_opts *const fopts,
>       return true;
>  }
>  
> -static char *
> -parse_inject_expression(const char *const s, char **buf,
> -                     struct inject_opts *const fopts,
> -                     const bool fault_tokens_only)
> +void
> +parse_inject_common_args(char *str, struct inject_opts *const opts,
> +                      const char *delim, const bool fault_tokens_only)
>  {
>       char *saveptr = NULL;
> -     char *name = NULL;
>       char *token;
>  
> -     *buf = xstrdup(s);
> -     for (token = strtok_r(*buf, ":", &saveptr); token;
> -          token = strtok_r(NULL, ":", &saveptr)) {
> -             if (!name)
> -                     name = token;
> -             else if (!parse_inject_token(token, fopts, fault_tokens_only))
> -                     goto parse_error;
> -     }
> +     opts->first = 1;
> +     opts->step = 1;
> +     opts->rval = INJECT_OPTS_RVAL_DEFAULT;
> +     opts->signo = 0;
> +     opts->init = false;
>  
> -     if (name)
> -             return name;
> +     for (token = strtok_r(str, delim, &saveptr); token;
> +          token = strtok_r(NULL, delim, &saveptr)) {
> +             if (!parse_inject_token(token, opts, fault_tokens_only))
> +                     return;
> +     }
>  
> -parse_error:
> -     free(*buf);
> -     return *buf = NULL;
> +     /* If neither of retval, error, or signal is specified, then ... */
> +     if (opts->rval == INJECT_OPTS_RVAL_DEFAULT && !opts->signo) {
> +             if (fault_tokens_only) {
> +                     /* in fault= syntax the default error code is ENOSYS. */
> +                     opts->rval = -ENOSYS;
> +             } else {
> +                     /* in inject= syntax this is not allowed. */
> +                     return;
> +             }
> +     }
> +     opts->init = true;
>  }
>  
>  static void
> -qualify_read(const char *const str)
> +parse_read(const char *const str)
>  {
> -     qualify_tokens(str, &read_set, string_to_uint, "descriptor");
> +     struct filter_action *action = find_or_add_action("read");
> +     struct filter *filter = create_filter(action, "fd");
> +
> +     parse_filter(filter, str);
> +     set_qualify_mode(action);
>  }
>  
>  static void
> -qualify_write(const char *const str)
> +parse_write(const char *const str)
>  {
> -     qualify_tokens(str, &write_set, string_to_uint, "descriptor");
> +     struct filter_action *action = find_or_add_action("write");
> +     struct filter *filter = create_filter(action, "fd");
> +
> +     parse_filter(filter, str);
> +     set_qualify_mode(action);
>  }
>  
>  static void
>  qualify_signals(const char *const str)
>  {
> -     qualify_tokens(str, &signal_set, sigstr_to_uint, "signal");
> +     parse_set(str, &signal_set, sigstr_to_uint, "signal");
>  }
>  
>  static void
> -qualify_trace(const char *const str)
> +parse_trace(const char *const str)
>  {
> -     qualify_syscall_tokens(str, trace_set, "system call");
> +     struct filter_action *action = find_or_add_action("trace");
> +     struct filter *filter = create_filter(action, "syscall");
> +
> +     parse_filter(filter, str);
> +     set_qualify_mode(action);
>  }
>  
>  static void
> -qualify_abbrev(const char *const str)
> +parse_abbrev(const char *const str)
>  {
> -     qualify_syscall_tokens(str, abbrev_set, "system call");
> +     struct filter_action *action = find_or_add_action("abbrev");
> +     struct filter *filter = create_filter(action, "syscall");
> +
> +     parse_filter(filter, str);
> +     set_qualify_mode(action);
>  }
>  
>  static void
> -qualify_verbose(const char *const str)
> +parse_verbose(const char *const str)
>  {
> -     qualify_syscall_tokens(str, verbose_set, "system call");
> +     struct filter_action *action = find_or_add_action("verbose");
> +     struct filter *filter = create_filter(action, "syscall");
> +
> +     parse_filter(filter, str);
> +     set_qualify_mode(action);
>  }
>  
>  static void
> -qualify_raw(const char *const str)
> +parse_raw(const char *const str)
>  {
> -     qualify_syscall_tokens(str, raw_set, "system call");
> +     struct filter_action *action = find_or_add_action("raw");
> +     struct filter *filter = create_filter(action, "syscall");
> +
> +     parse_filter(filter, str);
> +     set_qualify_mode(action);
>  }
>  
>  static void
> -qualify_inject_common(const char *const str,
> -                   const bool fault_tokens_only,
> -                   const char *const description)
> +parse_inject_common(const char *const str, const bool fault_tokens_only,
> +                 const char *const description)
I just noticed that you have two functions named parse_inject_common.
It's probably not a good idea.

>  {
> -     struct inject_opts opts = {
> -             .first = 1,
> -             .step = 1,
> -             .rval = INJECT_OPTS_RVAL_DEFAULT,
> -             .signo = 0
> -     };
> -     char *buf = NULL;
> -     char *name = parse_inject_expression(str, &buf, &opts, 
> fault_tokens_only);
> -     if (!name) {
> -             error_msg_and_die("invalid %s '%s'", description, str);
> -     }
> -
> -     /* If neither of retval, error, or signal is specified, then ... */
> -     if (opts.rval == INJECT_OPTS_RVAL_DEFAULT && !opts.signo) {
> -             if (fault_tokens_only) {
> -                     /* in fault= syntax the default error code is ENOSYS. */
> -                     opts.rval = -ENOSYS;
> -             } else {
> -                     /* in inject= syntax this is not allowed. */
> -                     error_msg_and_die("invalid %s '%s'", description, str);
> -             }
> -     }
> -
> -     struct number_set tmp_set[SUPPORTED_PERSONALITIES];
> -     memset(tmp_set, 0, sizeof(tmp_set));
> -     qualify_syscall_tokens(name, tmp_set, description);
> -
> +     struct inject_opts *opts = xmalloc(sizeof(struct inject_opts));
> +     char *buf = xstrdup(str);
> +     struct filter_action *action;
> +     struct filter *filter;
> +     char *args = strchr(buf, ':');
> +
> +     if (args)
> +             *(args++) = '\0';
> +
> +     action = find_or_add_action(fault_tokens_only ? "fault" : "inject");
> +     filter = create_filter(action, "syscall");
> +     parse_filter(filter, buf);
> +     set_qualify_mode(action);
> +     parse_inject_common_args(args, opts, ":", fault_tokens_only);
> +     if (!opts->init)
> +             error_msg_and_die("invalid %s '%s'", description,
> +                               args ? args : "");
>       free(buf);
> -
> -     /*
> -      * Initialize inject_vec accourding to tmp_set.
> -      * Merge tmp_set into inject_set.
> -      */
> -     unsigned int p;
> -     for (p = 0; p < SUPPORTED_PERSONALITIES; ++p) {
> -             if (!tmp_set[p].nslots && !tmp_set[p].not) {
> -                     continue;
> -             }
> -
> -             if (!inject_vec[p]) {
> -                     inject_vec[p] = xcalloc(nsyscall_vec[p],
> -                                            sizeof(*inject_vec[p]));
> -             }
> -
> -             unsigned int i;
> -             for (i = 0; i < nsyscall_vec[p]; ++i) {
> -                     if (is_number_in_set(i, &tmp_set[p])) {
> -                             add_number_to_set(i, &inject_set[p]);
> -                             inject_vec[p][i] = opts;
> -                     }
> -             }
> -
> -             free(tmp_set[p].vec);
> -     }
> +     set_filter_action_priv_data(action, opts);
>  }
>  
>  static void
> -qualify_fault(const char *const str)
> +parse_fault(const char *const str)
>  {
The same here.

> -     qualify_inject_common(str, true, "fault argument");
> +     parse_inject_common(str, true, "fault argument");
>  }
>  
>  static void
> -qualify_inject(const char *const str)
> +parse_inject(const char *const str)
And here.

>  {
> -     qualify_inject_common(str, false, "inject argument");
> +     parse_inject_common(str, false, "inject argument");
>  }
>  
>  static const struct qual_options {
>       const char *name;
>       void (*qualify)(const char *);
>  } qual_options[] = {
> -     { "trace",      qualify_trace   },
> -     { "t",          qualify_trace   },
> -     { "abbrev",     qualify_abbrev  },
> -     { "a",          qualify_abbrev  },
> -     { "verbose",    qualify_verbose },
> -     { "v",          qualify_verbose },
> -     { "raw",        qualify_raw     },
> -     { "x",          qualify_raw     },
> +     { "trace",      parse_trace     },
> +     { "t",          parse_trace     },
> +     { "abbrev",     parse_abbrev    },
> +     { "a",          parse_abbrev    },
> +     { "verbose",    parse_verbose   },
> +     { "v",          parse_verbose   },
> +     { "raw",        parse_raw       },
> +     { "x",          parse_raw       },
>       { "signal",     qualify_signals },
>       { "signals",    qualify_signals },
>       { "s",          qualify_signals },
> -     { "read",       qualify_read    },
> -     { "reads",      qualify_read    },
> -     { "r",          qualify_read    },
> -     { "write",      qualify_write   },
> -     { "writes",     qualify_write   },
> -     { "w",          qualify_write   },
> -     { "fault",      qualify_fault   },
> -     { "inject",     qualify_inject  },
> +     { "read",       parse_read      },
> +     { "reads",      parse_read      },
> +     { "r",          parse_read      },
> +     { "write",      parse_write     },
> +     { "writes",     parse_write     },
> +     { "w",          parse_write     },
> +     { "fault",      parse_fault     },
> +     { "inject",     parse_inject    },
>  };
>  
>  void
> -qualify(const char *str)
> +parse_qualify_filter(const char *str)
>  {
>       const struct qual_options *opt = qual_options;
>       unsigned int i;
> @@ -342,18 +328,3 @@ qualify(const char *str)
>  
>       opt->qualify(str);
>  }
> -
> -unsigned int
> -qual_flags(const unsigned int scno)
> -{
> -     return  (is_number_in_set(scno, &trace_set[current_personality])
> -                ? QUAL_TRACE : 0)
> -             | (is_number_in_set(scno, &abbrev_set[current_personality])
> -                ? QUAL_ABBREV : 0)
> -             | (is_number_in_set(scno, &verbose_set[current_personality])
> -                ? QUAL_VERBOSE : 0)
> -             | (is_number_in_set(scno, &raw_set[current_personality])
> -                ? QUAL_RAW : 0)
> -             | (is_number_in_set(scno, &inject_set[current_personality])
> -                ? QUAL_INJECT : 0);
> -}
> diff --git a/strace.c b/strace.c
> index 0015ad5..0e82cc5 100644
> --- a/strace.c
> +++ b/strace.c
> @@ -838,7 +838,8 @@ droptcb(struct tcb *tcp)
>  
>       int p;
>       for (p = 0; p < SUPPORTED_PERSONALITIES; ++p)
> -             free(tcp->inject_vec[p]);
> +             if (tcp->inject_vec[p])
> +                     free(tcp->inject_vec[p]);
>  
>       free_tcb_priv_data(tcp);
>  
> @@ -1644,13 +1645,13 @@ init(int argc, char *argv[])
>       shared_log = stderr;
>       set_sortby(DEFAULT_SORTBY);
>       set_personality(DEFAULT_PERSONALITY);
> -     qualify("trace=all");
> -     qualify("abbrev=all");
> -     qualify("verbose=all");
> +     parse_qualify_filter("trace=all");
> +     parse_qualify_filter("abbrev=all");
> +     parse_qualify_filter("verbose=all");
>  #if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE)
>  # error Bug in DEFAULT_QUAL_FLAGS
>  #endif
> -     qualify("signal=all");
> +     parse_qualify_filter("signal=all");
>       while ((c = getopt(argc, argv,
>               "+b:cCdfFhiqrtTvVwxyz"
>  #ifdef USE_LIBUNWIND
> @@ -1717,7 +1718,7 @@ init(int argc, char *argv[])
>                       show_fd_path++;
>                       break;
>               case 'v':
> -                     qualify("abbrev=none");
> +                     parse_qualify_filter("abbrev=none");
>                       break;
>               case 'V':
>                       print_version();
> @@ -1732,7 +1733,7 @@ init(int argc, char *argv[])
>                               error_opt_arg(c, optarg);
>                       break;
>               case 'e':
> -                     qualify(optarg);
> +                     parse_qualify_filter(optarg);
>                       break;
>               case 'o':
>                       outfname = optarg;
> @@ -1780,6 +1781,7 @@ init(int argc, char *argv[])
>                       break;
>               }
>       }
> +     filtering_parsing_finish();
>  
>       argv += optind;
>       argc -= optind;
> @@ -2478,6 +2480,8 @@ trace_syscall(struct tcb *tcp, unsigned int *sig)
>               case 0:
>                       return 0;
>               case 1:
> +                     if (!tcp->qual_flg)
> +                             filter_syscall(tcp);
>                       res = syscall_entering_trace(tcp, sig);
>               }
>               syscall_entering_finish(tcp, res);
> diff --git a/syscall.c b/syscall.c
> index f21a146..48ee62f 100644
> --- a/syscall.c
> +++ b/syscall.c
> @@ -382,7 +382,6 @@ decode_socket_subcall(struct tcb *tcp)
>               return;
>  
>       tcp->scno = scno;
> -     tcp->qual_flg = qual_flags(scno);
>       tcp->s_ent = &sysent[scno];
>  
>       unsigned int i;
> @@ -422,7 +421,6 @@ decode_ipc_subcall(struct tcb *tcp)
>       }
>  
>       tcp->scno = SYS_ipc_subcall + call;
> -     tcp->qual_flg = qual_flags(tcp->scno);
>       tcp->s_ent = &sysent[tcp->scno];
>  
>       const unsigned int n = tcp->s_ent->nargs;
> @@ -439,7 +437,6 @@ decode_mips_subcall(struct tcb *tcp)
>       if (!scno_is_valid(tcp->u_arg[0]))
>               return;
>       tcp->scno = tcp->u_arg[0];
> -     tcp->qual_flg = qual_flags(tcp->scno);
>       tcp->s_ent = &sysent[tcp->scno];
>       memmove(&tcp->u_arg[0], &tcp->u_arg[1],
>               sizeof(tcp->u_arg) - sizeof(tcp->u_arg[0]));
> @@ -468,7 +465,7 @@ dumpio(struct tcb *tcp)
>       if (fd < 0)
>               return;
>  
> -     if (is_number_in_set(fd, &read_set)) {
> +     if (dump_read(tcp)) {
>               switch (tcp->s_ent->sen) {
>               case SEN_read:
>               case SEN_pread:
> @@ -491,7 +488,7 @@ dumpio(struct tcb *tcp)
>                       return;
>               }
>       }
> -     if (is_number_in_set(fd, &write_set)) {
> +     if (dump_write(tcp)) {
>               switch (tcp->s_ent->sen) {
>               case SEN_write:
>               case SEN_pwrite:
> @@ -577,8 +574,6 @@ static void get_error(struct tcb *, const bool);
>  static int arch_set_error(struct tcb *);
>  static int arch_set_success(struct tcb *);
>  
> -struct inject_opts *inject_vec[SUPPORTED_PERSONALITIES];
> -
>  static struct inject_opts *
>  tcb_inject_opts(struct tcb *tcp)
>  {
> @@ -590,14 +585,6 @@ tcb_inject_opts(struct tcb *tcp)
>  static long
>  tamper_with_syscall_entering(struct tcb *tcp, unsigned int *signo)
>  {
> -     if (!tcp->inject_vec[current_personality]) {
> -             tcp->inject_vec[current_personality] =
> -                     xcalloc(nsyscalls, sizeof(**inject_vec));
> -             memcpy(tcp->inject_vec[current_personality],
> -                    inject_vec[current_personality],
> -                    nsyscalls * sizeof(**inject_vec));
> -     }
> -
>       struct inject_opts *opts = tcb_inject_opts(tcp);
>  
>       if (!opts || opts->first == 0)
> @@ -717,9 +704,7 @@ syscall_entering_trace(struct tcb *tcp, unsigned int *sig)
>                       break;
>       }
>  
> -     if (!(tcp->qual_flg & QUAL_TRACE)
> -      || (tracing_paths && !pathtrace_match(tcp))
> -     ) {
> +     if (!(tcp->qual_flg & QUAL_TRACE)) {
>               tcp->flags |= TCB_FILTERED;
>               return 0;
>       }
> @@ -1238,7 +1223,8 @@ get_scno(struct tcb *tcp)
>  
>       if (scno_is_valid(tcp->scno)) {
>               tcp->s_ent = &sysent[tcp->scno];
> -             tcp->qual_flg = qual_flags(tcp->scno);
> +             /* Clear qual_flg to differ valid syscall from printargs */
> +             tcp->qual_flg = 0;
>       } else {
>               struct sysent_buf *s = xcalloc(1, sizeof(*s));
>  
> -- 
> 2.1.4

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