utrace.c

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/* -*- C -*- */
/*
 * Copyright (c) 2011-2020 Seagate Technology LLC and/or its Affiliates
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */


#include <string.h>   /* memset, strlen */
#include <errno.h>
#include <err.h>      /* warn */
#include <sysexits.h> /* EX_* exit codes (EX_OSERR, EX_SOFTWARE) */
#include <stdio.h>
#include <stdlib.h>   /* getenv, strtoul */
#include <unistd.h>   /* getpagesize, getpid */
#include <fcntl.h>    /* open, O_RDWR|O_CREAT|O_TRUNC */
#include <sys/mman.h> /* mmap */
#include <sys/stat.h> /* fstat */
#include <limits.h>   /* CHAR_BIT */
#include <stddef.h>   /* ptrdiff_t */
#include <time.h>     /* strftime */

#include "lib/types.h"
#include "lib/arith.h"
#include "lib/memory.h"
#include "lib/string.h" /* m0_strdup */
#include "lib/trace.h"
#include "lib/trace_internal.h"
#include "lib/cookie.h" /* m0_addr_is_sane_and_aligned */

#include "motr/magic.h"

pid_t m0_pid_cached;

static int  logfd;
static bool use_mmaped_buffer = true;
static char trace_file_path[PATH_MAX];
static size_t trace_buf_size = M0_TRACE_UBUF_SIZE;

static int logbuf_map()
{
        struct    m0_trace_area *trace_area;
        size_t    trace_area_size = M0_TRACE_BUF_HEADER_SIZE + trace_buf_size;
        int       rc;
        m0_time_t stamp = m0_time_now();
        time_t    ts    = m0_time_seconds(stamp);
        struct tm tm;

        localtime_r(&ts, &tm);
        M0_PRE((trace_area_size % m0_pagesize_get()) == 0);

        if (strlen(trace_file_path) == 0) {
                if (getcwd(trace_file_path, sizeof trace_file_path) == NULL ) {
                        warn("failed to read CWD path, using relative path for"
                             " m0trace.PID file");
                        memset(trace_file_path, 0, sizeof trace_file_path);
                } else {
                        strncat(trace_file_path, "/", sizeof trace_file_path -
                                strlen(trace_file_path) - 1);
                }

                int available_bytes = sizeof trace_file_path -
                                      strlen(trace_file_path);
                rc = snprintf(trace_file_path + strlen(trace_file_path),
                        available_bytes,
                        "m0trace.%u.%04d-%02d-%02d-%02d:%02d:%02d",
                        m0_pid_cached, tm.tm_year + 1900,
                        tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
                if (rc < 0) {
                        warn("failed to construct trace file path");
                        return rc;
                }
                if (rc >= available_bytes) {
                        warnx("failed to construct trace file path, not enough"
                              " space in the path buffer");
                        return -ENOBUFS;
                }
        }

        if ((logfd = open(trace_file_path, O_RDWR|O_CREAT|O_TRUNC|O_CLOEXEC, 0700)) == -1) {
                warn("open(\"%s\")", trace_file_path);
        } else if ((errno = posix_fallocate(logfd, 0, trace_area_size)) != 0) {
                warn("fallocate(\"%s\", %zu)", trace_file_path, trace_area_size);
        } else if ((trace_area = mmap(NULL, trace_area_size, PROT_WRITE,
                                      MAP_SHARED, logfd, 0)) == MAP_FAILED)
        {
                warn("mmap(\"%s\")", trace_file_path);
        } else {
                m0_logbuf_header = &trace_area->ta_header;
                m0_logbuf = trace_area->ta_buf;
                memset(trace_area, 0, trace_area_size);
                m0_trace_buf_header_init(&trace_area->ta_header, trace_buf_size);
                m0_trace_logbuf_size_set(trace_buf_size);
        }

        return -errno;
}

M0_INTERNAL const char *m0_trace_file_path_get(void)
{
        return trace_file_path;
}

M0_INTERNAL int m0_trace_set_immediate_mask(const char *mask)
{
        if (mask != NULL) {
                char *endp;

                m0_trace_immediate_mask = strtoul(mask, &endp, 0);

                /*
                 * if mask string fails to convert to a number cleanly, then
                 * assume that mask string contains a comma separated list of
                 * subsystem names, which we use to build a numeric mask
                 */
                if (errno != 0 || *endp != 0) {
                        unsigned long  m = 0;
                        int            rc;
                        char          *s = m0_strdup(mask);

                        if (s == NULL)
                                return -ENOMEM;

                        rc = m0_trace_subsys_list_to_mask(s, &m);
                        m0_free(s);

                        if (rc != 0)
                                return rc;

                        m0_trace_immediate_mask = m;
                }
        }

        return 0;
}

M0_INTERNAL void m0_trace_stats_update(uint32_t rec_size)
{
}

M0_INTERNAL void m0_trace_set_mmapped_buffer(bool val)
{
        use_mmaped_buffer = val;
}

M0_INTERNAL bool m0_trace_use_mmapped_buffer(void)
{
        return use_mmaped_buffer;
}

int m0_trace_set_buffer_size(size_t size)
{
        if (m0_pid_cached) {
                m0_error_printf("motr: can't set trace buffer size after it's"
                                " been initialized\n");
                return -EBUSY;
        }

        if (size == 0 || !m0_is_po2(size) || size % m0_pagesize_get() != 0) {
                m0_error_printf("motr: incorrect value for trace buffer size"
                       " parameter (%zu), it can't be zero, should be a power of"
                       " 2 and a multiple of PAGE_SIZE(%u)\n",
                       size, m0_pagesize_get());
                return -EINVAL;
        }

        trace_buf_size = size;
        return 0;
}

static int set_trace_dir(const char *path)
{
        int rc;
        m0_time_t stamp = m0_time_now();
        time_t    ts    = m0_time_seconds(stamp);
        struct tm tm;

        if (path == NULL)
                return 0;
        localtime_r(&ts, &tm);
        rc = snprintf(trace_file_path, sizeof trace_file_path, "%s/m0trace.%u.%04d-%02d-%02d-%02d:%02d:%02d",
                      path, m0_pid_cached, tm.tm_year + 1900,
                      tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
        if (rc < 0) {
                warn("ignoring environment variable M0_TRACE_DIR - failed"
                     " to construct trace file path");
                memset(trace_file_path, 0, sizeof trace_file_path);
                return rc;
        }
        if (rc >= sizeof trace_file_path) {
                warnx("ignoring environment variable M0_TRACE_DIR - its content"
                      " is too long (%zu bytes), max allowed lengh is %zu bytes"
                      , strlen(path), (sizeof trace_file_path) - 16);
                memset(trace_file_path, 0, sizeof trace_file_path);
                return -EINVAL;
        }

        return 0;
}

M0_INTERNAL int m0_arch_trace_init()
{
        int         rc;
        const char *var;

        m0_pid_cached = getpid();

        var = getenv("M0_TRACE_IMMEDIATE_MASK");
        rc = m0_trace_set_immediate_mask(var);
        if (rc != 0)
                return rc;

        var = getenv("M0_TRACE_LEVEL");
        rc = m0_trace_set_level(var);
        if (rc != 0)
                return rc;

        var = getenv("M0_TRACE_PRINT_CONTEXT");
        rc = m0_trace_set_print_context(var);
        if (rc != 0)
                return rc;

        var = getenv("M0_TRACE_DIR");
        rc = set_trace_dir(var);
        if (rc != 0 && rc != -EINVAL)
                return rc;

        setlinebuf(stdout);
        return m0_trace_use_mmapped_buffer() ? logbuf_map() : 0;
}

M0_INTERNAL void m0_arch_trace_fini(void)
{
        void     *old_buffer      = m0_logbuf_header;
        uint32_t  old_buffer_size = M0_TRACE_BUF_HEADER_SIZE +
                                    m0_trace_logbuf_size_get();

        m0_logbuf_header->tbh_buf_flags &= ~M0_TRACE_BUF_DIRTY;

        m0_trace_switch_to_static_logbuf();

        if (m0_trace_use_mmapped_buffer())
                munmap(old_buffer, old_buffer_size);
        close(logfd);
}

M0_INTERNAL void m0_arch_trace_buf_header_init(struct m0_trace_buf_header *tbh)
{
        int     i;
        int     rc;
        int     cmdline_fd;
        ssize_t read_bytes;

        tbh->tbh_buf_type = M0_TRACE_BUF_USER;

#define CMDLINE "/proc/self/cmdline"
        cmdline_fd = open(CMDLINE, O_RDONLY);
        if (cmdline_fd == -1)
                return;

        read_bytes = read(cmdline_fd, tbh->tbh_cli_args,
                          sizeof(tbh->tbh_cli_args));
        if (read_bytes == -1) {
                warn("motr: failed to read " CMDLINE);
        } else {
                if (read_bytes == sizeof(tbh->tbh_cli_args)) {
                        warnx("motr: command line args don't fit into trace "
                              "buffer, truncating after %zu bytes", read_bytes);
                        tbh->tbh_cli_args[read_bytes - 1] = '\0';
                } else {
                        tbh->tbh_cli_args[read_bytes] = '\0';
                }
                /* cli args are separated with '\0', replace it with spaces */
                for (i = 0; i < read_bytes - 1; ++i)
                        if (tbh->tbh_cli_args[i] == '\0')
                                tbh->tbh_cli_args[i] = ' ';
        }

        rc = close(cmdline_fd);
        if (rc == -1)
                warn("motr: failed to close " CMDLINE ": errno=%d", errno);
#undef CMDLINE

        if (strstr(tbh->tbh_cli_args, "m0mkfs") != NULL)
                tbh->tbh_buf_flags |= M0_TRACE_BUF_MKFS;

        tbh->tbh_buf_flags |= M0_TRACE_BUF_DIRTY;
}

static unsigned align(FILE *file, uint64_t align, uint64_t pos)
{
        M0_ASSERT(m0_is_po2(align));
        while (!feof(file) && (pos & (align - 1))) {
                fgetc(file);
                pos++;
        }
        return pos;
}

static const struct m0_trace_buf_header *read_trace_buf_header(FILE *trace_file)
{
        const struct m0_trace_buf_header *tb_header;

        static char buf[M0_TRACE_BUF_HEADER_SIZE];
        size_t     n;

        n = fread(buf, 1, sizeof buf, trace_file);
        if (n != sizeof buf) {
                warnx("failed to read trace header (got %zu bytes instead of"
                      " %zu bytes)\n", n, sizeof buf);
                return NULL;
        }

        tb_header = (const struct m0_trace_buf_header *)buf;

        if (tb_header->tbh_magic != M0_TRACE_BUF_HEADER_MAGIC) {
                warnx("invalid trace header MAGIC value\n");
                return NULL;
        }

        if (tb_header->tbh_header_size != M0_TRACE_BUF_HEADER_SIZE)
                warnx("trace header has different size: expected=%u, actual=%u",
                      M0_TRACE_BUF_HEADER_SIZE, tb_header->tbh_header_size);

        return tb_header;
}

static void print_trace_buf_header(FILE *ofile,
                                   const struct m0_trace_buf_header *tbh)
{
        int        rc;
        struct tm  tm;
        struct tm *ptm;
        char       time_str[512];
        size_t     time_str_len;
        time_t     time;
        bool       need_comma = false;

        fprintf(ofile, "header:\n");

        fprintf(ofile, "  motr_version:       %s\n", tbh->tbh_motr_version);
        fprintf(ofile, "  motr_git_describe:  %s\n", tbh->tbh_motr_git_describe);
        fprintf(ofile, "  motr_kernel:        %s\n", tbh->tbh_motr_kernel_ver);

        rc = putenv("TZ=UTC0");
        if (rc != 0)
                warn("failed to set timezone to UTC\n");

        time = m0_time_seconds(tbh->tbh_log_time);
        ptm = localtime_r(&time, &tm);
        if (ptm != NULL) {
                time_str_len = strftime(time_str, sizeof time_str,
                                        "%FT%T%z", &tm);
                                        /*"%b %e %H:%M:%S %Z %Y", &tm);*/
                if (time_str_len == 0)
                        fprintf(stderr, "  failed to format trace file timestamp\n");
                fprintf(ofile, "  trace_time:         %s\n", time_str);
        } else {
                fprintf(stderr, "incorrect timestamp value in trace header\n");
                fprintf(ofile, "  trace_time:         ''\n");
        }

        fprintf(ofile, "  buffer_type:        %s\n",
                tbh->tbh_buf_type == M0_TRACE_BUF_KERNEL ? "KERNEL" :
                tbh->tbh_buf_type == M0_TRACE_BUF_USER   ? "USER"   :
                                                           "UNKNOWN"
        );
        fprintf(ofile, "  flags:              [ ");
        if (tbh->tbh_buf_flags & M0_TRACE_BUF_DIRTY) {
                need_comma = true;
                fprintf(ofile, "DIRTY");
        }
        if (tbh->tbh_buf_flags & M0_TRACE_BUF_MKFS) {
                if (need_comma)
                        fprintf(ofile, ", ");
                fprintf(ofile, "MKFS");
        }
        fprintf(ofile, " ]\n");

        fprintf(ofile, "  header_addr:        %p\n", tbh->tbh_header_addr);
        fprintf(ofile, "  header_size:        %u\t\t# bytes\n", tbh->tbh_header_size);
        fprintf(ofile, "  buffer_addr:        %p\n", tbh->tbh_buf_addr);
        fprintf(ofile, "  buffer_size:        %" PRId64 "\t\t# bytes\n",
                tbh->tbh_buf_size);

        if (tbh->tbh_buf_type == M0_TRACE_BUF_KERNEL) {
                fprintf(ofile, "  mod_struct_addr:    %p\n",
                                tbh->tbh_module_struct);
                fprintf(ofile, "  mod_core_addr:      %p\n",
                                tbh->tbh_module_core_addr);
                fprintf(ofile, "  mod_core_size:      %u\t\t# bytes\n",
                                tbh->tbh_module_core_size);
        }

        fprintf(ofile, "  cli_args:           '%s'\n", tbh->tbh_cli_args);
}

static int mmap_m0tr_ko(const char *m0tr_ko_path, void **ko_addr)
{
        int         rc;
        int         kofd;
        struct stat ko_stat;

        kofd = open(m0tr_ko_path, O_RDONLY);
        if (kofd == -1) {
                warn("failed to open '%s' file", m0tr_ko_path);
                return EX_NOINPUT;
        }

        rc = fstat(kofd, &ko_stat);
        if (rc != 0) {
                warn("failed to get stat info for '%s' file",
                     m0tr_ko_path);
                return EX_OSERR;
        }

        *ko_addr = mmap(NULL, ko_stat.st_size, PROT_READ, MAP_PRIVATE,
                        kofd, 0);
        if (*ko_addr == MAP_FAILED) {
                warn("failed to mmap '%s' file", m0tr_ko_path);
                return EX_OSERR;
        }

        return 0;
}

static int calc_trace_descr_offset(const struct m0_trace_buf_header *tbh,
                                   const char *m0tr_ko_path,
                                   ptrdiff_t *td_offset)
{
        if (tbh->tbh_buf_type == M0_TRACE_BUF_USER) {
                *td_offset = (char*)m0_trace_magic_sym_addr_get() -
                             (char*)tbh->tbh_magic_sym_addr;
        } else if (tbh->tbh_buf_type == M0_TRACE_BUF_KERNEL) {
                int       rc;
                void     *ko_addr;
                off_t     msym_file_offset;
                uint64_t *msym;

                msym_file_offset = (char*)tbh->tbh_magic_sym_addr -
                                   (char*)tbh->tbh_module_core_addr;

                rc = mmap_m0tr_ko(m0tr_ko_path, &ko_addr);
                if (rc != 0)
                        return rc;

                msym = (uint64_t*)((char*)ko_addr + msym_file_offset);
                if (*msym != M0_TRACE_MAGIC) {
                        warnx("invalid trace magic symbol value in '%s' file at"
                              " offset 0x%" PRIx64 ": 0x%"PRIx64
                              " (expected 0x%lx)",
                              m0tr_ko_path, msym_file_offset, *msym,
                              M0_TRACE_MAGIC);
                        return EX_DATAERR;
                }

                *td_offset = (char*)msym - (char*)tbh->tbh_magic_sym_addr;
        } else {
                return EX_DATAERR;
        }

        return 0;
}

static int calc_extra_trace_descr_offsets(const struct m0_trace_buf_header *tbh,
                                          const void *magic_symbols[],
                                          size_t nr, ptrdiff_t td_offsets[])
{
        int i;

        if (tbh->tbh_buf_type == M0_TRACE_BUF_USER) {
                if (tbh->tbh_magic_sym_addresses_nr < nr) {
                        warnx("There are only %u additional magic symbols"
                              " stored in trace log, but %zu were provided to"
                              " m0_trace_parse()",
                              tbh->tbh_magic_sym_addresses_nr, nr);
                        nr = tbh->tbh_magic_sym_addresses_nr;
                }
                if (nr == 0)
                        return -ENODATA;
                for (i = 0; i < nr; ++i)
                        td_offsets[i] = (char*)magic_symbols[i] -
                                        (char*)tbh->tbh_magic_sym_addresses[i];
        } else {
                warnx("Cannot use additional magic symbols information with"
                      " kernel mode trace log");
                return -EOPNOTSUPP;
        }

        return 0;
}

static void patch_trace_descr(struct m0_trace_descr *td, ptrdiff_t offset)
{
        td->td_fmt    = (char*)td->td_fmt + offset;
        td->td_func   = (char*)td->td_func + offset;
        td->td_file   = (char*)td->td_file + offset;
        td->td_offset = (typeof (td->td_offset))((char*)td->td_offset + offset);
        td->td_sizeof = (typeof (td->td_sizeof))((char*)td->td_sizeof + offset);
        td->td_isstr  = (typeof (td->td_isstr))((char*)td->td_isstr + offset);
}

enum {
        MAGIC_SYM_OFFSETS_MAX = ARRAY_SIZE(
                ((struct m0_trace_buf_header *)0)->tbh_magic_sym_addresses)
};

M0_INTERNAL int m0_trace_parse(FILE *trace_file, FILE *output_file,
                               const char *m0tr_ko_path,
                               enum m0_trace_parse_flags flags,
                               const void *magic_symbols[],
                               unsigned int magic_symbols_nr)
{
        const struct m0_trace_buf_header *tbh;
        struct m0_trace_rec_header        trh;
        struct m0_trace_descr            *td;
        struct m0_trace_descr             patched_td;

        int        rc;
        int        i;
        size_t     pos = 0;
        size_t     nr;
        size_t     n2r;
        size_t     size;
        size_t     invalid_td_count = 0;
        bool       td_is_sane;
        char      *buf;

        static char  yaml_buf[256 * 1024]; /* 256 KB */
        ptrdiff_t   *td_offset;
        ptrdiff_t    td_offsets[MAGIC_SYM_OFFSETS_MAX + 1] = { 0 };
        size_t       td_offsets_nr =
                        (magic_symbols_nr < MAGIC_SYM_OFFSETS_MAX ?
                         magic_symbols_nr : MAGIC_SYM_OFFSETS_MAX) + 1;

        tbh = read_trace_buf_header(trace_file);
        if (tbh == NULL)
                return EX_DATAERR;

        print_trace_buf_header(output_file, tbh);
        if (flags & M0_TRACE_PARSE_HEADER_ONLY)
                return 0;

        rc = calc_trace_descr_offset(tbh, m0tr_ko_path, &td_offsets[0]);
        if (rc != 0)
                return rc;

        if (magic_symbols != NULL) {
                rc = calc_extra_trace_descr_offsets(tbh, magic_symbols,
                                td_offsets_nr - 1, &td_offsets[1]);
                if (rc != 0)
                        /* something's not good with the additional magic
                         * symbols information, using only internal (libmotr)
                         * magic symbol */
                        td_offsets_nr = 1;
                else if (magic_symbols_nr > MAGIC_SYM_OFFSETS_MAX)
                        warnx("Using only first %u magic symbol offsets"
                              " out of %u provided to m0_trace_parse()",
                              MAGIC_SYM_OFFSETS_MAX, magic_symbols_nr);
        } else if (magic_symbols_nr > 0) {
                warnx("Not using additional magic symbol addresses"
                      " - inconsistent parameters");
        }

        if (flags & M0_TRACE_PARSE_YAML_SINGLE_DOC_OUTPUT)
                fprintf(output_file, "trace_records:\n");

        while (!feof(trace_file)) {

                /* At the beginning of a record */
                pos = align(trace_file, M0_TRACE_REC_ALIGN, pos);

                /* Find the complete record */
                do {
                        nr = fread(&trh.trh_magic, 1,
                                   sizeof trh.trh_magic, trace_file);

                        if (nr != sizeof trh.trh_magic) {
                                if (!feof(trace_file)) {
                                        warnx("Got %zu bytes of magic instead"
                                              " of %zu", nr,
                                              sizeof trh.trh_magic);
                                        return EX_DATAERR;
                                }
                                if (invalid_td_count > 0)
                                        warnx("Total number of unknown trace"
                                              " records, that were skipped:"
                                              " %zu", invalid_td_count);
                                return EX_OK;
                        }

                        pos += nr;
                } while (trh.trh_magic != M0_TRACE_MAGIC);

                /* Now we might have complete record */
                n2r = sizeof trh - sizeof trh.trh_magic;
                nr  = fread(&trh.trh_sp, 1, n2r, trace_file);
                if (nr != n2r) {
                        warnx("Got %zu bytes of record (need %zu)", nr, n2r);
                        return EX_DATAERR;
                }
                pos += nr;

                for (i = 0; i < td_offsets_nr; ++i) {
                        td_offset = &td_offsets[i];
                        td = (struct m0_trace_descr*)((char*)trh.trh_descr +
                                                      *td_offset);
                        td_is_sane =
                             m0_addr_is_sane_and_aligned((const uint64_t *)td);
                        if (td_is_sane && td->td_magic == M0_TRACE_DESCR_MAGIC)
                                        break;

                }

                if (!td_is_sane) {
                        warnx("Skipping non-existing trace descriptor %p",
                              trh.trh_descr);
                        continue;
                }

                if (td->td_magic != M0_TRACE_DESCR_MAGIC) {
                        if (invalid_td_count == 0)
                                warnx("Invalid trace descriptor - most probably"
                                      "the trace file was produced by a"
                                      "different version of Motr");
                        ++invalid_td_count;
                        continue;
                }

                patched_td = *td;
                if (tbh->tbh_buf_type == M0_TRACE_BUF_KERNEL)
                        patch_trace_descr(&patched_td, *td_offset);
                trh.trh_descr = &patched_td;
                size = m0_align(td->td_size + trh.trh_string_data_size,
                                M0_TRACE_REC_ALIGN);

                buf = m0_alloc(size);
                if (buf == NULL) {
                        warn("Failed to allocate %zu bytes of memory, looks like"
                             " a corrupted trace descriptor, skipping...", size);
                        continue;
                }

                nr = fread(buf, 1, size, trace_file);
                if (nr != size) {
                        warnx("Got %zu bytes of data (need %zu)", nr, size);
                        return EX_DATAERR;
                }
                pos += nr;

                rc = m0_trace_record_print_yaml(yaml_buf, sizeof yaml_buf, &trh,
                        buf, !(flags & M0_TRACE_PARSE_YAML_SINGLE_DOC_OUTPUT));
                if (rc == 0)
                        fprintf(output_file, "%s", yaml_buf);
                else if (rc == -ENOBUFS)
                        warnx("Internal buffer is too small to hold trace record");
                else
                        warnx("Failed to process trace record data for %p"
                              " descriptor", trh.trh_descr);
                m0_free(buf);
        }
        return EX_OK;
}

M0_INTERNAL void m0_console_vprintf(const char *fmt, va_list args)
{
        vprintf(fmt, args);
}

void m0_console_flush(void)
{
        fflush(stdout);
}

void m0_error_printf(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        va_end(ap);
}

/*
 *  Local variables:
 *  c-indentation-style: "K&R"
 *  c-basic-offset: 8
 *  tab-width: 8
 *  fill-column: 80
 *  scroll-step: 1
 *  End:
 */