strerror.c

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/*
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *   Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/** Support functions to allow libraries to provide errors to their callers
 *
 * @file src/lib/util/strerror.c
 *
 * @copyright 2017-2020 The FreeRADIUS server project
 * @copyright 2017-2020 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSID("$Id: f89a2134ca8d3b2092ca041081969f3cb6fe878b $")
 
#include <freeradius-devel/util/dlist.h>
#include <freeradius-devel/util/strerror.h>
#include <freeradius-devel/util/atexit.h>
 
 
#define FR_STRERROR_BUFSIZE (2048)
 
typedef struct fr_log_entry_s fr_log_entry_t;
struct fr_log_entry_s {
        fr_dlist_t      list;
        char const      *msg;           //!< Log message.
 
        char const      *subject;       //!< Subject for error markers.
        size_t          offset;         //!< Where to place the msg marker relative to the subject.
 
        char const      *file;          //!< File where the error was created.
        int             line;           //!< Line where the error occurred.
};
 
/** Holds data used by the logging stack
 *
 * pool_a and pool_b allow #fr_strerror and #fr_strerror_pop during
 * a call to #fr_strerror_printf or #fr_strerror_printf_push.
 */
typedef struct {
        TALLOC_CTX      *pool_a;        //!< Pool to avoid memory allocations.
        TALLOC_CTX      *pool_b;        //!< Pool to avoid memory allocations.
        TALLOC_CTX      *pool;          //!< Current pool in use.
 
        fr_dlist_head_t entries;
} fr_log_buffer_t;
 
static _Thread_local fr_log_buffer_t *fr_strerror_buffer;
static _Thread_local bool logging_stop; //!< Due to ordering issues we may get errors being
                                        ///< logged from within other thread local destructors
                                        ///< which cause a crash on exit if the logging buffer
                                        ///< has already been freed.
 
/*
 *      Explicitly cleanup the memory allocated to the error buffer,
 *      just in case valgrind complains about it.
 */
static int _fr_logging_free(void *arg)
{
        /*
         *      Free arg instead of thread local storage
         *      as address sanitizer does a better job
         *      of tracking and doesn't report a leak.
         */
        if (talloc_free(arg) < 0) return -1;
        fr_strerror_buffer = NULL;
 
        logging_stop = true;
 
        return 0;
}
 
/** Initialise thread local storage
 *
 * @return fr_buffer_t containing log messages.
 */
static fr_log_buffer_t *fr_strerror_init(void)
{
        fr_log_buffer_t *buffer;
 
        if (unlikely(logging_stop)) return NULL;        /* No more logging */
 
        buffer = fr_strerror_buffer;
        if (!buffer) {
                buffer = talloc(NULL, fr_log_buffer_t); /* One byte extra for status */
                if (!buffer) {
                oom:
                        fr_perror("Failed allocating memory for libradius error buffer");
                        return NULL;
                }
                buffer->pool_a = talloc_pool(buffer, FR_STRERROR_BUFSIZE);
                if (!buffer->pool_a) goto oom;
 
                buffer->pool_b = talloc_pool(buffer, FR_STRERROR_BUFSIZE);
                if (!buffer->pool_b) goto oom;
 
                buffer->pool = buffer->pool_a;
 
                fr_atexit_thread_local(fr_strerror_buffer, _fr_logging_free, buffer);
 
                fr_dlist_talloc_init(&buffer->entries, fr_log_entry_t, list);
        }
 
        return buffer;
}
 
/*
 *      If last pool was pool_a, allocate from pool_b
 *      ...and vice versa.  This prevents the pools
 *      from leaking due to non-contiguous allocations
 *      when we're using fr_strerror as an argument
 *      for another message.
 */
static inline CC_HINT(always_inline) TALLOC_CTX *pool_alt(fr_log_buffer_t *buffer)
{
        if (buffer->pool == buffer->pool_a) {
                buffer->pool = buffer->pool_b;
                return buffer->pool;
        }
        return buffer->pool = buffer->pool_a;
}
 
static inline CC_HINT(always_inline) void pool_alt_free_children(fr_log_buffer_t *buffer)
{
        if (buffer->pool == buffer->pool_a) {
                talloc_free_children(buffer->pool_b);
                return;
        }
        talloc_free_children(buffer->pool_a);
}
 
/** Create an entry in the thread local logging stack, clearing all other entries
 *
 * @note Can't be inlined.
 *
 * @hidecallergraph
 */
static fr_log_entry_t *strerror_vprintf(char const *file, int line, char const *fmt, va_list ap)
{
        va_list         ap_p;
        fr_log_entry_t  *entry;
        fr_log_buffer_t *buffer;
 
        buffer = fr_strerror_init();
        if (unlikely(buffer == NULL)) return NULL;
 
        /*
         *      Clear any existing log messages
         */
        if (!fmt) {
                fr_strerror_clear();
                return NULL;
        }
 
        entry = talloc(pool_alt(buffer), fr_log_entry_t);
        if (unlikely(!entry)) {
        oom:
                fr_perror("Failed allocating memory for libradius error buffer");
                return NULL;
        }
 
        va_copy(ap_p, ap);
        entry->msg = fr_vasprintf(entry, fmt, ap_p);
        va_end(ap_p);
        if (unlikely(!entry->msg)) goto oom;
        entry->subject = NULL;
        entry->offset = 0;
        entry->file = file;
        entry->line = line;
 
        pool_alt_free_children(buffer);
        fr_dlist_clear(&buffer->entries);
        fr_dlist_insert_tail(&buffer->entries, entry);
 
        return entry;
}
 
/** Add a message to an existing stack of messages
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] buffer    The log buffer to allocate memory from.
 * @param[in] fmt       printf style format string.
 * @param[in] ap        Arguments for the error string.
 *
 * @note Can't be inline.
 *
 * @hidecallergraph
 */
static fr_log_entry_t *strerror_vprintf_push(char const *file, int line,
                                             fr_log_buffer_t *buffer, char const *fmt, va_list ap)
{
        va_list         ap_p;
        fr_log_entry_t  *entry;
 
        if (!fmt) return NULL;
 
        entry = talloc(pool_alt(buffer), fr_log_entry_t);
        if (unlikely(!entry)) {
        oom:
                fr_perror("Failed allocating memory for libradius error buffer");
                return NULL;
        }
 
        va_copy(ap_p, ap);
        entry->msg = fr_vasprintf(entry, fmt, ap_p);
        va_end(ap_p);
        if (unlikely(!entry->msg)) goto oom;
 
        /*
         *      Address pathological case where we could leak memory
         *      if only a combination of fr_strerror and
         *      fr_strerror_printf_push are used.
         *
         *      Must run AFTER fr_vasprintf, otherwise pointer args
         *      referencing the old pool (e.g. from fr_strerror())
         *      would be freed before being consumed.
         */
        if (!fr_dlist_num_elements(&buffer->entries)) pool_alt_free_children(buffer);
 
        entry->subject = NULL;
        entry->offset = 0;
        entry->file = file;
        entry->line = line;
 
        return entry;
}
 
/** Log to thread local error buffer
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] fmt       printf style format string.
 *                      If NULL clears any existing messages.
 * @param[in] ap        Arguments for the format string.
 *
 * @hidecallergraph
 */
void _fr_strerror_vprintf(char const *file, int line, char const *fmt, va_list ap)
{
        va_list         our_ap;
 
        va_copy(our_ap, ap);
        strerror_vprintf(file, line, fmt, our_ap);
        va_end(our_ap);
}
 
/** Add a message to an existing stack of messages at the tail
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] fmt       printf style format string.
 * @param[in] ap        Arguments for the format string.
 *
 * @hidecallergraph
 */
void _fr_strerror_vprintf_push(char const *file, int line, char const *fmt, va_list ap)
{
        va_list                 our_ap;
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_init();
        if (unlikely(buffer == NULL)) return;
 
        va_copy(our_ap, ap);
        entry = strerror_vprintf_push(file, line, buffer, fmt, our_ap);
        va_end(our_ap);
 
        if (unlikely(!entry)) return;
 
        fr_dlist_insert_tail(&buffer->entries, entry);
}
 
/** Add a message to an existing stack of messages at the head
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] fmt       printf style format string.
 * @param[in] ap        Arguments for the format string.
 *
 * @hidecallergraph
 */
void _fr_strerror_vprintf_push_head(char const *file, int line, char const *fmt, va_list ap)
{
        va_list                 our_ap;
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_init();
        if (unlikely(buffer == NULL)) return;
 
        va_copy(our_ap, ap);
        entry = strerror_vprintf_push(file, line, buffer, fmt, our_ap);
        va_end(our_ap);
 
        if (unlikely(!entry)) return;
 
        fr_dlist_insert_head(&buffer->entries, entry);
}
 
/** Add an error marker to an existing stack of messages
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] subject   to mark up.
 * @param[in] offset    Positive offset to show where the error
 *                      should be positioned.
 * @param[in] fmt       Error string.
 * @param[in] ap        Arguments for the error string.
 *
 * @hidecallergraph
 */
void _fr_strerror_marker_vprintf(char const *file, int line,
                                 char const *subject, size_t offset, char const *fmt, va_list ap)
{
        va_list         our_ap;
        fr_log_entry_t  *entry;
 
        va_copy(our_ap, ap);
        entry = strerror_vprintf(file, line, fmt, our_ap);
        va_end(our_ap);
 
        if (unlikely(!entry)) return;
 
        entry->subject = talloc_strdup(entry, subject);
        entry->offset = offset;
}
 
/** Add an error marker to an existing stack of messages at the tail
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] subject   to mark up.
 * @param[in] offset    Positive offset to show where the error
 *                      should be positioned.
 * @param[in] fmt       Error string.
 * @param[in] ap        Arguments for the error string.
 *
 * @hidecallergraph
 */
void _fr_strerror_marker_vprintf_push(char const *file, int line,
                                      char const *subject, size_t offset, char const *fmt, va_list ap)
{
        va_list                 our_ap;
        fr_log_entry_t          *entry;
        fr_log_buffer_t         *buffer;
 
        buffer = fr_strerror_init();
        if (unlikely(buffer == NULL)) return;
 
        va_copy(our_ap, ap);
        entry = strerror_vprintf_push(file, line, buffer, fmt, our_ap);
        va_end(our_ap);
 
        if (unlikely(!entry)) return;
 
        entry->subject = talloc_strdup(entry, subject);
        entry->offset = offset;
 
        fr_dlist_insert_tail(&buffer->entries, entry);
}
 
/** Add an error marker to an existing stack of messages at the head
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] subject   to mark up.
 * @param[in] offset    Positive offset to show where the error
 *                      should be positioned.
 * @param[in] fmt       Error string.
 * @param[in] ap        Arguments for the error string.
 *
 * @hidecallergraph
 */
void _fr_strerror_marker_vprintf_push_head(char const *file, int line,
                                           char const *subject, size_t offset, char const *fmt, va_list ap)
{
        va_list                 our_ap;
        fr_log_entry_t          *entry;
        fr_log_buffer_t         *buffer;
 
        buffer = fr_strerror_init();
        if (unlikely(buffer == NULL)) return;
 
        va_copy(our_ap, ap);
        entry = strerror_vprintf_push(file, line, buffer, fmt, our_ap);
        va_end(our_ap);
 
        if (unlikely(!entry)) return;
 
        entry->subject = talloc_strdup(entry, subject);
        entry->offset = offset;
 
        fr_dlist_insert_head(&buffer->entries, entry);
}
 
/** Create an entry in the thread local logging stack using a const string, clearing all other entries
 *
 * @hidecallergraph
 */
static inline CC_HINT(always_inline) fr_log_entry_t *strerror_const(char const *file, int line, char const *msg)
{
        fr_log_entry_t  *entry;
        fr_log_buffer_t *buffer;
 
        buffer = fr_strerror_init();
        if (unlikely(buffer == NULL)) return NULL;
 
        entry = talloc(pool_alt(buffer), fr_log_entry_t);
        if (unlikely(!entry)) {
                fr_perror("Failed allocating memory for libradius error buffer");
                return NULL;
        }
        /*
         *      For some reason this is significantly
         *      more efficient than a compound literal
         *      even though in the majority of cases
         *      compound literals and individual field
         *      assignments result in the same byte
         *      code.
         */
        entry->file = file;
        entry->line = line;
        entry->msg = msg;
        entry->subject = NULL;
        entry->offset = 0;
 
        pool_alt_free_children(buffer);
        fr_dlist_clear(&buffer->entries);
        fr_dlist_insert_tail(&buffer->entries, entry);
 
        return entry;
}
 
/** Log to thread local error buffer
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] msg       To add to error stack. Must have a
 *                      lifetime equal to that of the program.
 * @hidecallergraph
 */
void _fr_strerror_const(char const *file, int line, char const *msg)
{
        (void)strerror_const(file, line, msg);
}
 
/** Add a message to an existing stack of messages
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] buffer    to add the message to.
 * @param[in] msg       To add to error stack. Must have a
 *                      lifetime equal to that of the program.
 *
 * @hidecallergraph
 */
static inline CC_HINT(always_inline) fr_log_entry_t *strerror_const_push(char const *file, int line,
                                                                         fr_log_buffer_t *buffer, char const *msg)
{
        fr_log_entry_t  *entry;
 
        /*
         *      Address pathological case where we could leak memory
         *      if only a combination of fr_strerror and
         *      fr_strerror_printf_push are used.
         */
        if (!fr_dlist_num_elements(&buffer->entries)) talloc_free_children(buffer->pool);
 
        entry = talloc(pool_alt(buffer), fr_log_entry_t);
        if (unlikely(!entry)) {
                fr_perror("Failed allocating memory for libradius error buffer");
                return NULL;
        }
        /*
         *      For some reason this is significantly
         *      more efficient than a compound literal
         *      even though in the majority of cases
         *      compound literals and individual field
         *      assignments result in the same byte
         *      code.
         */
        entry->msg = msg;
        entry->subject = NULL;
        entry->offset = 0;
        entry->file = file;
        entry->line = line;
 
        return entry;
}
 
/** Add a message to an existing stack of messages at the tail
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] msg       To add to error stack. Must have a
 *                      lifetime equal to that of the program.
 *
 * @hidecallergraph
 */
void _fr_strerror_const_push(char const *file, int line, char const *msg)
{
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_init();
        if (unlikely(buffer == NULL)) return;
 
        entry = strerror_const_push(file, line, buffer, msg);
        if (unlikely(!entry)) return;
 
        fr_dlist_insert_tail(&buffer->entries, entry);
}
 
/** Add a message to an existing stack of messages at the head
 *
 * @param[in] file      the error occurred in.
 * @param[in] line      the error occurred on.
 * @param[in] msg       To add to error stack. Must have a
 *                      lifetime equal to that of the program.
 *
 * @hidecallergraph
 */
void _fr_strerror_const_push_head(char const *file, int line, char const *msg)
{
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_init();
        if (unlikely(buffer == NULL)) return;
 
        entry = strerror_const_push(file, line, buffer, msg);
        if (unlikely(!entry)) return;
 
        fr_dlist_insert_head(&buffer->entries, entry);
}
 
/** Get the last library error
 *
 * Will only return the last library error once, after which it will return a zero length string.
 * If there are additional messages on the log stack they will be discarded.
 *
 * @return library error or zero length string.
 *
 * @hidecallergraph
 */
char const *fr_strerror(void)
{
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_buffer;
        if (unlikely(buffer == NULL)) return "";
 
        entry = fr_dlist_tail(&buffer->entries);
        if (!entry) return "";
 
        /*
         *      Memory gets freed on next call to
         *      fr_strerror_printf or fr_strerror_printf_push.
         */
        fr_dlist_clear(&buffer->entries);
 
        return entry->msg;
}
 
/** Clears all pending messages from the talloc pools
 *
 */
void fr_strerror_clear(void)
{
        fr_log_buffer_t         *buffer = fr_strerror_buffer;
 
        if (unlikely(buffer == NULL)) return;
 
        fr_dlist_clear(&buffer->entries);
        talloc_free_children(buffer->pool_a);
        talloc_free_children(buffer->pool_b);
}
 
/** Get the last library error marker
 *
 * @param[out] subject  The subject string the error relates to.
 * @param[out] offset   Where to place the marker.
 * @return
 *      - NULL if there are no pending errors.
 *      - The error message if there was an error.
 *
 * @hidecallergraph
 */
char const *fr_strerror_marker(char const **subject, size_t *offset)
{
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_buffer;
        if (unlikely(buffer == NULL)) return "";
 
        entry = fr_dlist_head(&buffer->entries);
        if (!entry) return "";
 
        /*
         *      Memory gets freed on next call to
         *      fr_strerror_printf or fr_strerror_printf_push.
         */
        fr_dlist_clear(&buffer->entries);
 
        *subject = entry->subject;
        *offset = entry->offset;
 
        return entry->msg;
}
 
/** Get the last library error
 *
 * @return library error or zero length string.
 *
 * @hidecallergraph
 */
char const *fr_strerror_peek(void)
{
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_buffer;
        if (unlikely(buffer == NULL)) return "";
 
        entry = fr_dlist_tail(&buffer->entries);
        if (!entry) return "";
 
        return entry->msg;
}
 
/** Get the last library error marker
 *
 * @param[out] subject  The subject string the error relates to.
 * @param[out] offset   Where to place the marker.
 * @return
 *      - NULL if there are no pending errors.
 *      - The error message if there was an error.
 *
 * @hidecallergraph
 */
char const *fr_strerror_marker_peek(char const **subject, size_t *offset)
{
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_buffer;
        if (unlikely(buffer == NULL)) return "";
 
        entry = fr_dlist_head(&buffer->entries);
        if (!entry) return "";
 
        *subject = entry->subject;
        *offset = entry->offset;
 
        return entry->msg;
}
 
/** Pop the last library error
 *
 * Return the first message added to the error stack using #fr_strerror_printf
 * or #fr_strerror_printf_push.
 *
 * @note  fr_strerror() will return NULL if no messages are pending.
 *
 * @return
 *      - A library error.
 *      - NULL if no errors are pending.
 *
 * @hidecallergraph
 */
char const *fr_strerror_pop(void)
{
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_buffer;
        if (unlikely(buffer == NULL)) return NULL;
 
        entry = fr_dlist_head(&buffer->entries);
        if (!entry) return NULL;
 
        fr_dlist_remove(&buffer->entries, entry);
 
        return entry->msg;
}
 
/** Pop the last library error with marker information
 *
 * Return the first message added to the error stack using #fr_strerror_printf
 * or #fr_strerror_printf_push.
 *
 * @return
 *      - A library error.
 *      - NULL if no errors are pending.
 *
 * @hidecallergraph
 */
char const *fr_strerror_marker_pop(char const **subject, size_t *offset)
{
        fr_log_buffer_t         *buffer;
        fr_log_entry_t          *entry;
 
        buffer = fr_strerror_buffer;
        if (unlikely(buffer == NULL)) return NULL;
 
        entry = fr_dlist_head(&buffer->entries);
        if (!entry) return NULL;
 
        fr_dlist_remove(&buffer->entries, entry);
 
        *subject = entry->subject;
        *offset = entry->offset;
 
        return entry->msg;
}
 
/** Print the current error to stderr with a prefix
 *
 * Used by utility functions lacking their own logging infrastructure
 *
 * @hidecallergraph
 */
void fr_perror(char const *fmt, ...)
{
        char const      *error;
        char const      *subject;
        size_t          offset;
        char            *prefix = NULL;
        va_list         ap;
 
        error = fr_strerror_marker_pop(&subject, &offset);
        if (fmt) {
                va_start(ap, fmt);
                prefix = talloc_vasprintf(NULL, fmt, ap);
                va_end(ap);
 
                if (error) {
                        fprintf(stderr, "%s: %s\n", prefix, error);
                } else {
                        fprintf(stderr, "%s\n", prefix);
                        talloc_free(prefix);
                        return;
                }
                talloc_free(prefix);
        } else {
                if (!error) return;
                fprintf(stderr, "%s\n", error);
        }
 
        while ((error = fr_strerror_marker_pop(&subject, &offset))) {
                if (error && (error[0] != '\0')) {
                        fprintf(stderr, "%s\n", error);
                }
        }
 
}
 
/** Print the stack of string buffers to a thread local buffer
 *
 * Used by utility functions lacking their own logging infrastructure
 *
 * @hidecallergraph
 *
 * @param[in] line_sep  to insert between the log lines.
 * @param[in] fmt       to prefix all log messages with.
 * @return
 *      - A thread local string buffer containing the concatenated messages.
 */
char const *fr_perror_to_str(char const *line_sep, char const *fmt, ...)
{
        char const      *error;
        char const      *subject;
        size_t          offset;
        char            *prefix;
        va_list         ap;
        fr_sbuff_t      *agg;
 
        FR_SBUFF_TALLOC_THREAD_LOCAL(&agg, 256, SIZE_MAX);
 
        va_start(ap, fmt);
        prefix = talloc_vasprintf(NULL, fmt, ap);
        if (unlikely(!prefix)) return NULL;
        va_end(ap);
 
        error = fr_strerror_marker_pop(&subject, &offset);
        if (error) {
                if (fr_sbuff_in_sprintf(agg, "%s: %s%s", prefix, error, line_sep) < 0) return NULL;
        } else {
                if (fr_sbuff_in_sprintf(agg, "%s%s", prefix, error, line_sep) < 0) return NULL;
                talloc_free(prefix);
                return NULL;
        }
 
        while ((error = fr_strerror_marker_pop(&subject, &offset))) {
                if (error && (error[0] != '\0')) {
                        if (fr_sbuff_in_sprintf(agg, "%s: %s%s", prefix, error, line_sep) < 0) return NULL;
                }
        }
        talloc_free(prefix);
 
        return fr_sbuff_start(agg);
}