talloc.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
 */
 
/** Functions which we wish were included in the standard talloc distribution
 *
 * @file src/lib/util/talloc.c
 *
 * @copyright 2017 The FreeRADIUS server project
 * @copyright 2017 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSID("$Id: cecafa57af391478aa6aaabed4e9b5ed94b7aab9 $")
 
#include <freeradius-devel/util/atexit.h>
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/util/dlist.h>
#include <freeradius-devel/util/syserror.h>
 
 
static TALLOC_CTX *global_ctx;
static _Thread_local TALLOC_CTX *thread_local_ctx;
 
/** A wrapper that can be passed to tree or hash alloc functions that take a #fr_free_t
 */
void talloc_free_data(void *data)
{
        talloc_free(data);
}
 
/** Retrieve the current talloc NULL ctx
 *
 * Talloc doesn't provide a function to retrieve the top level memory tracking context.
 * This function does that...
 *
 * @return the current talloc NULL context or NULL if memory tracking is not enabled.
 */
void *talloc_null_ctx(void)
{
        TALLOC_CTX *null_ctx;
        bool *tmp;
 
        tmp = talloc(NULL, bool);
        null_ctx = talloc_parent(tmp);
        talloc_free(tmp);
 
        return null_ctx;
}
 
/** Called with the fire_ctx is freed
 *
 */
static int _talloc_destructor_fire(fr_talloc_destructor_t *d)
{
        if (d->ds) {
                talloc_set_destructor(d->ds, NULL);     /* Disarm the disarmer */
                TALLOC_FREE(d->ds);                     /* Free the disarm trigger ctx */
        }
 
        return d->func(d->fire, d->uctx);
}
 
/** Called when the disarm_ctx ctx is freed
 *
 */
static int _talloc_destructor_disarm(fr_talloc_destructor_disarm_t *ds)
{
        talloc_set_destructor(ds->d, NULL);             /* Disarm the destructor */
        return talloc_free(ds->d);                      /* Free memory allocated to the destructor */
}
 
/** Add an additional destructor to a talloc chunk
 *
 * @param[in] fire_ctx          When this ctx is freed the destructor function
 *                              will be called.
 * @param[in] disarm_ctx        When this ctx is freed the destructor will be
 *                              disarmed. May be NULL.  #talloc_destructor_disarm
 *                              may be used to disarm the destructor too.
 * @param[in] func              to call when the fire_ctx is freed.
 * @param[in] uctx              data to pass to the above function.
 * @return
 *      - A handle to access the destructor on success.
 *      - NULL on failure.
 */
fr_talloc_destructor_t *talloc_destructor_add(TALLOC_CTX *fire_ctx, TALLOC_CTX *disarm_ctx,
                                              fr_talloc_free_func_t func, void const *uctx)
{
        fr_talloc_destructor_t *d;
 
        if (!fire_ctx) {
                fr_strerror_const("No firing ctx provided when setting destructor");
                return NULL;
        }
 
        d = talloc_zero(fire_ctx, fr_talloc_destructor_t);
        if (!d) {
        oom:
                fr_strerror_const("Out of Memory");
                return NULL;
        }
 
        d->fire = fire_ctx;
        d->func = func;
        memcpy(&d->uctx, &uctx, sizeof(d->uctx));
 
        if (disarm_ctx) {
                fr_talloc_destructor_disarm_t *ds;
 
                ds = talloc(disarm_ctx, fr_talloc_destructor_disarm_t);
                if (!ds) {
                        talloc_free(d);
                        goto oom;
                }
                ds->d = d;
                d->ds = ds;
                talloc_set_destructor(ds, _talloc_destructor_disarm);
        }
 
        talloc_set_destructor(d, _talloc_destructor_fire);
 
        return d;
}
 
/** Disarm a destructor and free all memory allocated in the trigger ctxs
 *
 */
void talloc_destructor_disarm(fr_talloc_destructor_t *d)
{
        if (d->ds) {
                talloc_set_destructor(d->ds, NULL);     /* Disarm the disarmer */
                TALLOC_FREE(d->ds);                     /* Free the disarmer ctx */
        }
 
        talloc_set_destructor(d, NULL);                 /* Disarm the destructor */
        talloc_free(d);                                 /* Free the destructor ctx */
}
 
static int _talloc_link_ctx_free(UNUSED void *parent, void *child)
{
        talloc_free(child);
 
        return 0;
}
 
/** Link two different parent and child contexts, so the child is freed before the parent
 *
 * @note This is not thread safe. Do not free parent before threads are joined, do not call from a
 *      child thread.
 *
 * @param parent who's fate the child should share.
 * @param child bound to parent's lifecycle.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int talloc_link_ctx(TALLOC_CTX *parent, TALLOC_CTX *child)
{
        if (!talloc_destructor_add(parent, child, _talloc_link_ctx_free, child)) return -1;
 
        return 0;
}
 
/** Return a page aligned talloc memory array
 *
 * Because we can't intercept talloc's malloc() calls, we need to do some tricks
 * in order to get the first allocation in the array page aligned, and to limit
 * the size of the array to a multiple of the page size.
 *
 * The reason for wanting a page aligned talloc array, is it allows us to
 * mprotect() the pages that belong to the array.
 *
 * Talloc chunks appear to be allocated within the protected region, so this should
 * catch frees too.
 *
 * @param[in] ctx       to allocate array memory in.
 * @param[out] start    The first aligned address in the array.
 * @param[in] alignment What alignment the memory chunk should have.
 * @param[in] size      How big to make the array.  Will be corrected to a multiple
 *                      of the page size.  The actual array size will be size
 *                      rounded to a multiple of the (page_size), + page_size
 * @return
 *      - A talloc chunk on success.
 *      - NULL on failure.
 */
TALLOC_CTX *talloc_aligned_array(TALLOC_CTX *ctx, void **start, size_t alignment, size_t size)
{
        size_t          rounded;
        size_t          array_size;
        void            *next;
        TALLOC_CTX      *array;
 
        rounded = ROUND_UP(size, alignment);            /* Round up to a multiple of the page size */
        if (rounded == 0) rounded = alignment;
 
        array_size = rounded + alignment;
        array = talloc_array(ctx, uint8_t, array_size);         /* Over allocate */
        if (!array) {
                fr_strerror_const("Out of memory");
                return NULL;
        }
 
        next = (void *)ROUND_UP((uintptr_t)array, alignment);           /* Round up address to the next multiple */
        *start = next;
 
        return array;
}
 
/** How big the chunk header is
 *
 * Non-zero portion will always fit in a uint8_t, so we don't need to worry about atomicity.
 */
static size_t           t_hdr_size;
 
/** Calculate the size of talloc chunk headers, once, on startup
 *
 */
static void _talloc_hdr_size(void)
{
        TALLOC_CTX      *pool;
        void            *chunk;
 
        pool = talloc_pool(NULL, 1024); /* Allocate 1k of memory, this will always be bigger than the chunk header */
        if (unlikely(pool == NULL)) {
        oom:
                fr_strerror_const("Out of memory");
                return;
        }
        chunk = talloc_size(pool, 1);   /* Get the starting address */
        if (unlikely(chunk == NULL)) goto oom;
 
        /*
         *      Sanity check... make sure the chunk is within the pool
         *      if it's not, we're in trouble.
         */
        if (!fr_cond_assert((chunk > pool) && ((uintptr_t)chunk < ((uintptr_t)pool + 1024)))) {
                fr_strerror_const("Initial allocation outside of pool memory");
                return;
        }
 
        /*
         *      Talloc returns the address after the chunk header, so
         *      the address of the pool is <malloc address> + <hdr_size>.
         *
         *      If we allocate a chunk inside the pool, then the address
         *      of the chunk will be <malloc address> + <hdr_size> + <hdr_size>.
         *      If we subtrace the chunk from the pool address, we get
         *      the size of the talloc header.
         */
        t_hdr_size = (uintptr_t)chunk - (uintptr_t)pool;
 
        talloc_free(pool); /* Free the memory we used */
}
 
/** Calculate the size of the talloc chunk header
 *
 * @return
 *      - >0 the size of the talloc chunk header.
 *      - -1 on error.
 */
ssize_t talloc_hdr_size(void)
{
        static pthread_once_t once_control = PTHREAD_ONCE_INIT;
 
        if (t_hdr_size > 0) return t_hdr_size;  /* We've already calculated it */
 
        if (pthread_once(&once_control, _talloc_hdr_size) != 0) {
                fr_strerror_printf("pthread_once failed: %s", fr_syserror(errno));
                return -1;
        }
        if (t_hdr_size == 0) return -1; /* Callback should set error */
 
        return t_hdr_size;
}
 
/** Return a page aligned talloc memory pool
 *
 * Because we can't intercept talloc's malloc() calls, we need to do some tricks
 * in order to get the first allocation in the pool page aligned, and to limit
 * the size of the pool to a multiple of the page size.
 *
 * The reason for wanting a page aligned talloc pool, is it allows us to
 * mprotect() the pages that belong to the pool.
 *
 * Talloc chunks appear to be allocated within the protected region, so this should
 * catch frees too.
 *
 * @param[in] ctx       to allocate pool memory in.
 * @param[out] start    A page aligned address within the pool.  This can be passed
 *                      to mprotect().
 * @param[out] end_len  how many bytes to protect.
 * @param[in] headers   how much room we should allocate for talloc headers.
 *                      This value should usually be >= 1.
 * @param[in] size      How big to make the pool.  Will be corrected to a multiple
 *                      of the page size.  The actual pool size will be size
 *                      rounded to a multiple of the (page_size), + page_size
 */
TALLOC_CTX *talloc_page_aligned_pool(TALLOC_CTX *ctx, void **start, size_t *end_len, unsigned int headers, size_t size)
{
        size_t          rounded, alloced, page_size = (size_t)getpagesize();
        ssize_t         hdr_size;
        void            *next;
        TALLOC_CTX      *pool;
 
        hdr_size = talloc_hdr_size();
        if (hdr_size < 0) return NULL;
 
        size += (hdr_size * headers);   /* Add more space for the chunks headers of the pool's children */
        size += hdr_size;               /* Add one more header to the pool for the padding allocation */
 
        /*
         *  Allocate enough space for the padding header the other headers
         *  and the actual data, and sure it's a multiple of the page_size.
         *
         *   |<--- page_size --->|<-- page_size -->|
         *   |<-- hdr_size -->|<-- size -->|
         */
        if (size % page_size == 0) {
                rounded = size;
        } else {
                rounded = ROUND_UP(size, page_size);
        }
 
        /*
         *  Add another page, so that we can align the first allocation in
         *  the pool to a page boundary.  We have no idea what chunk malloc
         *  will give to talloc, and what the first address after adding the
         *  pools header will be
         */
        alloced = rounded + page_size;
        pool = talloc_pool(ctx, alloced);
        if (!pool) {
                fr_strerror_const("Out of memory");
                return NULL;
        }
 
        /*
         *  If we didn't get lucky, and the first address in the pool is
         *  not the start of a page, we need to allocate some padding to
         *  get the first allocation in the pool to be on or after the
         *  start of the next page.
         */
        if ((uintptr_t)pool % page_size != 0) {
                size_t  pad_size;
                void    *padding;
 
                next = (void *)ROUND_UP((uintptr_t)pool, page_size);    /* Round up address to the next page */
 
                /*
                 *      We don't care if the first address if on a page
                 *      boundary, just that it comes after one.
                 */
                pad_size = ((uintptr_t)next - (uintptr_t)pool);
                if (pad_size > (size_t) hdr_size) {
                        pad_size -= hdr_size;                   /* Save ~111 bytes by not over-padding */
                } else {
                        pad_size = 0;                           /* Allocate as few bytes as possible */
                }
 
                padding = talloc_size(pool, pad_size);
                if (!fr_cond_assert(((uintptr_t)padding + (uintptr_t)pad_size) >= (uintptr_t)next)) {
                        fr_strerror_const("Failed padding pool memory");
                        return NULL;
                }
        } else {
                next = pool;
        }
 
        *start = next;                  /* This is the address we feed into mprotect */
        *end_len = rounded;             /* This is how much memory we protect */
 
        /*
         *      Start address must be page aligned
         */
        fr_assert(((uintptr_t)*start % page_size) == 0);
 
        /*
         *      For our sanity, length must be a multiple of the page size.
         *      mprotect will silently protect an entire additional page
         *      if length is not a multiple of page size.
         */
        fr_assert(((uintptr_t)*end_len % page_size) == 0);
 
        /*
         *      We can't protect pages before the pool
         */
        fr_assert(*start >= pool);
 
        /*
         *      We can't protect pages after the pool
         */
        fr_assert(((uintptr_t)*start + *end_len) <= ((uintptr_t)pool + alloced));
 
        return pool;
}
 
/** Version of talloc_realloc which zeroes out freshly allocated memory
 *
 * @param[in] ctx       talloc ctx to allocate in.
 * @param[in] ptr       the pointer to the old memory.
 * @param[in] elem_size the size of each element in the array.
 * @param[in] count     the number of elements in the array.
 * @param[in] name      the name of the new chunk.
 * @return
 *      - A pointer to the new memory.
 *      - NULL on error.
 */
void *_talloc_realloc_zero(const void *ctx, void *ptr, size_t elem_size, unsigned count, const char *name)
{
    size_t old_size = talloc_get_size(ptr);
    size_t new_size;
 
    void *new = _talloc_realloc_array(ctx, ptr, elem_size, count, name);
    if (!new) return NULL;
 
    new_size = talloc_array_length((uint8_t *) new);
    if (new_size > old_size) {
        memset((uint8_t *)new + old_size, 0, new_size - old_size);
    }
 
    return new;
}
 
/** Call talloc_memdup, setting the type on the new chunk correctly
 *
 * @param[in] ctx       The talloc context to hang the result off.
 * @param[in] in        The data you want to duplicate.
 * @param[in] inlen     the length of the data to be duplicated.
 * @return
 *      - Duplicated data.
 *      - NULL on error.
 *
 * @hidecallergraph
 */
uint8_t *talloc_typed_memdup(TALLOC_CTX *ctx, uint8_t const *in, size_t inlen)
{
        uint8_t *n;
 
        n = talloc_memdup(ctx, in, inlen);
        if (unlikely(!n)) return NULL;
        talloc_set_type(n, uint8_t);
 
        return n;
}
 
/** Call talloc_strdup, setting the type on the new chunk correctly
 *
 * For some bizarre reason the talloc string functions don't set the
 * memory chunk type to char, which causes all kinds of issues with
 * verifying fr_pair_ts.
 *
 * @param[in] ctx       The talloc context to hang the result off.
 * @param[in] p         The string you want to duplicate.
 * @return
 *      - Duplicated string.
 *      - NULL on error.
 *
 * @hidecallergraph
 */
char *talloc_typed_strdup(TALLOC_CTX *ctx, char const *p)
{
        char *n;
 
#undef talloc_strdup
        n = talloc_strdup(ctx, p);
        if (unlikely(!n)) return NULL;
        talloc_set_type(n, char);
 
        return n;
}
 
/** Call talloc_strndup, setting the type on the new chunk correctly
 *
 * This function is similar to talloc_typed_strdup but gets the chunk
 * length using talloc functions.
 *
 * @param[in] ctx       The talloc context to hang the result off.
 * @param[in] p         The string you want to duplicate.
 * @return
 *      - Duplicated string.
 *      - NULL on error.
 *
 * @hidecallergraph
 */
char *talloc_typed_strdup_buffer(TALLOC_CTX *ctx, char const *p)
{
        char *n;
 
        n = talloc_strndup(ctx, p, talloc_strlen(p));
        if (unlikely(!n)) return NULL;
        talloc_set_type(n, char);
 
        return n;
}
 
/** Call talloc_strndup, setting the type on the new chunk correctly
 *
 * For some bizarre reason the talloc string functions don't set the
 * memory chunk type to char, which causes all kinds of issues with
 * verifying fr_pair_ts.
 *
 * @param[in] ctx       The talloc context to hang the result off.
 * @param[in] p         The string you want to duplicate.
 * @param[in] len       The length of the string
 * @return
 *      - Duplicated string.
 *      - NULL on error.
 *
 * @hidecallergraph
 */
char *talloc_typed_strndup(TALLOC_CTX *ctx, char const *p, size_t len)
{
        char *n;
 
#undef talloc_strndup
        n = talloc_strndup(ctx, p, len);
        if (unlikely(!n)) return NULL;
        talloc_set_type(n, char);
 
        return n;
}
 
/** Call talloc vasprintf, setting the type on the new chunk correctly
 *
 * For some bizarre reason the talloc string functions don't set the
 * memory chunk type to char, which causes all kinds of issues with
 * verifying fr_pair_ts.
 *
 * @param[in] ctx       The talloc context to hang the result off.
 * @param[in] fmt       The format string.
 * @return
 *      - Formatted string.
 *      - NULL on error.
 */
char *talloc_typed_asprintf(TALLOC_CTX *ctx, char const *fmt, ...)
{
        char *n;
        va_list ap;
 
        va_start(ap, fmt);
        n = talloc_vasprintf(ctx, fmt, ap);
        va_end(ap);
        if (unlikely(!n)) return NULL;
        talloc_set_type(n, char);
 
        return n;
}
 
/** Call talloc vasprintf, setting the type on the new chunk correctly
 *
 * For some bizarre reason the talloc string functions don't set the
 * memory chunk type to char, which causes all kinds of issues with
 * verifying fr_pair_ts.
 *
 * @param[in] ctx       The talloc context to hang the result off.
 * @param[in] fmt       The format string.
 * @param[in] ap        varadic arguments.
 * @return
 *      - Formatted string.
 *      - NULL on error.
 */
char *talloc_typed_vasprintf(TALLOC_CTX *ctx, char const *fmt, va_list ap)
{
        char *n;
 
        n = talloc_vasprintf(ctx, fmt, ap);
        if (unlikely(!n)) return NULL;
        talloc_set_type(n, char);
 
        return n;
}
 
/** Binary safe strdup function
 *
 * @param[in] ctx       the talloc context to allocate new buffer in.
 * @param[in] in        String to dup, may contain embedded '\0'.
 * @return duped string.
 */
char *talloc_bstrdup(TALLOC_CTX *ctx, char const *in)
{
        char    *p;
        size_t  inlen = talloc_array_length(in);
 
        if (inlen == 0) inlen = 1;
 
        p = talloc_array(ctx, char, inlen);
        if (unlikely(!p)) return NULL;
 
        /*
         * C99 (7.21.1/2) - Length zero results in noop
         *
         * But ubsan still flags this, grrr.
         */
        if (inlen > 0) memcpy(p, in, inlen - 1);
        p[inlen - 1] = '\0';
 
        return p;
}
 
/** Binary safe strndup function
 *
 * @param[in] ctx       he talloc context to allocate new buffer in.
 * @param[in] in        String to dup, may contain embedded '\0'.
 * @param[in] inlen     Number of bytes to dup.
 * @return duped string.
 */
char *talloc_bstrndup(TALLOC_CTX *ctx, char const *in, size_t inlen)
{
        char *p;
 
        p = talloc_array(ctx, char, inlen + 1);
        if (unlikely(!p)) return NULL;
 
        /*
         * C99 (7.21.1/2) - Length zero results in noop
         *
         * But ubsan still flags this, grrr.
         */
        if (inlen > 0) memcpy(p, in, inlen);
        p[inlen] = '\0';
 
        return p;
}
 
/** Append a bstr to a bstr
 *
 * @param[in] ctx       to allocated.
 * @param[in] to        string to append to.
 * @param[in] from      string to append from.
 * @param[in] from_len  Length of from.
 * @return
 *      - Realloced buffer containing both to and from.
 *      - NULL on failure. To will still be valid.
 */
char *talloc_bstr_append(TALLOC_CTX *ctx, char *to, char const *from, size_t from_len)
{
        char    *n;
        size_t  to_len = 0;
 
        if (to) {
                to_len = talloc_array_length(to);
                if (to[to_len - 1] == '\0') to_len--;   /* Inlen should be length of input string */
        }
 
        n = talloc_realloc_size(ctx, to, to_len + from_len + 1);
        if (!n) {
                fr_strerror_printf("Extending bstr buffer to %zu bytes failed", to_len + from_len + 1);
                return NULL;
        }
 
        memcpy(n + to_len, from, from_len);
        n[to_len + from_len] = '\0';
        talloc_set_type(n, char);
 
        return n;
}
 
/** Trim a bstr (char) buffer
 *
 * Reallocs to inlen + 1 and '\0' terminates the string buffer.
 *
 * @param[in] ctx       to realloc buffer into.
 * @param[in] in        string to trim.  Will be invalid after
 *                      this function returns. If NULL a new zero terminated
 *                      buffer of inlen bytes will be allocated.
 * @param[in] inlen     Length to trim string to.
 * @return
 *      - The realloced string on success.  in then points to invalid memory.
 *      - NULL on failure. In will still be valid.
 */
char *talloc_bstr_realloc(TALLOC_CTX *ctx, char *in, size_t inlen)
{
        char *n;
 
        if (!in) {
                n = talloc_array(ctx, char, inlen + 1);
                if (!n) return NULL;
                n[0] = '\0';
                return n;
        }
 
        n = talloc_realloc_size(ctx, in, inlen + 1);
        if (unlikely(!n)) return NULL;
 
        n[inlen] = '\0';
        talloc_set_type(n, char);
 
        return n;
}
 
/** Concatenate to + ...
 *
 * @param[in] ctx       to allocate realloced buffer in.
 * @param[in] to        talloc string buffer to append to.
 * @param[in] argc      how many variadic arguments were passed.
 * @param[in] ...       talloc string buffer(s) to append.
 *                      Arguments can be NULL to simplify
 *                      calling logic.
 * @return
 *      - NULL if to or from are NULL or if the realloc fails.
 *        Note: You'll still need to free to if this function
 *        returns NULL.
 *      - The concatenation of to + from.  After this function
 *        returns to may point to invalid memory and should
 *        not be used.
 */
char *talloc_buffer_append_variadic_buffer(TALLOC_CTX *ctx, char *to, int argc, ...)
{
        va_list         ap_val, ap_len;
        int             i;
 
        size_t          to_len, total_len = 0;
        char            *out, *p;
 
        if (!to) return NULL;
 
        va_start(ap_val, argc);
        va_copy(ap_len, ap_val);
 
        total_len += to_len = talloc_strlen(to);
 
        /*
         *      Figure out how much we need to realloc
         */
        for (i = 0; i < argc; i++) {
                char *arg;
 
                arg = va_arg(ap_len, char *);
                if (!arg) continue;
 
                total_len += (talloc_strlen(arg));
        }
 
        /*
         *      It's a noop...
         */
        if (total_len == to_len) {
                va_end(ap_val);
                va_end(ap_len);
                return to;
        }
 
        out = talloc_realloc(ctx, to, char, total_len + 1);
        if (!out) goto finish;
 
        p = out + to_len;
 
        /*
         *      Copy the args in
         */
        for (i = 0; i < argc; i++) {
                char    *arg;
                size_t  len;
 
                arg = va_arg(ap_val, char *);
                if (!arg) continue;
 
                len = talloc_strlen(arg);
 
                memcpy(p, arg, len);
                p += len;
        }
        *p = '\0';
 
finish:
        va_end(ap_val);
        va_end(ap_len);
 
        return out;
}
 
/** Compares two talloced char arrays with memcmp
 *
 * Talloc arrays carry their length as part of the structure, so can be passed to a generic
 * comparison function.
 *
 * @param a     Pointer to first array.
 * @param b     Pointer to second array.
 * @return
 *      - 0 if the arrays match.
 *      - a positive or negative integer otherwise.
 */
int talloc_memcmp_bstr(char const *a, char const *b)
{
        size_t a_len, b_len;
 
        a_len = talloc_array_length(a);
        b_len = talloc_array_length(b);
 
        if (a_len > b_len) return +1;
        if (a_len < b_len) return -1;
 
        return memcmp(a, b, a_len);
}
 
/** Decrease the reference count on a ptr
 *
 * Ptr will be freed if count reaches zero.
 *
 * This is equivalent to talloc 1.0 behaviour of talloc_free.
 *
 * @param ptr to decrement ref count for.
 * @return
 *      - 0     The memory was freed.
 *      - >0    How many references remain.
 */
int talloc_decrease_ref_count(void const *ptr)
{
        size_t ref_count;
        void *to_free;
 
        if (!ptr) return 0;
 
        memcpy(&to_free, &ptr, sizeof(to_free));
 
        ref_count = talloc_reference_count(to_free);
        if (ref_count == 0) {
                talloc_free(to_free);
        } else {
                talloc_unlink(talloc_parent(ptr), to_free);
                if (talloc_reference_count(to_free) == 0) talloc_free(to_free);
        }
 
        return ref_count;
}
 
/** Add a NULL pointer to an array of pointers
 *
 * This is needed by some 3rd party libraries which take NULL terminated
 * arrays for arguments.
 *
 * If allocation fails, NULL will be returned and the original array
 * will not be touched.
 *
 * @param[in] array to null terminate.  Will be invalidated (realloced).
 * @return
 *      - NULL if array is NULL, or if reallocation fails.
 *      - A realloced version of array with an additional NULL element.
 */
void **talloc_array_null_terminate(void **array)
{
        size_t          len;
        TALLOC_CTX      *ctx;
        void            **new;
        size_t          size;
 
        if (!array) return NULL;
 
        len = talloc_array_length(array);
        ctx = talloc_parent(array);
        size = talloc_get_size(array) / talloc_array_length(array);
 
        new = _talloc_realloc_array(ctx, array, size, len + 1, talloc_get_name(array));
        if (!new) return NULL;
 
        new[len] = NULL;
 
        return new;
}
 
/** Callback to free the autofree ctx on global exit
 *
 */
static int _autofree_on_exit(void *af)
{
        talloc_set_destructor(af, NULL);
        return talloc_free(af);
}
 
/** Ensures in the autofree ctx is manually freed, things don't explode atexit
 *
 */
static int _autofree_global_destructor(TALLOC_CTX *af)
{
        return fr_atexit_global_disarm(true, _autofree_on_exit, af);
}
 
TALLOC_CTX *talloc_autofree_context_global(void)
{
        TALLOC_CTX *af = global_ctx;
 
        if (!af) {
                af = talloc_init_const("global_autofree_context");
                if (unlikely(!af)) return NULL;
 
                talloc_set_destructor(af, _autofree_global_destructor);
 
                fr_atexit_global(_autofree_on_exit, af);
                global_ctx = af;
        }
 
        return af;
}
 
/** Ensures in the autofree ctx is manually freed, things don't explode atexit
 *
 */
static int _autofree_thread_local_destructor(TALLOC_CTX *af)
{
        return fr_atexit_thread_local_disarm(true, _autofree_on_exit, af);
}
 
/** Get a thread-safe autofreed ctx that will be freed when the thread or process exits
 *
 * @note This should be used in place of talloc_autofree_context (which is now deprecated)
 * @note Will not be thread-safe if NULL tracking is enabled.
 *
 * @return A talloc ctx which will be freed when the thread or process exits.
 */
TALLOC_CTX *talloc_autofree_context_thread_local(void)
{
        TALLOC_CTX *af = thread_local_ctx;
 
        if (!af) {
                af = talloc_init_const("thread_local_autofree_context");
                if (unlikely(!af)) return NULL;
 
                talloc_set_destructor(af, _autofree_thread_local_destructor);
 
                fr_atexit_thread_local(thread_local_ctx, _autofree_on_exit, af);
        }
 
        return af;
}