[FFmpeg-devel] [PATCH] lavu/mem: add av_dynarray2_add()
Clément Bœsch
ubitux at gmail.com
Mon May 13 13:12:19 CEST 2013
On Mon, May 13, 2013 at 01:02:01PM +0200, Stefano Sabatini wrote:
> On date Saturday 2013-05-11 14:31:53 +0200, Stefano Sabatini encoded:
> > On date Friday 2013-05-10 18:39:07 +0200, Clément Bœsch encoded:
> > > On Fri, May 10, 2013 at 06:30:14PM +0200, Stefano Sabatini wrote:
> > > > On date Friday 2013-05-10 18:16:59 +0200, Clément Bœsch encoded:
> > > > > On Fri, May 10, 2013 at 10:26:13AM +0200, Stefano Sabatini wrote:
> > > > > [...]
> > > > > > Updated. If someone has an idea about a better name
> > > > > > (av_dynarray_alloc_elem() doesn't match very well with
> > > > > > av_dynarray_add()), please tell.
> > > > > >
> > > > >
> > > > > Well, they don't work on the same type of array, they are in a sense
> > > > > "incompatible", so I think the names are even too close.
> > > >
> > > > What about:
> > > > void *av_dynbuf_add(void **tab_ptr, int *nb_ptr, char *buf, size_t buf_size)
> > > >
> > > > which prepends the content of buf to the dynamic buffer, or extends
> > > > the size in case buf is NULL.
> > > >
> > >
> > > Note that we have dyn_buf things in avio API, might be a little
> > > "confusing".
> > >
> > > > This should be even handier for my specific use case. Consider the
> > > > patch suspended for the moment since I need to experiment a bit with
> > > > it.
> > >
> > > I think the current code has various useful use-cases (see following
> > > patches in the thread).
> >
> > Indeed, and I doubt of the utility of my dynbuf_add API, so I'll push
> > av_dynarray_alloc_elem() as is.
>
> New patch, new name and new interface which should be more flexible
> and possibly less confusing.
> --
> FFmpeg = Foolish and Fostering Minimal Pacific Eretic Geisha
> From 909be8fc3d946c9feda57bbd46d40a3eb021b0ee Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab at gmail.com>
> Date: Sun, 14 Apr 2013 03:07:54 +0200
> Subject: [PATCH] lavu/mem: add av_dynarray2_add()
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
>
> Based on a patch by Clément Bœsch.
>
> See thread:
> From: Clément Bœsch <ubitux at gmail.com>
> Subject: [FFmpeg-devel] [PATCH 1/5] lavu: add av_dynarray_alloc_elem().
> Date: Sun, 14 Apr 2013 03:07:54 +0200
> ---
> doc/APIchanges | 3 +++
> libavutil/mem.c | 32 ++++++++++++++++++++++++++++++++
> libavutil/mem.h | 25 +++++++++++++++++++++++++
> libavutil/version.h | 2 +-
> 4 files changed, 61 insertions(+), 1 deletion(-)
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index 1c5f6d1..4e5e5bd 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -15,6 +15,9 @@ libavutil: 2012-10-22
>
> API changes, most recent first:
>
> +2013-05-13 - xxxxxxx - lavu 52.31.100 - mem.h
> + Add av_dynarray2_add().
> +
> 2013-05-12 - xxxxxxx - lavfi 3.65.100
> Add AVFILTER_FLAG_SUPPORT_TIMELINE* filter flags.
>
> diff --git a/libavutil/mem.c b/libavutil/mem.c
> index 9b22609..295882c 100644
> --- a/libavutil/mem.c
> +++ b/libavutil/mem.c
> @@ -270,6 +270,38 @@ fail:
> *nb_ptr = 0;
> }
>
> +void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
> + const uint8_t *elem_data)
> +{
> + int nb = *nb_ptr, nb_alloc;
> + uint8_t *tab = *tab_ptr;
> +
> + if ((nb & (nb - 1)) == 0) {
> + if (nb == 0) {
> + nb_alloc = 1;
> + } else {
> + if (nb > INT_MAX / (2 * elem_size))
> + goto fail;
> + nb_alloc = nb * 2;
> + }
> + tab = av_realloc(tab, nb_alloc * elem_size);
> + if (!tab)
> + goto fail;
> + *tab_ptr = tab;
> + }
> + *nb_ptr = nb + 1;
> + if (elem_data)
> + memcpy(tab + nb*elem_size, elem_data, elem_size);
> + else if (CONFIG_MEMORY_POISONING)
> + memset(tab + nb*elem_size, FF_MEMORY_POISON, elem_size);
> + return tab + nb*elem_size;
Note: you could use a temporary pointer for writing tab + nb*elem_size 3
times.
> +
> +fail:
> + av_freep(tab_ptr);
> + *nb_ptr = 0;
> + return NULL;
> +}
> +
> static void fill16(uint8_t *dst, int len)
> {
> uint32_t v = AV_RN16(dst - 2);
> diff --git a/libavutil/mem.h b/libavutil/mem.h
> index 8433ada..233b35b 100644
> --- a/libavutil/mem.h
> +++ b/libavutil/mem.h
> @@ -215,10 +215,35 @@ void av_freep(void *ptr);
> * @param tab_ptr pointer to the array to grow
> * @param nb_ptr pointer to the number of elements in the array
> * @param elem element to add
> + * @see av_dynarray2_add()
> */
> void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem);
>
> /**
> + * Add an element of size elem_size to a dynamic array.
> + *
> + * The array is reallocated when its number of elements reaches powers of 2.
> + * Therefore, the amortized cost of adding an element is constant.
> + *
> + * In case of success, the pointer to the array is updated in order to
> + * point to the new grown array, and the number pointed to by nb_ptr
> + * is incremented.
> + * In case of failure, the array is freed, *tab_ptr is set to NULL and
> + * *nb_ptr is set to 0.
> + *
> + * @param tab_ptr pointer to the array to grow
> + * @param nb_ptr pointer to the number of elements in the array
> + * @param elem_size size in bytes of the elements in the array
> + * @param elem_data pointer to the data of the element to add. If NULL, the space of
> + * the new added element is not filled.
"pointer to the data of the element to copy in the new allocated space. If
NULL, the new allocated space is left uninitialized."
> + * @return pointer to the elem_size allocated space at the end of the
> + * array, or NULL in case of memory error
> + * @see av_dynarray_add()
> + */
> +void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
> + const uint8_t *elem_data);
> +
> +/**
> * Multiply two size_t values checking for overflow.
> * @return 0 if success, AVERROR(EINVAL) if overflow.
> */
> diff --git a/libavutil/version.h b/libavutil/version.h
> index 4d87631..f9a7040 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -75,7 +75,7 @@
> */
>
> #define LIBAVUTIL_VERSION_MAJOR 52
> -#define LIBAVUTIL_VERSION_MINOR 30
> +#define LIBAVUTIL_VERSION_MINOR 31
> #define LIBAVUTIL_VERSION_MICRO 100
>
> #define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
LGTM otherwise.
> From 93a7ccf0d9c5d391e562303bfe2bb2168934e14c Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab at gmail.com>
> Date: Sat, 27 Apr 2013 22:46:49 +0200
> Subject: [PATCH] tools/ffeval: use av_dynarray2_add()
>
> Simplify, increment robustness.
> ---
> tools/ffeval.c | 33 +++++++++++++++------------------
> 1 file changed, 15 insertions(+), 18 deletions(-)
>
> diff --git a/tools/ffeval.c b/tools/ffeval.c
> index 0fab877..49463bb 100644
> --- a/tools/ffeval.c
> +++ b/tools/ffeval.c
> @@ -24,6 +24,7 @@
> #endif
>
> #include "libavutil/eval.h"
> +#include "libavutil/mem.h"
>
> #if !HAVE_GETOPT
> #include "compat/getopt.c"
> @@ -47,20 +48,27 @@ static void usage(void)
> "-p PROMPT set output prompt\n");
> }
>
> -#define MAX_BLOCK_SIZE SIZE_MAX
> -
> int main(int argc, char **argv)
> {
> - size_t buf_size = 256;
> - char *buf = av_malloc(buf_size);
> + int buf_size = 0;
> + char *buf = NULL;
> const char *outfilename = NULL, *infilename = NULL;
> FILE *outfile = NULL, *infile = NULL;
> const char *prompt = "=> ";
> int count = 0, echo = 0;
> int c;
>
> - av_max_alloc(MAX_BLOCK_SIZE);
> +#define GROW_ARRAY() \
> + do { \
> + av_dynarray2_add((void **)&buf, &buf_size, 1, NULL); \
> + if (!buf) { \
if (!av_dynarray2_add...
> + av_log(NULL, AV_LOG_ERROR, \
> + "Memory allocation problem occurred\n"); \
> + return 1; \
> + } \
> + } while (0)
>
> + GROW_ARRAY();
> while ((c = getopt(argc, argv, "ehi:o:p:")) != -1) {
> switch (c) {
> case 'e':
> @@ -120,19 +128,8 @@ int main(int argc, char **argv)
> }
> count = 0;
> } else {
> - if (count >= buf_size-1) {
> - if (buf_size == MAX_BLOCK_SIZE) {
> - av_log(NULL, AV_LOG_ERROR, "Memory allocation problem, "
> - "max block size '%zd' reached\n", MAX_BLOCK_SIZE);
> - return 1;
> - }
> - buf_size = FFMIN(buf_size, MAX_BLOCK_SIZE / 2) * 2;
> - buf = av_realloc_f((void *)buf, buf_size, 1);
> - if (!buf) {
> - av_log(NULL, AV_LOG_ERROR, "Memory allocation problem occurred\n");
> - return 1;
> - }
> - }
> + if (count >= buf_size-1)
> + GROW_ARRAY();
> buf[count++] = c;
> }
> }
Should be OK
--
Clément B.
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