Re: [alsa-devel] [PATCH alsa-utils 2/4] Avoid pointer arithmetic on `void *`

[Takashi Sakamoto <o-takashi@sakamocchi.jp>]

On Wed, Feb 05, 2020 at 12:12:19AM -0800, Michael Forney wrote:
> The pointer operand to the binary `+` operator must be to a complete
> object type.
> 
> Signed-off-by: Michael Forney <mforney@mforney.org>
> ---
>  aplay/aplay.c                     | 4 ++--
>  axfer/xfer-libasound-irq-mmap.c   | 7 ++++---
>  axfer/xfer-libasound-timer-mmap.c | 4 ++--
>  bat/common.c                      | 2 +-
>  seq/aplaymidi/aplaymidi.c         | 2 +-
>  5 files changed, 10 insertions(+), 9 deletions(-)

These changes look good to me.

Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

> diff --git a/aplay/aplay.c b/aplay/aplay.c
> index 908093c..08395f6 100644
> --- a/aplay/aplay.c
> +++ b/aplay/aplay.c
> @@ -442,7 +442,7 @@ static ssize_t xwrite(int fd, const void *buf, size_t count)
>  	size_t offset = 0;
>  
>  	while (offset < count) {
> -		written = write(fd, buf + offset, count - offset);
> +		written = write(fd, (char *)buf + offset, count - offset);
>  		if (written <= 0)
>  			return written;
>  
> @@ -1210,7 +1210,7 @@ static int test_au(int fd, void *buffer)
>  	hwparams.channels = BE_INT(ap->channels);
>  	if (hwparams.channels < 1 || hwparams.channels > 256)
>  		return -1;
> -	if ((size_t)safe_read(fd, buffer + sizeof(AuHeader), BE_INT(ap->hdr_size) - sizeof(AuHeader)) != BE_INT(ap->hdr_size) - sizeof(AuHeader)) {
> +	if ((size_t)safe_read(fd, (char *)buffer + sizeof(AuHeader), BE_INT(ap->hdr_size) - sizeof(AuHeader)) != BE_INT(ap->hdr_size) - sizeof(AuHeader)) {
>  		error(_("read error"));
>  		prg_exit(EXIT_FAILURE);
>  	}
> diff --git a/axfer/xfer-libasound-irq-mmap.c b/axfer/xfer-libasound-irq-mmap.c
> index a13b3c3..386e741 100644
> --- a/axfer/xfer-libasound-irq-mmap.c
> +++ b/axfer/xfer-libasound-irq-mmap.c
> @@ -146,9 +146,10 @@ static int irq_mmap_process_frames(struct libasound_state *state,
>  	// TODO: Perhaps, the complex layout can be supported as a variation of
>  	// vector type. However, there's no driver with this layout.
>  	if (layout->vector == NULL) {
> -		frame_buf = areas[0].addr;
> -		frame_buf += snd_pcm_frames_to_bytes(state->handle,
> -						     frame_offset);
> +		char *buf;
> +		buf = areas[0].addr;
> +		buf += snd_pcm_frames_to_bytes(state->handle, frame_offset);
> +		frame_buf = buf;
>  	} else {
>  		int i;
>  		for (i = 0; i < layout->samples_per_frame; ++i) {
> diff --git a/axfer/xfer-libasound-timer-mmap.c b/axfer/xfer-libasound-timer-mmap.c
> index 1c642fe..ba26e29 100644
> --- a/axfer/xfer-libasound-timer-mmap.c
> +++ b/axfer/xfer-libasound-timer-mmap.c
> @@ -100,8 +100,8 @@ static void *get_buffer(struct libasound_state *state,
>  
>  	if (layout->vector == NULL) {
>  		char *buf;
> -		buf = areas[0].addr + snd_pcm_frames_to_bytes(state->handle,
> -							      frame_offset);
> +		buf = areas[0].addr;
> +		buf += snd_pcm_frames_to_bytes(state->handle, frame_offset);
>  		frame_buf = buf;
>  	} else {
>  		int i;
> diff --git a/bat/common.c b/bat/common.c
> index d3d1f28..339e749 100644
> --- a/bat/common.c
> +++ b/bat/common.c
> @@ -231,7 +231,7 @@ int generate_input_data(struct bat *bat, void *buffer, int bytes, int frames)
>  		load = 0;
>  
>  		while (1) {
> -			err = fread(buffer + load, 1, bytes - load, bat->fp);
> +			err = fread((char *)buffer + load, 1, bytes - load, bat->fp);
>  			if (0 == err) {
>  				if (feof(bat->fp)) {
>  					fprintf(bat->log,
> diff --git a/seq/aplaymidi/aplaymidi.c b/seq/aplaymidi/aplaymidi.c
> index 12d6fac..b086e70 100644
> --- a/seq/aplaymidi/aplaymidi.c
> +++ b/seq/aplaymidi/aplaymidi.c
> @@ -633,7 +633,7 @@ static void handle_big_sysex(snd_seq_event_t *ev)
>  		check_snd("sync output", err);
>  		if (sleep(1))
>  			fatal("aborted");
> -		ev->data.ext.ptr += MIDI_BYTES_PER_SEC;
> +		ev->data.ext.ptr = (char *)ev->data.ext.ptr + MIDI_BYTES_PER_SEC;
>  		length -= MIDI_BYTES_PER_SEC;
>  	}
>  	ev->data.ext.len = length;
> -- 
> 2.25.0
> 
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