[alsa-devel] [PATCH 0/2] pcm_file write file assert case handling
patched possible case where failed file write can cause assert in pcm_file plugin, by reporting error EPIPE and printing debug message.
reporting an error with debug hint message is preferred to assert, user may have a way to recover in upper API level. providing a debug message makes it easier to debug the issue from logs. previously, reaching assert did not provide useful message to API level user.
Adam Miartus (2): pcm_file: do not disrupt playback on output file write fail pcm_file: report write output file error to api user
src/pcm/pcm_file.c | 63 +++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 46 insertions(+), 17 deletions(-)
previously playback could be interrupted by snd_pcm_file_add_frames: assert(file->wbuf_used_bytes < file->wbuf_size_bytes)
in case snd_pcm_file_write_bytes fails to write full amount of bytes to file, variable wbuf_used_bytes would not be fully decremented by requested amount of bytes function was called with
for the assert to trigger, multiple write fails need to happen, so that wbuf_used_bytes overflows wbuf_size_bytes,
this patch will allow application to report error code to api user who might have an idea how to recover, before assert is triggered, also reporting error along with the print out message might give user a better idea of what is going on, where previously reason for mentioned assert was not immediately clear
Signed-off-by: Adam Miartus amiartus@de.adit-jv.com --- src/pcm/pcm_file.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-)
diff --git a/src/pcm/pcm_file.c b/src/pcm/pcm_file.c index 1ef80b5..a1d15d6 100644 --- a/src/pcm/pcm_file.c +++ b/src/pcm/pcm_file.c @@ -381,27 +381,31 @@ static void fixup_wav_header(snd_pcm_t *pcm)
-static void snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) +/* return error code in case write failed */ +static int snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) { snd_pcm_file_t *file = pcm->private_data; + snd_pcm_sframes_t err = 0; assert(bytes <= file->wbuf_used_bytes);
if (file->format == SND_PCM_FILE_FORMAT_WAV && !file->wav_header.fmt) { - if (write_wav_header(pcm) < 0) - return; + err = write_wav_header(pcm); + if (err < 0) { + SYSERR("%s write failed, file data may be corrupt", file->fname); + return err; + } }
while (bytes > 0) { - snd_pcm_sframes_t err; size_t n = bytes; size_t cont = file->wbuf_size_bytes - file->file_ptr_bytes; if (n > cont) n = cont; err = write(file->fd, file->wbuf + file->file_ptr_bytes, n); if (err < 0) { - SYSERR("write failed"); - break; + SYSERR("%s write failed, file data may be corrupt", file->fname); + return err; } bytes -= err; file->wbuf_used_bytes -= err; @@ -412,15 +416,18 @@ static void snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) if ((snd_pcm_uframes_t)err != n) break; } + + return 0; }
-static void snd_pcm_file_add_frames(snd_pcm_t *pcm, - const snd_pcm_channel_area_t *areas, - snd_pcm_uframes_t offset, - snd_pcm_uframes_t frames) +static int snd_pcm_file_add_frames(snd_pcm_t *pcm, + const snd_pcm_channel_area_t *areas, + snd_pcm_uframes_t offset, + snd_pcm_uframes_t frames) { snd_pcm_file_t *file = pcm->private_data; while (frames > 0) { + int err = 0; snd_pcm_uframes_t n = frames; snd_pcm_uframes_t cont = file->wbuf_size - file->appl_ptr; snd_pcm_uframes_t avail = file->wbuf_size - snd_pcm_bytes_to_frames(pcm, file->wbuf_used_bytes); @@ -437,10 +444,15 @@ static void snd_pcm_file_add_frames(snd_pcm_t *pcm, if (file->appl_ptr == file->wbuf_size) file->appl_ptr = 0; file->wbuf_used_bytes += snd_pcm_frames_to_bytes(pcm, n); - if (file->wbuf_used_bytes > file->buffer_bytes) - snd_pcm_file_write_bytes(pcm, file->wbuf_used_bytes - file->buffer_bytes); + if (file->wbuf_used_bytes > file->buffer_bytes) { + err = snd_pcm_file_write_bytes(pcm, file->wbuf_used_bytes - file->buffer_bytes); + if (err < 0) { + return err; + } + } assert(file->wbuf_used_bytes < file->wbuf_size_bytes); } + return 0; }
static int snd_pcm_file_close(snd_pcm_t *pcm)
On 2019-06-07 14:23, Adam Miartus wrote:
previously playback could be interrupted by snd_pcm_file_add_frames: assert(file->wbuf_used_bytes < file->wbuf_size_bytes)
in case snd_pcm_file_write_bytes fails to write full amount of bytes to file, variable wbuf_used_bytes would not be fully decremented by requested amount of bytes function was called with
for the assert to trigger, multiple write fails need to happen, so that wbuf_used_bytes overflows wbuf_size_bytes,
this patch will allow application to report error code to api user who might have an idea how to recover, before assert is triggered, also reporting error along with the print out message might give user a better idea of what is going on, where previously reason for mentioned assert was not immediately clear
Signed-off-by: Adam Miartus amiartus@de.adit-jv.com
src/pcm/pcm_file.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-)
diff --git a/src/pcm/pcm_file.c b/src/pcm/pcm_file.c index 1ef80b5..a1d15d6 100644 --- a/src/pcm/pcm_file.c +++ b/src/pcm/pcm_file.c @@ -381,27 +381,31 @@ static void fixup_wav_header(snd_pcm_t *pcm)
-static void snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) +/* return error code in case write failed */ +static int snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) { snd_pcm_file_t *file = pcm->private_data;
snd_pcm_sframes_t err = 0; assert(bytes <= file->wbuf_used_bytes);
if (file->format == SND_PCM_FILE_FORMAT_WAV && !file->wav_header.fmt) {
if (write_wav_header(pcm) < 0)return;
err = write_wav_header(pcm);if (err < 0) {SYSERR("%s write failed, file data may be corrupt", file->fname);return err;}
write_wav_header already dumps "Write error" on failure. Both messages are quite similar. Your message dumps filename though, so it's clearly more descriptive - consider updating write_wav_header SYSERR message all along while simplifying code here.
}
while (bytes > 0) {
snd_pcm_sframes_t err;SYSERR("write failed");break;
SYSERR("%s write failed, file data may be corrupt", file->fname);return err;@@ -412,15 +416,18 @@ static void snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) if ((snd_pcm_uframes_t)err != n) break; }
- return 0; }
-static void snd_pcm_file_add_frames(snd_pcm_t *pcm,
const snd_pcm_channel_area_t *areas,snd_pcm_uframes_t offset,snd_pcm_uframes_t frames)+static int snd_pcm_file_add_frames(snd_pcm_t *pcm,
const snd_pcm_channel_area_t *areas,snd_pcm_uframes_t offset,snd_pcm_uframes_t frames)int err = 0;@@ -437,10 +444,15 @@ static void snd_pcm_file_add_frames(snd_pcm_t *pcm, if (file->appl_ptr == file->wbuf_size) file->appl_ptr = 0; file->wbuf_used_bytes += snd_pcm_frames_to_bytes(pcm, n);
if (file->wbuf_used_bytes > file->buffer_bytes)snd_pcm_file_write_bytes(pcm, file->wbuf_used_bytes - file->buffer_bytes);
if (file->wbuf_used_bytes > file->buffer_bytes) {err = snd_pcm_file_write_bytes(pcm, file->wbuf_used_bytes - file->buffer_bytes);if (err < 0) {return err;}
Suggestion: drop unnecessary brackets.
}- return 0;
Hmm. For snd_pcm_file_write_bytes you've chosen a different form: newline + return. Code looks more cohesive if it's "formatted" in the same fashion.
}
static int snd_pcm_file_close(snd_pcm_t *pcm)
-----Original Message----- From: Cezary Rojewski cezary.rojewski@intel.com Sent: Samstag, 8. Juni 2019 20:38 To: Miartus, Adam (Arion Recruitment; ADITG/ESM) <amiartus@de.adit- jv.com>; patch@alsa-project.org Cc: alsa-devel@alsa-project.org Subject: Re: [alsa-devel] [PATCH 1/2] pcm_file: do not disrupt playback on output file write fail
On 2019-06-07 14:23, Adam Miartus wrote:
previously playback could be interrupted by snd_pcm_file_add_frames: assert(file->wbuf_used_bytes < file->wbuf_size_bytes)
in case snd_pcm_file_write_bytes fails to write full amount of bytes to file, variable wbuf_used_bytes would not be fully decremented by requested amount of bytes function was called with
for the assert to trigger, multiple write fails need to happen, so that wbuf_used_bytes overflows wbuf_size_bytes,
this patch will allow application to report error code to api user who might have an idea how to recover, before assert is triggered, also reporting error along with the print out message might give user a better idea of what is going on, where previously reason for mentioned assert was not immediately clear
Signed-off-by: Adam Miartus amiartus@de.adit-jv.com
src/pcm/pcm_file.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-)
diff --git a/src/pcm/pcm_file.c b/src/pcm/pcm_file.c index 1ef80b5..a1d15d6 100644 --- a/src/pcm/pcm_file.c +++ b/src/pcm/pcm_file.c @@ -381,27 +381,31 @@ static void fixup_wav_header(snd_pcm_t *pcm)
-static void snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) +/* return error code in case write failed */ +static int snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) { snd_pcm_file_t *file = pcm->private_data;
snd_pcm_sframes_t err = 0; assert(bytes <= file->wbuf_used_bytes);
if (file->format == SND_PCM_FILE_FORMAT_WAV && !file->wav_header.fmt) {
if (write_wav_header(pcm) < 0)return;
err = write_wav_header(pcm);if (err < 0) {SYSERR("%s write failed, file data may be corrupt",file->fname);
return err;}write_wav_header already dumps "Write error" on failure. Both messages are quite similar. Your message dumps filename though, so it's clearly more descriptive - consider updating write_wav_header SYSERR message all along while simplifying code here.
}
while (bytes > 0) {
snd_pcm_sframes_t err;SYSERR("write failed");break;
SYSERR("%s write failed, file data may be corrupt",file->fname);
return err;@@ -412,15 +416,18 @@ static void snd_pcm_file_write_bytes(snd_pcm_t
*pcm, size_t bytes)
if ((snd_pcm_uframes_t)err != n) break;}
- return 0; }
-static void snd_pcm_file_add_frames(snd_pcm_t *pcm,
const snd_pcm_channel_area_t *areas,snd_pcm_uframes_t offset,snd_pcm_uframes_t frames)+static int snd_pcm_file_add_frames(snd_pcm_t *pcm,
const snd_pcm_channel_area_t *areas,snd_pcm_uframes_t offset,snd_pcm_uframes_t frames)int err = 0;snd_pcm_bytes_to_frames(pcm, file->wbuf_used_bytes);
@@ -437,10 +444,15 @@ static void snd_pcm_file_add_frames(snd_pcm_t
*pcm,
if (file->appl_ptr == file->wbuf_size) file->appl_ptr = 0; file->wbuf_used_bytes += snd_pcm_frames_to_bytes(pcm,n);
if (file->wbuf_used_bytes > file->buffer_bytes)snd_pcm_file_write_bytes(pcm, file-wbuf_used_bytes - file->buffer_bytes);
if (file->wbuf_used_bytes > file->buffer_bytes) {err = snd_pcm_file_write_bytes(pcm, file-wbuf_used_bytes - file->buffer_bytes);
if (err < 0) {return err;}Suggestion: drop unnecessary brackets.
}- return 0;
Hmm. For snd_pcm_file_write_bytes you've chosen a different form: newline + return. Code looks more cohesive if it's "formatted" in the same fashion.
}
static int snd_pcm_file_close(snd_pcm_t *pcm)
Thank you for the review, I removed the whitespace, brackets and moved the log to be printed at first error occurrence.
Should I send a new patch request or copy paste here is ok?
From 5f347b41ed78b5f033c6e5d62ae9bef944dbb1b0 Mon Sep 17 00:00:00 2001 From: Adam Miartus amiartus@de.adit-jv.com Date: Tue, 11 Jun 2019 09:42:21 +0200 Subject: [PATCH] pcm_file: do not disrupt playback on output file write fail
previously playback could be interrupted by snd_pcm_file_add_frames: assert(file->wbuf_used_bytes < file->wbuf_size_bytes)
in case snd_pcm_file_write_bytes fails to write full amount of bytes to file, variable wbuf_used_bytes would not be fully decremented by requested amount of bytes function was called with
for the assert to trigger, multiple write fails need to happen, so that wbuf_used_bytes overflows wbuf_size_bytes,
this patch will allow application to report error code to api user who might have an idea how to recover, before assert is triggered, also reporting error along with the print out message might give user a better idea of what is going on, where previously reason for mentioned assert was not immediately clear
Signed-off-by: Adam Miartus amiartus@de.adit-jv.com --- src/pcm/pcm_file.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/src/pcm/pcm_file.c b/src/pcm/pcm_file.c index 1ef80b5..0a8d98d 100644 --- a/src/pcm/pcm_file.c +++ b/src/pcm/pcm_file.c @@ -346,7 +346,7 @@ static int write_wav_header(snd_pcm_t *pcm) sizeof(file->wav_header) || write(file->fd, header2, sizeof(header2)) != sizeof(header2)) { int err = errno; - SYSERR("Write error.\n"); + SYSERR("%s write header failed, file data may be corrupt", file->fname); return -err; } return 0; @@ -381,27 +381,29 @@ static void fixup_wav_header(snd_pcm_t *pcm)
-static void snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) +/* return error code in case write failed */ +static int snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) { snd_pcm_file_t *file = pcm->private_data; + snd_pcm_sframes_t err = 0; assert(bytes <= file->wbuf_used_bytes);
if (file->format == SND_PCM_FILE_FORMAT_WAV && !file->wav_header.fmt) { - if (write_wav_header(pcm) < 0) - return; + err = write_wav_header(pcm); + if (err < 0) + return err; }
while (bytes > 0) { - snd_pcm_sframes_t err; size_t n = bytes; size_t cont = file->wbuf_size_bytes - file->file_ptr_bytes; if (n > cont) n = cont; err = write(file->fd, file->wbuf + file->file_ptr_bytes, n); if (err < 0) { - SYSERR("write failed"); - break; + SYSERR("%s write failed, file data may be corrupt", file->fname); + return err; } bytes -= err; file->wbuf_used_bytes -= err; @@ -412,15 +414,17 @@ static void snd_pcm_file_write_bytes(snd_pcm_t *pcm, size_t bytes) if ((snd_pcm_uframes_t)err != n) break; } + return 0; }
-static void snd_pcm_file_add_frames(snd_pcm_t *pcm, - const snd_pcm_channel_area_t *areas, - snd_pcm_uframes_t offset, - snd_pcm_uframes_t frames) +static int snd_pcm_file_add_frames(snd_pcm_t *pcm, + const snd_pcm_channel_area_t *areas, + snd_pcm_uframes_t offset, + snd_pcm_uframes_t frames) { snd_pcm_file_t *file = pcm->private_data; while (frames > 0) { + int err = 0; snd_pcm_uframes_t n = frames; snd_pcm_uframes_t cont = file->wbuf_size - file->appl_ptr; snd_pcm_uframes_t avail = file->wbuf_size - snd_pcm_bytes_to_frames(pcm, file->wbuf_used_bytes); @@ -437,10 +441,14 @@ static void snd_pcm_file_add_frames(snd_pcm_t *pcm, if (file->appl_ptr == file->wbuf_size) file->appl_ptr = 0; file->wbuf_used_bytes += snd_pcm_frames_to_bytes(pcm, n); - if (file->wbuf_used_bytes > file->buffer_bytes) - snd_pcm_file_write_bytes(pcm, file->wbuf_used_bytes - file->buffer_bytes); + if (file->wbuf_used_bytes > file->buffer_bytes) { + err = snd_pcm_file_write_bytes(pcm, file->wbuf_used_bytes - file->buffer_bytes); + if (err < 0) + return err; + } assert(file->wbuf_used_bytes < file->wbuf_size_bytes); } + return 0; }
static int snd_pcm_file_close(snd_pcm_t *pcm)
On Tue, 11 Jun 2019 09:52:19 +0200, Miartus, Adam (Arion Recruitment; ADITG/ESM) wrote:
Thank you for the review, I removed the whitespace, brackets and moved the log to be printed at first error occurrence.
Should I send a new patch request or copy paste here is ok?
Please resubmit the patchset as v2 later. But it's better if you guys take internal reviews and get reviewed-by tag before resubmission.
thanks,
Takashi
when writing to output file fails, api user is notified and can handle recovery
Signed-off-by: Adam Miartus amiartus@de.adit-jv.com --- src/pcm/pcm_file.c | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-)
diff --git a/src/pcm/pcm_file.c b/src/pcm/pcm_file.c index a1d15d6..7df5e89 100644 --- a/src/pcm/pcm_file.c +++ b/src/pcm/pcm_file.c @@ -576,7 +576,10 @@ static snd_pcm_sframes_t snd_pcm_file_writei(snd_pcm_t *pcm, const void *buffer, if (n > 0) { snd_pcm_areas_from_buf(pcm, areas, (void*) buffer); __snd_pcm_lock(pcm); - snd_pcm_file_add_frames(pcm, areas, 0, n); + if (snd_pcm_file_add_frames(pcm, areas, 0, n) < 0) { + __snd_pcm_unlock(pcm); + return -EPIPE; + } __snd_pcm_unlock(pcm); } return n; @@ -591,7 +594,10 @@ static snd_pcm_sframes_t snd_pcm_file_writen(snd_pcm_t *pcm, void **bufs, snd_pc if (n > 0) { snd_pcm_areas_from_bufs(pcm, areas, bufs); __snd_pcm_lock(pcm); - snd_pcm_file_add_frames(pcm, areas, 0, n); + if (snd_pcm_file_add_frames(pcm, areas, 0, n) < 0) { + __snd_pcm_unlock(pcm); + return -EPIPE; + } __snd_pcm_unlock(pcm); } return n; @@ -612,6 +618,11 @@ static snd_pcm_sframes_t snd_pcm_file_readi(snd_pcm_t *pcm, void *buffer, snd_pc snd_pcm_file_areas_read_infile(pcm, areas, 0, frames); __snd_pcm_lock(pcm); snd_pcm_file_add_frames(pcm, areas, 0, frames); + if (snd_pcm_file_add_frames(pcm, areas, 0, frames) < 0) { + __snd_pcm_unlock(pcm); + return -EPIPE; + } + __snd_pcm_unlock(pcm);
return frames; @@ -631,7 +642,11 @@ static snd_pcm_sframes_t snd_pcm_file_readn(snd_pcm_t *pcm, void **bufs, snd_pcm snd_pcm_areas_from_bufs(pcm, areas, bufs); snd_pcm_file_areas_read_infile(pcm, areas, 0, frames); __snd_pcm_lock(pcm); - snd_pcm_file_add_frames(pcm, areas, 0, frames); + if (snd_pcm_file_add_frames(pcm, areas, 0, frames) < 0) { + __snd_pcm_unlock(pcm); + return -EPIPE; + } + __snd_pcm_unlock(pcm);
return frames; @@ -653,8 +668,10 @@ static snd_pcm_sframes_t snd_pcm_file_mmap_commit(snd_pcm_t *pcm, if (result >= 0) { assert(ofs == offset && siz == size); result = snd_pcm_mmap_commit(file->gen.slave, ofs, siz); - if (result > 0) - snd_pcm_file_add_frames(pcm, areas, ofs, result); + if (result > 0) { + if (snd_pcm_file_add_frames(pcm, areas, ofs, result) < 0) + return -EPIPE; + } } return result; }
participants (4)
-
Adam Miartus -
Cezary Rojewski -
Miartus, Adam (Arion Recruitment; ADITG/ESM)
-
Takashi Iwai