[PATCH v2] aplay: Introduce and use xwrite helper

[PATCH v2] aplay: Introduce and use xwrite helper

[Daniel Baluta]

Write can return less then requested bytes, but we treat this as
an error thus ending up with confusing error messages.

Fix this by introducing xwrite helper, which makes sure all bytes
are written or an error is returned.

With this patch an usecase where disk is filled by recording will
print:
$ /mnt/msc/audio.wav: No space left on device

instead of random messages like:

$/mnt/msc/audio.wav: No such file or directory

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
---
Changes since v1:
	* return the correct number of bytes

 aplay/aplay.c | 55 +++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 37 insertions(+), 18 deletions(-)

diff --git a/aplay/aplay.c b/aplay/aplay.c
index ee480f2..f793c82 100644
--- a/aplay/aplay.c
+++ b/aplay/aplay.c
@@ -429,6 +429,25 @@ enum {
 	OPT_FATAL_ERRORS,
 };
 
+/*
+ * make sure we write all bytes or return an error
+ */
+static ssize_t xwrite(int fd, const void *buf, size_t count)
+{
+	ssize_t written;
+	size_t offset = 0;
+
+	while (offset < count) {
+		written = write(fd, buf + offset, count - offset);
+		if (written <= 0)
+			return written;
+
+		offset += written;
+	};
+
+	return offset;
+}
+
 static long parse_long(const char *str, int *err)
 {
 	long val;
@@ -2428,7 +2447,7 @@ static void voc_play(int fd, int ofs, char *name)
 			l = nextblock;
 		if (l) {
 			if (output && !quiet_mode) {
-				if (write(2, data, l) != l) {	/* to stderr */
+				if (xwrite(2, data, l) != l) {	/* to stderr */
 					error(_("write error"));
 					prg_exit(EXIT_FAILURE);
 				}
@@ -2480,7 +2499,7 @@ static void begin_voc(int fd, size_t cnt)
 	vh.version = LE_SHORT(VOC_ACTUAL_VERSION);
 	vh.coded_ver = LE_SHORT(0x1233 - VOC_ACTUAL_VERSION);
 
-	if (write(fd, &vh, sizeof(VocHeader)) != sizeof(VocHeader)) {
+	if (xwrite(fd, &vh, sizeof(VocHeader)) != sizeof(VocHeader)) {
 		error(_("write error"));
 		prg_exit(EXIT_FAILURE);
 	}
@@ -2489,14 +2508,14 @@ static void begin_voc(int fd, size_t cnt)
 		bt.type = 8;
 		bt.datalen = 4;
 		bt.datalen_m = bt.datalen_h = 0;
-		if (write(fd, &bt, sizeof(VocBlockType)) != sizeof(VocBlockType)) {
+		if (xwrite(fd, &bt, sizeof(VocBlockType)) != sizeof(VocBlockType)) {
 			error(_("write error"));
 			prg_exit(EXIT_FAILURE);
 		}
 		eb.tc = LE_SHORT(65536 - 256000000L / (hwparams.rate << 1));
 		eb.pack = 0;
 		eb.mode = 1;
-		if (write(fd, &eb, sizeof(VocExtBlock)) != sizeof(VocExtBlock)) {
+		if (xwrite(fd, &eb, sizeof(VocExtBlock)) != sizeof(VocExtBlock)) {
 			error(_("write error"));
 			prg_exit(EXIT_FAILURE);
 		}
@@ -2506,13 +2525,13 @@ static void begin_voc(int fd, size_t cnt)
 	bt.datalen = (u_char) (cnt & 0xFF);
 	bt.datalen_m = (u_char) ((cnt & 0xFF00) >> 8);
 	bt.datalen_h = (u_char) ((cnt & 0xFF0000) >> 16);
-	if (write(fd, &bt, sizeof(VocBlockType)) != sizeof(VocBlockType)) {
+	if (xwrite(fd, &bt, sizeof(VocBlockType)) != sizeof(VocBlockType)) {
 		error(_("write error"));
 		prg_exit(EXIT_FAILURE);
 	}
 	vd.tc = (u_char) (256 - (1000000 / hwparams.rate));
 	vd.pack = 0;
-	if (write(fd, &vd, sizeof(VocVoiceData)) != sizeof(VocVoiceData)) {
+	if (xwrite(fd, &vd, sizeof(VocVoiceData)) != sizeof(VocVoiceData)) {
 		error(_("write error"));
 		prg_exit(EXIT_FAILURE);
 	}
@@ -2581,10 +2600,10 @@ static void begin_wave(int fd, size_t cnt)
 	cd.type = WAV_DATA;
 	cd.length = LE_INT(cnt);
 
-	if (write(fd, &h, sizeof(WaveHeader)) != sizeof(WaveHeader) ||
-	    write(fd, &cf, sizeof(WaveChunkHeader)) != sizeof(WaveChunkHeader) ||
-	    write(fd, &f, sizeof(WaveFmtBody)) != sizeof(WaveFmtBody) ||
-	    write(fd, &cd, sizeof(WaveChunkHeader)) != sizeof(WaveChunkHeader)) {
+	if (xwrite(fd, &h, sizeof(WaveHeader)) != sizeof(WaveHeader) ||
+	    xwrite(fd, &cf, sizeof(WaveChunkHeader)) != sizeof(WaveChunkHeader) ||
+	    xwrite(fd, &f, sizeof(WaveFmtBody)) != sizeof(WaveFmtBody) ||
+	    xwrite(fd, &cd, sizeof(WaveChunkHeader)) != sizeof(WaveChunkHeader)) {
 		error(_("write error"));
 		prg_exit(EXIT_FAILURE);
 	}
@@ -2614,7 +2633,7 @@ static void begin_au(int fd, size_t cnt)
 	}
 	ah.sample_rate = BE_INT(hwparams.rate);
 	ah.channels = BE_INT(hwparams.channels);
-	if (write(fd, &ah, sizeof(AuHeader)) != sizeof(AuHeader)) {
+	if (xwrite(fd, &ah, sizeof(AuHeader)) != sizeof(AuHeader)) {
 		error(_("write error"));
 		prg_exit(EXIT_FAILURE);
 	}
@@ -2628,7 +2647,7 @@ static void end_voc(int fd)
 	size_t cnt;
 	char dummy = 0;		/* Write a Terminator */
 
-	if (write(fd, &dummy, 1) != 1) {
+	if (xwrite(fd, &dummy, 1) != 1) {
 		error(_("write error"));
 		prg_exit(EXIT_FAILURE);
 	}
@@ -2644,7 +2663,7 @@ static void end_voc(int fd)
 	bt.datalen_m = (u_char) ((cnt & 0xFF00) >> 8);
 	bt.datalen_h = (u_char) ((cnt & 0xFF0000) >> 16);
 	if (lseek64(fd, length_seek, SEEK_SET) == length_seek)
-		write(fd, &bt, sizeof(VocBlockType));
+		xwrite(fd, &bt, sizeof(VocBlockType));
 	if (fd != 1)
 		close(fd);
 }
@@ -2664,9 +2683,9 @@ static void end_wave(int fd)
 	filelen = fdcount + 2*sizeof(WaveChunkHeader) + sizeof(WaveFmtBody) + 4;
 	rifflen = filelen > 0x7fffffff ? LE_INT(0x7fffffff) : LE_INT(filelen);
 	if (lseek64(fd, 4, SEEK_SET) == 4)
-		write(fd, &rifflen, 4);
+		xwrite(fd, &rifflen, 4);
 	if (lseek64(fd, length_seek, SEEK_SET) == length_seek)
-		write(fd, &cd, sizeof(WaveChunkHeader));
+		xwrite(fd, &cd, sizeof(WaveChunkHeader));
 	if (fd != 1)
 		close(fd);
 }
@@ -2679,7 +2698,7 @@ static void end_au(int fd)
 	length_seek = (char *)&ah.data_size - (char *)&ah;
 	ah.data_size = fdcount > 0xffffffff ? 0xffffffff : BE_INT(fdcount);
 	if (lseek64(fd, length_seek, SEEK_SET) == length_seek)
-		write(fd, &ah.data_size, sizeof(ah.data_size));
+		xwrite(fd, &ah.data_size, sizeof(ah.data_size));
 	if (fd != 1)
 		close(fd);
 }
@@ -3078,7 +3097,7 @@ static void capture(char *orig_name)
 				in_aborting = 1;
 				break;
 			}
-			if (write(fd, audiobuf, c) != c) {
+			if (xwrite(fd, audiobuf, c) != c) {
 				perror(name);
 				in_aborting = 1;
 				break;
@@ -3187,7 +3206,7 @@ static void capturev_go(int* fds, unsigned int channels, off64_t count, int rtyp
 			break;
 		rv = r * bits_per_sample / 8;
 		for (channel = 0; channel < channels; ++channel) {
-			if ((size_t)write(fds[channel], bufs[channel], rv) != rv) {
+			if ((size_t)xwrite(fds[channel], bufs[channel], rv) != rv) {
 				perror(names[channel]);
 				prg_exit(EXIT_FAILURE);
 			}
-- 
2.7.4

Re: [PATCH v2] aplay: Introduce and use xwrite helper

[Takashi Iwai]

On Mon, 10 Apr 2017 09:04:33 +0200,
Daniel Baluta wrote:
> 
> Write can return less then requested bytes, but we treat this as
> an error thus ending up with confusing error messages.
> 
> Fix this by introducing xwrite helper, which makes sure all bytes
> are written or an error is returned.
> 
> With this patch an usecase where disk is filled by recording will
> print:
> $ /mnt/msc/audio.wav: No space left on device
> 
> instead of random messages like:
> 
> $/mnt/msc/audio.wav: No such file or directory
> 
> Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
> ---
> Changes since v1:
> 	* return the correct number of bytes

Applied, thanks.


Takashi