[alsa-devel] [PATCH - alsa-utils 1/1] arecord: Remove only regular files
arecord removes a file before writing into it. It's not appropriate in some cases. For example, if you a pass a symlink to a file, then the symlink will be removed while the user expects to record into the symlink's target. Another case is recording into the device file. Some modems provide a tty device file as a voice device. And it's not possible to write into it under root with arecord, because it removes the device file.
So check the type of a file before writing into it and remove only regular files.
Signed-off-by: Alexander Volkov a.volkov@rusbitech.ru
diff --git a/aplay/aplay.c b/aplay/aplay.c index 459f7dd..1b2cdfc 100644 --- a/aplay/aplay.c +++ b/aplay/aplay.c @@ -2929,6 +2929,7 @@ static void capture(char *orig_name) char *name = orig_name; /* current filename */ char namebuf[PATH_MAX+1]; off64_t count, rest; /* number of bytes to capture */ + struct stat statbuf;
/* get number of bytes to capture */ count = calc_count(); @@ -2973,7 +2974,10 @@ static void capture(char *orig_name) } /* open a new file */ - remove(name); + if (!lstat(name, &statbuf)) { + if (S_ISREG(statbuf.st_mode)) + remove(name); + } fd = safe_open(name); if (fd < 0) { perror(name);
On 21 September 2015 at 18:35, Alexander Volkov a.volkov@rusbitech.ru wrote:
arecord removes a file before writing into it. It's not appropriate in some cases. For example, if you a pass a symlink to a file, then the symlink will be removed while the user expects to record into the symlink's target. Another case is recording into the device file. Some modems provide a tty device file as a voice device. And it's not possible to write into it under root with arecord, because it removes the device file.
So check the type of a file before writing into it and remove only regular files.
Signed-off-by: Alexander Volkov a.volkov@rusbitech.ru
diff --git a/aplay/aplay.c b/aplay/aplay.c index 459f7dd..1b2cdfc 100644 --- a/aplay/aplay.c +++ b/aplay/aplay.c @@ -2929,6 +2929,7 @@ static void capture(char *orig_name) char *name = orig_name; /* current filename */ char namebuf[PATH_MAX+1]; off64_t count, rest; /* number of bytes to capture */
struct stat statbuf; /* get number of bytes to capture */ count = calc_count();@@ -2973,7 +2974,10 @@ static void capture(char *orig_name) }
/* open a new file */
remove(name);
if (!lstat(name, &statbuf)) {if (S_ISREG(statbuf.st_mode))remove(name);} fd = safe_open(name); if (fd < 0) { perror(name);
Would it work to just open with O_TRUNC?
-- Arun
22.09.2015 16:24, Arun Raghavan пишет:
On 21 September 2015 at 18:35, Alexander Volkov a.volkov@rusbitech.ru wrote:
arecord removes a file before writing into it. It's not appropriate in some cases. For example, if you a pass a symlink to a file, then the symlink will be removed while the user expects to record into the symlink's target. Another case is recording into the device file. Some modems provide a tty device file as a voice device. And it's not possible to write into it under root with arecord, because it removes the device file.
So check the type of a file before writing into it and remove only regular files.
Signed-off-by: Alexander Volkov a.volkov@rusbitech.ru
diff --git a/aplay/aplay.c b/aplay/aplay.c index 459f7dd..1b2cdfc 100644 --- a/aplay/aplay.c +++ b/aplay/aplay.c @@ -2929,6 +2929,7 @@ static void capture(char *orig_name) char *name = orig_name; /* current filename */ char namebuf[PATH_MAX+1]; off64_t count, rest; /* number of bytes to capture */
struct stat statbuf; /* get number of bytes to capture */ count = calc_count();@@ -2973,7 +2974,10 @@ static void capture(char *orig_name) }
/* open a new file */
remove(name);
if (!lstat(name, &statbuf)) {if (S_ISREG(statbuf.st_mode))remove(name);} fd = safe_open(name); if (fd < 0) { perror(name);Would it work to just open with O_TRUNC?
-- Arun
I guess that "remove" is used here to exclude mutual access to the file. We can record to the created file while some program may read the removed file. Using O_TRUNC will break this use case.
On Tue, 22 Sep 2015 16:07:21 +0200, Александр Волков wrote:
22.09.2015 16:24, Arun Raghavan пишет:
On 21 September 2015 at 18:35, Alexander Volkov a.volkov@rusbitech.ru wrote:
arecord removes a file before writing into it. It's not appropriate in some cases. For example, if you a pass a symlink to a file, then the symlink will be removed while the user expects to record into the symlink's target. Another case is recording into the device file. Some modems provide a tty device file as a voice device. And it's not possible to write into it under root with arecord, because it removes the device file.
So check the type of a file before writing into it and remove only regular files.
Signed-off-by: Alexander Volkov a.volkov@rusbitech.ru
diff --git a/aplay/aplay.c b/aplay/aplay.c index 459f7dd..1b2cdfc 100644 --- a/aplay/aplay.c +++ b/aplay/aplay.c @@ -2929,6 +2929,7 @@ static void capture(char *orig_name) char *name = orig_name; /* current filename */ char namebuf[PATH_MAX+1]; off64_t count, rest; /* number of bytes to capture */
struct stat statbuf; /* get number of bytes to capture */ count = calc_count();@@ -2973,7 +2974,10 @@ static void capture(char *orig_name) }
/* open a new file */
remove(name);
if (!lstat(name, &statbuf)) {if (S_ISREG(statbuf.st_mode))remove(name);} fd = safe_open(name); if (fd < 0) { perror(name);Would it work to just open with O_TRUNC?
-- Arun
I guess that "remove" is used here to exclude mutual access to the file. We can record to the created file while some program may read the removed file. Using O_TRUNC will break this use case.
Yeah, it's a good argument. I applied your patch as is now.
thanks,
Takashi
participants (4)
-
Alexander Volkov -
Arun Raghavan -
Takashi Iwai -
Александр Волков