| Message ID | 1442840757-5403-1-git-send-email-a.volkov@rusbitech.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 ?????: > 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, ????????? ?????? wrote: > > 22.09.2015 16:24, Arun Raghavan ?????: > > 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
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);
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>