BurnApp - blokování

14.6.2010 14:58 | Přečteno: 1340× | Jiné | poslední úprava: 14.6.2010 19:22

Už mě to fakt deptá, proč to pořád blokuje? Ten udisks i HAL jsou tak podělaný, že po vložení DVD+RW pořád jebou a spouštěj si tu heuristickou analýzu média a blokuje mi to mojí vypalovací aplikaci. Proč? Manuálová stránka pro open() mi tvrdí, že mi open() blokovat nebude, když použiju O_NONBLOCK. Ale mně blokuje ... taky tvrdí, že open() může být přerušen signálem. No, asi těžko, když se mi nepřerušuje, a to ani SIGKILL signálem. A né, že se blokuje jen moje aplikace, ale ono to zablokuje i ostatní aplikace, jako např. Brasero, to se neobtěžuje ani zobrazením "Detekuji zařízení, čekejte" a vypadá, že se ani nespouští... navíc to udisks neotvírá s O_EXCL, takže aplikace klidně můžou začít pálit, ale HAL i udisk to vypalování podělá, protože jeho READ může způsobit SYNCHRONIZE CACHE a celý proces vypalování tak podělat.

Nejhnusnější na tom je, že snad neexistuje žádné API pro zjištění, jestli nějaké zařízení je používáno..., před tím, než ho otevřu a zablokuje mi tak na 10 minut aplikaci.

To mám jako uživateli říct "Hele vole, vypni udisk, HAL, ať to neblokuje.". Protože když ty šmejďárny neběžej, tak to fakt neblokuje. Jenže bez nich se zase podělaj KDE a GNOME aplikace, který nejsou schopné spolehnout se pouze na udev...

Už fakt nevím, jak to naimplementovat, aby to neblokovalo. Přece nebudu kvůli každý palírně vytvářet extra thread (i když těžko někdo bude mít víc jak 2,3 palírny, ale spoléhejte na to ....), abych při zablokování jednoho mohl použít druhý, atd ...

Update #1

Tak nakonec nalezena šmejďárna jménem blkid, která na tom blokuje (a tak zablokuje chudáky, co to volají):

open("/dev/sr0", O_RDONLY)              = 3
fadvise64(3, 0, 0, POSIX_FADV_RANDOM)   = 0
fstat(3, {st_mode=S_IFBLK|0660, st_rdev=makedev(11, 0), ...}) = 0
uname({sys="Linux", node="Jardik-PC", ...}) = 0
ioctl(3, BLKGETSIZE64, 0x1e18020)       = 0
fstat(3, {st_mode=S_IFBLK|0660, st_rdev=makedev(11, 0), ...}) = 0
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
ioctl(3, BLKSSZGET, 0x1e18030)          = 0
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 512)                 = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 28672, SEEK_SET)               = 28672
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 3072, SEEK_SET)                = 3072
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 3072, SEEK_SET)                = 3072
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 3072, SEEK_SET)                = 3072
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 3072, SEEK_SET)                = 3072
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 7168, SEEK_SET)                = 7168
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 7168, SEEK_SET)                = 7168
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 7168, SEEK_SET)                = 7168
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 7168, SEEK_SET)                = 7168
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 15360, SEEK_SET)               = 15360
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 15360, SEEK_SET)               = 15360
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 15360, SEEK_SET)               = 15360
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 15360, SEEK_SET)               = 15360
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 31744, SEEK_SET)               = 31744
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 31744, SEEK_SET)               = 31744
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 31744, SEEK_SET)               = 31744
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 31744, SEEK_SET)               = 31744
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 64512, SEEK_SET)               = 64512
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 64512, SEEK_SET)               = 64512
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 64512, SEEK_SET)               = 64512
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 64512, SEEK_SET)               = 64512
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 3072, SEEK_SET)                = 3072
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 3072, SEEK_SET)                = 3072
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 7168, SEEK_SET)                = 7168
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 7168, SEEK_SET)                = 7168
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 15360, SEEK_SET)               = 15360
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 15360, SEEK_SET)               = 15360
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 31744, SEEK_SET)               = 31744
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 31744, SEEK_SET)               = 31744
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 64512, SEEK_SET)               = 64512
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 64512, SEEK_SET)               = 64512
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 8192, SEEK_SET)                = 8192
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 65536, SEEK_SET)               = 65536
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 65536, SEEK_SET)               = 65536
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 65536, SEEK_SET)               = 65536
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 8192, SEEK_SET)                = 8192
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 65536, SEEK_SET)               = 65536
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 32768, SEEK_SET)               = 32768
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 131072, SEEK_SET)              = 131072
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 131072, SEEK_SET)              = 131072
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 135168, SEEK_SET)              = 135168
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 135168, SEEK_SET)              = 135168
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 139264, SEEK_SET)              = 139264
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 139264, SEEK_SET)              = 139264
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 393216, SEEK_SET)              = 393216
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 393216, SEEK_SET)              = 393216
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 397312, SEEK_SET)              = 397312
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 397312, SEEK_SET)              = 397312
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 401408, SEEK_SET)              = 401408
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 401408, SEEK_SET)              = 401408
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1377)                = -1 EIO (Input/output error)
lseek(3, 8192, SEEK_SET)                = 8192
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 512, SEEK_SET)                 = 512
read(3, 0x1e18808, 512)                 = -1 EIO (Input/output error)
lseek(3, 2048, SEEK_SET)                = 2048
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 2048, SEEK_SET)                = 2048
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 65536, SEEK_SET)               = 65536
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 65536, SEEK_SET)               = 65536
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 8192, SEEK_SET)                = 8192
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 2048, SEEK_SET)                = 2048
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 4096, SEEK_SET)                = 4096
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 8192, SEEK_SET)                = 8192
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 1024, SEEK_SET)                = 1024
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 4096, SEEK_SET)                = 4096
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 65536, SEEK_SET)               = 65536
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 0, SEEK_SET)                   = 0
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
lseek(3, 2097152, SEEK_SET)             = 2097152
read(3, 0x1e18808, 1024)                = -1 EIO (Input/output error)
close(3)                                = 0
exit_group(2)

Update #2

Tohle se spouští: blkid -o udev -p -u noraid /dev/sr0
A trvá a trvá:

time blkid -o udev -p -u noraid /dev/sr0

real    18m6.889s
user    0m0.000s
sys     0m0.010s

A výsledek? Žádný výstup ... nevíte, kde najdu zdrojáky blid, že bych si ho opravil?        

Komentáře

[CEST]

A nejde to treba resit zavolanim nejaky funkce HALu a udisku, aby ignorovaly to jednotku DVD? Proste pri startu tvyho programu zjistit, co se pouziva HAL a/nebo udisks, a pak jim poslat zpravu, aby ignorovaly zarizeni ABC. A nakonci jim zase rict, ze device je volnej a muzou s nim pracovat (pripadne zjistit pri startu stav, jestli s nim pracujou nebo ignorujou a nakonci ten stav obnovit).

[pc2005]

A nejde to treba resit zavolanim nejaky funkce HALu a udisku, aby ignorovaly to jednotku DVD?

Něco jako killall hald?

[Jardík]

Tak řekni co mám zavolat. Zkoušel jsem snad všechno, ale stejně si to v tom jebe jak chce dál...

[martin]

tohle nepomuze ?
http://diablo.ucsc.edu/cgi-bin/man/man2html?hal-disable-polling+1

[Jardík]

Ne, HAL nemám, ale dělal to taky. Teď to hnije udisks, stejný problém, disable polling nepomáhá. BTW nakonec to není ani chyba přímo udisku, ale asi šmejďárny, co spouští - blkid, viz update blogu.

[vlastikroot]

Takovej blbej nápad - nedalo by se adoptovat lsof a zjistit si, jestli má HAL zrovna tu mechaniku otevřenou? Nebo to má otevřený furt?

[Jardík]

Dík, tím jsem našel ten blkid. Co s tím ...

[vlastikroot]

No já právě myslel něco jako zaintegrovat to do toho programu, že když to bude běžet ta analýza tak program ukáže dialog a počká než se do toho začne hrabat. Lsof vlastně prochází /proc a hledá otevřený FD, mmapovaný soubory a podobně. Implementovat to by pro tebe neměl být žadný problém (s inspirací v busyboxu třeba). O lepšim řešení já nevim, ale třeba se tu ještě někdo objeví.

[Jardík]

busybox je GPL, tam se inspirovat nemůžu

[vlastikroot]

Teda v busyboxu spíš fuser, to je podobně funkční věc (jen mnohem jednodušší). Případně mužeš zneužít zdrojáky psmisc (tam je zrovna fuser), do verze 19 pod BSD. Zrovna těhle věcí bych se nebál, pokud to opravdu neskopíruješ, ale jen si přečteš, jak to vubec funguje. To neni jak M$ open source

[xkucf03]

A proč se nekoukneš do jiných vypalovacích programů? Tam přece musí řešit totéž. To je přece jedna z výhod otevřeného softwaru, můžeš se inspirovat.

P.S. i když jestli se GPL kódu štítíš natolik, že ho nebudeš ani číst, tak to budeš mít těžké

[Jardík]

Očividně to neřeší. Brasero se zablokuje a čeká a čeká (protože používá k detekci asi wodim, nebo tak něco, kterej se při skenování taky zablokuje), k3b zase nenajde nic, protože potřebuje k detekci HAL a já mám jenom udisks a nepotřebuju. aby se to vzájemně hádalo.

[Jardík]

BTW mě to fakt jebe. Protože když mi pořádně nefunguje tohle, tak nemám ani chuť pouštět se do dalších věcí. Ať mi to nikdo nevymlouvá, ale linuxu prostě chybí k tomuhle pořádné jednotné API a v podstatě ve všech programech je to různě nahackované. A pokud mi to někdo vymlouvat chce, ať to API (které není deprecated, jako např. prosení HALu či Udisks, které stejně nefungujou pořádně) ukážou.

[kralyk z abclinuxu]

Blkid je část e2fsprogs a je to poměrně klíčová součást systému. Čtou se tim UUID, LABELy a další věci,... používá to i mount, když nezadáš -t, hádá typ FS právě pomocí blkid.

[kralyk z abclinuxu]

A ty chyby co to hází jsou divný, stejně jako doba, jakou to trvá. Nemáš možnost to zkusit ještě na dalším stroji?

[Jardík]

No ono to přečte totiž kulový, na tom DVD+RW mám titiž zapsaná "RAW" data bez filesystému a open() samozřejmě DVD+RW otevře, je totiž naformátované (né ve smyslu vytvoření FS), mechanika nikdy u DVD+RW nehlásí, že je fyzicky prázné. blkid si pak čte snad celé médium a hledá na něm filesystém, který tam ale není ...

[kralyk z abclinuxu]

Hm, podívej se semhle na položku EVALUATE, vyzerá to zajímavě, cituji:

The "udev" method uses udev /dev/disk/by-* symlinks and the "scan" method scans all block devices from the /proc/partitions file.

[chrono]

blkid najskôr zisťuje počet sektorov a tam dostane správnu odpoveď.

Potom začne postupne testovať jednotlivé súborové systémy (vlastne úplne na začiatku sa testuje, či tam je MDRAID) a pri tom sa mechanika pokúša načítať požadovaný sektor a kým pošle chybu, trvá to dosť dlho.

Ak by zlyhalo volanie lseek, tak by sa ten sektor ani nenačítaval a keďže chyba nenastane, tá knižnica nemôže vedieť, že je v niečom problém. Ak sa ten blok načíta, pri nasledujúcom prístupe sa tie údaje môžu znovu použiť, takže by to bolo dosť rýchle, ale v prípade chyby sa žiadne optimalizácie nerobia (teoreticky by sa možno mohli preskočiť testy, ktoré potrebujú dáta z rovnakého bloku, ktorý sa nepodarilo načítať, ale tým by sa to zbytočne skomplikovalo a pravdepodobne by kvôli tomu mohlo prestať niečo fungovať).

PS: Ak to chceš opraviť, pozri súbor probe.c a v ňom funkcie blkid_verify a get_buffer. :)

[Jardík]

Mně už připadá dost hnusný toto:

char *blkid_devno_to_devname(dev_t devno)
{
	struct dir_list *list = NULL, *new_list = NULL;
	char *devname = NULL;
	const char **dir;

	/*
	 * Add the starting directories to search in reverse order of
	 * importance, since we are using a stack...
	 */
	for (dir = devdirs; *dir; dir++)
		add_to_dirlist(*dir, NULL, &list);

	while (list) {
		struct dir_list *current = list;

		list = list->next;
		DBG(DEBUG_DEVNO, printf("directory %s\n", current->name));
		blkid__scan_dir(current->name, devno, &new_list, &devname);
		free(current->name);
		free(current);
		if (devname)
			break;
		/*
		 * If we're done checking at this level, descend to
		 * the next level of subdirectories. (breadth-first)
		 */
		if (list == NULL) {
			list = new_list;
			new_list = NULL;
		}
	}
	free_dirlist(&list);
	free_dirlist(&new_list);

	if (!devname) {
		DBG(DEBUG_DEVNO,
		    printf("blkid: couldn't find devno 0x%04lx\n",
			   (unsigned long) devno));
	} else {
		DBG(DEBUG_DEVNO,
		    printf("found devno 0x%04llx as %s\n", (long long)devno, devname));
	}


	return devname;
}

Hledání souboru zařízení skenováním předdefinovaných adresářů a na každý nalezený soubor volat fstat(), aby ho našel, to se na mě nezlobte, ale je to prasárna. Ono to totiž zatím "nějak" funguje, tak to nikoho netrápí.
Dále se mi nelíbí tento přístup:

if (S_ISBLK(sb.st_mode) && ioctl(fd, CDROM_GET_CAPABILITY, NULL) >= 0)
		pr->flags |= BLKID_CDROM_DEV;

To jako, že character device nemůže být CD-ROM? Např /dev/sg1 u mě je character device a CD-ROM to teda je. Ale pravda, že udisks testuje jen blokové zařízení.

[chrono]

Blkid je část e2fsprogs a je to poměrně klíčová součást systému.

Niektoré distribúcie používajú verziu knižnice, ktoré je v util-linux-ng.

[Jardík]

Takže problém je opravdu někde v blkid() nebo přímo někde zakopanej v kernelu (sr modul?).
blkid() otevře mechaniku jako obyč blokové zařízení. Problém je, že si nepřečte přes ioctl(), kde je poslední stopa a z ní nečte SCSI příkazem READ. Prostě si zavolá "obyč" lseek() a "obyč" read(). Tento read() trvá nechutně dlouho, koukněte na strace i s časy:

....
nějaký věcičky k zavádění procesu do paměti a tak
....

23:56:09 open("/dev/sr0", O_RDONLY)     = 3
23:56:09 fadvise64(3, 0, 0, POSIX_FADV_RANDOM) = 0
23:56:09 fstat(3, {st_mode=S_IFBLK|0660, st_rdev=makedev(11, 0), ...}) = 0
23:56:09 uname({sys="Linux", node="Jardik-PC", ...}) = 0
23:56:09 ioctl(3, BLKGETSIZE64, 0xe11020) = 0
23:56:09 fstat(3, {st_mode=S_IFBLK|0660, st_rdev=makedev(11, 0), ...}) = 0
23:56:09 lseek(3, 0, SEEK_SET)          = 0
23:56:09 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:56:27 lseek(3, 0, SEEK_SET)          = 0
23:56:27 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:56:35 lseek(3, 0, SEEK_SET)          = 0
23:56:35 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:56:44 lseek(3, 0, SEEK_SET)          = 0
23:56:44 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:56:53 ioctl(3, BLKSSZGET, 0xe11030)  = 0
23:56:53 lseek(3, 0, SEEK_SET)          = 0
23:56:53 read(3, 0xe11808, 512)         = -1 EIO (Input/output error)
23:57:02 lseek(3, 0, SEEK_SET)          = 0
23:57:02 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:57:11 lseek(3, 0, SEEK_SET)          = 0
23:57:11 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:57:20 lseek(3, 0, SEEK_SET)          = 0
23:57:20 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:57:29 lseek(3, 0, SEEK_SET)          = 0
23:57:29 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:57:38 lseek(3, 28672, SEEK_SET)      = 28672
23:57:38 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:57:47 lseek(3, 0, SEEK_SET)          = 0
23:57:47 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:57:56 lseek(3, 0, SEEK_SET)          = 0
23:57:56 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:58:05 lseek(3, 0, SEEK_SET)          = 0
23:58:05 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:58:14 lseek(3, 0, SEEK_SET)          = 0
23:58:14 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:58:22 lseek(3, 0, SEEK_SET)          = 0
23:58:22 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:58:31 lseek(3, 0, SEEK_SET)          = 0
23:58:31 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:58:40 lseek(3, 0, SEEK_SET)          = 0
23:58:40 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:58:49 lseek(3, 0, SEEK_SET)          = 0
23:58:49 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:58:58 lseek(3, 0, SEEK_SET)          = 0
23:58:58 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:59:07 lseek(3, 0, SEEK_SET)          = 0
23:59:07 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:59:16 lseek(3, 0, SEEK_SET)          = 0
23:59:16 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:59:25 lseek(3, 0, SEEK_SET)          = 0
23:59:25 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:59:34 lseek(3, 3072, SEEK_SET)       = 3072
23:59:34 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:59:43 lseek(3, 3072, SEEK_SET)       = 3072
23:59:43 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
23:59:52 lseek(3, 3072, SEEK_SET)       = 3072
23:59:52 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:00:00 lseek(3, 3072, SEEK_SET)       = 3072
00:00:00 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:00:09 lseek(3, 7168, SEEK_SET)       = 7168
00:00:09 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:00:18 lseek(3, 7168, SEEK_SET)       = 7168
00:00:18 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:00:27 lseek(3, 7168, SEEK_SET)       = 7168
00:00:27 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:00:36 lseek(3, 7168, SEEK_SET)       = 7168
00:00:36 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:00:45 lseek(3, 15360, SEEK_SET)      = 15360
00:00:45 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:00:54 lseek(3, 15360, SEEK_SET)      = 15360
00:00:54 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:01:03 lseek(3, 15360, SEEK_SET)      = 15360
00:01:03 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:01:12 lseek(3, 15360, SEEK_SET)      = 15360
00:01:12 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:01:21 lseek(3, 31744, SEEK_SET)      = 31744
00:01:21 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:01:30 lseek(3, 31744, SEEK_SET)      = 31744
00:01:30 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:01:38 lseek(3, 31744, SEEK_SET)      = 31744
00:01:38 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:01:47 lseek(3, 31744, SEEK_SET)      = 31744
00:01:47 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:01:56 lseek(3, 64512, SEEK_SET)      = 64512
00:01:56 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:02:05 lseek(3, 64512, SEEK_SET)      = 64512
00:02:05 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:02:14 lseek(3, 64512, SEEK_SET)      = 64512
00:02:14 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:02:23 lseek(3, 64512, SEEK_SET)      = 64512
00:02:23 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:02:32 lseek(3, 3072, SEEK_SET)       = 3072
00:02:32 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:02:41 lseek(3, 3072, SEEK_SET)       = 3072
00:02:41 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:02:50 lseek(3, 7168, SEEK_SET)       = 7168
00:02:50 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:02:59 lseek(3, 7168, SEEK_SET)       = 7168
00:02:59 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:03:08 lseek(3, 15360, SEEK_SET)      = 15360
00:03:08 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:03:17 lseek(3, 15360, SEEK_SET)      = 15360
00:03:17 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:03:25 lseek(3, 31744, SEEK_SET)      = 31744
00:03:25 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:03:34 lseek(3, 31744, SEEK_SET)      = 31744
00:03:34 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:03:43 lseek(3, 64512, SEEK_SET)      = 64512
00:03:43 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:03:52 lseek(3, 64512, SEEK_SET)      = 64512
00:03:52 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:04:01 lseek(3, 0, SEEK_SET)          = 0
00:04:01 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:04:10 lseek(3, 1024, SEEK_SET)       = 1024
00:04:10 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:04:19 lseek(3, 1024, SEEK_SET)       = 1024
00:04:19 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:04:28 lseek(3, 1024, SEEK_SET)       = 1024
00:04:28 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:04:37 lseek(3, 1024, SEEK_SET)       = 1024
00:04:37 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:04:46 lseek(3, 1024, SEEK_SET)       = 1024
00:04:46 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:04:55 lseek(3, 8192, SEEK_SET)       = 8192
00:04:55 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:05:04 lseek(3, 65536, SEEK_SET)      = 65536
00:05:04 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:05:12 lseek(3, 65536, SEEK_SET)      = 65536
00:05:12 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:05:20 lseek(3, 65536, SEEK_SET)      = 65536
00:05:20 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:05:28 lseek(3, 8192, SEEK_SET)       = 8192
00:05:28 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:05:37 lseek(3, 65536, SEEK_SET)      = 65536
00:05:37 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:05:46 lseek(3, 32768, SEEK_SET)      = 32768
00:05:46 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:05:54 lseek(3, 32768, SEEK_SET)      = 32768
00:05:54 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:06:03 lseek(3, 32768, SEEK_SET)      = 32768
00:06:03 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:06:12 lseek(3, 32768, SEEK_SET)      = 32768
00:06:12 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:06:21 lseek(3, 32768, SEEK_SET)      = 32768
00:06:21 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:06:30 lseek(3, 32768, SEEK_SET)      = 32768
00:06:30 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:06:39 lseek(3, 32768, SEEK_SET)      = 32768
00:06:39 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:06:48 lseek(3, 32768, SEEK_SET)      = 32768
00:06:48 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:06:57 lseek(3, 32768, SEEK_SET)      = 32768
00:06:57 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:07:06 lseek(3, 32768, SEEK_SET)      = 32768
00:07:06 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:07:15 lseek(3, 131072, SEEK_SET)     = 131072
00:07:15 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:07:23 lseek(3, 131072, SEEK_SET)     = 131072
00:07:23 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:07:31 lseek(3, 135168, SEEK_SET)     = 135168
00:07:31 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:07:39 lseek(3, 135168, SEEK_SET)     = 135168
00:07:39 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:07:48 lseek(3, 139264, SEEK_SET)     = 139264
00:07:48 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:07:56 lseek(3, 139264, SEEK_SET)     = 139264
00:07:56 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:08:04 lseek(3, 393216, SEEK_SET)     = 393216
00:08:04 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:08:12 lseek(3, 393216, SEEK_SET)     = 393216
00:08:12 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:08:21 lseek(3, 397312, SEEK_SET)     = 397312
00:08:21 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:08:29 lseek(3, 397312, SEEK_SET)     = 397312
00:08:29 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:08:37 lseek(3, 401408, SEEK_SET)     = 401408
00:08:37 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:08:46 lseek(3, 401408, SEEK_SET)     = 401408
00:08:46 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:08:54 lseek(3, 1024, SEEK_SET)       = 1024
00:08:54 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:09:03 lseek(3, 1024, SEEK_SET)       = 1024
00:09:03 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:09:12 lseek(3, 1024, SEEK_SET)       = 1024
00:09:12 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:09:21 lseek(3, 1024, SEEK_SET)       = 1024
00:09:21 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:09:30 lseek(3, 0, SEEK_SET)          = 0
00:09:30 read(3, 0xe11808, 1377)        = -1 EIO (Input/output error)
00:09:39 lseek(3, 8192, SEEK_SET)       = 8192
00:09:39 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:09:48 lseek(3, 512, SEEK_SET)        = 512
00:09:48 read(3, 0xe11808, 512)         = -1 EIO (Input/output error)
00:09:56 lseek(3, 2048, SEEK_SET)       = 2048
00:09:56 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:10:05 lseek(3, 2048, SEEK_SET)       = 2048
00:10:05 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:10:14 lseek(3, 0, SEEK_SET)          = 0
00:10:14 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:10:23 lseek(3, 0, SEEK_SET)          = 0
00:10:23 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:10:32 lseek(3, 0, SEEK_SET)          = 0
00:10:32 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:10:41 lseek(3, 0, SEEK_SET)          = 0
00:10:41 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:10:50 lseek(3, 1024, SEEK_SET)       = 1024
00:10:50 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:10:59 lseek(3, 1024, SEEK_SET)       = 1024
00:10:59 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:11:08 lseek(3, 1024, SEEK_SET)       = 1024
00:11:08 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:11:17 lseek(3, 1024, SEEK_SET)       = 1024
00:11:17 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:11:26 lseek(3, 1024, SEEK_SET)       = 1024
00:11:26 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:11:34 lseek(3, 65536, SEEK_SET)      = 65536
00:11:34 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:11:43 lseek(3, 65536, SEEK_SET)      = 65536
00:11:43 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:11:51 lseek(3, 8192, SEEK_SET)       = 8192
00:11:51 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:12:00 lseek(3, 1024, SEEK_SET)       = 1024
00:12:00 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:12:09 lseek(3, 2048, SEEK_SET)       = 2048
00:12:09 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:12:18 lseek(3, 4096, SEEK_SET)       = 4096
00:12:18 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:12:27 lseek(3, 8192, SEEK_SET)       = 8192
00:12:27 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:12:36 lseek(3, 0, SEEK_SET)          = 0
00:12:36 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:12:45 lseek(3, 1024, SEEK_SET)       = 1024
00:12:45 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:12:54 lseek(3, 0, SEEK_SET)          = 0
00:12:54 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:13:03 lseek(3, 0, SEEK_SET)          = 0
00:13:03 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:13:11 lseek(3, 0, SEEK_SET)          = 0
00:13:11 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:13:20 lseek(3, 0, SEEK_SET)          = 0
00:13:20 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:13:29 lseek(3, 4096, SEEK_SET)       = 4096
00:13:29 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:13:38 lseek(3, 65536, SEEK_SET)      = 65536
00:13:38 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:13:46 lseek(3, 0, SEEK_SET)          = 0
00:13:46 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:13:55 lseek(3, 0, SEEK_SET)          = 0
00:13:55 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:14:04 lseek(3, 2097152, SEEK_SET)    = 2097152
00:14:04 read(3, 0xe11808, 1024)        = -1 EIO (Input/output error)
00:14:13 close(3)                       = 0
00:14:13 exit_group(2)                  = ?

Pro každej typ FS, co to zná to v podstatě hledá, jestli tam je superblok a pod. Jenže vždy čtení selže. Otázkou je proč. Schválně jsem si napsal testovací prográmek, kterej čte bloky o velikostech 512B - 32k. U CD/DVD/BD je správná velikost bloku 2k, jenže tam je taky chyba. I u 32k (velikost ECC bloku) je chyba. MMC standard nám říká:

When recorded, DVD+RW medium is ECC block readable. An intelligent controller may separate individual sector data from a decoded ECC block. Thus for the Host, DVD+RW media is 2 048 byte sector readable.