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libmount Reference Manual | |
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| Top | Description | ||||
struct libmnt_lock; void mnt_free_lock (struct libmnt_lock *ml); int mnt_lock_file (struct libmnt_lock *ml); struct libmnt_lock * mnt_new_lock (const char *datafile,pid_t id); void mnt_unlock_file (struct libmnt_lock *ml); int mnt_lock_block_signals (struct libmnt_lock *ml,int enable);
The mtab lock is backwardly compatible with the standard linux /etc/mtab locking. Note, it's necessary to use the same locking schema in all application that access the file.
void mnt_free_lock (struct libmnt_lock *ml);
Deallocates mnt_lock.
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struct libmnt_lock handler |
int mnt_lock_file (struct libmnt_lock *ml);
Creates lock file (e.g. /etc/mtab~). Note that this function may
use alarm().
Your application has to always call mnt_unlock_file() before exit.
Traditional mtab locking scheme:
1. create linkfile (e.g. /etc/mtab~.$PID)
2. link linkfile --> lockfile (e.g. /etc/mtab~.$PID --> /etc/mtab~)
3. a) link() success: setups F_SETLK lock (see fcnlt(2))
b) link() failed: wait (max 30s) on F_SETLKW lock, goto 2.
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pointer to struct libmnt_lock instance |
Returns : |
0 on success or negative number in case of error (-ETIMEOUT is case of stale lock file). |
struct libmnt_lock * mnt_new_lock (const char *datafile,pid_t id);
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the file that should be covered by the lock |
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unique linkfile identifier or 0 (default is getpid()) |
Returns : |
newly allocated lock handler or NULL on case of error. |
void mnt_unlock_file (struct libmnt_lock *ml);
Unlocks the file. The function could be called independently on the lock status (for example from exit(3)).
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lock struct |