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author | yar <yar@FreeBSD.org> | 2004-05-17 23:09:10 +0000 |
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committer | yar <yar@FreeBSD.org> | 2004-05-17 23:09:10 +0000 |
commit | 75331fe5be2c94da9c5ef4db51ded9f039f78410 (patch) | |
tree | c91b8ed3b77526e170afd00035d74d30b0184dd5 /lib | |
parent | 7730ed4e269438738132eddf46a10fcec2e1a0f4 (diff) | |
download | FreeBSD-src-75331fe5be2c94da9c5ef4db51ded9f039f78410.zip FreeBSD-src-75331fe5be2c94da9c5ef4db51ded9f039f78410.tar.gz |
Clarify and extend paragraphs on interoperation
of fcntl(2), flock(2), and lockf(3) advisory locks.
Add such a paragraph to the flock(2) manpage for the
sake of consistency.
Reviewed by: Cyrille Lefevre and Kirk McKusick on -arch
MFC after: 2 weeks
Diffstat (limited to 'lib')
-rw-r--r-- | lib/libc/gen/lockf.3 | 16 | ||||
-rw-r--r-- | lib/libc/sys/fcntl.2 | 22 | ||||
-rw-r--r-- | lib/libc/sys/flock.2 | 23 |
3 files changed, 55 insertions, 6 deletions
diff --git a/lib/libc/gen/lockf.3 b/lib/libc/gen/lockf.3 index abb00ac..63cf669 100644 --- a/lib/libc/gen/lockf.3 +++ b/lib/libc/gen/lockf.3 @@ -173,10 +173,22 @@ error. .Pp The .Fn lockf , -.Xr fcntl 2 +.Xr fcntl 2 , and .Xr flock 2 -locks may be safely used concurrently. +locks are compatible. +Processes using different locking interfaces can cooperate +over the same file safely. +However, only one of such interfaces should be used within +the same process. +If a file is locked by a process through +.Xr flock 2 , +any record within the file will be seen as locked +from the viewpoint of another process using +.Xr fcntl 2 +or +.Fn lockf , +and vice versa. .Pp Blocking on a section is interrupted by any signal. .Sh RETURN VALUES diff --git a/lib/libc/sys/fcntl.2 b/lib/libc/sys/fcntl.2 index c888890..92b7440 100644 --- a/lib/libc/sys/fcntl.2 +++ b/lib/libc/sys/fcntl.2 @@ -341,11 +341,26 @@ The system call is recommended for applications that want to ensure the integrity of their locks when using library routines or wish to pass locks to their children. -Note that -.Xr flock 2 +.Pp +The +.Fn fcntl , +.Xr flock 2 , and +.Xr lockf 3 +locks are compatible. +Processes using different locking interfaces can cooperate +over the same file safely. +However, only one of such interfaces should be used within +the same process. +If a file is locked by a process through +.Xr flock 2 , +any record within the file will be seen as locked +from the viewpoint of another process using .Fn fcntl -locks may be safely used concurrently but +or +.Xr lockf 3 , +and vice versa. +Note that .Fn fcntl F_GETLK returns \-1 in .Fa l_pid @@ -558,6 +573,7 @@ for the reasons as stated in .Xr getdtablesize 2 , .Xr open 2 , .Xr sigvec 2 , +.Xr lockf 3 , .Xr tcgetpgrp 3 , .Xr tcsetpgrp 3 .Sh HISTORY diff --git a/lib/libc/sys/flock.2 b/lib/libc/sys/flock.2 index 3cfc7cc..1d095bd 100644 --- a/lib/libc/sys/flock.2 +++ b/lib/libc/sys/flock.2 @@ -112,6 +112,25 @@ references to a single lock. If a process holding a lock on a file forks and the child explicitly unlocks the file, the parent will lose its lock. .Pp +The +.Fn flock , +.Xr fcntl 2 , +and +.Xr lockf 3 +locks are compatible. +Processes using different locking interfaces can cooperate +over the same file safely. +However, only one of such interfaces should be used within +the same process. +If a file is locked by a process through +.Fn flock , +any record within the file will be seen as locked +from the viewpoint of another process using +.Xr fcntl 2 +or +.Xr lockf 3 , +and vice versa. +.Pp Processes blocked awaiting a lock may be awakened by signals. .Sh RETURN VALUES .Rv -std flock @@ -141,8 +160,10 @@ refers to an object that does not support file locking. .Xr close 2 , .Xr dup 2 , .Xr execve 2 , +.Xr fcntl 2 , .Xr fork 2 , -.Xr open 2 +.Xr open 2 , +.Xr lockf 3 .Sh HISTORY The .Fn flock |