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Diffstat (limited to 'lib/libc/sys/write.2')
| -rw-r--r-- | lib/libc/sys/write.2 | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/lib/libc/sys/write.2 b/lib/libc/sys/write.2 index de2d3aef59ab..a1e4a517cbe2 100644 --- a/lib/libc/sys/write.2 +++ b/lib/libc/sys/write.2 @@ -115,6 +115,53 @@ and may write fewer bytes than requested; the return value must be noted, and the remainder of the operation should be retried when possible. +.Sh IMPLEMENTATION NOTES +.Pp +In the non-threaded library +.Fn write +is implemented as the +.Va write +syscall. +.Pp +In the threaded library, the +.Va write +syscall is assembled to +.Fn _thread_sys_write +and +.Fn write +is implemented as a function which locks +.Va d +for read and write, then calls +.Fn _thread_sys_write . +If the call to +.Fn _thread_sys_write +would block, a context switch is performed. Before returning, +.Fn write +unlocks +.Va d . +.Pp +In the non-threaded library +.Fn writev +is implemented as the +.Va writev +syscall. +.Pp +In the threaded library, the +.Va writev +syscall is assembled to +.Fn _thread_sys_writev +and +.Fn writev +is implemented as a function which locks +.Va d +for read and write, then calls +.Fn _thread_sys_writev . +If the call to +.Fn _thread_sys_writev +would block, a context switch is performed. Before returning, +.Fn writev +unlocks +.Va d . .Sh RETURN VALUES Upon successful completion the number of bytes which were written is returned. Otherwise a -1 is returned and the global variable |