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Diffstat (limited to 'manual')
| -rw-r--r-- | manual/process.texi | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/manual/process.texi b/manual/process.texi index 68361c3f61..8254e5ee86 100644 --- a/manual/process.texi +++ b/manual/process.texi @@ -33,6 +33,7 @@ primitive functions to do each step individually instead. * Process Creation Concepts:: An overview of the hard way to do it. * Process Identification:: How to get the process ID of a process. * Creating a Process:: How to fork a child process. +* Querying a Process:: How to query a child process. * Executing a File:: How to make a process execute another program. * Process Completion:: How to tell when a child process has completed. * Process Completion Status:: How to interpret the status value @@ -362,6 +363,43 @@ the proper precautions for using @code{vfork}, your program will still work even if the system uses @code{fork} instead. @end deftypefun +@node Querying a Process +@section Querying a Process + +The file descriptor returned by the @code{pidfd_fork} function can be used to +query process extra information. + +@deftypefun pid_t pidfd_getpid (int @var{fd}) +@standards{GNU, sys/pidfd.h} +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} + +The @code{pidfd_getpid} function retrieves the process ID associated with process +file descriptor created with @code{pid_spawn}, @code{pidfd_fork}, or +@code{pidfd_open}. + +If the operation fails, @code{pidfd_getpid} return @code{-1} and the following +@code{errno} error conditionas are defined: + +@table @code +@item EBADF +The input file descriptor is invalid, does not have a pidfd associated, or an +error has occurred parsing the kernel data. +@item EREMOTE +There is no process ID to denote the process in the current namespace. +@item ESRCH +The process for which the file descriptor refers to is terminated. +@item ENOENT +The procfs is not mounted. +@item ENFILE. +Too many open files in system (@code{pidfd_open} tries to open a procfs file and +read its contents). +@item ENOMEM +Insufficient kernel memory was available. +@end table + +This function is specific to Linux. +@end deftypefun + @node Executing a File @section Executing a File @cindex executing a file |