peps: 425f831fddf7 (original) (raw)
Mercurial > peps
changeset 4978:425f831fddf7
PEP 446: enhance the Rationale to take into account Cameron Simpson's remarks * mention the name of the close-on-exec flag: HANDLE_FLAG_INHERIT, O_CLOEXEC * mention the name of the blocking flag: O_NONBLOCK * explain that file attributes are duplicated at fork
| Victor Stinner victor.stinner@gmail.com | |
|---|---|
| date | Sat, 06 Jul 2013 14:27:23 +0200 |
| parents | 39553edc98e2 |
| children | cc4da4be3838 |
| files | pep-0446.txt |
| diffstat | 1 files changed, 21 insertions(+), 7 deletions(-)[+] [-] pep-0446.txt 28 |
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--- a/pep-0446.txt
+++ b/pep-0446.txt
@@ -27,14 +27,25 @@ The inheritance of file descriptors in c
on each file descriptor using a close-on-exec flag. By default, the
close-on-exec flag is not set.
-On Windows, file descriptors are not inherited if the
-bInheritHandles parameter of the CreateProcess() function is
-FALSE, even if the close-on-exec flag is not set.
+On Windows, the close-on-exec flag is HANDLE_FLAG_INHERIT. File
+descriptors are not inherited if the bInheritHandles parameter of
+the CreateProcess() function is FALSE, even if the
+HANDLE_FLAG_INHERIT flag is set. If bInheritHandles is TRUE,
+only file descriptors with HANDLE_FLAG_INHERIT flag set are
+inherited, others are not.
-On UNIX, file descriptors with the close-and-exec flag set are closed at
-the execution of a new program (ex: when calling execv()). The flag
-has no effect on fork(), all file descriptors are inherited by the
-child process.
+On UNIX, the close-on-exec flag is O_CLOEXEC. File descriptors with
+the O_CLOEXEC flag set are closed at the execution of a new program
+(ex: when calling execv()).
+
+The O_CLOEXEC flag has no effect on fork(), all file descriptors
+are inherited by the child process. Futhermore, most properties file
+descriptors are shared between the parent and the child processes,
+except file attributes which are duplicated (O_CLOEXEC is the only
+file attribute). Setting O_CLOEXEC flag of a file descriptor in the
+child process does not change the O_CLOEXEC flag of the file
+descriptor in the parent process.
+
Issues of the inheritance of file descriptors
---------------------------------------------
@@ -62,6 +73,9 @@ operation would block.
By default, newly created sockets are blocking. Setting the non-blocking
mode requires additional system calls.
+On UNIX, the blocking flag is O_NONBLOCK: a pipe and a socket are
+non-blocking if the O_NONBLOCK flag is set.
+
Setting flags at the creation of the file descriptor
----------------------------------------------------