From a47f745fd19b53306643882c5891180259bb8981 Mon Sep 17 00:00:00 2001 From: Nicholas Clark Date: Sun, 12 Nov 2000 21:35:53 +0000 Subject: [PATCH] Many subdocumented return values of the IO extension now documented. ungetc and write still left subdocumented. Subject: [PATCH] (was Re: IO::Handle::ungetc) Message-ID: <20001112213552.A3034@Bagpuss.unfortu.net> p4raw-id: //depot/perl@7659 --- ext/IO/lib/IO/Handle.pm | 44 +++++++++++++++++++++++++++++--------------- 1 file changed, 29 insertions(+), 15 deletions(-) diff --git a/ext/IO/lib/IO/Handle.pm b/ext/IO/lib/IO/Handle.pm index b6cb410..9266f33 100644 --- a/ext/IO/lib/IO/Handle.pm +++ b/ext/IO/lib/IO/Handle.pm @@ -110,7 +110,8 @@ or a file descriptor number. =item $io->opened -Returns true if the object is currently a valid file descriptor. +Returns true if the object is currently a valid file descriptor, false +otherwise. =item $io->getline @@ -139,31 +140,37 @@ called C. =item $io->error Returns a true value if the given handle has experienced any errors -since it was opened or since the last call to C. +since it was opened or since the last call to C, or if the +handle is invalid. It only returns false for a valid handle with no +outstanding errors. =item $io->clearerr -Clear the given handle's error indicator. +Clear the given handle's error indicator. Returns -1 if the handle is +invalid, 0 otherwise. =item $io->sync C synchronizes a file's in-memory state with that on the physical medium. C does not operate at the perlio api level, but -operates on the file descriptor, this means that any data held at the -perlio api level will not be synchronized. To synchronize data that is -buffered at the perlio api level you must use the flush method. C -is not implemented on all platforms. See L. +operates on the file descriptor (similar to sysread, sysseek and +systell). This means that any data held at the perlio api level will not +be synchronized. To synchronize data that is buffered at the perlio api +level you must use the flush method. C is not implemented on all +platforms. Returns 0 on success, -1 on error, -1 for an invalid handle. +See L. =item $io->flush C causes perl to flush any buffered data at the perlio api level. Any unread data in the buffer will be discarded, and any unwritten data -will be written to the underlying file descriptor. +will be written to the underlying file descriptor. Returns 0 on success, +or a negative value on error. =item $io->printflush ( ARGS ) Turns on autoflush, print ARGS and then restores the autoflush status of the -C object. +C object. Returns the return value from print. =item $io->blocking ( [ BOOL ] ) @@ -183,11 +190,17 @@ C and C set the buffering policy for an IO::Handle. The calling sequences for the Perl functions are the same as their C counterparts--including the constants C<_IOFBF>, C<_IOLBF>, and C<_IONBF> for setvbuf()--except that the buffer parameter -specifies a scalar variable to use as a buffer. WARNING: A variable -used as a buffer by C or C must not be modified in any -way until the IO::Handle is closed or C or C is called -again, or memory corruption may result! Note that you need to import -the constants C<_IOFBF>, C<_IOLBF>, and C<_IONBF> explicitly. +specifies a scalar variable to use as a buffer. You should only +change the buffer before any I/O, or immediately after calling flush. + +WARNING: A variable used as a buffer by C or C B in any way until the IO::Handle is closed or C or +C is called again, or memory corruption may result! Remember that +the order of global destruction is undefined, so even if your buffer +variable remains in scope until program termination, it may be undefined +before the file IO::Handle is closed. Note that you need to import the +constants C<_IOFBF>, C<_IOLBF>, and C<_IONBF> explicitly. Like C, setbuf +returns nothing, setvbuf returns 0 on success, -1 on failure. Lastly, there is a special method for working under B<-T> and setuid/gid scripts: @@ -199,7 +212,8 @@ scripts: Marks the object as taint-clean, and as such data read from it will also be considered taint-clean. Note that this is a very trusting action to take, and appropriate consideration for the data source and potential -vulnerability should be kept in mind. +vulnerability should be kept in mind. Returns 0 on success, -1 if setting +the taint-clean flag failed. (eg invalid handle) =back -- 2.7.4