Req #39598 [Opn->Csd]: error verification after fwrite()

Edit report at https://bugs.php.net/bug.php?id=39598&edit=1 ID: 39598 Updated by: nikic@php.net Reported by: max at nucleus dot it Summary: error verification after fwrite() -Status: Open +Status: Closed Type: Feature/Change Request -Package: Feature/Change Request +Package: *General Issues Operating System: Linux PHP Version: 5.2.0 -Assigned To: +Assigned To: nikic Block user comment: N Private report: N New Comment: In PHP 7.4 fwrite() will return 0 for EAGAIN/EWOULDBLOCK and false for other errors, in line with the requested behavior. Previous Comments: ------------------------------------------------------------------------ [2018-06-30 20:24:33] novelesco at centrum dot cz Please, at least fix the documentation. ------------------------------------------------------------------------ [2016-01-22 14:04:55] salsi at icosaedro dot it Missing error detection in streams and filters is a general flaw in the internal i/o handling affecting all the related functions (fopen, fread, fwrite, fflush, fclose) which is really severe, because it affects the safety of any file and data transfer, and would deserve maximum attention and urgency for being fix asap. I may list several other reports that demonstrates missing detection of corrupted file system missing detection of invalid encoded data and so on: fread() does not detect file access error https://bugs.php.net/bug.php?id=71384 (Also includes disk image containing a damaged file for testing.) require* and include* do not detect input/output error https://bugs.php.net/bug.php?id=71385 (Probably related to the bug above.) fread() does not detect decoding errors from filter zlib.inflate https://bugs.php.net/bug.php?id=71417 (Probably missing propagation of errors through streams.) fread() does not detects decoding errors from filter bzip2.decompress https://bugs.php.net/bug.php?id=71263 (Probably the same as above.) All these share the same common denominator: missing error propagation from libc to PHP user's space. ------------------------------------------------------------------------ [2013-03-01 00:04:00] gauthierm@php.net Here's a simple reproduce test case: http://labs.silverorange.com/files/php-bug39598/php-bug-39598-test.phps In this case, and EPIPE occurs. The fwrite call writes 0 bytes. No error code is available and no PHP error is raised. ------------------------------------------------------------------------ [2006-11-22 22:53:31] max at nucleus dot it Description: ------------ The documentation states tha fwrite() returns false in case of error, but it doesn't do so if the actual write fails. For example if I asynchronously write to a pipe (such as those obtained by proc_open()) I and the pipe is not ready or is broken, fwrite() returns 0. This could be a correct behaviour it I had a way to determine the error. The problem is that EAGAIN or EPIPE are completely impossible to determine and I can't know if I need to wait or I have to close the stream. A possible solution would be to implement ferror() or errno. Reproduce code: --------------- $Proc = proc_open($Cmd, $Streams, $Pipes, $CWD, $Env); stream_set_blocking($Pipes[0], 0); $Result = fwrite($Pipes[0], "test"); // If $Pipes[0] is not ready to receive data // $Result is 0, but I can't know why. // The real code I'm writing involves // stream_select() and repeated reads and writes // on multiple pipes. Expected result: ---------------- fwrite() should return 0 when the stream is asynchrounous, the C write() returns 0 and errno is EAGAIN. fwrite() should return false in all other cases where the C write() returns 0. Alternatively a way to access ferror() or errno is needed. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=39598&edit=1