Bug #53465 [PATCH]: Cannot open file descriptor streams

Edit report at http://bugs.php.net/bug.php?id=53465&edit=1 ID: 53465 Patch added by: cataphract@php.net Reported by: dchurch at sciencelogic dot com Summary: Cannot open file descriptor streams Status: Open Type: Bug Package: Filesystem function related Operating System: Linux PHP Version: 5.3.3 Block user comment: N Private report: N New Comment: The following patch has been added/updated: Patch Name: php_fd_open.diff Revision: 1291674246 URL: http://bugs.php.net/patch-display.php?bug=53465&patch=php_fd_open.diff&revision=1291674246 Previous Comments: ------------------------------------------------------------------------ [2010-12-03 18:24:11] dchurch at sciencelogic dot com Description: ------------ PHP cannot open, read from, or write to arbitrary file descriptors, a feature that is necessary for communications with certain utilities that expect input or output on certain file descriptors. When programming in C, this functionality is provided by fdopen(). A feature request was filed over seven years ago for PHP to have a similar capability through the php:// stream wrapper (#26158), but the bug was marked as bogus for no adequately defined reason. The alternative to being able to use a fdopen()-like function is to open the file descriptor as a named file through /dev/fd/ or /proc/self/fd/. This works in C using fopen("/dev/fd/<descriptor>", "w"), but it does not work in PHP because PHP incorrectly attempts to dereference the pseudo-symlink before opening it. I have a C program and a PHP script that both attempt to do the same thing: open file descriptor 3 for writing using /dev/fd/3, read until EOF from standard in and write to the file descriptor. Both should be run as: (executable) 3>&1 | cat Test script: --------------- PHP script: <?php $file = fopen("/dev/fd/3", "w"); if (!$file) exit(1); $input = stream_get_contents(STDIN); fwrite($file, $input); fclose($file); C program: #include <stdio.h> int main() { char buf[8192]; int count; FILE *file; file = fopen("/dev/fd/3", "w"); if (file == NULL) { perror("Opening /dev/fd/3"); return 1; } while ((count = fread(buf, 1, sizeof(buf), stdin)) > 0) { fwrite(buf, count, 1, file); if (feof(stdin)) break; } return 0; } Expected result: ---------------- Input should be mirrored to file descriptor 3; when called using the command line above, it should be mirrored to standard output. Actual result: -------------- I get the following warning: PHP Warning: fopen(/dev/fd/3): failed to open stream: No such file or directory in test.php on line 2 An strace of the PHP process shows the incorrect behavior: lstat("/dev/fd/3", {st_mode=S_IFLNK|0300, st_size=64, ...}) = 0 readlink("/dev/fd/3", "pipe:[637257]", 4096) = 13 lstat("/dev/fd/pipe:[637257]", 0x7fff76ae8140) = -1 ENOENT (No such file or directory) lstat("/dev/fd", {st_mode=S_IFLNK|0777, st_size=13, ...}) = 0 readlink("/dev/fd", "/proc/self/fd"..., 4096) = 13 lstat("/proc/self/fd", {st_mode=S_IFDIR|0500, st_size=0, ...}) = 0 lstat("/proc/self", {st_mode=S_IFLNK|0777, st_size=64, ...}) = 0 readlink("/proc/self", "28234"..., 4096) = 5 lstat("/proc/28234", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0 lstat("/proc", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0 open("/proc/28234/fd/pipe:[637257]", O_WRONLY|O_CREAT|O_TRUNC, 0666) = -1 ENOENT (No such file or directory) ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=53465&edit=1