Dirty errors with PHP popen() - php

I call a file with popen():
$fp = #popen("/usr/bin/openssl ...");
the specific details don't matter, but what happens here is that when I run the command I receive these errors on a Windows CMD:
The system cannot find message text
for message number 0x3 in the message
file for System.
I know that the file don't exist on Windows, but why doesn't # silence the errors? My library just tries a few different ways to achieve the same thing.

This is not a error message issued by PHP, so PHP's error suppression won't apply.
You'll have to check whether you can run the operation beforehand or suppress the output of system errors.
For suppressing, 2>NUL should work, as you say. Wouldn't it be better though to test whether the file exists at all? On a Windows machine, your executable is most probably not located in /usr/bin/openssl.
if (file_exists("/usr/bin/...."))
popen(".....");

Here's the answer I found:
I just wrote " 2>NUL" in the end of the CMD call to make all Windows errors to disappear.

Related

PHP suppress warning with the # character not working on command line

I have an external include file in my php script which triggers a Warning when executing it in the browser. So I put an # character before it and very nice, now the Warning doesn't happen anymore. My problem is that if I now execute the script on the CLI the warning is not suppressed. How can I also suppress the warning for CLI?
This is a new VPS running PHP 7.3.
#include_once('externalsourcefile.php');
Result is:
WARNING : ""continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"?" at line xx (externalsourcefile.php)
UPDATE: the point is that die include file is an external source, which I can't edit to resolve the Warning by my own.
You must refer to https://www.php.net/manual/en/function.include-once.php#84108 , It will give you an idea how include_once works. You must remove # soon as possible, bad practice!
if(include_once('externalsourcefile.php') == false) {
} else {
}
# suppresses warnings for that statement, in your case the actual include_once, not the stuff that happens inside it.
I'm writing this as an answer, because it is too long to put in a comment. Saying that # should never be used is wrong. It's using it without thinking that is wrong.
Consider this simple code being run in a busy multi-process environment:
clearstatcache(true, $pathname);
if(is_dir($pathname) && $dh=opendir($pathname)) {
// readdir() loop here
}else{
// error handling here
}
This code has a race condition. It has happened for me numerous times that the directory has disappeared between the is_dir() return and the opendir() call, leading to warnings on the console:
PHP Warning: opendir(/the/path/in/use): failed to open dir: No such file or directory in /path/to/script.php on line 2
So how could this race be worked around without disabling warnings from opendir(), I ask you?
Disabling globally is IMHO worse than doing it on specific statements like the opendir() call above.
As already said, the error is not caused by the include_once statement itself but by the code running inside the included file (you can determine that by reading carefully the error message).
It should work, anyway. There must be something else going on.
I can think of three possibilities:
The CLI interpreter in your VPS is configured to use a custom error handler that doesn't support the error suppression operator:
the standard PHP error handler is completely bypassed for the error types specified by error_types unless the callback function returns FALSE. error_reporting() settings will have no effect and your error handler will be called regardless - however you are still able to read the current value of error_reporting and act appropriately. Of particular note is that this value will be 0 if the statement that caused the error was prepended by the # error-control operator.
The interpreter is configured for debugging and Xdebug has been set up with the xdebug.scream directive:
If this setting is 1, then Xdebug will disable the # (shut-up) operator so that notices, warnings and errors are no longer hidden.
The browser interpreter is running an earlier PHP version then the CLI one. The "continue" targeting switch is equivalent to "break" warning is a backwards-incompatible change in PHP/7.3. It didn't trigger a warning before.
In either case, and as also already noted, the question itself illustrates that suppressing errors can lead to hard-to-diagnose bugs.

http error 500 aws bitnami wordpress hosting [duplicate]

I am having an issue when I have a php application that is returning an internal server error (500) however nothing is showing up in the error log.
Now I know there are error with what I am trying to run, I know I have missing some files and what not but something should show in the apache error log (otherwise how are I supposed to know exactly what I am missing).
I created a test script is errors it in under the same vhost configuration and those error show up fine so everything seems configured right as far as php/apache. Are there certain php errors that does show up in the error log (php is configure to display any type of notice, warning, , error, fatal error, etc...)?
This is running on ubunut 10.04 with the standard apache and php from the ubuntu repo with apt-get.
Scan your source files to find #.
From php documentation site
Currently the "#" error-control operator prefix will even disable
error reporting for critical errors that will terminate script
execution. Among other things, this means that if you use "#" to
suppress errors from a certain function and either it isn't available
or has been mistyped, the script will die right there with no
indication as to why.
Copy and paste the following into a new .htaccess file and place it on your website's root folder :
php_flag display_errors on
php_flag display_startup_errors on
Errors will be shown directly in your page.
That's the best way to debug quickly but don't use it for long time because it could be a security breach.
If you still have 500 error and no logs you can try to execute from command line:
php -f file.php
it will not work exactly like in a browser (from server) but if there is syntax error in your code, you will see error message in console.
Maybe something turns off error output. (I understand that you are trying to say that other scripts properly output their errors to the errorlog?)
You could start debugging the script by determining where it exits the script (start by adding a echo 1; exit; to the first line of the script and checking whether the browser outputs 1 and then move that line down).
In the past, I had no error logs in two cases:
The user under which Apache was running had no permissions to modify php_error_log file.
Error 500 occurred because of bad configuration of .htaccess, for example wrong rewrite module settings. In this situation errors are logged to Apache error_log file.
For Symfony projects, be sure to check files in the project'es app/logs
More details available on this post :
How to debug 500 Error in Symfony 2
Btw, other frameworks or CMS share this kind of behaviour.
Here is another reason why errors might not be visible:
I had the same issue. In my case, I had copied the source from a production environment. Hence the ENVIRONMENT variable defined in index.php was set to 'production'. This caused error_reporting to be set to 0 (no logging). Just set it to 'development' and you should start seeing error messages in apache log.
Turned out the 500 was due to a semi colon missing in database config :-)
Another case which happened to me, is I did a CURL to some of my pages, and got internal server error and nothing was in the apache logs, even when I enabled all error reporting.
My problem was that in the CURL I set
curl_setopt($CR, CURLOPT_FAILONERROR, true);
Which then didn't show me my error, though there was one, this happened because the error was on a framework level and not a PHP one, so it didn't appear in the logs.
You need to enable the PHP error log.
This is due to some random glitch in the web server when you have a php error, it throws a 500 internal error (i have the same issue).
If you look in the PHP error log, you should find your solution.
see here in the doc of how to enable it in the php.ini
Be sure your file permissions are correct. If apache doesn't have permission to read the file then it can't write to the log.
What happened for me when this was an issue, was that the site had used too much memory, so I'm guessing that it couldn't write to an error log or displayed the error. For clarity, it was a Wordpress site that did this. Upping the memory limit on the server showed the site again.
SOLVED
I struggled with this and later on, I realized that I was working on PHP 5.6, so I upgraded to PHP 7.0, then I released there were comments placed by git for conflicting codes. I found something like this in my code <<<<<<<< But solved it.

PHP task terminated but no error condition raised

A PHP script is using the ZipArchive class and is potentially long running.
Since it is dying silently but writing a partial zip file, I wrapped error_log() statements around the $zip->close(). (ini_set sets error logging to a file and E_ALL just before this code)
error_log("calling zip->close()");
$rc = $zip->close();
error_log("zip->close() returned $rc");
The logging file shows the first error_log, but never the second.
A unix top command shows the process running for a total CPU time of c. 2.5 minutes before it goes defunct.
I have also tried trapping the error with set_error_handler(), and the handler using error_log() to record the catch. But nothing shows up in the log file.
I'm assuming the process is being bounced, maybe by Apache (I have no control over Apache or PHP).
My question is: why can't I see this error in the file being used by error_log?
Thanks for the suggestions for circumventing the problem, but my question remains:
Why can't I see this error in the log? Or why can't I catch this error via set_error_handler()?
set_time_limit(0);
0 = Indefinitely

php return 500 error but no error log

I am having an issue when I have a php application that is returning an internal server error (500) however nothing is showing up in the error log.
Now I know there are error with what I am trying to run, I know I have missing some files and what not but something should show in the apache error log (otherwise how are I supposed to know exactly what I am missing).
I created a test script is errors it in under the same vhost configuration and those error show up fine so everything seems configured right as far as php/apache. Are there certain php errors that does show up in the error log (php is configure to display any type of notice, warning, , error, fatal error, etc...)?
This is running on ubunut 10.04 with the standard apache and php from the ubuntu repo with apt-get.
Scan your source files to find #.
From php documentation site
Currently the "#" error-control operator prefix will even disable
error reporting for critical errors that will terminate script
execution. Among other things, this means that if you use "#" to
suppress errors from a certain function and either it isn't available
or has been mistyped, the script will die right there with no
indication as to why.
Copy and paste the following into a new .htaccess file and place it on your website's root folder :
php_flag display_errors on
php_flag display_startup_errors on
Errors will be shown directly in your page.
That's the best way to debug quickly but don't use it for long time because it could be a security breach.
If you still have 500 error and no logs you can try to execute from command line:
php -f file.php
it will not work exactly like in a browser (from server) but if there is syntax error in your code, you will see error message in console.
Maybe something turns off error output. (I understand that you are trying to say that other scripts properly output their errors to the errorlog?)
You could start debugging the script by determining where it exits the script (start by adding a echo 1; exit; to the first line of the script and checking whether the browser outputs 1 and then move that line down).
In the past, I had no error logs in two cases:
The user under which Apache was running had no permissions to modify php_error_log file.
Error 500 occurred because of bad configuration of .htaccess, for example wrong rewrite module settings. In this situation errors are logged to Apache error_log file.
For Symfony projects, be sure to check files in the project'es app/logs
More details available on this post :
How to debug 500 Error in Symfony 2
Btw, other frameworks or CMS share this kind of behaviour.
Here is another reason why errors might not be visible:
I had the same issue. In my case, I had copied the source from a production environment. Hence the ENVIRONMENT variable defined in index.php was set to 'production'. This caused error_reporting to be set to 0 (no logging). Just set it to 'development' and you should start seeing error messages in apache log.
Turned out the 500 was due to a semi colon missing in database config :-)
Another case which happened to me, is I did a CURL to some of my pages, and got internal server error and nothing was in the apache logs, even when I enabled all error reporting.
My problem was that in the CURL I set
curl_setopt($CR, CURLOPT_FAILONERROR, true);
Which then didn't show me my error, though there was one, this happened because the error was on a framework level and not a PHP one, so it didn't appear in the logs.
You need to enable the PHP error log.
This is due to some random glitch in the web server when you have a php error, it throws a 500 internal error (i have the same issue).
If you look in the PHP error log, you should find your solution.
see here in the doc of how to enable it in the php.ini
Be sure your file permissions are correct. If apache doesn't have permission to read the file then it can't write to the log.
What happened for me when this was an issue, was that the site had used too much memory, so I'm guessing that it couldn't write to an error log or displayed the error. For clarity, it was a Wordpress site that did this. Upping the memory limit on the server showed the site again.
SOLVED
I struggled with this and later on, I realized that I was working on PHP 5.6, so I upgraded to PHP 7.0, then I released there were comments placed by git for conflicting codes. I found something like this in my code <<<<<<<< But solved it.

MYSQL queries not executing or not showing errors

Just installed a nginx server with ubuntu 11.04 and after loading my php program i was writing i noticed that no MYSQL queries run. I get no errores, either from PHP nor MYSQL.
The user my PDO connection uses has all priviledges.
When i change the host to any value, i do not get any error either.
I believe mysql is not showing any connection error. How do i check it's enabled? Just checked mysql.conf and i see nothing related to error reporting. Also looked php.ini and all error options are enabled, i also enabled it in-code.
I have no clue, it's useless to work with no kind of error reporting!
Thanks!
Where are your error logs for nginx? Have you looked in those? Is mysql running? Try service mysql status. PHP should still give you an error though if it can't connect to the database. How do you know the queries are not running? What I mean is, what are the symptoms? Maybe the queries are running but your input is bad?
Most important is to try to isolate the problem. 1) Use curl -v http://your_server to make sure nginx is actually serving the pages. 2) Set up a phpinfo.php file in the root web directory with <? phpinfo(); ?> and check the mysql settings and verify where log files for php are being written 3) Try installing phpmyadmin and see if you can connect to the database using that.
Each one of the above eliminates at least 1 of the elements (your program, PHP, nginx, mysql), helping you to narrow down the cause of your problem.
EDIT: Additional instructions for item 2. You are looking for the php error_log setting. If it is not set, the errors should go to stderr, which in this case I think would be your nginx log files (true at least for apache). You could also check that error_reporting is set to some reasonable value (try error_reporting=E_ALL for now). You can set both of these in your php.ini file, or in your program. See the manual in section PHP Error Handling Runtime Configuration. I would do a sanity check by triggering an error in my program at the beginning of the program and making sure the error shows up in the log file:
trigger_error('Want to be a rock star test message', E_USER_WARNING);
If you see your message, you've got the right log file and you should find your other errors (if any - mysql might not be the problem, could be bad input as I mentioned before).

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