Need help with Open (/file/path, O_RDWR)!!!

[vypergal]

Hi. I am currently running PHP 4 on a Redhat Linux 7.2 machine.

I am calling a C program using the exec() function in PHP. In the C program, it actually assigns the return value from the open() function as shown below.
fd = open("/path/to/file", O_RDWR);

When I compile and run my C program on the console window, I can run it smoothly (i.e. I obtain an output fd = 3). But if I run it from PHP, I got a value fd = -1 instead indicating that it is erronous.

Does anyone have any idea why this is so?? 😕

Thanks in advanced

[ednark]

php executes all programs as the user who is running the webserver,

make sure that if you file lives in

/home/ednark/www/my_file

that the user Apache or the user Nobody or whomever that is running the server also has write permisssion to that directory or that file...

perhaps your solution is a chmod or chown away

[vypergal]

Hi. Thanks for the advice but I am not very sure how to go about checking if I have access to that directory.

In apache, I have set the user to be "nobody". I have Apache running in this directory /usr/local/Apache and the c program to be executed is in this directory /usr/local/Application. How do I check if the user has access to that directory?

Is there anything else I need to check???

Thanks!

[ednark]

get to a command line on your linux box...

go to the directory
do a 'ls -al'

you need either the directory to be owned by nobody, in the group nobody or have the permissions set so that nobody can read/write/execute rwx the whoel directory

[vypergal]

It still can't work. I have given the directory's permission to the user nobody as well as the group nobody that i just created. I have changed the permission to RWX but it still can't work. :`(

Any advice??

[jerdo]

Since you are using RedHat I believe the user that Apache runs under is apache and not nobody. Since you had to create the nobody user and group that would mean there is most likely nothing running under it, unless you then specified that apache should start under the nobody user. Try changing ownership to apache.

[vypergal]

Ermm.... I tried to change the user to apache using the command
% chmod apache test
where test is the executable file name, i get an error message stating that apache is an invalid mode string.

In my Apache configuration file i have set the user and group to nobody.
When I try to change it to apache, an error message is displayed when i start the apache server.

Now I am puzzled. When I go to the control panel, looking at the list of users created, there is no user called 'nobody' . Am I looking at the correct thing??? is there a way to list all the users as well as all the groups that have been created?

Please advice.

[vypergal]

A thought just occured to me. Could it be that PHP does not suppor t the open function that is used in C?

Snippets of the C code is as shown below:
struct usbdev *usbOpenByNumber( unsigned int a, unsigned int b){
.....
int fd;
char tmp[PATH_MAX+1];
.......
fd = open(tmp, O_RDWR)
//tmp has been traced to hold the string "/proc/bus/usb/001/003"
if(fd == -1)
return NULL;
.......
};

I am using exec() in PHP to call the program that resides in "/usr/local/Application"

Has anyone faced this previously? Any suggestion is appericiated.

[jerdo]

Look for user apache, and the command to change ownership isn't chmod it's chown.

[vypergal]

Dear all,
thanks for the advice. Found the root of the problem lied in the privilege given to the file that the open function was called. The privilege given to that file should be -rw-r--rw- . Got it working.
Thanks again. 🙂

[ednark]

be carefull....

there is no reason to give everybody more premissions than the group owner

on a *nix system there are three permissions, and a flag

owner group public
- rw- r-- rw-

the full permission is

d rwx rwx rwx

the first thing mean wether or not this is a directory

then there are the Read/Write/eXecute

first trio are permissions for the user owner of the dir/file
2nd trio are premissions for the group owner of the group
3rd trio are permissions for everyone else

you can set who owns the files and what group ownes the files like such

chown user.group ./
chown nobody.www ./file.php