Question

Under Linux ,if I want to pass pure string from PHP to C, how do i do that?
what I’ve tried do far is:

exec("./myexec.bin -a mystring");

in PHP and

getopt(argc,argv, "a:");

in C

everything works, but when i pass strings longers than MAX_ARG_STRLEN (131072), it will no longer return 0 instead it returns 127 which is command not found….

is there any other ways to pass string data to a linux executable? or is there any way to overcome the MAX_ARG_STRLEN problem?

Answer 1

You could use popen() to open a pipe to the executable:

$fp = popen('./myexec.bin', 'w');
fwrite($fp, $data);
pclose($fp);

Then, as previously suggested, read from stdin in your C program:

fopen(stdin, "r");
// ...

It is “safer” to use popen() rather than exec('/bin/echo') because you can write characters that would otherwise be interpreted by the shell (&, |, …). Note that the handle returned from PHP’s popen() must be closed with pclose().