SEG Fault in PHP extension

Question

I wrote a PHP extension to access functions in a static lib, I built PHP as a CGI, and everything seemed to work (after days of working on it..) Thrilled once everything worked, I re-compiled PHP without debugging messages I had in it. (`php_printf("here111");` .... `php_printf("sending arguments...");`) Then, it just stopped working. The function I'm calling in the static lib works, I've tested it by calling it directly from another executable. I built PHP with debugging symbols (`--enable-debug`) and can debug it to a certain degree in gdb. I'm still struggling to figure out what's wrong. It seems that the function in the lib (`diffFst`) cannot seem to read the input arguments. ``` 268 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "ssssssd", 269 &filA, &filA_len, 270 &nomvarA, &nomvarA_len, 271 &filB, &filB_len, 272 &nomvarB, &nomvarB_len, 273 &filO, &filO_len, 274 &newnomvar, &newnomvar_len, 275 &mult 276 ) == FAILURE) { 277 RETURN_LONG(-100); 278 } 279 280 php_printf("Read…

Accepted Answer

Took a while, and needed additional help (issues like this)

Basically two things had to change:

- Pass integers by reference

- Accept strings properly

The first is easy, simply `ier=func(..., &integer_var, ...)`

The second involved passing the length of the string. There may have been an easier way to do this (sensing string length by looking for the \0) but they didn't work out. So, now I pass

```
ier = func(str,strlen,...)
```

Then in Fortran, I accept the string as

```
character(kind=c_char,len=strlen), intent(IN) :: str
```

The specific changes to the fortran code above are

```
11     use, intrinsic :: iso_c_binding
12     use interfaces_rmnutils
13     implicit none
16     integer(kind=c_int), intent(IN) :: len_filA, len_filB, len_filO
17     character (kind=c_char,len=len_filA), intent(IN) :: filA
18     character (kind=c_char,len=len_filB), intent(IN) :: filB
19     character (kind=c_char,len=len_filO), intent(IN) :: filO
```

When it was working, it must have been before I attempted to read in the strings as `(len=*)`, and integers were being passed in as references, so they'd have had random values essentially.

Thanks for everyone's else!

SEG Fault in PHP extension

Solution

Problem