Being part of that discussion, it is important to note that process substitution returns the path to an anonymous pipe which stops existing after the process finishes.

Hi,

I was able to reproduce the problem with a small test C snippet that mimics what php-src is doing:

-------------------------------------

#include <stdio.h>
#include <stdlib.h>
int main(int argc, char* argv[]) {
    FILE *fp;

    fp = fopen(argv[1], "rb");
    char a = fgetc(fp);
    rewind(fp);
    char ch;
    while(1) {
        ch = fgetc(fp);
        if(feof(fp)) {
            break;
        }
        printf("%c", ch);
    }

    return 0;
}

-------------------------------------

`rewind()` fills `errno` with the value `29` which means `Illegal seek`.


The lines

char a = fgetc(fp);
rewind(fp);

mimic what php-src is doing here on line 606 and 620:

https://github.com/php/php-src/blob/e6f86fb17cd3a2dfe94ca1a0113a23194cb1915a/sapi/cli/php_cli.c#L606-L620

It calls fgetc() to find out if shebang exists on the file pointer but rewind() doesn't work correctly.

... Call the above snippet as specified in the bug report:

gcc test.c

./a.out <(echo '<?php print("hello"); ?>')

-----------------------------

Output:

?php print("hello"); ?>

As pipes are simply not seekable a possible fix could be implemented by checking errno for ESPIPE as described here http://man7.org/linux/man-pages/man3/errno.3.html and either let it fail or do some /tmp redirect magic.

We should probably move handling of shebang lines into the lexer.

It should break all instances where the script file is a fifo.

Blame shows commit 71ea95354b [1]:

    MFH: Corrected fix for bug #46844 to only trigger on the 1st line of CLI

    opened files.

Which in turn references bug #46844:

    First line of included files not output if they begin with #


[1] https://github.com/php/php-src/commit/71ea95354b4133f12dcf8207bc7b36e1562bdd65

[2] https://bugs.php.net/bug.php?id=46844

Fixed by https://github.com/php/php-src/commit/c5f1b384b591009310370f0b06b10868d2d62741 for 7.4.