Bug #78066 [Com]: PHP eats the first byte of a program that comes from process substitution

Edit report at https://bugs.php.net/bug.php?id=78066&edit=1 ID: 78066 Comment by: octalbugsphp at alvarezp dot org Reported by: octalbugsphp at alvarezp dot org Summary: PHP eats the first byte of a program that comes from process substitution Status: Open Type: Bug Package: *General Issues Operating System: Linux PHP Version: 7.3.5 Block user comment: N Private report: N New Comment: 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 Previous Comments: ------------------------------------------------------------------------ [2019-05-25 20:31:08] nikic@php.net We should probably move handling of shebang lines into the lexer. ------------------------------------------------------------------------ [2019-05-25 20:23:26] xatenev@php.net 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. ------------------------------------------------------------------------ [2019-05-25 20:07:32] xatenev@php.net ... Call the above snippet as specified in the bug report: gcc test.c ./a.out <(echo '<?php print("hello"); ?>') ----------------------------- Output: ?php print("hello"); ?> ------------------------------------------------------------------------ [2019-05-25 20:03:45] xatenev@php.net 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. ------------------------------------------------------------------------ [2019-05-25 16:53:55] simon at ikanobori dot jp 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. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=78066 -- Edit this bug report at https://bugs.php.net/bug.php?id=78066&edit=1