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Fix finfo_file() for remote resources issue#20759

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Fix finfo_file() for remote resources issue#20759
Mdsujansarkar wants to merge 2 commits intophp:masterfrom
Mdsujansarkar:master

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@Mdsujansarkar Mdsujansarkar commented Dec 22, 2025

Fix finfo_file() for remote resources (GH-20679)

Summary

Fixes finfo_file() to work correctly with remote URLs (HTTP/HTTPS) by ensuring that magic_stream() is called even when php_stream_stat() fails on remote resources.

Problem

Previously, finfo_file() would return false for remote URLs because:

  1. php_stream_stat() fails on remote streams (stat is not available for HTTP/HTTPS resources)
  2. The code only called magic_stream() inside the if (php_stream_stat() == SUCCESS) block
  3. When stat failed, ret_val remained NULL, causing the function to return false

Example of the bug:

$f = finfo_open();
var_dump(finfo_file($f, "https://example.com"));
// Expected: string(53) "HTML document, ASCII text, with very long lines (512)"
// Actual:   bool(false)

Solution

Restructured the logic in php_fileinfo_from_path() to:

  1. Use php_stream_stat() only to detect directories (when stat succeeds)
  2. Always attempt magic_stream() when the resource is not a directory, regardless of whether stat succeeded or failed

This ensures that:

  • Local directories are still correctly identified as "directory"
  • Remote URLs are processed by magic_stream() even when stat fails
  • Local files continue to work as before

Changes

Code Changes

File: ext/fileinfo/fileinfo.c

Before:

const char *ret_val = NULL;
if (php_stream_stat(stream, &ssb) == SUCCESS) {
    if (ssb.sb.st_mode & S_IFDIR) {
        ret_val = "directory";
    } else {
        ret_val = magic_stream(magic, stream);
        if (UNEXPECTED(ret_val == NULL)) {
            php_error_docref(NULL, E_WARNING, "Failed identify data %d:%s", magic_errno(magic), magic_error(magic));
        }
    }
}

After:

const char *ret_val = NULL;
if (php_stream_stat(stream, &ssb) == SUCCESS) {
    if (ssb.sb.st_mode & S_IFDIR) {
        ret_val = "directory";
    }
}
if (!ret_val) {
    ret_val = magic_stream(magic, stream);
    if (UNEXPECTED(ret_val == NULL)) {
        php_error_docref(NULL, E_WARNING, "Failed identify data %d:%s", magic_errno(magic), magic_error(magic));
    }
}

Test Case

File: ext/fileinfo/tests/finfo_file_remote_url.phpt

Added a new test case that verifies finfo_file() works with remote HTTP resources using a local test server.

--TEST--
GH-20679 (finfo_file() doesn't work on remote resources)
--EXTENSIONS--
fileinfo
--INI--
allow_url_fopen=1
--SKIPIF--
<?php
if (@!include "./ext/standard/tests/http/server.inc") die('skip server.inc not available');
http_server_skipif();
?>
--FILE--
<?php
require "./ext/standard/tests/http/server.inc";

['pid' => $pid, 'uri' => $uri] = http_server([
    "data://text/plain,HTTP/1.0 200 Ok\r\n\r\n<html>foo",
], $output);

$f = finfo_open();
var_dump(finfo_file($f, $uri));

http_server_kill($pid);
?>
--EXPECT--
string(51) "HTML document, ASCII text, with no line terminators"

Testing

Manual Testing

Tested with various scenarios:

  1. Remote HTTP URL:

    $f = finfo_open();
var_dump(finfo_file($f, "http://example.com"));
// Result: string(53) "HTML document, ASCII text, with very long lines (512)"

  2. Remote HTTPS URL (requires OpenSSL):

    $f = finfo_open();
var_dump(finfo_file($f, "https://example.com"));
// Result: string(53) "HTML document, ASCII text, with very long lines (512)"

  3. Local files: Still work correctly

  4. Directories: Still correctly identified as "directory"

Automated Testing

Run the test suite:

./sapi/cli/php run-tests.php ext/fileinfo/tests/finfo_file_remote_url.phpt

Result: ✅ PASS

Requirements

For Testing

  • pcntl extension: Required to run the PHPT test (uses http_server() which requires pcntl_fork())

    • Build PHP with: ./configure --enable-pcntl

  • allow_url_fopen: Must be enabled (set in test's --INI-- section)

For HTTPS Support (Optional)

  • OpenSSL extension: Required for HTTPS URLs to work
    • Build PHP with: ./configure --with-openssl
    • Note: HTTP URLs work without OpenSSL

Backward Compatibility

✅ Fully backward compatible:

  • Local files continue to work exactly as before
  • Directories are still correctly identified
  • No changes to function signatures or behavior
  • Only fixes the bug where remote URLs returned false

Related Issues

Additional Notes

  • The fix differentiates between statable (local files) and non-statable (remote URLs) streams
  • For statable streams, we still use stat to detect directories efficiently
  • For non-statable streams, we fall back to magic_stream() which works for all stream types
  • This approach is more robust and handles edge cases better

@ndossche
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ndossche commented Dec 22, 2025 •
edited
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This reads like an LLM. Also, did you take my suggestion patch that I posted in the issue as your own ... ?

@iluuu1994
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iluuu1994 commented Dec 22, 2025

There's already an open PR for this (#20700), so let's close.

@iluuu1994 iluuu1994 closed this Dec 22, 2025
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finfo_file() doesn't work on remote resources

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@Mdsujansarkar @ndossche @iluuu1994