PHP script processing all lines of a file twice - php

Question

I have a PHP script that generates an HTML form for users to upload a file. I save that file on the server using move_uploaded_file then read it using fgets() and perform database inserts based on certain check. Here's a simplified version of the code:
$cart_id = 18566;
if (empty($_POST))
{
echo "<form name=\"upload\" action=\"myscan.php\" id=\"myScan\" method=\"POST\" enctype=\"multipart/form-data\">";
echo "Choose the file to upload:<br>\r\n";
echo "<input type=\"hidden\" name=\"MAX_FILE_SIZE\" value=\"300000\" form=\"myScan\" />";
echo "<input type=\"file\" name=\"file\" form=\"myScan\" id=\"fileUp\" /><br>";
echo "<input type=\"submit\" value=\"Upload\" name=\"sub\" form=\"myScan\" />";
echo "<input type=\"hidden\" name=\"ck\" form=\"myScan\" value=\"".$cart_id."\" />";
echo "</form><br>";
}
else
{
// link to cart goes here
}
$fname = "1SCAN20131031123456";
if (!empty($_POST))
{
$allowedExts = array("txt", "csv");
$extension = end(explode(".", $_FILES["file"]["name"]));
if ( ($_FILES["file"]["type"] == "text/plain"
|| $_FILES["file"]["type"] == "application/vnd.ms-excel")
&& array_search(strtolower($extension), array_map('strtolower', $allowedExts)) !== FALSE )
{
if ($_FILES["file"]["error"] > 0)
{
echo "Error: " . $_FILES["file"]["error"] . "<br>";
}
else
{
echo "Upload: " . $_FILES["file"]["name"] . "<br>";
echo "Type: " . $_FILES["file"]["type"] . "<br>";
echo "Size: " . ($_FILES["file"]["size"] / 1024) . " kB<br>";
echo "Stored in: " . $_FILES["file"]["tmp_name"]."<br>";
if (file_exists("upload/" . $_FILES["file"]["name"]))
{
echo $_FILES["file"]["name"] . " already exists. ";
}
else
{
move_uploaded_file($_FILES["file"]["tmp_name"], $fname);
echo "Moved to: " . $fname . "<br>";
}
}
}
else
{
echo "Invalid file<br>";
echo "Type: " . $_FILES["file"]["type"] . "<br>";
echo "Upload: " . $_FILES["file"]["name"] . "<br>";
echo "Extension: " . $extension . "<br>\n";
}
At this point the file $fname is ok, no duplicated lines. The next part is called as a function declared in the same PHP file. $link, $fname, and $cart_id are declared as globals
$bn = basename($fname);
$sfd = fopen($fname, "r");
$store_number = "$bn[0]";
if(is_numeric($bn[1]))
$store_number .= $bn[1];
$a = stripos($bn, "SCAN");
$a += 4;
$dt = substr($bn, $a);
// echo "Date = $dt \n";
$fy = substr($dt, 0, 4);
$fM = substr($dt, 4, 2);
$fd = substr($dt, 6, 2);
$fh = substr($dt, 8, 2);
$fm = substr($dt, 10, 2);
$fs = substr($dt, 12, 2);
$fdate = "$fy-$fM-$fd $fh:$fm:$fs";
// echo $fname . ",";
// echo $store_number . ",";
while ($line = fgets($sfd))
{
$li = explode(",", $line);
if (sizeof($li) == 5)
{
$scan = $li[0];
$poQty = $li[1];
$cntQty = $li[2];
$limd = $li[3];
$lihms = $li[4];
$query = "INSERT INTO upload_datalog (file_name, store, filedate, scan, po_qty, cnt_qty, scan_md, scan_hms, cart_id)\n"
. "VALUES (\"$bn\", $store_number, \"$fdate\", \"$scan\", $poQty, $cntQty, \"$limd\", \"$lihms\", $cart_id)";
mysqli_query($link, $query);
}
else if ($fM < 8 || ($fM == 8 && $fd < 16 ))
{
$scan = $li[0];
$poQty = $li[2];
$cntQty = $li[1];
$limd = $li[3];
$lihms = $li[4];
$query = "INSERT INTO upload_datalog (file_name, store, filedate, scan, po_qty, cnt_qty, scan_md, scan_hms, cart_id)\n"
. "VALUES (\"$bn\", $store_number, \"$fdate\", \"$scan\", $poQty, $cntQty, \"$limd\", \"$lihms\", $cart_id)";
mysqli_query($link, $query);
}
else if (sizeof($li) == 3 && $li[0] != "" && $li[1] != "" &&$li[2] != "" )
{
$scan = $li[0];
$poQty = $li[2];
$cntQty = $li[1];
$query = "INSERT INTO upload_datalog (file_name, store, filedate, scan, po_qty, cnt_qty)\n"
. "VALUES (\"$bn\", $store_number, \"$fdate\", \"$scan\", $poQty, $cntQty)";
mysqli_query($link, $query);
}
}
fclose($sfd);
The file contains this information:
This all works more than 99 percent of the time, but twice in the past 2 weeks, the entries in the upload_datalog table have been duplicated. There is another function after this that also reads the file and performs inserts based on different checks, and those are duplicated as well.
I know this is an edge case, but I couldn't find any information as to why this would happen on php.net or through google, and I have not been able to reproduce it mysqlf. But I know it occurs in the wild.
Is there a race condition I'm not seeing here?

Answer 1

You do your inserts in a while loop, so you run twice through that loop?
For debugging, add a counter in your loop and create a small debug function, and a debug table. Insert the counter and data in your debug table. Compare these values with your expectations