Base64_decoded image string saved to directory doesn't show image - php

Question

I am trying to upload an image from my android application to a php script on my server. In my script, I am attempting to decode the image (using base64_decode) and then use file_put_contents() to save the image as a file in my directory. My problem is that the file 'appears' empty when I have .jpg at the end of the file name. When I removed that to see what was added for the image encoding, I see a very long string of characters, (65214 bytes specifically that were written to the file). When I run the code again, only this time uploading the $_POST['sent_image'] without decoding, I get the same exact string of text.
I am not sure what I am doing wrong... The end goal would be to save the image on the server, so it could be viewed elsewhere online, and also be able to retrieve it and get back into another activity in my android application.
All suggestions are appreciated!
NOTE: I have also tried imagecreatefromstring(), but that causes 0 bytes to be written.
My Code:PHP that gets encoded android image and tries to save to server directory:
<?php
include('inc.php');
if ((isset($_POST['searchinput'])) && (isset($_POST['newUnitStatus'])) && (isset($_POST['generalCause'])) && (isset($_POST['newUnitStatusComment'])) && (isset($_POST['newUnitStatusPhoto'])) && (isset($_POST['lexauser'])) && (isset($_POST['password']))) {
$sgref = "";
$searchinput = $_POST['searchinput'];
$newUnitStatus = $_POST['newUnitStatus'];
$generalCause = $_POST['generalCause'];
$newUnitStatusComment = $_POST['newUnitStatusComment'];
$lexauser = $_POST['lexauser'];
$pass = $_POST['password'];
if ((strpos($searchinput, "/") !== false)) {
$barcodesplit = preg_split('/\D/im', $searchinput, 4);
$sgref = $barcodesplit[0];
$lineitem = $barcodesplit[1];
$unitnumber = $barcodesplit[2];
$totalunits = $barcodesplit[3];
$unitname = $sgref."-".$lineitem."-".$unitnumber."_of_".$totalunits;
$photo = $_POST['newUnitStatusPhoto'];
$decodedPhoto = str_replace('data:image/jpg;base64,', '', $photo);
$decodedPhoto = str_replace(' ', '+', $decodedPhoto);
$newUnitStatusPhoto = base64_decode($decodedPhoto);
//$newUnitStatusPhoto = imagecreatefromstring($decodedPhoto);
$fileName = "".$unitname."_rej";
$target = '../LEXA/modules/bms/uploads/';
$newFile = $target.$fileName;
$docType = "Reject";
$success = file_put_contents($newFile, $newUnitStatusPhoto);
if($success === false) {
$response['message'] = "Couldn not write file.";
echo json_encode($response);
} else {
$response['message'] = "Wrote $success bytes. ";
echo json_encode($response);
}
} else {
$sgref = $searchinput;
$response['message'] = "I'm sorry, but you must enter a unit's uniqueid value to add a unit exception. Please view the siblings for this SG and pick the unit you need. Then you can add the new status.";
echo json_encode($response);
}
} else {
$response['message'] = "Your search value did not get sent. Please try again.";
echo json_encode($response);
}//End logic for post values.
?>
Thank you!

Answer 1

Using str_replace may be problematic if image format is other than jpg, for example.
Example code:
<?php
$photo = $_POST['newUnitStatusPhoto'];
if(substr($photo, 0,5) !== "data:"){
//do error treatment as it's not datauri
die("Error: no data: scheme");
};
$decodedPhoto = substr($photo, 5);
$mimeTerminator = stripos($decodedPhoto,";");
if($mimeTerminator === false){
die("Error: no mimetype found");
};
$decodedPhoto = substr($decodedPhoto, $mimeTerminator+8); //1<;>+4<base>+2<64>+1<,>
// $decodedPhoto = str_replace('data:image/jpg;base64,', '', $photo);
// $decodedPhoto = str_replace(' ', '+', $decodedPhoto);
$newUnitStatusPhoto = base64_decode($decodedPhoto);
//$newUnitStatusPhoto = imagecreatefromstring($decodedPhoto);
$unitname = "testando";
$fileName = "".$unitname."_rej.jpg";
$target = 'img/';
$newFile = $target.$fileName;
if(file_exists($newFile))
unlink($newFile);
$success = file_put_contents($newFile, $newUnitStatusPhoto);
echo $success;