StoreProhibited error while trying to read file to PROGMEM

Question

I'm trying to read a file from micro SD on an ESP32-cam board and upload to an FTP server, but when I try to read data from the opened file to an unsigned char, it gives me the following error:

Guru Meditation Error: Core  1 panic'ed (StoreProhibited). Exception was unhandled.
Core 1 register dump:
PC      : 0x4008c674  PS      : 0x00060030  A0      : 0x800ed1c7  A1      : 0x3ffb1e20  
A2      : 0x00000000  A3      : 0x3ffd7c78  A4      : 0x00000080  A5      : 0x00000000  
A6      : 0x474e5089  A7      : 0x0a1a0a0d  A8      : 0x00000000  A9      : 0x3ffb1df0  
A10     : 0x00000080  A11     : 0x3ffb66e4  A12     : 0x3ffd7c78  A13     : 0x00000080  
A14     : 0x00002494  A15     : 0xff000000  SAR     : 0x00000018  EXCCAUSE: 0x0000001d  
EXCVADDR: 0x00000000  LBEG    : 0x4008c670  LEND    : 0x4008c68c  LCOUNT  : 0x00000007  

ELF file SHA256: 0000000000000000

Backtrace: 0x4008c674:0x3ffb1e20 0x400ed1c4:0x3ffb1e30 0x400ed245:0x3ffb1e60 0x400d06e7:0x3ffb1e80 0x400d084f:0x3ffb1f20 0x400d2b5a:0x3ffb1fb0 0x4008efde:0x3ffb1fd0

Rebooting...

The code is the following:

// Wifi and FTP Client Lib
#include <WiFi.h>
#include <WiFiClient.h> 
#include "ESP32_FTPClient.h"

// MicroSD
#include "driver/sdmmc_host.h"
#include "driver/sdmmc_defs.h"
#include "sdmmc_cmd.h"
#include "esp_vfs_fat.h"

// FTP Server credentials
char ftp_server[] = "192.168.1.50";
char ftp_user[]   = "username";
char ftp_pass[]   = "password";

// wifi access
const char* ssid = "ssid";
const char* password = "psk";

// file to be read and uploaded
FILE *fileUpload = NULL;

// ftp client object
ESP32_FTPClient ftp (ftp_server, ftp_user, ftp_pass);

// micro sd initialization
static esp_err_t init_sdcard()
{
  esp_err_t ret = ESP_FAIL;
  sdmmc_host_t host = SDMMC_HOST_DEFAULT();
  sdmmc_slot_config_t slot_config = SDMMC_SLOT_CONFIG_DEFAULT();
  esp_vfs_fat_sdmmc_mount_config_t mount_config = {
    .format_if_mount_failed = false,
    .max_files = 10,
  };
  sdmmc_card_t *card;
  ret = esp_vfs_fat_sdmmc_mount("/sdcard", &host, &slot_config, &mount_config, &card);
}

void FTP_upload( void );
void FTP_upload()
{

  // initialize file name
  char fileName[100];
  sprintf(fileName, "/sdcard/img.png");
  fileUpload = fopen(fileName, "r+");
  
  // notify reading of the file
  Serial.print("Reading file: ");
  Serial.println(fileName);
  if (fileUpload == NULL) 
  {
    Serial.println("Cannot open file");
    return;
  }

  // retrieve file size
  fseek(fileUpload, 0, SEEK_END);
  long int size = ftell(fileUpload);
  fclose(fileUpload);

  // print file size to serial
  Serial.print("File size: ");
  Serial.println(size);
  
  // Reading data to array of unsigned chars
  fileUpload = fopen(fileName, "r+");
  unsigned char * in PROGMEM = (unsigned char *) malloc(size);
  
  // display allocated memory
  Serial.print("Allocated memory: ");
  Serial.println(sizeof(in));

  // read file to allocated memory
  int bytes_read = fread(in, sizeof(unsigned char), size, fileUpload); // <------- THIS ROW RISES THE ERROR
  
// close file
  fclose(fileUpload);

  // Open FTP connection
  Serial.println("Starting FTP upload...");
  ftp.OpenConnection();
  
  //Create a file and write the image data to it;
  ftp.InitFile("Type I");

  // change remote directory
  ftp.ChangeWorkDir("/Shared/");

  // specify remote file name
  String strNome = "img.png";

  // convert String to char
  const char *f_name = strNome.c_str();
  
  // create a new file with the given name inside the remote directory
  ftp.NewFile( f_name );

  // write data read above from local file to remote file
  ftp.WriteData(in, sizeof(in));

  // close remote file
  ftp.CloseFile();

  // notify completed upload
  Serial.println("File uploaded successfully");
  
  // wait
  delay(100);

}

void setup() {

  // begin serial communication
  Serial.begin(115200);

  // initialize micro sd
  esp_err_t errSD = init_sdcard();
  if (errSD != ESP_OK) {
    Serial.printf("Cannot initialize SD. Error code: 0x%x", errSD);
    return;
  }

  // begin wifi connection
  WiFi.begin(ssid, password);

  // wait for the connection to be estabilished
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  // notify successful connection
  Serial.println("");
  Serial.println("WiFi connected");

  // show the assigned IP
  Serial.print("IP: ");
  Serial.println(WiFi.localIP());

  // call the FTP upload procedure
  FTP_upload();
  
}

void loop() {
  // empty
}

How can I solve this? Thank you

Answer 1

Solved, I changed the method a little.

In a loop, I read a portion of the file and write it to the opened FTP remote file, then I close both at the end of the cycle

// open FTP connection
ftp.OpenConnection();

// open local file
fileUpload = fopen("/sdcard/img.png", "r+");

// initialize file type
ftp.InitFile("Type I");

// change remote directory
ftp.ChangeWorkDir("/Shared/");

// define remote file name
String strName = "img.png";

// convert to char
const char *f_name = strName.c_str();

// create remote file with given name
ftp.NewFile( f_name );

// read all file in a loop
unsigned char buff[64];
while(!feof(fileUpload)){
    
    // read a portion of the file
    fread(buff, sizeof(char), sizeof(buff), fileUpload);

    // write that portion to the remote file
    ftp.WriteData(buff, sizeof(buff));
}

// close both the local and the remote file
fclose(fileUpload);
ftp.CloseFile();