dump I2C EEPROM memory from Linux device ioctl

dump_i2c_eeprom.c

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/i2c-dev.h>


#define READ_SIZE       (256)
#define NB_PAGES        (128)

void dump_to_file(const char *output_file_path,
                  const uint8_t *buffer, const int buffer_length)
{
        int output_file = open(output_file_path, O_RDWR|O_APPEND|O_CREAT);
        if (output_file < 0) {
                printf("Failed opening output file %s\n", output_file_path);
                return;
        }

        write(output_file, buffer, buffer_length);
}


int main(int argc, char *argv[])
{

        const char *i2c_device = "/dev/i2c-4";
        const int device_address = 0x50;

        int file = open(i2c_device, O_RDWR);
        if (file < 0) {
                printf("Failed opening %s\n", i2c_device);
                return 1;
        }

        if (ioctl(file, I2C_SLAVE, device_address) < 0) {
                printf("Failed addressing device at %02X\n", device_address);
                close(file);
                return 1;
        }

        int i = 0;

        write(file,'\x00\x00',2); // ADDRESS

        for (i = 0; i < NB_PAGES; i++) {
                char buf[READ_SIZE] = {0};

                if (read(file, buf, READ_SIZE) != READ_SIZE) {
                        printf("Failed reading\n");
                        close(file);
                        return 1;
                }

                dump_to_file(argv[1], buf, READ_SIZE);
        }

        close(file);

        return 0;
}

Forked from gquere/dump_i2c_eeprom.c

He forgot to initialize the starting address to read the eeprom. Without this addition you will read the eprom starting from a random page.
To set the page to 0x00 all that was needed was:

write(file,'\x00\x00',2); // ADDRESS