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Editorial Team
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Asked: 2026-06-15T14:11:16+00:00

In my pure C++ native process (that I run from the terminal with adb)

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In my pure C++ native process (that I run from the terminal with adb) I’m trying to read a block directly from the SD Card in Android 2.3 SGS2. My code is running with root permissions so it shouldn’t matter.

I know that the SD Card memory mapped to /sys/block/mmcblk1 so I open it: 

int fd = open("/sys/block/mmcblk1", O_RDONLY);

which succeeds. Now, when I’m trying to read from it:

bytes_read = read(fd, buffer, 4096);

I get an error: “Is a directory”

Well, I know that this is a directory but it’s still supposed to work, maybe with some other flags in the open?

How can I do this?

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1 Answer

  1. Editorial Team

    Haha!
    My mistake was indeed that I tried to read from a directory /sys/block/mmcblk1.
    But I should have try to read from /dev/block/mmcblk1!

    Which works perfectly.

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