I have a question about USB memory with write protection (buffalo, unknown model number) in an embedded Linux environment.
This memory has a SW so you can turn on/off write protection.
Mounting this memory with Protect ON
mount:/dev/sda1 is write-protected, mounting read-only
You can mount the message.
In this state, opening the file with read attributes will result in an error:
fp=fopen("/mdeia/usb/test.txt", "r");
When opened, an error occurs and errno=2 returns.
You can mount it manually from the command line and view the contents of the file in cat.
Protect OFF will open normally.
The ls-al file attributes show no difference between Protect ON/OFF.
Is it impossible to open with fopen() with Protect ON?
fd=open("/media/usb/test.txt", O_RDONLY);
I also tried it.It's the same as fopen(), but -1 was returned for Protect ON and opened for Protect OFF.
I looked at the GNU cat source.
If you don't have an option, you might want to try it because it seems to be loaded with O_RDWR|O_BINARY.
if (!( number | | show_ends | | squeeze_blank )
{
file_open_mode | = O_BINARY;
xset_binary_mode (STDOUT_FILENO, O_BINARY);
}
/* Check if any of the input files are the same as the output file.*/
/* Main loop.*/
file="-";
argind = optind;
do
{
if(argind<argc)
infile=argv [argind];
if(STREQ(infile, "-"))
{
have_read_stdin = true;
input_desc = STDIN_FILENO;
if(file_open_mode&O_BINARY)
xset_binary_mode(STDIN_FILENO, O_BINARY);
}
else
{
input_desc=open(infile,file_open_mode);
if(input_desc<0)
{
error(0, errno, "%s", quotef(infile)));
ok = false;
continue;
}
}
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