Cygwin B20 - fseek under gcc fails to reposition on text files

[Earnie Boyd]

You need to read the docs about "text mode processing".  This is
exactly the expected behavior.  If you're going to use these functions
then you must process in binary mode.

Regards,
Earnie.

---Peter Kabal <kabal@ECE.McGill.CA> wrote:
>
> Consider a text file (CR/LF line endings).  Read a line, save the
> current position, seek to end-of-file, seek to the saved position,
> read a line.  The second read does not return the second line of
> the file.
> 
> A shell script which tests the problem is included below:
> ---------------------------------------------------------------------
> #!/bin/sh
> #
> # Test fseek bug
> # On Cygwin 20.1, a file is not correctly repositioned after seeking
to the
> # end-of-file on a text file (CR/LF line endings).
> 
> cat > tfrepos.c << EoF
> #include <stdio.h>
> int main (int argc, char *argv[])
> {
>   FILE *fp;
>   long int pos, size;
>   char line[200];
>   char *p;
> 
>   fp = fopen (argv[1], "r");
>   p = fgets (line, 200, fp);
>   printf (" Line: %s", p);
> 
>   pos = ftell (fp);
>   fseek (fp, 0L, SEEK_END);
>   fseek (fp, pos, SEEK_SET);
> 
>   p = fgets (line, 200, fp);
>   printf (" Line: %s", p);
> 
>   return 0;
> }
> EoF
> 
> # Run the test program with the c-program as input
> gcc tfrepos.c -o tfrepos
> ./tfrepos tfrepos.c
> 
> # Clean up
> rm -f tfrepos tfrepos.c
> ---------------------------------------------------------------------
> 
> Peter Kabal  kabal@ECE.McGill.CA
> Dept. Electrical & Computer Eng.
> McGill University 
> 

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