Once upon a time, file size was capped to 2G because of 2^31 - 1 = 2G. Has such, open will fail on files bigger than 2G.

this tutorial will show how to get standard C to handle large file.

As per man open:

O_LARGEFILE
(LFS) Allow files whose sizes cannot be represented in an off_t (but can be represented in an off64_t) to be opened. The _LARGEFILE64_SOURCE macro must be defined
in order to obtain this definition. Setting the _FILE_OFFSET_BITS feature test macro to 64 (rather than using O_LARGEFILE) is the preferred method of obtaining
method of accessing large files on 32-bit systems (see feature_test_macros(7)).

thus, we will need to compile out code with -D_FILE_OFFSET_BITS=64 in order to get open to succeed.

Let's create a 2.1G file:

$ dd if=/dev/zero of=2.1Gfile bs=1M count=2150
2150+0 records in
2150+0 records out
2254438400 bytes (2.3 GB) copied, 79.7822 s, 28.3 MB/s

And a code sample to open this file:

Now, compile it the old good way and try to open 2.1Gfile:

$ gcc largefiles.c
$ ./a.out 2.1Gfile
Filename is 2.1Gfile
Could not open file: Value too large for defined data type

and, when compiling it with -D_FILE_OFFSET_BITS=64 :

$ gcc -D_FILE_OFFSET_BITS=64 largefiles.c
$ ./a.out 2.1Gfile
Filename is 2.1Gfile
File 2.1Gfile was open success fully