Sean Anderson <[email protected]> schrieb am Mo., 20. Okt. 2025, 16:21:
> On 10/18/25 03:21, Heinrich Schuchardt wrote: > > On 10/17/25 23:35, Sean Anderson wrote: > >> When semihosting 32-bit systems, the return value of FLEN will be stored > >> in a 32-bit integer. To prevent wraparound, return -1 and set EOVERFLOW. >> This matches the behavior of stat(2). Static files don't need to be > >> checked, since are always small. > >> > >> Signed-off-by: Sean Anderson <[email protected]> > >> --- > >> > >> semihosting/arm-compat-semi.c | 17 ++++++++++++++--- > >> 1 file changed, 14 insertions(+), 3 deletions(-) > >> > >> diff --git a/semihosting/arm-compat-semi.c > b/semihosting/arm-compat-semi.c > >> index c5a07cb947..57453ca6be 100644 > >> --- a/semihosting/arm-compat-semi.c > >> +++ b/semihosting/arm-compat-semi.c > >> @@ -305,8 +305,19 @@ static uint64_t common_semi_flen_buf(CPUState *cs) > >> return sp - 64; > >> } > >> +static void common_semi_flen_cb(CPUState *cs, uint64_t ret, int err) > >> +{ > >> + CPUArchState *env = cpu_env(cs); > >> + > >> + if (!err && !is_64bit_semihosting(env) && ret > INT32_MAX) { > > > > > > The issue with the current implementation is that files with file sizes > over 4 GiB will be reported as file size < 4 -GiB on 32bit systems. Thanks > for addressing this. > > > > But unfortunately with your change you are additionally dropping support > for file sizes 2 GiB to 4 GiB on 32bit devices. This should be avoided. > > > > The semihosting specification specifies that the value returned in r0 > should be -1 if an error occurs. So on 32 bit systems 0xffffffff should be > returned. > > > > As file sizes cannot be negative there is not reason to assume that the > value in r0 has to be interpreted by semihosting clients as signed. > > > > Please, change your commit to check against 0xffffffff. > > > > It might make sense to contact ARM to make their specification clearer. > > stat(2) will return -1/EOVERFLOW on 32-bit hosts for files over 2 GiB. I > believe we should be consistent. > That may have been true historically. Current 32-bit Linux supports 64-bit file systems and reports the length of files beyond 2 GiB without error. Best regards Heinrich
