[PATCH] fs: semihosting: Use correct variable for error check

[Sean Anderson]

On 10/2/25 05:52, Heinrich Schuchardt wrote:
> On 10/2/25 11:39, Andrew Goodbody wrote:
>> After calling a function that can return an error, the test to detect
>> that error should use the return value not a different variable. Fix it.
>>
>> This issue was found by Smatch.
>>
> 
> Fixes: f676b45151c3 ("fs: Add semihosting filesystem")
> 
>> Signed-off-by: Andrew Goodbody <andrew.goodbody at linaro.org>
>> ---
>>   fs/semihostingfs.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/semihostingfs.c b/fs/semihostingfs.c
>> index 77e39ca407e4d240a1fd573497c5b6b908816454..9d7a136b9ba9b035545b34b31df58e2d65de7db9 100644
>> --- a/fs/semihostingfs.c
>> +++ b/fs/semihostingfs.c
>> @@ -35,7 +35,7 @@ static int smh_fs_read_at(const char *filename, loff_t pos, void *buffer,
>>       }
>>       if (!maxsize) {
>>           size = smh_flen(fd);
>> -        if (ret < 0) {
>> +        if (size < 0) {
> 
> The ARM specification (https://cas5-0-urlprotect.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%2f%2fdeveloper.arm.com%2fdocumentation%2fdui0203%2fj%2fsemihosting%2fsemihosting%2doperations%2fsys%2dflen%2d%2d0x0c%2d&umid=f17ab8fc-2d9d-4cce-91e2-e7e66f117613&rct=1759398729&auth=d807158c60b7d2502abde8a2fc01f40662980862-e0799d2d4d61f93cae033d54733c8fa50ef84918) has:
> 
> SYS_FLEN (0x0C)
> 
> Returns the length of a specified file.
> On exit, R0 contains:
>     the current length of the file object, if the call is successful
>     -1 if an error occurs.
> 
> Please, consider that the file length on 32bit systems may exceed 2^31 You must not consider this as an error.
> 
> %s/if (size < 0)/if (size == -1L)/

This cannot occur because on a 32-bit system SYS_FLEN only returns
32-bits of information. The host must detect files that exceed 2 GiB in
size and return -1 (simulating EOVERFLOW).

--Sean