clang warnings in fat.c and file.c

[glennmatthews]

clang -g -O2 -DVERSION="1.0.0-beta" -Wall -fmessage-length=0 -fdiagnostics-print-source-range-info -fdiagnostics-show-category=id -fdiagnostics-parseable-fixits -Wno-trigraphs -Wmissing-prototypes -Wreturn-type -Wparentheses -Wswitch -Wno-unused-parameter -Wunused-variable -Wunused-value -Wno-sign-conversion -c -o .o/backtrace.o backtrace.c
clang -g -O2 -DVERSION="1.0.0-beta" -Wall -fmessage-length=0 -fdiagnostics-print-source-range-info -fdiagnostics-show-category=id -fdiagnostics-parseable-fixits -Wno-trigraphs -Wmissing-prototypes -Wreturn-type -Wparentheses -Wswitch -Wno-unused-parameter -Wunused-variable -Wunused-value -Wno-sign-conversion -c -o .o/fat.o fat.c
fat.c:30:23: warning: unused variable 'FAT_FILE_VFAT_CHAR' [-Wunused-const-variable,24]
 static const uint32_t FAT_FILE_VFAT_CHAR            = 0x01;
                       ^
fat.c:35:23: warning: unused variable 'FAT_ATTR_IS_READ_ONLY' [-Wunused-const-variable,24]
 static const uint32_t FAT_ATTR_IS_READ_ONLY         = 0x01;
                       ^
fat.c:36:23: warning: unused variable 'FAT_ATTR_IS_HIDDEN' [-Wunused-const-variable,24]
 static const uint32_t FAT_ATTR_IS_HIDDEN            = 0x02;
                       ^
fat.c:37:23: warning: unused variable 'FAT_ATTR_IS_SYSTEM' [-Wunused-const-variable,24]
 static const uint32_t FAT_ATTR_IS_SYSTEM            = 0x04;
                       ^
fat.c:38:23: warning: unused variable 'FAT_ATTR_IS_LABEL' [-Wunused-const-variable,24]
 static const uint32_t FAT_ATTR_IS_LABEL             = 0x08;
                       ^
5 warnings generated.
clang -g -O2 -DVERSION="1.0.0-beta" -Wall -fmessage-length=0 -fdiagnostics-print-source-range-info -fdiagnostics-show-category=id -fdiagnostics-parseable-fixits -Wno-trigraphs -Wmissing-prototypes -Wreturn-type -Wparentheses -Wswitch -Wno-unused-parameter -Wunused-variable -Wunused-value -Wno-sign-conversion -c -o .o/command.o command.c
clang -g -O2 -DVERSION="1.0.0-beta" -Wall -fmessage-length=0 -fdiagnostics-print-source-range-info -fdiagnostics-show-category=id -fdiagnostics-parseable-fixits -Wno-trigraphs -Wmissing-prototypes -Wreturn-type -Wparentheses -Wswitch -Wno-unused-parameter -Wunused-variable -Wunused-value -Wno-sign-conversion -c -o .o/file.o file.c
file.c:413:29:{413:29-413:60}: warning: the value of the size argument in 'strncat' is too large, might lead to a buffer overflow [-Wstrncat-size,2]
                             sizeof(regexp) - strlen(regexp));
                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
file.c:413:29: note: change the argument to be the free space in the destination buffer minus the terminating null byte [2]
                             sizeof(regexp) - strlen(regexp));
                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                             sizeof(regexp) - strlen(regexp) - 1
fix-it:"file.c":{413:29-413:60}:"sizeof(regexp) - strlen(regexp) - 1"
file.c:419:25:{419:25-419:56}: warning: the value of the size argument in 'strncat' is too large, might lead to a buffer overflow [-Wstrncat-size,2]
                         sizeof(regexp) - strlen(regexp));
                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
file.c:419:25: note: change the argument to be the free space in the destination buffer minus the terminating null byte [2]
                         sizeof(regexp) - strlen(regexp));
                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                         sizeof(regexp) - strlen(regexp) - 1
fix-it:"file.c":{419:25-419:56}:"sizeof(regexp) - strlen(regexp) - 1"
file.c:424:25:{424:25-424:56}: warning: the value of the size argument in 'strncat' is too large, might lead to a buffer overflow [-Wstrncat-size,2]
                         sizeof(regexp) - strlen(regexp));
                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
file.c:424:25: note: change the argument to be the free space in the destination buffer minus the terminating null byte [2]
                         sizeof(regexp) - strlen(regexp));
                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                         sizeof(regexp) - strlen(regexp) - 1
fix-it:"file.c":{424:25-424:56}:"sizeof(regexp) - strlen(regexp) - 1"
3 warnings generated.