_is_executable

Syntax

#include <sys/stat.h> int _is_executable(const char *path, int fhandle, const char *extension);

Description

This function determines if a file is executable under DOS/DJGPP environment. The file may be given either by its path or its file handle fhandle. If extension is non-NULL and non-empty, it is used first to look up in a list of known extensions which determine whether the file is executable. (If the _STAT_EXEC_EXT bit of the _djstat_flags global variable (see section _djstat_flags) is not set, this step is skipped.) If extension is unavailable or not enough to determine the result, the first 2 bytes of the file are checked to contain one of the known magic numbers identifying the file as executable. If the file's 2 first bytes need to be read but the read fails, 0 is returned and errno is set. (The file is only searched for magic number if the _STAT_EXEC_MAGIC bit of the _djstat_flags variable is set.)

Note that if _STAT_EXEC_MAGIC is set, but _STAT_EXEC_EXT is not, some files which shouldn't be flagged as executables (e.g., COFF `*.o' object files) will have their execute bit set, because they have the magic number signature at their beginning. Therefore, only use the above combination if you want to debug the list of extensions provided in `is_exec.c' file from the library sources.

If the file passed by its handle was open as write-only, and the extension alone isn't enough to determine whether the file is executable, then this function returns 0, because it cannot look at the magic number.

This function is used internally by f?stat; you are not supposed to call it directly. However, if you call it, and pass file through path, it's up to you to resolve symlinks there.

Return Value

1 for executable file, 0 otherwise (including in case of errors in accessing the file).

Portability

ANSI/ISO C	No
POSIX	No