Walk a file tree
#include <ftw.h> int ftw( const char *path, int (*fn)( const char *fname, const struct stat *sbuf, int flags), int depth ); int ftw64( const char *path, int (*fn)( const char *fname, const struct stat64 *sbuf, int flags), int depth );
If depth is zero or negative, the effect is the same as if it were 1. The depth must not be greater than the number of file descriptors currently available for use. The ftw() function is faster if depth is at least as large as the number of levels in the tree.
Use the -l c option to qcc to link against this library. This library is usually included automatically.
|These functions are in libc.a, but not in libc.so (in order to save space).|
The ftw() and ftw64() functions recursively descend the directory hierarchy identified by path. The ftw64() function is a large-file support version of ftw().
For each object in the hierarchy, ftw() calls the user-defined function fn(), passing to it:
The ftw() function visits a directory before visiting any of its descendants.
The tree traversal continues until the tree is exhausted, an invocation of fn() returns a nonzero value, or some error is detected within ftw() (such as an I/O error). If the tree is exhausted, ftw() returns zero. If fn() returns a nonzero value, ftw() stops its tree traversal and returns whatever value was returned by fn().
When ftw() returns, it closes any file descriptors it opened; it doesn't close any file descriptors that may have been opened by fn().
ftw() is POSIX 1003.1 XSI; ftw64() is Large-file support
Because ftw() is recursive, it might terminate with a memory fault when applied to very deep file structures.
This function uses malloc() to allocate dynamic storage during its operation. If ftw() is forcibly terminated, for example if longjmp() is executed by fn() or an interrupt routine, ftw() doesn't have a chance to free that storage, so it remains permanently allocated. A safe way to handle interrupts is to store the fact that an interrupt has occurred, and arrange to have fn() return a nonzero value at its next invocation.
longjmp(), malloc(), nftw(), readdir(), stat()