Ultrix-3.1/src/libc/sysV/ftw.c
/**********************************************************************
* Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. *
* All Rights Reserved. *
* Reference "/usr/src/COPYRIGHT" for applicable restrictions. *
**********************************************************************/
/* SCCSID: @(#)ftw.c 3.0 4/22/86 */
/* (System 5) 1.2 */
/*LINTLIBRARY*/
/***************************************************************
* ftw - file tree walk
*
* int ftw (path, fn, depth) char *path; int (*fn)(); int depth;
*
* Given a path name, ftw starts from the file given by that path
* name and visits each file and directory in the tree beneath
* that file. If a single file has multiple links within the
* structure, it will be visited once for each such link.
* For each object visited, fn is called with three arguments.
* The first contains the path name of the object, the second
* contains a pointer to a stat buffer which will usually hold
* appropriate information for the object and the third will
* contain an integer value giving additional information about
*
* FTW_F The object is a file for which stat was
* successful. It does not guarantee that the
* file can actually be read.
*
* FTW_D The object is a directory for which stat and
* open for read were both successful.
*
* FTW_DNR The object is a directory for which stat
* succeeded, but which cannot be read. Because
* the directory cannot be read, fn will not be
* called for any descendants of this directory.
*
* FTW_NS Stat failed on the object because of lack of
* appropriate permission. This indication will
* be given, for example, for each file in a
* directory with read but no execute permission.
* Because stat failed, it is not possible to
* determine whether this object is a file or a
* directory. The stat buffer passed to fn will
* contain garbage. Stat failure for any reason
* other than lack of permission will be
* considered an error and will cause ftw to stop
* and return -1 to its caller.
*
* If fn returns nonzero, ftw stops and returns the same value
* to its caller. If ftw gets into other trouble along the way,
* it returns -1 and leaves an indication of the cause in errno.
*
* The third argument to ftw does not limit the depth to which
* ftw will go. Rather, it limits the depth to which ftw will
* go before it starts recycling file descriptors. In general,
* it is necessary to use a file descriptor for each level of the
* tree, but they can be recycled for deep trees by saving the
* position, closing, re-opening, and seeking. It is possible
* to start recycling file descriptors by sensing when we have
* run out, but in general this will not be terribly useful if
* fn expects to be able to open files. We could also figure out
* how many file descriptors are available and guarantee a certain
* number to fn, but we would not know how many to guarantee,
* and we do not want to impose the extra overhead on a caller who
* knows how many are available without having to figure it out.
*
* It is possible for ftw to die with a memory fault in the event
* of a file system so deeply nested that the stack overflows.
**************************************************************/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/dir.h>
#include <errno.h>
#include <ftw.h>
#define NULL 0
extern char *malloc(), *strcpy();
extern long lseek();
extern int errno;
int
ftw(path, fn, depth)
char *path;
int (*fn)();
int depth;
{
int rc, rl, n, fd;
char *subpath, *component;
struct stat sb;
struct direct dir;
/* Try to get file status.
If unsuccessful, errno will say why. */
if(stat(path, &sb) < 0)
return(errno == EACCES? (*fn)(path, &sb, FTW_NS): -1);
/*
* The stat succeeded, so we know the object exists.
* If not a directory, call the user function and return.
*/
if((sb.st_mode & S_IFMT) != S_IFDIR)
return((*fn)(path, &sb, FTW_F));
/*
* The object was a directory.
*
* Open a file to read the directory
*/
fd = open(path, 0);
/*
* Call the user function, telling it whether
* the directory can be read. If it can't be read
* call the user function or indicate an error,
* depending on the reason it couldn't be read.
*/
if(fd < 0)
return(errno == EACCES? (*fn)(path, &sb, FTW_DNR): -1);
/* We could read the directory. Call user function. */
rc = (*fn)(path, &sb, FTW_D);
if(rc != 0)
return(rc);
/* Allocate a buffer to hold generated pathnames. */
n = strlen(path);
subpath = malloc((unsigned)(n+DIRSIZ+2));
if(subpath == NULL) {
(void)close(fd);
errno = ENOMEM;
return(-1);
}
/* Create a prefix to which we will append component names */
(void)strcpy(subpath, path);
if(subpath[0] != '\0' && subpath[n-1] != '/')
subpath[n++] = '/';
component = &subpath[n];
/*
* Read the directory one component at a time.
* We must ignore "." and "..", but other than that,
* just create a path name and call self to check it out.
*/
while((rl = read(fd, (char*)&dir, sizeof(struct direct))) ==
sizeof(struct direct)) {
if(dir.d_ino != 0 && strcmp(dir.d_name, ".") != 0 &&
strcmp(dir.d_name, "..") != 0) {
int i;
char *p, *q;
long here;
/* Append component name to the working path */
p = component;
q = dir.d_name;
for(i=0; i < DIRSIZ && *q != '\0'; i++)
*p++ = *q++;
*p = '\0';
/*
* If we are about to exceed our depth,
* remember where we are and close a file.
*/
if(depth <= 1) {
here = lseek(fd, 0L, 1);
if(close(fd) < 0) {
free(subpath);
return(-1);
}
}
/*
* Do a recursive call to process the file.
* (watch this, sports fans)
*/
rc = ftw(subpath, fn, depth-1);
if(rc != 0) {
free(subpath);
if(depth > 1)
(void)close(fd);
return(rc);
}
/*
* If we closed the file, try to reopen it.
*/
if(depth <= 1) {
fd = open(path, 0);
if(fd < 0) {
free(subpath);
return(-1);
}
if(lseek(fd, here, 0) < 0) {
(void)close(fd);
free(subpath);
return(-1);
}
}
}
}
/*
* We got out of the subdirectory loop. The return from
* the final read is in rl. Clean up and then check if
* the final read was successful. If not, give an
* error return.
*/
free(subpath);
if(close(fd) < 0 || rl != 0)
return(-1);
return(0);
}