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/* vi: set sw=4 ts=4 :*/
/* dirtree.c - Functions for dealing with directory trees.
*
* Copyright 2007 Rob Landley <rob@landley.net>
*/
#include "toys.h"
// Create a dirtree node from a path, with stat and symlink info.
// (This doesn't open directory filehandles yet so as not to exhaust the
// filehandle space on large trees. handle_callback() does that instead.)
struct dirtree *dirtree_add_node(int dirfd, char *name)
{
struct dirtree *dt = NULL;
struct stat st;
char buf[4096];
int len = 0, linklen = 0;
if (name) {
if (fstatat(dirfd, name, &st, AT_SYMLINK_NOFOLLOW)) goto error;
if (S_ISLNK(st.st_mode)) {
if (0>(linklen = readlinkat(dirfd, name, buf, 4095))) goto error;
buf[linklen++]=0;
}
len = strlen(name);
}
dt = xzalloc((len = sizeof(struct dirtree)+len+1)+linklen);
if (name) {
memcpy(&(dt->st), &st, sizeof(struct stat));
strcpy(dt->name, name);
if (linklen) {
dt->symlink = memcpy(len+(char *)dt, buf, linklen);
dt->data = --linklen;
}
}
return dt;
error:
perror_msg("%s",name);
free(dt);
return 0;
}
// Return path to this node, assembled recursively.
char *dirtree_path(struct dirtree *node, int *plen)
{
char *path;
int len;
if (!node || !node->name) {
path = xmalloc(*plen);
*plen = 0;
return path;
}
len = (plen ? *plen : 0)+strlen(node->name)+1;
path = dirtree_path(node->parent, &len);
if (len) path[len++]='/';
len = (stpcpy(path+len, node->name) - path);
if (plen) *plen = len;
return path;
}
// Default callback, filters out "." and "..".
int dirtree_notdotdot(struct dirtree *catch)
{
// Should we skip "." and ".."?
if (catch->name[0]=='.' && (!catch->name[1] ||
(catch->name[1]=='.' && !catch->name[2])))
return 0;
return DIRTREE_SAVE|DIRTREE_RECURSE;
}
// depth first recursion
int dirtree_comeagain(struct dirtree *try, int recurse)
{
int ret = dirtree_notdotdot(try);
if (ret) {
if (S_ISDIR(try->st.st_mode)) {
if (!try->extra) {
try->extra = xdup(try->data);
if (recurse) return DIRTREE_COMEAGAIN;
}
} else try->extra = openat(try->parent ? try->parent->data : AT_FDCWD,
try->name, 0);
}
return ret;
}
// Handle callback for a node in the tree. Returns saved node(s) or NULL.
//
// By default, allocates a tree of struct dirtree, not following symlinks
// If callback==NULL, or callback always returns 0, allocate tree of struct
// dirtree and return root of tree. Otherwise call callback(node) on each
// hit, free structures after use, and return NULL.
//
struct dirtree *handle_callback(struct dirtree *new,
int (*callback)(struct dirtree *node))
{
int flags, dir = S_ISDIR(new->st.st_mode);
if (!callback) callback = dirtree_notdotdot;
// Directory always has filehandle for examining contents. Whether or
// not we'll recurse into it gets decided later.
if (dir)
new->data = openat(new->parent ? new->parent->data : AT_FDCWD,
new->name, 0);
flags = callback(new);
if (dir) {
if (flags & (DIRTREE_RECURSE|DIRTREE_COMEAGAIN)) {
dirtree_recurse(new, callback);
if (flags & DIRTREE_COMEAGAIN) flags = callback(new);
} else close(new->data);
}
// If this had children, it was callback's job to free them already.
if (!(flags & DIRTREE_SAVE)) {
free(new);
new = NULL;
}
return (flags & DIRTREE_ABORT)==DIRTREE_ABORT ? DIRTREE_ABORTVAL : new;
}
// Recursively read/process children of directory node (with dirfd in data),
// filtering through callback().
void dirtree_recurse(struct dirtree *node,
int (*callback)(struct dirtree *node))
{
struct dirtree *new, **ddt = &(node->child);
struct dirent *entry;
DIR *dir;
if (!(dir = fdopendir(node->data))) {
char *path = dirtree_path(node, 0);
perror_msg("No %s", path);
free(path);
close(node->data);
return;
}
// according to the fddir() man page, the filehandle in the DIR * can still
// be externally used by things that don't lseek() it.
// The extra parentheses are to shut the stupid compiler up.
while ((entry = readdir(dir))) {
if (!(new = dirtree_add_node(node->data, entry->d_name))) continue;
new->parent = node;
new = handle_callback(new, callback);
if (new == DIRTREE_ABORTVAL) break;
if (new) {
*ddt = new;
ddt = &((*ddt)->next);
}
}
// This closes filehandle as well, so note it
closedir(dir);
node->data = -1;
}
// Create dirtree from path, using callback to filter nodes.
// If callback == NULL allocate a tree of struct dirtree nodes and return
// pointer to root node.
struct dirtree *dirtree_read(char *path, int (*callback)(struct dirtree *node))
{
struct dirtree *root = dirtree_add_node(AT_FDCWD, path);
return root ? handle_callback(root, callback) : DIRTREE_ABORTVAL;
}
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