examples/minitar/tree.c - third_party/libarchive - Git at Google

 /*-
  * Copyright (c) 2003-2004 Tim Kientzle
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer
  *    in this position and unchanged.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 /*-
  * There is a single list of "tree_entry" items that represent
  * filesystem objects that require further attention.  Non-directories
  * are not kept in memory: they are pulled from readdir(), returned to
  * the client, then freed as soon as possible.  Any directory entry to
  * be traversed gets pushed onto the stack.
  *
  * There is surprisingly little information that needs to be kept for
  * each item on the stack.  Just the name, depth (represented here as the
  * string length of the parent directory's pathname), and some markers
  * indicating how to get back to the parent (via chdir("..") for a
  * regular dir or via fchdir(2) for a symlink).
  */

 #include <sys/stat.h>
 #include <dirent.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>

 #include "tree.h"

 /*
  * TODO:
  *    1) Loop checking.
  *    3) Arbitrary logical traversals by closing/reopening intermediate fds.
  */

 struct tree_entry {
 	struct tree_entry *next;
 	char *name;
 	size_t dirname_length;
 	int fd;
 	int flags;
 };

 /* Definitions for tree_entry.flags bitmap. */
 #define isDir 1 /* This entry is a regular directory. */
 #define isDirLink 2 /* This entry is a symbolic link to a directory. */
 #define needsTraversal 4 /* This entry hasn't yet been traversed. */

 /*
  * Local data for this package.
  */
 struct tree {
 	struct tree_entry	*stack;
 	DIR	*d;
 	int	 initialDirFd;
 	int	 flags;

 	char	*buff;
 	char	*basename;
 	size_t	 buff_length;
 	size_t	 path_length;
 	size_t	 dirname_length;

 	int	 depth;
 	int	 openCount;
 	int	 maxOpenCount;

 	struct stat	lst;
 	struct stat	st;
 };

 /* Definitions for tree.flags bitmap. */
 #define needsReturn 8  /* Marks first entry as not having been returned yet. */
 #define hasStat 16  /* The st entry is set. */
 #define hasLstat 32 /* The lst entry is set. */


 #define HAVE_DIRENT_D_NAMLEN 1
 #ifdef HAVE_DIRENT_D_NAMLEN
 /* BSD extension; avoids need for a strlen() call. */
 #define D_NAMELEN(dp)	(dp)->d_namlen
 #else
 #define D_NAMELEN(dp)	(strlen((dp)->d_name))
 #endif

 #if 0
 static void
 dumpStack(struct tree *t)
 {
 	struct tree_entry *te;

 	printf("\tbuff: %s\n", t->buff);
 	printf("\tpwd: "); fflush(stdout); system("pwd");
 	printf("\tstack:\n");
 	for (te = t->stack; te != NULL; te = te->next) {
 		printf("\t\tte->name: %s %s\n", te->name, te->flags & needsTraversal ? "" : "*");
 	}
 }
 #endif

 /*
  * Add a directory path to the current stack.
  */
 static void
 tree_add(struct tree *t, const char *path)
 {
 	struct tree_entry *te;

 	te = malloc(sizeof(*te));
 	memset(te, 0, sizeof(*te));
 	te->next = t->stack;
 	t->stack = te;
 	te->fd = -1;
 	te->name = strdup(path);
 	te->flags = needsTraversal;
 	te->dirname_length = t->dirname_length;
 }

 /*
  * Append a name to the current path.
  */
 static void
 tree_append(struct tree *t, const char *name, size_t name_length)
 {
 	if (t->buff != NULL)
 		t->buff[t->dirname_length] = '\0';

 	/* Resize pathname buffer as needed. */
 	while (name_length + 1 + t->dirname_length >= t->buff_length) {
 		t->buff_length *= 2;
 		if (t->buff_length < 1024)
 			t->buff_length = 1024;
 		t->buff = realloc(t->buff, t->buff_length);
 	}
 	t->basename = t->buff + t->dirname_length;
 	t->path_length = t->dirname_length + name_length;
 	if (t->dirname_length > 0) {
 		*t->basename++ = '/';
 		t->path_length ++;
 	}
 	strcpy(t->basename, name);
 }

 /*
  * Open a directory tree for traversal.
  */
 struct tree *
 tree_open(const char *path)
 {
 	struct tree *t;

 	t = malloc(sizeof(*t));
 	memset(t, 0, sizeof(*t));
 	tree_append(t, path, strlen(path));
 	t->initialDirFd = open(".", O_RDONLY);
 	/*
 	 * During most of the traversal, items are set up and then
 	 * returned immediately from tree_next().  That doesn't work
 	 * for the very first entry, so we set a flag for this special
 	 * case.
 	 */
 	t->flags = needsReturn;
 	return (t);
 }

 /*
  * We've finished a directory; ascend back to the parent.
  */
 static void
 tree_ascend(struct tree *t)
 {
 	struct tree_entry *te;

 	te = t->stack;
 	t->depth--;
 	if (te->flags & isDirLink) {
 		fchdir(te->fd);
 		close(te->fd);
 		t->openCount--;
 	} else {
 		chdir("..");
 	}
 }

 /*
  * Pop the working stack.
  */
 static void
 tree_pop(struct tree *t)
 {
 	struct tree_entry *te;

 	te = t->stack;
 	t->stack = te->next;
 	t->dirname_length = te->dirname_length;
 	free(te->name);
 	free(te);
 }

 /*
  * Get the next item in the tree traversal.
  */
 int
 tree_next(struct tree *t)
 {
 	struct dirent *de = NULL;

 	/* Handle the startup case by returning the initial entry. */
 	if (t->flags & needsReturn) {
 		t->flags &= ~needsReturn;
 		return (1);
 	}

 	while (t->stack != NULL) {
 		/* If there's an open dir, get the next entry from there. */
 		while (t->d != NULL) {
 			de = readdir(t->d);
 			if (de == NULL) {
 				closedir(t->d);
 				t->d = NULL;
 			} else if (de->d_name[0] == '.'
 			    && de->d_name[1] == '\0') {
 				/* Skip '.' */
 			} else if (de->d_name[0] == '.'
 			    && de->d_name[1] == '.'
 			    && de->d_name[2] == '\0') {
 				/* Skip '..' */
 			} else {
 				/*
 				 * Append the path to the current path
 				 * and return it.
 				 */
 				tree_append(t, de->d_name, D_NAMELEN(de));
 				t->flags &= ~hasLstat;
 				t->flags &= ~hasStat;
 				return (1);
 			}
 		}

 		/* If the current dir needs to be traversed, set it up. */
 		if (t->stack->flags & needsTraversal) {
 			tree_append(t, t->stack->name, strlen(t->stack->name));
 			t->stack->flags &= ~needsTraversal;
 			/* If it is a link, set up fd for the ascent. */
 			if (t->stack->flags & isDirLink) {
 				t->stack->fd = open(".", O_RDONLY);
 				t->openCount++;
 				if (t->openCount > t->maxOpenCount)
 					t->maxOpenCount = t->openCount;
 			}
 			if (chdir(t->stack->name) == 0) {
 				t->depth++;
 				t->dirname_length = t->path_length;
 				t->d = opendir(".");
 			} else
 				tree_pop(t);
 			continue;
 		}

 		/* We've done everything necessary for the top stack entry. */
 		tree_ascend(t);
 		tree_pop(t);
 	}
 	return (0);
 }

 /*
  * Called by the client to mark the directory just returned from
  * tree_next() as needing to be visited.
  */
 void
 tree_descend(struct tree *t)
 {
 	const struct stat *s = tree_current_lstat(t);

 	if (S_ISDIR(s->st_mode)) {
 		tree_add(t, t->basename);
 		t->stack->flags |= isDir;
 	}

 	if (S_ISLNK(s->st_mode) && S_ISDIR(tree_current_stat(t)->st_mode)) {
 		tree_add(t, t->basename);
 		t->stack->flags |= isDirLink;
 	}
 }

 /*
  * Get the stat() data for the entry just returned from tree_next().
  */
 const struct stat *
 tree_current_stat(struct tree *t)
 {
 	if (!(t->flags & hasStat)) {
 		stat(t->basename, &t->st);
 		t->flags |= hasStat;
 	}
 	return (&t->st);
 }

 /*
  * Get the lstat() data for the entry just returned from tree_next().
  */
 const struct stat *
 tree_current_lstat(struct tree *t)
 {
 	if (!(t->flags & hasLstat)) {
 		lstat(t->basename, &t->lst);
 		t->flags |= hasLstat;
 	}
 	return (&t->lst);
 }

 /*
  * Return the access path for the entry just returned from tree_next().
  */
 const char *
 tree_current_access_path(struct tree *t)
 {
 	return (t->basename);
 }

 /*
  * Return the full path for the entry just returned from tree_next().
  */
 const char *
 tree_current_path(struct tree *t)
 {
 	return (t->buff);
 }

 /*
  * Return the length of the path for the entry just returned from tree_next().
  */
 size_t
 tree_current_pathlen(struct tree *t)
 {
 	return (t->path_length);
 }

 /*
  * Return the nesting depth of the entry just returned from tree_next().
  */
 int
 tree_current_depth(struct tree *t)
 {
 	return (t->depth);
 }

 /*
  * Terminate the traversal and release any resources.
  */
 void
 tree_close(struct tree *t)
 {
 	/* Release anything remaining in the stack. */
 	while (t->stack != NULL)
 		tree_pop(t);
 	if (t->buff)
 		free(t->buff);
 	/* chdir() back to where we started. */
 	if (t->initialDirFd >= 0) {
 		fchdir(t->initialDirFd);
 		close(t->initialDirFd);
 		t->initialDirFd = -1;
 	}
 	free(t);
 }


 #if 0
 /* Main function for testing. */
 #include <stdio.h>

 int main(int argc, char **argv)
 {
 	size_t max_path_len = 0;
 	int max_depth = 0;

 	system("pwd");
 	while (*++argv) {
 		struct tree *t = tree_open(*argv);
 		while (tree_next(t)) {
 			size_t path_len = tree_current_pathlen(t);
 			int depth = tree_current_depth(t);
 			if (path_len > max_path_len)
 				max_path_len = path_len;
 			if (depth > max_depth)
 				max_depth = depth;
 			printf("%s\n", tree_current_path(t));
 			if (S_ISDIR(tree_current_lstat(t)->st_mode))
 				tree_descend(t); /* Descend into every dir. */
 		}
 		tree_close(t);
 		printf("Max path length: %d\n", max_path_len);
 		printf("Max depth: %d\n", max_depth);
 		printf("Final open count: %d\n", t->openCount);
 		printf("Max open count: %d\n", t->maxOpenCount);
 		fflush(stdout);
 		system("pwd");
 	}
 	return (0);
 }
 #endif
	/*-
	* Copyright (c) 2003-2004 Tim Kientzle
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer
	* in this position and unchanged.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	/*-
	* There is a single list of "tree_entry" items that represent
	* filesystem objects that require further attention. Non-directories
	* are not kept in memory: they are pulled from readdir(), returned to
	* the client, then freed as soon as possible. Any directory entry to
	* be traversed gets pushed onto the stack.
	*
	* There is surprisingly little information that needs to be kept for
	* each item on the stack. Just the name, depth (represented here as the
	* string length of the parent directory's pathname), and some markers
	* indicating how to get back to the parent (via chdir("..") for a
	* regular dir or via fchdir(2) for a symlink).
	*/

	#include <sys/stat.h>
	#include <dirent.h>
	#include <fcntl.h>
	#include <stdlib.h>
	#include <string.h>
	#include <unistd.h>

	#include "tree.h"

	/*
	* TODO:
	* 1) Loop checking.
	* 3) Arbitrary logical traversals by closing/reopening intermediate fds.
	*/

	struct tree_entry {
	struct tree_entry *next;
	char *name;
	size_t dirname_length;
	int fd;
	int flags;
	};

	/* Definitions for tree_entry.flags bitmap. */
	#define isDir 1 /* This entry is a regular directory. */
	#define isDirLink 2 /* This entry is a symbolic link to a directory. */
	#define needsTraversal 4 /* This entry hasn't yet been traversed. */

	/*
	* Local data for this package.
	*/
	struct tree {
	struct tree_entry *stack;
	DIR *d;
	int initialDirFd;
	int flags;

	char *buff;
	char *basename;
	size_t buff_length;
	size_t path_length;
	size_t dirname_length;

	int depth;
	int openCount;
	int maxOpenCount;

	struct stat lst;
	struct stat st;
	};

	/* Definitions for tree.flags bitmap. */
	#define needsReturn 8 /* Marks first entry as not having been returned yet. */
	#define hasStat 16 /* The st entry is set. */
	#define hasLstat 32 /* The lst entry is set. */


	#define HAVE_DIRENT_D_NAMLEN 1
	#ifdef HAVE_DIRENT_D_NAMLEN
	/* BSD extension; avoids need for a strlen() call. */
	#define D_NAMELEN(dp) (dp)->d_namlen
	#else
	#define D_NAMELEN(dp) (strlen((dp)->d_name))
	#endif

	#if 0
	static void
	dumpStack(struct tree *t)
	{
	struct tree_entry *te;

	printf("\tbuff: %s\n", t->buff);
	printf("\tpwd: "); fflush(stdout); system("pwd");
	printf("\tstack:\n");
	for (te = t->stack; te != NULL; te = te->next) {
	printf("\t\tte->name: %s %s\n", te->name, te->flags & needsTraversal ? "" : "*");
	}
	}
	#endif

	/*
	* Add a directory path to the current stack.
	*/
	static void
	tree_add(struct tree t, const char path)
	{
	struct tree_entry *te;

	te = malloc(sizeof(*te));
	memset(te, 0, sizeof(*te));
	te->next = t->stack;
	t->stack = te;
	te->fd = -1;
	te->name = strdup(path);
	te->flags = needsTraversal;
	te->dirname_length = t->dirname_length;
	}

	/*
	* Append a name to the current path.
	*/
	static void
	tree_append(struct tree t, const char name, size_t name_length)
	{
	if (t->buff != NULL)
	t->buff[t->dirname_length] = '\0';

	/* Resize pathname buffer as needed. */
	while (name_length + 1 + t->dirname_length >= t->buff_length) {
	t->buff_length *= 2;
	if (t->buff_length < 1024)
	t->buff_length = 1024;
	t->buff = realloc(t->buff, t->buff_length);
	}
	t->basename = t->buff + t->dirname_length;
	t->path_length = t->dirname_length + name_length;
	if (t->dirname_length > 0) {
	*t->basename++ = '/';
	t->path_length ++;
	}
	strcpy(t->basename, name);
	}

	/*
	* Open a directory tree for traversal.
	*/
	struct tree *
	tree_open(const char *path)
	{
	struct tree *t;

	t = malloc(sizeof(*t));
	memset(t, 0, sizeof(*t));
	tree_append(t, path, strlen(path));
	t->initialDirFd = open(".", O_RDONLY);
	/*
	* During most of the traversal, items are set up and then
	* returned immediately from tree_next(). That doesn't work
	* for the very first entry, so we set a flag for this special
	* case.
	*/
	t->flags = needsReturn;
	return (t);
	}

	/*
	* We've finished a directory; ascend back to the parent.
	*/
	static void
	tree_ascend(struct tree *t)
	{
	struct tree_entry *te;

	te = t->stack;
	t->depth--;
	if (te->flags & isDirLink) {
	fchdir(te->fd);
	close(te->fd);
	t->openCount--;
	} else {
	chdir("..");
	}
	}

	/*
	* Pop the working stack.
	*/
	static void
	tree_pop(struct tree *t)
	{
	struct tree_entry *te;

	te = t->stack;
	t->stack = te->next;
	t->dirname_length = te->dirname_length;
	free(te->name);
	free(te);
	}

	/*
	* Get the next item in the tree traversal.
	*/
	int
	tree_next(struct tree *t)
	{
	struct dirent *de = NULL;

	/* Handle the startup case by returning the initial entry. */
	if (t->flags & needsReturn) {
	t->flags &= ~needsReturn;
	return (1);
	}

	while (t->stack != NULL) {
	/* If there's an open dir, get the next entry from there. */
	while (t->d != NULL) {
	de = readdir(t->d);
	if (de == NULL) {
	closedir(t->d);
	t->d = NULL;
	} else if (de->d_name[0] == '.'
	&& de->d_name[1] == '\0') {
	/* Skip '.' */
	} else if (de->d_name[0] == '.'
	&& de->d_name[1] == '.'
	&& de->d_name[2] == '\0') {
	/* Skip '..' */
	} else {
	/*
	* Append the path to the current path
	* and return it.
	*/
	tree_append(t, de->d_name, D_NAMELEN(de));
	t->flags &= ~hasLstat;
	t->flags &= ~hasStat;
	return (1);
	}
	}

	/* If the current dir needs to be traversed, set it up. */
	if (t->stack->flags & needsTraversal) {
	tree_append(t, t->stack->name, strlen(t->stack->name));
	t->stack->flags &= ~needsTraversal;
	/* If it is a link, set up fd for the ascent. */
	if (t->stack->flags & isDirLink) {
	t->stack->fd = open(".", O_RDONLY);
	t->openCount++;
	if (t->openCount > t->maxOpenCount)
	t->maxOpenCount = t->openCount;
	}
	if (chdir(t->stack->name) == 0) {
	t->depth++;
	t->dirname_length = t->path_length;
	t->d = opendir(".");
	} else
	tree_pop(t);
	continue;
	}

	/* We've done everything necessary for the top stack entry. */
	tree_ascend(t);
	tree_pop(t);
	}
	return (0);
	}

	/*
	* Called by the client to mark the directory just returned from
	* tree_next() as needing to be visited.
	*/
	void
	tree_descend(struct tree *t)
	{
	const struct stat *s = tree_current_lstat(t);

	if (S_ISDIR(s->st_mode)) {
	tree_add(t, t->basename);
	t->stack->flags \|= isDir;
	}

	if (S_ISLNK(s->st_mode) && S_ISDIR(tree_current_stat(t)->st_mode)) {
	tree_add(t, t->basename);
	t->stack->flags \|= isDirLink;
	}
	}

	/*
	* Get the stat() data for the entry just returned from tree_next().
	*/
	const struct stat *
	tree_current_stat(struct tree *t)
	{
	if (!(t->flags & hasStat)) {
	stat(t->basename, &t->st);
	t->flags \|= hasStat;
	}
	return (&t->st);
	}

	/*
	* Get the lstat() data for the entry just returned from tree_next().
	*/
	const struct stat *
	tree_current_lstat(struct tree *t)
	{
	if (!(t->flags & hasLstat)) {
	lstat(t->basename, &t->lst);
	t->flags \|= hasLstat;
	}
	return (&t->lst);
	}

	/*
	* Return the access path for the entry just returned from tree_next().
	*/
	const char *
	tree_current_access_path(struct tree *t)
	{
	return (t->basename);
	}

	/*
	* Return the full path for the entry just returned from tree_next().
	*/
	const char *
	tree_current_path(struct tree *t)
	{
	return (t->buff);
	}

	/*
	* Return the length of the path for the entry just returned from tree_next().
	*/
	size_t
	tree_current_pathlen(struct tree *t)
	{
	return (t->path_length);
	}

	/*
	* Return the nesting depth of the entry just returned from tree_next().
	*/
	int
	tree_current_depth(struct tree *t)
	{
	return (t->depth);
	}

	/*
	* Terminate the traversal and release any resources.
	*/
	void
	tree_close(struct tree *t)
	{
	/* Release anything remaining in the stack. */
	while (t->stack != NULL)
	tree_pop(t);
	if (t->buff)
	free(t->buff);
	/* chdir() back to where we started. */
	if (t->initialDirFd >= 0) {
	fchdir(t->initialDirFd);
	close(t->initialDirFd);
	t->initialDirFd = -1;
	}
	free(t);
	}


	#if 0
	/* Main function for testing. */
	#include <stdio.h>

	int main(int argc, char **argv)
	{
	size_t max_path_len = 0;
	int max_depth = 0;

	system("pwd");
	while (*++argv) {
	struct tree t = tree_open(argv);
	while (tree_next(t)) {
	size_t path_len = tree_current_pathlen(t);
	int depth = tree_current_depth(t);
	if (path_len > max_path_len)
	max_path_len = path_len;
	if (depth > max_depth)
	max_depth = depth;
	printf("%s\n", tree_current_path(t));
	if (S_ISDIR(tree_current_lstat(t)->st_mode))
	tree_descend(t); /* Descend into every dir. */
	}
	tree_close(t);
	printf("Max path length: %d\n", max_path_len);
	printf("Max depth: %d\n", max_depth);
	printf("Final open count: %d\n", t->openCount);
	printf("Max open count: %d\n", t->maxOpenCount);
	fflush(stdout);
	system("pwd");
	}
	return (0);
	}
	#endif