tree: new applet

Adds the tree program to list directories and files in a tree structure.

function                                             old     new   delta
tree_print                                             -     343    +343
scandir64                                              -     330    +330
scandir                                                -     330    +330
tree_main                                              -      86     +86
.rodata                                           105150  105228     +78
packed_usage                                       34511   34557     +46
alphasort64                                            -      31     +31
alphasort                                              -      31     +31
strcoll                                                -       5      +5
applet_names                                        2801    2806      +5
applet_main                                         1616    1620      +4
applet_suid                                          101     102      +1
applet_install_loc                                   202     203      +1
------------------------------------------------------------------------------
(add/remove: 11/0 grow/shrink: 6/0 up/down: 1291/0)          Total: 1291 bytes

Signed-off-by: Roger Knecht <rknecht@pm.me>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 118 insertions, 0 deletions

diff --git a/miscutils/tree.c b/miscutils/tree.c
new file mode 100644
index 000000000..8b16c5383
--- /dev/null
+++ b/miscutils/tree.c
@@ -0,0 +1,118 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Copyright (C) 2022 Roger Knecht <rknecht@pm.me>
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ */
+//config:config TREE
+//config:       bool "tree (0.6 kb)"
+//config:       default y
+//config:       help
+//config:       List files and directories in a tree structure.
+
+//applet:IF_TREE(APPLET(tree, BB_DIR_USR_BIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_TREE) += tree.o
+
+//usage:#define tree_trivial_usage NOUSAGE_STR
+//usage:#define tree_full_usage ""
+
+#include "libbb.h"
+#include "common_bufsiz.h"
+
+#define prefix_buf bb_common_bufsiz1
+
+static void tree_print(unsigned count[2], const char* directory_name, char* prefix_pos)
+{
+        struct dirent **entries;
+        int index, size;
+
+        // read directory entries
+        size = scandir(directory_name, &entries, NULL, alphasort);
+
+        if (size < 0) {
+                fputs_stdout(directory_name);
+                puts(" [error opening dir]");
+                return;
+        }
+
+        // print directory name
+        puts(directory_name);
+
+        // switch to sub directory
+        xchdir(directory_name);
+
+        // print all directory entries
+        for (index = 0; index < size;) {
+                struct dirent *dirent = entries[index++];
+
+                // filter hidden files and directories
+                if (dirent->d_name[0] != '.') {
+                        int status;
+                        struct stat statBuf;
+
+//TODO: when -l is implemented, use stat, not lstat, if -l
+                        status = lstat(dirent->d_name, &statBuf);
+
+                        if (index == size) {
+                                strcpy(prefix_pos, "└── ");
+                        } else {
+                                strcpy(prefix_pos, "├── ");
+                        }
+                        fputs_stdout(prefix_buf);
+
+                        if (status == 0 && S_ISLNK(statBuf.st_mode)) {
+                                // handle symlink
+                                char* symlink_path = xmalloc_readlink(dirent->d_name);
+                                printf("%s -> %s\n", dirent->d_name, symlink_path);
+                                free(symlink_path);
+                                count[1]++;
+                        } else if (status == 0 && S_ISDIR(statBuf.st_mode)
+                         && (prefix_pos - prefix_buf) < (COMMON_BUFSIZE - 16)
+                        ) {
+                                // handle directory
+                                char* pos;
+                                if (index == size) {
+                                        pos = stpcpy(prefix_pos, "    ");
+                                } else {
+                                        pos = stpcpy(prefix_pos, "│   ");
+                                }
+                                tree_print(count, dirent->d_name, pos);
+                                count[0]++;
+                        } else {
+                                // handle file
+                                puts(dirent->d_name);
+                                count[1]++;
+                        }
+                }
+
+                // release directory entry
+                free(dirent);
+        }
+
+        // release directory array
+        free(entries);
+
+        // switch to parent directory
+        xchdir("..");
+}
+
+int tree_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int tree_main(int argc UNUSED_PARAM, char **argv)
+{
+        unsigned count[2] = { 0, 0 };
+
+        setup_common_bufsiz();
+
+        if (!argv[1])
+                *argv-- = (char*)".";
+
+        // list directories given as command line arguments
+        while (*(++argv))
+                tree_print(count, *argv, prefix_buf);
+
+        // print statistic
+        printf("\n%u directories, %u files\n", count[0], count[1]);
+
+        return EXIT_SUCCESS;
+}