Add primitive du(1)

Defaults to a 512-byte blocksize.

Makefile

@@ -39,6 +39,7 @@ SRC = \
 	cut.c      \
 	date.c     \
 	dirname.c  \
+	du.c       \
 	echo.c     \
 	env.c      \
 	expand.c   \

du.1

@@ -0,0 +1,18 @@
+.TH DU 1 sbase\-VERSION
+.SH NAME
+du \- display disk usage statistics
+.SH SYNOPSIS
+.B du
+.RB [ \-a ]
+.RI [ file ...]
+.SH DESCRIPTION
+.B du
+displays the file system block usage for each
+.I file
+argument and for each directory in the file hierarchy rooted in directory argument.
+If no file is specified, the block usage of the hierarchy rooted in the current
+directory is displayed.
+.SH OPTIONS
+.TP
+.BI \-a
+Display an entry for each file in the file hierarchy.

du.c

@@ -0,0 +1,120 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <limits.h>
+#include "util.h"
+
+static long blksize = 512;
+
+static bool aflag = false;
+
+static long du(const char *);
+
+void
+usage(void)
+{
+	eprintf("usage: %s [-a] [file...]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	char *bsize;
+
+	ARGBEGIN {
+	case 'a':
+		aflag = true;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	bsize = getenv("BLOCKSIZE");
+	if (bsize)
+		blksize = estrtol(bsize, 0);
+
+	if (argc < 1) {
+		du(".");
+	} else {
+		for (; argc > 0; argc--, argv++)
+			du(argv[0]);
+	}
+	return EXIT_SUCCESS;
+}
+
+static void
+print(long n, char *path)
+{
+	printf("%lu\t%s\n", n, path);
+	free(path);
+}
+
+static char *
+push(const char *path)
+{
+	char *cwd;
+
+	cwd = agetcwd();
+	if (chdir(path) < 0)
+		eprintf("chdir: %s:", path);
+	return cwd;
+}
+
+static void
+pop(char *path)
+{
+	if (chdir(path) < 0)
+		eprintf("chdir: %s:", path);
+	free(path);
+}
+
+static long
+du(const char *path)
+{
+	DIR *dp;
+	char *cwd;
+	struct dirent *dent;
+	struct stat st;
+	long n = 0, m;
+
+	if (lstat(path, &st) < 0)
+		eprintf("stat: %s:", path);
+	n = 512 * st.st_blocks / blksize;
+
+	if (S_ISDIR(st.st_mode)) {
+		dp = opendir(path);
+		if (!dp) {
+			fprintf(stderr, "opendir: %s: %s\n", path,
+				strerror(errno));
+		} else {
+			cwd = push(path);
+			while ((dent = readdir(dp))) {
+				if (strcmp(dent->d_name, ".") == 0 ||
+				    strcmp(dent->d_name, "..") == 0)
+					continue;
+				if (lstat(dent->d_name, &st) < 0)
+					eprintf("stat: %s:", dent->d_name);
+				if (S_ISDIR(st.st_mode)) {
+					n += du(dent->d_name);
+				} else {
+					m = 512 * st.st_blocks / blksize;
+					n += m;
+					if (aflag)
+						print(m, realpath(dent->d_name, NULL));
+				}
+			}
+			pop(cwd);
+			closedir(dp);
+		}
+	}
+
+	print(n, realpath(path, NULL));
+	return n;
+}