From 3d18255f314091023f47d377de93c6715908d1c7 Mon Sep 17 00:00:00 2001
From: Louis Burda <quent.burda@gmail.com>
Date: Sat, 22 Jul 2023 23:03:29 +0200
Subject: Add initial version

---
 .gitignore |  1 +
 Makefile   | 21 ++++++++++++++++
 wd.c       | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 104 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 wd.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..20b605e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+wd
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..73edfbc
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,21 @@
+PREFIX ?= /usr/local
+BINDIR ?= /bin
+
+CFLAGS = -Wunused-variable -Wunused-function -Wconversion
+
+all: wd
+
+clean:
+	rm -f wd
+
+wd: wd.c
+	$(CC) -o $@ $^ $(CFLAGS) $(LDFLAGS)
+
+install:
+	install -d "$(DESTDIR)$(PREFIX)$(BINDIR)"
+	install -m755 wd -t "$(DESTDIR)$(PREFIX)$(BINDIR)"
+
+uninstall:
+	rm -f "$(DESTDIR)$(PREFIX)$(BINDIR)/wd"
+
+.PHONY: all install uninstall
diff --git a/wd.c b/wd.c
new file mode 100644
index 0000000..3fb2b46
--- /dev/null
+++ b/wd.c
@@ -0,0 +1,82 @@
+#include <linux/limits.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+static void
+die(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fprintf(stderr, "wd: ");
+	vfprintf(stderr, fmt, ap);
+	if (*fmt && fmt[strlen(fmt)-1] == ':') {
+		fputc(' ', stderr);
+		perror(NULL);
+	} else {
+		fputc('\n', stderr);
+	}
+	va_end(ap);
+
+	exit(1);
+}
+
+static void
+findbin(char *dst, const char *name)
+{
+	char *env, *tok;
+	struct dirent *ent;
+	int len;
+	DIR *d;
+
+	env = getenv("PATH");
+	if (!env) die("PATH not set");
+
+	env = strdup(env);
+	if (!env) die("strdup:");
+
+	for (tok = strtok(env, ":"); tok; tok = strtok(NULL, ":")) {
+		if (!*tok) continue;
+		d = opendir(tok);
+		if (!d) continue;
+		while ((ent = readdir(d))) {
+			if (!strcmp(ent->d_name, name)) {
+				closedir(d);
+				free(env);
+				len = snprintf(dst, PATH_MAX,
+					"%s/%s", tok, ent->d_name);
+				if (len > PATH_MAX) abort();
+				return;
+			}
+		}
+		closedir(d);
+	}
+
+	free(env);
+
+	die("'%s' not found", name);
+}
+
+int
+main(int argc, char **argv)
+{
+	char binpath[PATH_MAX];
+
+	if (argc < 3) {
+		fprintf(stderr, "Usage: wd DIR CMD..\n");
+		return 1;
+	}
+
+	if (chdir(argv[1])) die("chdir:");
+
+	findbin(binpath, argv[2]);
+
+	execv(binpath, argv + 2);
+
+	die("execv:");
+}
-- 
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