Add a "fork" of musl as //fusl.

fusl/src/process/execvp.c

Index: fusl/src/process/execvp.c
diff --git a/fusl/src/process/execvp.c b/fusl/src/process/execvp.c
new file mode 100644
index 0000000000000000000000000000000000000000..3a8bbe83295ab3e76abcec90c30c3dee0378f75a
--- /dev/null
+++ b/fusl/src/process/execvp.c
@@ -0,0 +1,55 @@
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <limits.h>
+#include "libc.h"
+
+extern char **__environ;
+
+int __execvpe(const char *file, char *const argv[], char *const envp[])
+{
+	const char *p, *z, *path = getenv("PATH");
+	size_t l, k;
+	int seen_eacces = 0;
+
+	errno = ENOENT;
+	if (!*file) return -1;
+
+	if (strchr(file, '/'))
+		return execve(file, argv, envp);
+
+	if (!path) path = "/usr/local/bin:/bin:/usr/bin";
+	k = strnlen(file, NAME_MAX+1);
+	if (k > NAME_MAX) {
+		errno = ENAMETOOLONG;
+		return -1;
+	}
+	l = strnlen(path, PATH_MAX-1)+1;
+
+	for(p=path; ; p=z) {
+		char b[l+k+1];
+		z = strchr(p, ':');
+		if (!z) z = p+strlen(p);
+		if (z-p >= l) {
+			if (!*z++) break;
+			continue;
+		}
+		memcpy(b, p, z-p);
+		b[z-p] = '/';
+		memcpy(b+(z-p)+(z>p), file, k+1);
+		execve(b, argv, envp);
+		if (errno == EACCES) seen_eacces = 1;
+		else if (errno != ENOENT) return -1;
+		if (!*z++) break;
+	}
+	if (seen_eacces) errno = EACCES;
+	return -1;
+}
+
+int execvp(const char *file, char *const argv[])
+{
+	return __execvpe(file, argv, __environ);
+}
+
+weak_alias(__execvpe, execvpe);