libc: initial implementation of posix_spawn

lib/libc/exec/unistd/exec.c

@@ -0,0 +1,94 @@
+#include <errno.h>
+#include <stdarg.h>
+
+#define LD_EXTERN extern __attribute__((weak))
+LD_EXTERN int ld_execl(const char *path, const char *arg1, va_list arg);
+LD_EXTERN int ld_execlp(const char *file, const char *arg1, va_list arg);
+LD_EXTERN int ld_execle(const char *path, const char *arg1, va_list arg);
+LD_EXTERN int ld_execv(const char *path, char *const argv[]);
+LD_EXTERN int ld_execvp(const char *file, char *const argv[]);
+LD_EXTERN int ld_execvpe(
+	const char *file,
+	char *const argv[],
+	char *const envp[]);
+
+int execl(const char *path, const char *arg, ...)
+{
+	va_list arglist;
+	va_start(arglist, arg);
+	int err = ld_execl(path, arg, arglist);
+	va_end(arglist);
+
+	if (err < 0) {
+		return __set_errno(-err);
+	}
+
+	/* this shouldn't happen */
+	return __set_errno(ENOEXEC);
+}
+
+int execlp(const char *file, const char *arg, ...)
+{
+	va_list arglist;
+	va_start(arglist, arg);
+	int err = ld_execlp(file, arg, arglist);
+	va_end(arglist);
+
+	if (err < 0) {
+		return __set_errno(-err);
+	}
+
+	/* this shouldn't happen */
+	return __set_errno(ENOEXEC);
+}
+
+int execle(const char *path, const char *arg, ...)
+{
+	va_list arglist;
+	va_start(arglist, arg);
+	int err = ld_execle(path, arg, arglist);
+	va_end(arglist);
+
+	if (err < 0) {
+		return __set_errno(-err);
+	}
+
+	/* this shouldn't happen */
+	return __set_errno(ENOEXEC);
+}
+
+int execv(const char *path, char *const argv[])
+{
+	int err = ld_execv(path, argv);
+
+	if (err < 0) {
+		return __set_errno(-err);
+	}
+
+	/* this shouldn't happen */
+	return __set_errno(ENOEXEC);
+}
+
+int execvp(const char *file, char *const argv[])
+{
+	int err = ld_execvp(file, argv);
+
+	if (err < 0) {
+		return __set_errno(-err);
+	}
+
+	/* this shouldn't happen */
+	return __set_errno(ENOEXEC);
+}
+
+int execvpe(const char *file, char *const argv[], char *const envp[])
+{
+	int err = ld_execvpe(file, argv, envp);
+
+	if (err < 0) {
+		return __set_errno(-err);
+	}
+
+	/* this shouldn't happen */
+	return __set_errno(ENOEXEC);
+}