Rewrite the exec family.
* Removes duplication.
* Removes fixed PATH_MAX limit.
* Adds basic tests.
Bug: http://b/30032507
Change-Id: I4087a9de3e53884ac3297ebafbec4e6f8a9871b6
diff --git a/libc/bionic/exec.cpp b/libc/bionic/exec.cpp
new file mode 100644
index 0000000..c1e73a5
--- /dev/null
+++ b/libc/bionic/exec.cpp
@@ -0,0 +1,163 @@
+/*-
+ * Copyright (c) 1991, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/uio.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <paths.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+extern "C" char** environ;
+
+enum ExecVariant { kIsExecL, kIsExecLE, kIsExecLP };
+
+static int __execl(const char* name, const char* argv0, ExecVariant variant, va_list ap) {
+ // Count the arguments.
+ va_list count_ap;
+ va_copy(count_ap, ap);
+ size_t n = 1;
+ while (va_arg(count_ap, char*) != nullptr) {
+ ++n;
+ }
+ va_end(count_ap);
+
+ // Construct the new argv.
+ char* argv[n + 1];
+ argv[0] = const_cast<char*>(argv0);
+ n = 1;
+ while ((argv[n] = va_arg(ap, char*)) != nullptr) {
+ ++n;
+ }
+
+ // Collect the argp too.
+ char** argp = (variant == kIsExecLE) ? va_arg(ap, char**) : environ;
+
+ va_end(ap);
+
+ return (variant == kIsExecLP) ? execvp(name, argv) : execve(name, argv, argp);
+}
+
+int execl(const char* name, const char* arg, ...) {
+ va_list ap;
+ va_start(ap, arg);
+ return __execl(name, arg, kIsExecL, ap);
+}
+
+int execle(const char* name, const char* arg, ...) {
+ va_list ap;
+ va_start(ap, arg);
+ return __execl(name, arg, kIsExecLE, ap);
+}
+
+int execlp(const char* name, const char* arg, ...) {
+ va_list ap;
+ va_start(ap, arg);
+ return __execl(name, arg, kIsExecLP, ap);
+}
+
+int execv(const char* name, char* const* argv) {
+ return execve(name, argv, environ);
+}
+
+int execvp(const char* name, char* const* argv) {
+ return execvpe(name, argv, environ);
+}
+
+static int __exec_as_script(char* buf, char* const* argv, char* const* envp) {
+ size_t arg_count = 0;
+ while (argv[arg_count] != nullptr) ++arg_count;
+
+ char* script_argv[arg_count + 2];
+ script_argv[0] = const_cast<char*>("sh");
+ script_argv[1] = buf;
+ bcopy(argv + 1, script_argv + 2, arg_count * sizeof(char*));
+ return execve(_PATH_BSHELL, script_argv, envp);
+}
+
+int execvpe(const char* name, char* const* argv, char* const* envp) {
+ // Do not allow null name.
+ if (name == nullptr || *name == '\0') {
+ errno = ENOENT;
+ return -1;
+ }
+
+ // If it's an absolute or relative path name, it's easy.
+ if (strchr(name, '/')) return execve(name, argv, envp);
+
+ // Get the path we're searching.
+ const char* path = getenv("PATH");
+ if (path == nullptr) path = _PATH_DEFPATH;
+
+ // Make a writable copy.
+ size_t len = strlen(path) + 1;
+ char writable_path[len];
+ memcpy(writable_path, path, len);
+
+ bool saw_EACCES = false;
+
+ // Try each element of $PATH in turn...
+ char* strsep_buf = writable_path;
+ const char* dir;
+ while ((dir = strsep(&strsep_buf, ":"))) {
+ // It's a shell path: double, leading and trailing colons
+ // mean the current directory.
+ if (*dir == '\0') dir = const_cast<char*>(".");
+
+ size_t dir_len = strlen(dir);
+ size_t name_len = strlen(name);
+
+ char buf[dir_len + 1 + name_len + 1];
+ mempcpy(mempcpy(mempcpy(buf, dir, dir_len), "/", 1), name, name_len + 1);
+
+ execve(buf, argv, envp);
+ switch (errno) {
+ case EISDIR:
+ case ELOOP:
+ case ENAMETOOLONG:
+ case ENOENT:
+ case ENOTDIR:
+ break;
+ case ENOEXEC:
+ return __exec_as_script(buf, argv, envp);
+ case EACCES:
+ saw_EACCES = true;
+ break;
+ default:
+ return -1;
+ }
+ }
+ if (saw_EACCES) errno = EACCES;
+ return -1;
+}