libc: Propagate all errors in execl() and execvpe() + add execle().

libc/include/unistd.h

@@ -64,6 +64,9 @@ extern "C"
     /* Replace the current process with another one. On success, does not return. */
     int execl(const char* path, const char* arg, ...);
 
+    /* Replace the current process with another one. On success, does not return. */
+    int execle(const char* path, const char* arg, ...);
+
     /* Replace the current process with another one. On success, does not return. */
     int execve(const char* path, char* const* argv, char* const* envp);
 

libc/src/unistd.cpp

@@ -15,6 +15,71 @@ extern "C" long arch_invoke_syscall(long, uintptr_t, uintptr_t, uintptr_t, uintp
 
 extern char** environ;
 
+static Result<int> try_execvpe(const char* name, char* const* argv, char* const* envp)
+{
+    if (strchr(name, '/')) return execve(name, argv, envp);
+
+    char* path = getenv("PATH");
+    if (!path) path = const_cast<char*>("/bin:/sbin");
+
+    Vector<String> paths = TRY(StringView { path }.split(":"));
+
+    for (const auto& dir : paths)
+    {
+        StringBuilder sb;
+        TRY(sb.add(dir));
+        TRY(sb.add('/'));
+        TRY(sb.add(StringView { name }));
+
+        String file = TRY(sb.string());
+
+        int err = errno;
+        execve(file.chars(), argv, envp);
+
+        if (errno != ENOENT && errno != EACCES && errno != ENOEXEC) return -1;
+
+        if (errno == ENOEXEC)
+        {
+            Vector<char*> shell_argv;
+            TRY(shell_argv.try_append(const_cast<char*>("sh")));
+            char* const* arg = argv;
+            do {
+                TRY(shell_argv.try_append(*arg));
+            } while (*(arg++));
+
+            execve("/bin/sh", shell_argv.data(), envp);
+            errno = ENOEXEC;
+            return -1;
+        }
+
+        if (err == EACCES) errno = err;
+    }
+
+    return -1;
+}
+
+static Result<int> try_execl(const char* path, const char* arg, bool use_environ, va_list ap)
+{
+    Vector<char*> args;
+    TRY(args.try_append(const_cast<char*>(arg)));
+
+    while (true)
+    {
+        char* str = va_arg(ap, char*);
+        TRY(args.try_append(str));
+        if (!str) break;
+    }
+
+    if (use_environ)
+    {
+        char* const* envp = va_arg(ap, char* const*);
+
+        return execve(path, args.data(), envp);
+    }
+
+    return execv(path, args.data());
+}
+
 extern "C"
 {
     pid_t fork(void)
@@ -102,50 +167,13 @@ extern "C"
 
     int execvpe(const char* name, char* const* argv, char* const* envp)
     {
-        if (strchr(name, '/')) return execve(name, argv, envp);
+        auto rc = try_execvpe(name, argv, envp);
-
+        if (rc.has_error())
-        char* path = getenv("PATH");
-        if (!path) path = const_cast<char*>("/bin:/sbin");
-
-        Vector<String> paths;
-        bool ok = StringView { path }.split(":").try_move_value_or_error(paths, errno);
-        if (!ok) return -1;
-
-        for (const auto& dir : paths)
         {
-            // FIXME: Check for errors.
+            errno = rc.error();
-            StringBuilder sb;
+            return -1;
-            sb.add(dir);
-            sb.add('/');
-            sb.add(StringView { name });
-
-            String file;
-            ok = sb.string().try_move_value_or_error(file, errno);
-            if (!ok) return -1;
-
-            int err = errno;
-            execve(file.chars(), argv, envp);
-
-            if (errno != ENOENT && errno != EACCES && errno != ENOEXEC) return -1;
-
-            if (errno == ENOEXEC)
-            {
-                Vector<char*> shell_argv;
-                shell_argv.try_append(const_cast<char*>("sh"));
-                char* const* arg = argv;
-                do {
-                    shell_argv.try_append(*arg);
-                } while (*(arg++));
-
-                execve("/bin/sh", shell_argv.data(), envp);
-                errno = ENOEXEC;
-                return -1;
-            }
-
-            if (err == EACCES) errno = err;
         }
-
+        return rc.value();
-        return -1;
     }
 
     int execvp(const char* name, char* const* argv)
@@ -158,19 +186,33 @@ extern "C"
         va_list ap;
         va_start(ap, arg);
 
-        Vector<char*> args;
+        auto rc = try_execl(path, arg, false, ap);
-        if (args.try_append(const_cast<char*>(arg)).has_error()) return -1;
-
-        while (true)
-        {
-            char* str = va_arg(ap, char*);
-            if (args.try_append(str).has_error()) return -1;
-            if (!str) break;
-        }
 
         va_end(ap);
 
-        return execv(path, args.data());
+        if (rc.has_error())
+        {
+            errno = rc.error();
+            return -1;
+        }
+        return rc.value();
+    }
+
+    int execle(const char* path, const char* arg, ...)
+    {
+        va_list ap;
+        va_start(ap, arg);
+
+        auto rc = try_execl(path, arg, true, ap);
+
+        va_end(ap);
+
+        if (rc.has_error())
+        {
+            errno = rc.error();
+            return -1;
+        }
+        return rc.value();
     }
 
     long syscall(long num, ...)