1 files changed, 99 insertions, 0 deletions
diff --git a/CC/foreign/expand_exec.c b/CC/foreign/expand_exec.c
new file mode 100644
index 0000000..a4ff311
--- /dev/null
+++ b/CC/foreign/expand_exec.c
@@ -0,0 +1,99 @@
+/*
+ * Copyright 2023 Huawei Cloud Computing Technology Co., Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* usage: ./expand_exec [VARS...] -- ARGS... */
+int main(int argc, const char *argv[]) {
+  char **outv;
+  const char **varv;
+  int i, j, varc, sep = 0, retval = 0;
+  for (i = 1; i < argc; ++i)
+    if (strcmp(argv[i], "--") == 0) {
+      sep = i;
+      break;
+    }
+  varc = sep - 1;
+  argc -= sep + 1;
+  if (sep == 0 || argc < 1)
+    return 1; /* error: missing sep or args */
+  varv = &argv[1];
+  argv = &argv[sep + 1];
+  outv = (char **)calloc((size_t)(argc + 1), sizeof(char *));
+  for (i = 0; i < argc; ++i) { /* iterate ARGS */
+    const char *arg = argv[i];
+    size_t arg_pos = 0, arg_len = strlen(arg);
+    size_t out_pos = 0, out_len = arg_len;
+    size_t str_pos = 0, str_len = 0;
+    char *out = (char *)calloc((size_t)(out_len + 1), sizeof(char));
+    for (; arg_pos < arg_len; ++arg_pos) {
+      if (strncmp(&arg[arg_pos], "$(", 2) == 0) {
+        const char *start = &arg[arg_pos + 2];
+        const char *end = strchr(start, ')');
+        if (end == NULL) {
+          retval = 2; /* error: unterminated $(VAR) expression */
+          free(out);
+          goto cleanup;
+        }
+        for (j = 0; j < varc; ++j) { /* lookup VAR */
+          const char *var = varv[j];
+          size_t len_var = strlen(var);
+          if ((size_t)(end - start) != len_var)
+            continue;
+          if (strncmp(&arg[arg_pos + 2], var, len_var) == 0) {
+            size_t val_len, out_len_new;
+            const char *val = getenv(var);
+            if (val == NULL)
+              val = "";
+            val_len = strlen(val);
+            out_len_new = out_pos + str_len + val_len;
+            if (out_len_new > out_len) {
+              out = (char *)realloc(out, out_len_new + 1);
+              out_len = out_len_new;
+            }
+            strncat(out, &arg[str_pos], str_len); /* concat preceding substr */
+            strncat(out, val, val_len);           /* concat variable value */
+            arg_pos += len_var + 2;
+            out_pos += str_len + val_len;
+            str_pos = arg_pos + 1;
+            str_len = 0;
+            break;
+          }
+        }
+        if (j != varc)
+          continue; /* success */
+      }
+      ++str_len;
+    }
+    if (str_len > 0) {
+      if (out_pos + str_len > out_len) {
+        out = (char *)realloc(out, out_pos + str_len + 1);
+      }
+      strncat(out, &arg[str_pos], str_len);
+    }
+    outv[i] = out;
+  }
+  execvp(outv[0], outv);
+  retval = 3; /* error: exec failed */
+cleanup:
+  for (i = 0; i < argc; ++i)
+    if (outv[i] != NULL)
+      free(outv[i]);
+  free(outv);
+  return retval;
+}