Merge pull request #566 from banglday/master

Return error code -1 when closing file descriptors < 3 (stdin, stdout, stderr)

Author: jserv

src/emulate.c

@@ -1078,11 +1078,17 @@ void rv_step(void *arg)
         assert(block->satp == rv->csr_satp);
 #endif
 
-        /* After emulating the previous block, it is determined whether the
-         * branch is taken or not. The IR array of the current block is then
-         * assigned to either the branch_taken or branch_untaken pointer of
-         * the previous block.
-         */
+#if !RV32_HAS(SYSTEM)
+        /* on exit */
+        if (unlikely(block->ir_head->pc == PRIV(rv)->exit_addr))
+            PRIV(rv)->on_exit = true;
+#endif
+
+            /* After emulating the previous block, it is determined whether the
+             * branch is taken or not. The IR array of the current block is then
+             * assigned to either the branch_taken or branch_untaken pointer of
+             * the previous block.
+             */
 
 #if RV32_HAS(BLOCK_CHAINING)
         if (prev

src/riscv.c

@@ -434,6 +434,15 @@ riscv_t *rv_create(riscv_user_t rv_attr)
     if ((end = elf_get_symbol(elf, "_end")))
         attr->break_addr = end->st_value;
 
+#if !RV32_HAS(SYSTEM)
+    /* set not exiting */
+    attr->on_exit = false;
+
+    const struct Elf32_Sym *exit;
+    if ((exit = elf_get_symbol(elf, "exit")))
+        attr->exit_addr = exit->st_value;
+#endif
+
     assert(elf_load(elf, attr->mem));
 
     /* set the entry pc */

src/riscv.h

@@ -548,6 +548,14 @@ typedef struct {
     /* the data segment break address */
     riscv_word_t break_addr;
 
+#if !RV32_HAS(SYSTEM)
+    /* the exit entry address */
+    riscv_word_t exit_addr;
+
+    /* flag to determine if the emulator exits the target program */
+    bool on_exit;
+#endif
+
     /* SBI timer */
     uint64_t timer;
 } vm_attr_t;

src/syscall.c

@@ -230,6 +230,22 @@ static void syscall_close(riscv_t *rv)
     /* _close(fd); */
     uint32_t fd = rv_get_reg(rv, rv_reg_a0);
 
+#if !RV32_HAS(SYSTEM)
+    /*
+     * The crt0 closes standard file descriptor(0, 1, 2) when
+     * the process exits. Thus, the operations by the crt0
+     * should not considered as error.
+     */
+    if (fd < 3 && !PRIV(rv)->on_exit) {
+        rv_set_reg(rv, rv_reg_a0, -1);
+        rv_log_error(
+            "Attempted to close a file descriptor < 3 (fd=%u). Operation "
+            "not supported.",
+            fd);
+        return;
+    }
+#endif
+
     if (fd >= 3) { /* lookup the file descriptor */
         map_iter_t it;
         map_find(attr->fd_map, &it, &fd);