From 74267d94dfa52c00dd3f2937f91c406ec2eaa2d2 Mon Sep 17 00:00:00 2001
From: Toby Jaffey <toby@ringtailsoftware.co.uk>
Date: Fri, 12 Dec 2025 14:45:25 +0000
Subject: [PATCH] Handle syscall cstring argument when pointing to extram

---
 test/extram/rom/rom.c    | 19 ++++++++++++++
 test/extram/test/tests.c | 40 +++++++++++++++++++++++++++++
 uvm32/uvm32.c            | 54 ++++++++++++++++++++++++++++++----------
 3 files changed, 100 insertions(+), 13 deletions(-)

diff --git a/test/extram/rom/rom.c b/test/extram/rom/rom.c
index 9b8367e..2bc3b0f 100644
--- a/test/extram/rom/rom.c
+++ b/test/extram/rom/rom.c
@@ -42,6 +42,25 @@ void main(void) {
             uint16_t *p = (uint16_t *)UVM32_EXTRAM_BASE;
             printdec(p[7]); // short read
         } break;
+        case TEST9: {
+            uint8_t *p = (uint8_t *)UVM32_EXTRAM_BASE;
+            p[0] = 'h';
+            p[1] = 'e';
+            p[2] = 'l';
+            p[3] = 'l';
+            p[4] = 'o';
+            printbuf(p, 5); // try to print from extram (unterminated)
+        } break;
+        case TEST10: {
+            uint8_t *p = (uint8_t *)UVM32_EXTRAM_BASE;
+            p[0] = 'h';
+            p[1] = 'e';
+            p[2] = 'l';
+            p[3] = 'l';
+            p[4] = 'o';
+            p[5] = '\0';
+            println(p); // try to print from extram (terminated)
+        } break;
 
     }
 }
diff --git a/test/extram/test/tests.c b/test/extram/test/tests.c
index 21e8e9a..88e3bdd 100644
--- a/test/extram/test/tests.c
+++ b/test/extram/test/tests.c
@@ -189,4 +189,44 @@ void test_extram_short_read(void) {
     TEST_ASSERT_EQUAL(0xCDEF, uvm32_getval(&vmst, &evt, ARG0));
 }
 
+void test_extram_buf_unterminated(void) {
+    // run the vm
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
+
+    // check for picktest syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, SYSCALL_PICKTEST);
+    uvm32_setval(&vmst, &evt, RET, TEST9);
+
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(true, uvm32_extramDirty(&vmst));
+    // check for printbuf of val
+    TEST_ASSERT_EQUAL(UVM32_EVT_SYSCALL, evt.typ);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, UVM32_SYSCALL_PRINTBUF);
+    uvm32_evt_syscall_buf_t buf = uvm32_getbuf(&vmst, &evt, ARG0, ARG1);
+    TEST_ASSERT_EQUAL(5, buf.len);
+    TEST_ASSERT_EQUAL(0, memcmp(buf.ptr, "hello", 5));
+}
+
+void test_extram_buf_terminated(void) {
+    // run the vm
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(false, uvm32_extramDirty(&vmst));
+
+    // check for picktest syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, SYSCALL_PICKTEST);
+    uvm32_setval(&vmst, &evt, RET, TEST9);
+
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(true, uvm32_extramDirty(&vmst));
+    // check for printbuf of val
+    TEST_ASSERT_EQUAL(UVM32_EVT_SYSCALL, evt.typ);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, UVM32_SYSCALL_PRINTBUF);
+    const char *str = uvm32_getcstr(&vmst, &evt, ARG0);
+    TEST_ASSERT_NOT_EQUAL(NULL, str);
+    TEST_ASSERT_EQUAL(0, strcmp(str, "hello"));
+}
+
 
diff --git a/uvm32/uvm32.c b/uvm32/uvm32.c
index 122bd33..9ce2c68 100644
--- a/uvm32/uvm32.c
+++ b/uvm32/uvm32.c
@@ -104,26 +104,54 @@ bool uvm32_load(uvm32_state_t *vmst, const uint8_t *rom, int len) {
 
 // Read C-string up to terminator and return len,ptr
 bool get_safeptr_null_terminated(uvm32_state_t *vmst, uint32_t addr, uvm32_evt_syscall_buf_t *buf) {
-    uint32_t ptrstart = addr - MINIRV32_RAM_IMAGE_OFFSET;
-    uint32_t p = ptrstart;
-    if (p >= UVM32_MEMORY_SIZE) {
-        setStatusErr(vmst, UVM32_ERR_MEM_RD);
-        buf->ptr = (uint8_t *)NULL;
-        buf->len = 0;
-        return false;
-    }
-    while(vmst->memory[p] != '\0') {
-        p++;
+    if (MINIRV32_MMIO_RANGE(addr)) {
+        if (vmst->extram == NULL) {
+            return false;
+        } else {
+            
+            uint32_t ptrstart = addr - UVM32_EXTRAM_BASE;;
+            uint32_t p = ptrstart;
+            if (p >= vmst->extramLen) {
+                setStatusErr(vmst, UVM32_ERR_MEM_RD);
+                buf->ptr = (uint8_t *)NULL;
+                buf->len = 0;
+                return false;
+            }
+            while(vmst->memory[p] != '\0') {
+                p++;
+                if (p >= vmst->extramLen) {
+                    setStatusErr(vmst, UVM32_ERR_MEM_RD);
+                    buf->ptr = (uint8_t *)NULL;
+                    buf->len = 0;
+                    return false;
+                }
+            }
+            buf->ptr = (uint8_t *)&vmst->extram[ptrstart/4];    // extram is uint32_t*
+            buf->len = p - ptrstart;
+            return true;
+        }
+    } else {
+        uint32_t ptrstart = addr - MINIRV32_RAM_IMAGE_OFFSET;
+        uint32_t p = ptrstart;
         if (p >= UVM32_MEMORY_SIZE) {
             setStatusErr(vmst, UVM32_ERR_MEM_RD);
             buf->ptr = (uint8_t *)NULL;
             buf->len = 0;
             return false;
         }
+        while(vmst->memory[p] != '\0') {
+            p++;
+            if (p >= UVM32_MEMORY_SIZE) {
+                setStatusErr(vmst, UVM32_ERR_MEM_RD);
+                buf->ptr = (uint8_t *)NULL;
+                buf->len = 0;
+                return false;
+            }
+        }
+        buf->ptr = &vmst->memory[ptrstart];
+        buf->len = p - ptrstart;
+        return true;
     }
-    buf->ptr = &vmst->memory[ptrstart];
-    buf->len = p - ptrstart;
-    return true;
 }
 
 bool get_safeptr(uvm32_state_t *vmst, uint32_t addr, uint32_t len, uvm32_evt_syscall_buf_t *buf) {