semihosting: split console_out into string and char versions

This is ostensibly to avoid the weirdness of len looking like it might
come from a guest and sometimes being used. While we are at it fix up
the error checking for the arm-linux-user implementation of the API
which got flagged up by Coverity (CID 1401700).

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

1 files changed, 28 insertions, 3 deletions

diff --git a/linux-user/arm/semihost.c b/linux-user/arm/semihost.c
index 9554102a85..a16b525eec 100644
--- a/linux-user/arm/semihost.c
+++ b/linux-user/arm/semihost.c
@@ -15,10 +15,35 @@
 #include "hw/semihosting/console.h"
 #include "qemu.h"
 
-int qemu_semihosting_console_out(CPUArchState *env, target_ulong addr, int len)
+int qemu_semihosting_console_outs(CPUArchState *env, target_ulong addr)
 {
-    void *s = lock_user_string(addr);
-    len = write(STDERR_FILENO, s, len ? len : strlen(s));
+    int len = target_strlen(addr);
+    void *s;
+    if (len < 0){
+       qemu_log_mask(LOG_GUEST_ERROR,
+                     "%s: passed inaccessible address " TARGET_FMT_lx,
+                     __func__, addr);
+       return 0;
+    }
+    s = lock_user(VERIFY_READ, addr, (long)(len + 1), 1);
+    g_assert(s);  /* target_strlen has already verified this will work */
+    len = write(STDERR_FILENO, s, len);
     unlock_user(s, addr, 0);
     return len;
 }
+
+void qemu_semihosting_console_outc(CPUArchState *env, target_ulong addr)
+{
+    char c;
+
+    if (get_user_u8(c, addr)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: passed inaccessible address " TARGET_FMT_lx,
+                      __func__, addr);
+    } else {
+        if (write(STDERR_FILENO, &c, 1) != 1) {
+            qemu_log_mask(LOG_UNIMP, "%s: unexpected write to stdout failure",
+                          __func__);
+        }
+    }
+}