plugins: return bool from register r/w API

The qemu_plugin_{read,write} register API previously was inconsistent
with regard to its docstring (where a return value of both -1 and 0
would indicate an error) and to the memory read/write APIs, which
already return a boolean value to indicate success or failure.
Returning the number of bytes read or written is superfluous, as the
GByteArray* passed to the API functions already encodes the length.
See the linked thread for more details.

This patch moves from returning an int (number of bytes read/written) to
returning a bool from the register read/write API, bumps the plugin API
version, and adjusts plugins and tests accordingly.

Signed-off-by: Florian Hofhammer <florian.hofhammer@fhofhammer.de>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Link: https://lore.kernel.org/qemu-devel/f877dd79-1285-4752-811e-f0d430ff27fe@fhofhammer.de
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>

1 files changed, 8 insertions, 7 deletions

diff --git a/plugins/api.c b/plugins/api.c
index 478d0c8889..04ca7da7f1 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -441,27 +441,28 @@ GArray *qemu_plugin_get_registers(void)
     return create_register_handles(regs);
 }
 
-int qemu_plugin_read_register(struct qemu_plugin_register *reg, GByteArray *buf)
+bool qemu_plugin_read_register(struct qemu_plugin_register *reg,
+                               GByteArray *buf)
 {
     g_assert(current_cpu);
 
     if (qemu_plugin_get_cb_flags() == QEMU_PLUGIN_CB_NO_REGS) {
-        return -1;
+        return false;
     }
 
-    return gdb_read_register(current_cpu, buf, GPOINTER_TO_INT(reg) - 1);
+    return (gdb_read_register(current_cpu, buf, GPOINTER_TO_INT(reg) - 1) > 0);
 }
 
-int qemu_plugin_write_register(struct qemu_plugin_register *reg,
-                               GByteArray *buf)
+bool qemu_plugin_write_register(struct qemu_plugin_register *reg,
+                                GByteArray *buf)
 {
     g_assert(current_cpu);
 
     if (buf->len == 0 || qemu_plugin_get_cb_flags() != QEMU_PLUGIN_CB_RW_REGS) {
-        return -1;
+        return false;
     }
 
-    return gdb_write_register(current_cpu, buf->data, GPOINTER_TO_INT(reg) - 1);
+    return (gdb_write_register(current_cpu, buf->data, GPOINTER_TO_INT(reg) - 1) > 0);
 }
 
 bool qemu_plugin_read_memory_vaddr(uint64_t addr, GByteArray *data, size_t len)