gdbstub/user-target: Convert host errno to GDB File-I/O errno

Use host_to_gdb_errno to convert host-supplied errnos to their GDB
File-I/O remote protocol values, and use them in F reply packets.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2751
Reported-by: Dominik 'Disconnect3d' Czarnota <dominik.b.czarnota@gmail.com>
Signed-off-by: Yodel Eldar <yodel.eldar@yodel.dev>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20260116014612.226183-4-yodel.eldar@yodel.dev>
Message-ID: <20260203115201.2387721-10-alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

gdbstub/user-target.c

@@ -10,6 +10,7 @@
 #include "qemu/osdep.h"
 #include "exec/gdbstub.h"
 #include "gdbstub/commands.h"
+#include "gdbstub/syscalls.h"
 #include "qemu.h"
 #include "internals.h"
 #ifdef CONFIG_LINUX
@@ -315,7 +316,8 @@ void gdb_handle_v_file_open(GArray *params, void *user_ctx)
     int fd = open(filename, flags, mode);
 #endif
     if (fd < 0) {
-        g_string_printf(gdbserver_state.str_buf, "F-1,%x", errno);
+        int gdb_errno = host_to_gdb_errno(errno);
+        g_string_printf(gdbserver_state.str_buf, "F-1,%x", gdb_errno);
     } else {
         g_string_printf(gdbserver_state.str_buf, "F%x", fd);
     }
@@ -327,7 +329,8 @@ void gdb_handle_v_file_close(GArray *params, void *user_ctx)
     int fd = gdb_get_cmd_param(params, 0)->val_ul;
 
     if (close(fd) == -1) {
-        g_string_printf(gdbserver_state.str_buf, "F-1,%x", errno);
+        int gdb_errno = host_to_gdb_errno(errno);
+        g_string_printf(gdbserver_state.str_buf, "F-1,%x", gdb_errno);
         gdb_put_strbuf();
         return;
     }
@@ -350,7 +353,8 @@ void gdb_handle_v_file_pread(GArray *params, void *user_ctx)
 
     ssize_t n = pread(fd, buf, bufsiz, offset);
     if (n < 0) {
-        g_string_printf(gdbserver_state.str_buf, "F-1,%x", errno);
+        int gdb_errno = host_to_gdb_errno(errno);
+        g_string_printf(gdbserver_state.str_buf, "F-1,%x", gdb_errno);
         gdb_put_strbuf();
         return;
     }
@@ -373,7 +377,8 @@ void gdb_handle_v_file_readlink(GArray *params, void *user_ctx)
     ssize_t n = readlink(filename, buf, BUFSIZ);
 #endif
     if (n < 0) {
-        g_string_printf(gdbserver_state.str_buf, "F-1,%x", errno);
+        int gdb_errno = host_to_gdb_errno(errno);
+        g_string_printf(gdbserver_state.str_buf, "F-1,%x", gdb_errno);
         gdb_put_strbuf();
         return;
     }