[PATCH 02/10] linux-user/strace: add fsmount series of syscalls

[Helge Deller <deller@kernel.org>]

From: Xinhui Yang <cyan@cyano.uk>

Following the addition of fsmount(2) series of syscalls in the syscall
handler, strace support is added, with a dedicated function to print the
parameters of fsconfig(2), which contains parameters that can be
interpreted as multiple types.

Snippet of the strace dump when running `mount -t tmpfs tmpfs /media`:

18 fsopen(tmpfs,1) = 3
18 read(3,0x407fcf1c,8191) = -1 errno=61 (No data available)
18 fsconfig(3,FSCONFIG_SET_STRING,"source","tmpfs",0) = 0
18 read(3,0x407fce3c,8191) = -1 errno=61 (No data available)
18 fsconfig(3,FSCONFIG_CMD_CREATE,NULL,NULL,0) = 0
18 read(3,0x407fce3c,8191) = -1 errno=61 (No data available)
18 fsmount(3,1,0) = 4
18 read(3,0x407fce3c,8191) = -1 errno=61 (No data available)
18 statx(4,"",AT_EMPTY_PATH|AT_STATX_SYNC_AS_STAT,0x1000,0x407fee98) = 0
18 move_mount(4,,-100,/media,4) = 0
18 read(3,0x407fcfcc,8191) = -1 errno=61 (No data available)
18 close(3) = 0
18 close(4) = 0

Signed-off-by: Xinhui Yang <cyan@cyano.uk>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>
Signed-off-by: Helge Deller <deller@gmx.de>
---
 linux-user/strace.c    | 105 +++++++++++++++++++++++++++++++++++++++++
 linux-user/strace.list |  15 ++++++
 2 files changed, 120 insertions(+)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 2cbaf94c89..d861f311f6 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -4344,6 +4344,111 @@ print_statx(CPUArchState *cpu_env, const struct syscallname *name,
 }
 #endif
 
+#ifdef TARGET_NR_fsconfig
+static void
+print_fsconfig_cmd_name(int cmd)
+{
+    switch (cmd) {
+    case FSCONFIG_SET_FLAG:
+        qemu_log("%s%s", "FSCONFIG_SET_FLAG", get_comma(0));
+        break;
+    case FSCONFIG_SET_STRING:
+        qemu_log("%s%s", "FSCONFIG_SET_STRING", get_comma(0));
+        break;
+    case FSCONFIG_SET_BINARY:
+        qemu_log("%s%s", "FSCONFIG_SET_BINARY", get_comma(0));
+        break;
+    case FSCONFIG_SET_PATH:
+        qemu_log("%s%s", "FSCONFIG_SET_PATH", get_comma(0));
+        break;
+    case FSCONFIG_SET_PATH_EMPTY:
+        qemu_log("%s%s", "FSCONFIG_SET_PATH_EMPTY", get_comma(0));
+        break;
+    case FSCONFIG_SET_FD:
+        qemu_log("%s%s", "FSCONFIG_SET_FD", get_comma(0));
+        break;
+    case FSCONFIG_CMD_CREATE:
+        qemu_log("%s%s", "FSCONFIG_CMD_CREATE", get_comma(0));
+        break;
+    case FSCONFIG_CMD_RECONFIGURE:
+        qemu_log("%s%s", "FSCONFIG_CMD_RECONFIGURE", get_comma(0));
+        break;
+#ifdef FSCONFIG_CMD_CREATE_EXCL
+    case FSCONFIG_CMD_CREATE_EXCL:
+        /* Only available since Linux 6.6. */
+        qemu_log("%s%s", "FSCONFIG_CMD_CREATE_EXCL", get_comma(0));
+        break;
+#endif
+    default:
+        qemu_log("%s (%d)%s", "UNKNOWN_CMD", cmd, get_comma(0));
+        break;
+    }
+}
+
+static void
+print_fsconfig(CPUArchState *cpu_env, const struct syscallname *name,
+            abi_long arg0, abi_long arg1, abi_long arg2,
+            abi_long arg3, abi_long arg4, abi_long arg5)
+{
+    /*
+     * fsconfig(int fd, int cmd, char* key, void* value, int aux)
+     * Where:
+     * fd: file descriptor returned by fsopen().
+     * cmd: integer constant specifying a command.
+     * key: a string, can be NULL on certain commands.
+     * value: any data in a buffer, can be NULL, raw buffer or a string.
+     * aux: axillary values such as flags for FSCONFIG_SET_PATH.
+     */
+    int cmd = (int) arg1;
+    print_syscall_prologue(name);
+    print_raw_param("%d", arg0, 0);
+    print_fsconfig_cmd_name(cmd);
+    /* Process arg2 (key). */
+    switch (cmd) {
+    case FSCONFIG_SET_FLAG:
+    case FSCONFIG_SET_STRING:
+    case FSCONFIG_SET_BINARY:
+    case FSCONFIG_SET_PATH:
+    case FSCONFIG_SET_PATH_EMPTY:
+    case FSCONFIG_SET_FD:
+        print_string(arg2, 0);
+        break;
+    default:
+        print_pointer(arg2, 0);
+        break;
+    }
+    /* Process arg3 (value). */
+    switch (cmd) {
+    case FSCONFIG_SET_STRING:
+    case FSCONFIG_SET_PATH:
+    case FSCONFIG_SET_PATH_EMPTY:
+        print_string(arg3, 0);
+        break;
+    default:
+        print_pointer(arg3, 0);
+        break;
+    }
+    /*
+     * Process arg4 (aux).
+     * On FSCONFIG_SET_PATH and FSCONFIG_SET_PATH_EMPTY, aux can
+     * be either 0 or AT_FDCWD.
+     * On FSCONFIG_SET_BINARY, aux is an integer to state the length
+     * of the buffer pointed by arg3.
+     * Otherwise, it must be 0.
+     */
+    switch (cmd) {
+    case FSCONFIG_SET_PATH:
+    case FSCONFIG_SET_PATH_EMPTY:
+        print_at_dirfd(arg4, 1);
+        break;
+    default:
+        print_raw_param("%d", arg4, 1);
+        break;
+    }
+    print_syscall_epilogue(name);
+}
+#endif
+
 #ifdef TARGET_NR_ioctl
 static void
 print_ioctl(CPUArchState *cpu_env, const struct syscallname *name,
diff --git a/linux-user/strace.list b/linux-user/strace.list
index 6162a407f9..3a366b8cac 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -1722,3 +1722,18 @@
 #ifdef TARGET_NR_rseq
 { TARGET_NR_rseq, "rseq" , "%s(%p,%u,%d,%#x)", NULL, NULL },
 #endif
+#ifdef TARGET_NR_fsopen
+{ TARGET_NR_fsopen, "fsopen", "%s(%s,%d)", NULL, NULL },
+#endif
+#ifdef TARGET_NR_fsconfig
+{ TARGET_NR_fsconfig, "fsconfig", NULL, print_fsconfig, NULL },
+#endif
+#ifdef TARGET_NR_fsmount
+{ TARGET_NR_fsmount, "fsmount", "%s(%d,%d,%d)", NULL, NULL },
+#endif
+#ifdef TARGET_NR_move_mount
+{ TARGET_NR_move_mount, "move_mount", "%s(%d,%s,%d,%s,%d)", NULL, NULL },
+#endif
+#ifdef TARGET_NR_fspick
+{ TARGET_NR_fspick, "fspick", "%s(%d,%s,%d)", NULL, NULL },
+#endif
-- 
2.54.0