linux-user: Add strace support for printing arguments of truncate()/ftruncate() and getsid()

This patch implements strace argument printing functionality for following syscalls:

    * truncate, ftruncate - truncate a file to a specified length

        int truncate/truncate64(const char *path, off_t length)
        int ftruncate/ftruncate64(int fd, off_t length)
        man page: https://man7.org/linux/man-pages/man2/truncate.2.html

    * getsid - get session ID

        pid_t getsid(pid_t pid)
        man page: https://man7.org/linux/man-pages/man2/getsid.2.html

Implementation notes:

    Syscalls truncate/truncate64 take string argument types and thus a
    separate print function "print_truncate/print_truncate64" is stated in
    file "strace.list". This function is defined and implemented in "strace.c"
    by using an existing function used to print string arguments: "print_string()".
    For syscall ftruncate64, a separate printing function was also stated in
    "strace.c" as it requires a special kind of handling.
    The other syscalls have only primitive argument types, so the rest of the
    implementation was handled by stating an appropriate printing format in file
    "strace.list".
    Function "regpairs_aligned()" was cut & pasted from "syscall.c" to "qemu.h"
    as it is used by functions "print_truncate64()" and "print_ftruncate64()"
    to print the offset arguments of "truncate64()" and "ftruncate64()".

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200811164553.27713-3-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 47 insertions, 0 deletions

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 2dcc15496a..31c7be24eb 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -1962,6 +1962,53 @@ print_lseek(void *cpu_env, const struct syscallname *name,
 }
 #endif
 
+#ifdef TARGET_NR_truncate
+static void
+print_truncate(void *cpu_env, const struct syscallname *name,
+               abi_long arg0, abi_long arg1, abi_long arg2,
+               abi_long arg3, abi_long arg4, abi_long arg5)
+{
+    print_syscall_prologue(name);
+    print_string(arg0, 0);
+    print_raw_param(TARGET_ABI_FMT_ld, arg1, 1);
+    print_syscall_epilogue(name);
+}
+#endif
+
+#ifdef TARGET_NR_truncate64
+static void
+print_truncate64(void *cpu_env, const struct syscallname *name,
+                 abi_long arg0, abi_long arg1, abi_long arg2,
+                 abi_long arg3, abi_long arg4, abi_long arg5)
+{
+    print_syscall_prologue(name);
+    print_string(arg0, 0);
+    if (regpairs_aligned(cpu_env, TARGET_NR_truncate64)) {
+        arg1 = arg2;
+        arg2 = arg3;
+    }
+    print_raw_param("%" PRIu64, target_offset64(arg1, arg2), 1);
+    print_syscall_epilogue(name);
+}
+#endif
+
+#ifdef TARGET_NR_ftruncate64
+static void
+print_ftruncate64(void *cpu_env, const struct syscallname *name,
+                  abi_long arg0, abi_long arg1, abi_long arg2,
+                  abi_long arg3, abi_long arg4, abi_long arg5)
+{
+    print_syscall_prologue(name);
+    print_raw_param("%d", arg0, 0);
+    if (regpairs_aligned(cpu_env, TARGET_NR_ftruncate64)) {
+        arg1 = arg2;
+        arg2 = arg3;
+    }
+    print_raw_param("%" PRIu64, target_offset64(arg1, arg2), 1);
+    print_syscall_epilogue(name);
+}
+#endif
+
 #if defined(TARGET_NR_socket)
 static void
 print_socket(void *cpu_env, const struct syscallname *name,