[PATCH v4 0/6] Add strace support for printing arguments of selected syscalls

[PATCH v4 0/6] Add strace support for printing arguments of selected syscalls

[Filip Bozuta]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

This series covers strace support for printing arguments of following syscalls:

    *acct()           *lgetxattr()       *removexattr()       *lchown()
    *fsync()          *fgetxattr()       *lremovexattr()      *fallocate()
    *fdatasync()      *listxattr()       *fremovexattr()
    *listen()         *llistxattr()      *lseek()
    *getxattr()       *flistxattr()      *chown()

The implementation details for strace support is described in this series patch
commit messages.

Testing method:

    Mini test programs were written that run these syscalls for different arguments.
    Those programs were compiled (sometimes using cross-compilers) for the following
    architectures:

        * Intel 64-bit (little endian) (gcc)
        * Power pc 32-bit (big endian) (powerpc-linux-gnu-gcc)
        * Power pc 64-bit (big endian) (powerpc64-linux-gnu-gcc)
        * Mips 32-bit (little endian) (mipsel-linux-gnu-gcc)
        * Mips 64-bit (little endian) (mips64el-linux-gnuabi64-gcc)

    The corresponding native programs were executed with strace, without using
    QEMU, on Intel Core i7-4790K (x86_64) host.

    All applicable compiled programs were in turn executed with "-strace"
    through QEMU and the strace printing results obtained were the same 
    ones gotten for native execution.

v2:

    * Added patch that extends strace support by enabling argument printing
      after syscall execution
    * Added strace support for argument printing for syscalls:
      removexattr(), lremovexattr(), fremovexattr()
    * Added "print_syscall_ret_listxattr()" that prints list of extended
      attributes after execution of syscalls: listxattr(), llistxattr(),
      flistxattr()
    * Corrected formats in some printing functions
    * Moved target_offset64() function definition from "syscall.c" to
      "qemu.h"

v3:

    * Added generic function SYSCALL_RET_ERR() that checks the return value
      and prints the approppriate error message
    * Added "print_syscall_ret_llistxattr" and "print_syscall_ret_flistxattr"
      in strace.list for "llistxattr()" and "flistxattr()" that have same
      definition as "print_syscall_ret_listxattr"

v4:

    * Changed error printing from macro SYSCALL_RET_ERR() to function
      print_syscall_err()
    * Changed while loop in print_syscall_ret_listxattr() to check printed
      bytes against size of the return value


Filip Bozuta (6):
  linux-user: Extend strace support to enable argument printing after
    syscall execution
  linux-user: Add strace support for a group of syscalls
  linux-user: Add strace support for printing argument of syscalls used
    for extended attributes
  linux-user: Add strace support for printing arguments of lseek()
  linux-user: Add strace support for printing arguments of
    chown()/lchown()
  linux-user: Add strace support for printing arguments of fallocate()

 linux-user/qemu.h      |  20 ++-
 linux-user/strace.c    | 286 +++++++++++++++++++++++++++++++++++++----
 linux-user/strace.list |  37 +++---
 linux-user/syscall.c   |  18 +--
 4 files changed, 298 insertions(+), 63 deletions(-)

-- 
2.17.1

[PATCH v4 1/6] linux-user: Extend strace support to enable argument printing after syscall execution

[Filip Bozuta]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

    Structure "struct syscallname" in file "strace.c" is used for "-strace"
    to print arguments and return values of syscalls. The last field of
    this structure "result" represents the calling function that prints the
    return values. This field was extended in this patch so that this function
    takes all syscalls arguments beside the return value. In this way, it enables
    "-strace" to print arguments of syscalls that have changed after the syscall
    execution. This extension will be useful as there are many syscalls that
    return values inside their arguments (i.e. listxattr() that returns the list
    of extended attributes inside the "list" argument).

Implementation notes:

    Since there are already three existing "print_syscall_ret*" functions inside
    "strace.c" ("print_syscall_ret_addr()", "print_syscall_ret_adjtimex()",
    "print_syscall_ret_newselect()"), they were changed to have all syscall arguments
    beside the return value. This was done so that these functions don't cause build
    errors (even though syscall arguments are not used in these functions).
    There is code repetition in these functions for checking the return value
    and printing the approppriate error message (this code is also located in
    print_syscall_ret() at the end of "strace.c"). That is the reason why a
    function "syscall_print_err()" was added for this code and put inside these
    functions.

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
---
 linux-user/qemu.h    |  4 ++-
 linux-user/strace.c  | 67 ++++++++++++++++++++++++++------------------
 linux-user/syscall.c |  2 +-
 3 files changed, 43 insertions(+), 30 deletions(-)

diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index ce902f5132..8f938b8105 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -383,7 +383,9 @@ int host_to_target_waitstatus(int status);
 void print_syscall(int num,
                    abi_long arg1, abi_long arg2, abi_long arg3,
                    abi_long arg4, abi_long arg5, abi_long arg6);
-void print_syscall_ret(int num, abi_long arg1);
+void print_syscall_ret(int num, abi_long ret,
+                       abi_long arg1, abi_long arg2, abi_long arg3,
+                       abi_long arg4, abi_long arg5, abi_long arg6);
 /**
  * print_taken_signal:
  * @target_signum: target signal being taken
diff --git a/linux-user/strace.c b/linux-user/strace.c
index 0d9095c674..805fcb9fd1 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -19,7 +19,9 @@ struct syscallname {
     void (*call)(const struct syscallname *,
                  abi_long, abi_long, abi_long,
                  abi_long, abi_long, abi_long);
-    void (*result)(const struct syscallname *, abi_long);
+    void (*result)(const struct syscallname *, abi_long,
+                   abi_long, abi_long, abi_long,
+                   abi_long, abi_long, abi_long);
 };
 
 #ifdef __GNUC__
@@ -736,17 +738,29 @@ print_ipc(const struct syscallname *name,
  */
 
 static void
-print_syscall_ret_addr(const struct syscallname *name, abi_long ret)
+print_syscall_err(abi_long ret)
 {
     const char *errstr = NULL;
 
+    qemu_log(" = ");
     if (ret < 0) {
+        qemu_log("-1 errno=%d", errno);
         errstr = target_strerror(-ret);
+        if (errstr) {
+            qemu_log(" (%s)", errstr);
+        }
     }
-    if (errstr) {
-        qemu_log(" = -1 errno=%d (%s)\n", (int)-ret, errstr);
-    } else {
-        qemu_log(" = 0x" TARGET_ABI_FMT_lx "\n", ret);
+}
+
+static void
+print_syscall_ret_addr(const struct syscallname *name, abi_long ret,
+                       abi_long arg0, abi_long arg1, abi_long arg2,
+                       abi_long arg3, abi_long arg4, abi_long arg5)
+{
+    print_syscall_err(ret);
+
+    if (ret >= 0) {
+        qemu_log("0x" TARGET_ABI_FMT_lx "\n", ret);
     }
 }
 
@@ -760,7 +774,9 @@ print_syscall_ret_raw(struct syscallname *name, abi_long ret)
 
 #ifdef TARGET_NR__newselect
 static void
-print_syscall_ret_newselect(const struct syscallname *name, abi_long ret)
+print_syscall_ret_newselect(const struct syscallname *name, abi_long ret,
+                            abi_long arg0, abi_long arg1, abi_long arg2,
+                            abi_long arg3, abi_long arg4, abi_long arg5)
 {
     qemu_log(" = 0x" TARGET_ABI_FMT_lx " (", ret);
     print_fdset(newselect_arg1,newselect_arg2);
@@ -783,18 +799,13 @@ print_syscall_ret_newselect(const struct syscallname *name, abi_long ret)
 #define TARGET_TIME_ERROR    5   /* clock not synchronized */
 #ifdef TARGET_NR_adjtimex
 static void
-print_syscall_ret_adjtimex(const struct syscallname *name, abi_long ret)
+print_syscall_ret_adjtimex(const struct syscallname *name, abi_long ret,
+                           abi_long arg0, abi_long arg1, abi_long arg2,
+                           abi_long arg3, abi_long arg4, abi_long arg5)
 {
-    const char *errstr = NULL;
+    print_syscall_err(ret);
 
-    qemu_log(" = ");
-    if (ret < 0) {
-        qemu_log("-1 errno=%d", errno);
-        errstr = target_strerror(-ret);
-        if (errstr) {
-            qemu_log(" (%s)", errstr);
-        }
-    } else {
+    if (ret >= 0) {
         qemu_log(TARGET_ABI_FMT_ld, ret);
         switch (ret) {
         case TARGET_TIME_OK:
@@ -2847,25 +2858,25 @@ print_syscall(int num,
 
 
 void
-print_syscall_ret(int num, abi_long ret)
+print_syscall_ret(int num, abi_long ret,
+                  abi_long arg1, abi_long arg2, abi_long arg3,
+                  abi_long arg4, abi_long arg5, abi_long arg6)
 {
     int i;
-    const char *errstr = NULL;
 
     for(i=0;i<nsyscalls;i++)
         if( scnames[i].nr == num ) {
             if( scnames[i].result != NULL ) {
-                scnames[i].result(&scnames[i], ret);
+                scnames[i].result(&scnames[i], ret,
+                                  arg1, arg2, arg3,
+                                  arg4, arg5, arg6);
             } else {
-                if (ret < 0) {
-                    errstr = target_strerror(-ret);
-                }
-                if (errstr) {
-                    qemu_log(" = -1 errno=" TARGET_ABI_FMT_ld " (%s)\n",
-                             -ret, errstr);
-                } else {
-                    qemu_log(" = " TARGET_ABI_FMT_ld "\n", ret);
+                print_syscall_err(ret);
+
+                if (ret >= 0) {
+                    qemu_log(TARGET_ABI_FMT_ld, ret);
                 }
+                qemu_log("\n");
             }
             break;
         }
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 05f03919ff..009bb67422 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -12441,7 +12441,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
                       arg5, arg6, arg7, arg8);
 
     if (unlikely(qemu_loglevel_mask(LOG_STRACE))) {
-        print_syscall_ret(num, ret);
+        print_syscall_ret(num, ret, arg1, arg2, arg3, arg4, arg5, arg6);
     }
 
     record_syscall_return(cpu, num, ret);
-- 
2.17.1

[PATCH v4 2/6] linux-user: Add strace support for a group of syscalls

[Filip Bozuta]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

This patch implements strace argument printing functionality for following syscalls:

    *acct - switch process accounting on or off

        int acct(const char *filename)
        man page: https://www.man7.org/linux/man-pages/man2/acct.2.html

    *fsync, fdatasync - synchronize a file's in-core state with storage device

        int fsync(int fd)
        int fdatasync(int fd)
        man page: https://www.man7.org/linux/man-pages/man2/fsync.2.html

    *listen - listen for connections on a socket

        int listen(int sockfd, int backlog)
        man page: https://www.man7.org/linux/man-pages/man2/listen.2.html

Implementation notes:

    Syscall acct() takes string as its only argument and thus a separate
    print function "print_acct" 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()".
    All 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".

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/strace.c    | 13 ++++++++++++-
 linux-user/strace.list |  8 ++++----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 805fcb9fd1..6d7accaa4c 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -1364,6 +1364,18 @@ print_access(const struct syscallname *name,
 }
 #endif
 
+#ifdef TARGET_NR_acct
+static void
+print_acct(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, 1);
+    print_syscall_epilogue(name);
+}
+#endif
+
 #ifdef TARGET_NR_brk
 static void
 print_brk(const struct syscallname *name,
@@ -1628,7 +1640,6 @@ print_fcntl(const struct syscallname *name,
 #define print_fcntl64   print_fcntl
 #endif
 
-
 #ifdef TARGET_NR_futimesat
 static void
 print_futimesat(const struct syscallname *name,
diff --git a/linux-user/strace.list b/linux-user/strace.list
index d49a1e92a8..fb9799e7e6 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -13,7 +13,7 @@
 { TARGET_NR_access, "access" , NULL, print_access, NULL },
 #endif
 #ifdef TARGET_NR_acct
-{ TARGET_NR_acct, "acct" , NULL, NULL, NULL },
+{ TARGET_NR_acct, "acct" , NULL, print_acct, NULL },
 #endif
 #ifdef TARGET_NR_add_key
 { TARGET_NR_add_key, "add_key" , NULL, NULL, NULL },
@@ -215,7 +215,7 @@
 { TARGET_NR_fcntl64, "fcntl64" , NULL, print_fcntl64, NULL },
 #endif
 #ifdef TARGET_NR_fdatasync
-{ TARGET_NR_fdatasync, "fdatasync" , NULL, NULL, NULL },
+{ TARGET_NR_fdatasync, "fdatasync" , "%s(%d)", NULL, NULL },
 #endif
 #ifdef TARGET_NR_fgetxattr
 { TARGET_NR_fgetxattr, "fgetxattr" , NULL, NULL, NULL },
@@ -251,7 +251,7 @@
 { TARGET_NR_fstatfs64, "fstatfs64" , "%s(%d,%p)", NULL, NULL },
 #endif
 #ifdef TARGET_NR_fsync
-{ TARGET_NR_fsync, "fsync" , NULL, NULL, NULL },
+{ TARGET_NR_fsync, "fsync" , "%s(%d)", NULL, NULL },
 #endif
 #ifdef TARGET_NR_ftime
 { TARGET_NR_ftime, "ftime" , NULL, NULL, NULL },
@@ -492,7 +492,7 @@
 { TARGET_NR_Linux, "Linux" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_listen
-{ TARGET_NR_listen, "listen" , NULL, NULL, NULL },
+{ TARGET_NR_listen, "listen" , "%s(%d,%d)", NULL, NULL },
 #endif
 #ifdef TARGET_NR_listxattr
 { TARGET_NR_listxattr, "listxattr" , NULL, NULL, NULL },
-- 
2.17.1

[PATCH v4 3/6] linux-user: Add strace support for printing argument of syscalls used for extended attributes

[Filip Bozuta]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

This patch implements strace argument printing functionality for following syscalls:

    *getxattr, lgetxattr, fgetxattr - retrieve an extended attribute value

        ssize_t getxattr(const char *path, const char *name, void *value, size_t size)
        ssize_t lgetxattr(const char *path, const char *name, void *value, size_t size)
        ssize_t fgetxattr(int fd, const char *name, void *value, size_t size)
        man page: https://www.man7.org/linux/man-pages/man2/getxattr.2.html

    *listxattr, llistxattr, flistxattr - list extended attribute names

        ssize_t listxattr(const char *path, char *list, size_t size)
        ssize_t llistxattr(const char *path, char *list, size_t size)
        ssize_t flistxattr(int fd, char *list, size_t size)
        man page: https://www.man7.org/linux/man-pages/man2/listxattr.2.html

    *removexattr, lremovexattr, fremovexattr - remove an extended attribute

         int removexattr(const char *path, const char *name)
         int lremovexattr(const char *path, const char *name)
         int fremovexattr(int fd, const char *name)
         man page: https://www.man7.org/linux/man-pages/man2/removexattr.2.html

Implementation notes:

    All of the syscalls have strings as argument types and thus a separate
    printing function was stated in file "strace.list" for every one of them.
    All of these printing functions were defined in "strace.c" using existing
    printing functions for appropriate argument types:
       "print_string()" - for (const char*) type
       "print_pointer()" - for (char*) and (void *) type
       "print_raw_param()" for (int) and (size_t) type
    Syscalls "getxattr()" and "lgetxattr()" have the same number and type of
    arguments and thus their print functions ("print_getxattr", "print_lgetxattr")
    share a same definition. The same statement applies to syscalls "listxattr()"
    and "llistxattr()".
    Function "print_syscall_ret_listxattr()" was added to print the returned list
    of extended attributes for syscalls "print_listxattr(), print_llistxattr() and
    print_flistxattr()".

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
---
 linux-user/strace.c    | 122 +++++++++++++++++++++++++++++++++++++++++
 linux-user/strace.list |  21 ++++---
 2 files changed, 134 insertions(+), 9 deletions(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 6d7accaa4c..f76bbbc1ff 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -833,6 +833,41 @@ print_syscall_ret_adjtimex(const struct syscallname *name, abi_long ret,
 }
 #endif
 
+#if defined(TARGET_NR_listxattr) || defined(TARGET_NR_llistxattr) \
+ || defined(TARGGET_NR_flistxattr)
+static void
+print_syscall_ret_listxattr(const struct syscallname *name, abi_long ret,
+                            abi_long arg0, abi_long arg1, abi_long arg2,
+                            abi_long arg3, abi_long arg4, abi_long arg5)
+{
+    print_syscall_err(ret);
+
+    if (ret >= 0) {
+        qemu_log(TARGET_ABI_FMT_ld, ret);
+        qemu_log(" (list = ");
+        if (arg1 != 0) {
+            abi_long bts_printed = 0;
+            abi_long attr = arg1;
+            while (bts_printed < ret) {
+                if (attr != arg1) {
+                    qemu_log(",");
+                }
+                print_string(attr, 1);
+                bts_printed += target_strlen(attr) + 1;
+                attr += target_strlen(attr) + 1;
+            }
+        } else {
+            qemu_log("NULL");
+        }
+        qemu_log(")");
+    }
+
+    qemu_log("\n");
+}
+#define print_syscall_ret_llistxattr     print_syscall_ret_listxattr
+#define print_syscall_ret_flistxattr     print_syscall_ret_listxattr
+#endif
+
 UNUSED static struct flags access_flags[] = {
     FLAG_GENERIC(F_OK),
     FLAG_GENERIC(R_OK),
@@ -1640,6 +1675,93 @@ print_fcntl(const struct syscallname *name,
 #define print_fcntl64   print_fcntl
 #endif
 
+#ifdef TARGET_NR_fgetxattr
+static void
+print_fgetxattr(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);
+    print_string(arg1, 0);
+    print_pointer(arg2, 0);
+    print_raw_param(TARGET_FMT_lu, arg3, 1);
+    print_syscall_epilogue(name);
+}
+#endif
+
+#ifdef TARGET_NR_flistxattr
+static void
+print_flistxattr(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);
+    print_pointer(arg1, 0);
+    print_raw_param(TARGET_FMT_lu, arg2, 1);
+    print_syscall_epilogue(name);
+}
+#endif
+
+#if defined(TARGET_NR_getxattr) || defined(TARGET_NR_lgetxattr)
+static void
+print_getxattr(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_string(arg1, 0);
+    print_pointer(arg2, 0);
+    print_raw_param(TARGET_FMT_lu, arg3, 1);
+    print_syscall_epilogue(name);
+}
+#define print_lgetxattr     print_getxattr
+#endif
+
+#if defined(TARGET_NR_listxattr) || defined(TARGET_NR_llistxattr)
+static void
+print_listxattr(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_pointer(arg1, 0);
+    print_raw_param(TARGET_FMT_lu, arg2, 1);
+    print_syscall_epilogue(name);
+}
+#define print_llistxattr     print_listxattr
+#endif
+
+#if defined(TARGET_NR_fremovexattr)
+static void
+print_fremovexattr(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);
+    print_string(arg1, 1);
+    print_syscall_epilogue(name);
+}
+#endif
+
+#if defined(TARGET_NR_removexattr) || defined(TARGET_NR_lremovexattr)
+static void
+print_removexattr(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_string(arg1, 1);
+    print_syscall_epilogue(name);
+}
+#define print_lremovexattr     print_removexattr
+#endif
+
 #ifdef TARGET_NR_futimesat
 static void
 print_futimesat(const struct syscallname *name,
diff --git a/linux-user/strace.list b/linux-user/strace.list
index fb9799e7e6..af12b23276 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -218,13 +218,14 @@
 { TARGET_NR_fdatasync, "fdatasync" , "%s(%d)", NULL, NULL },
 #endif
 #ifdef TARGET_NR_fgetxattr
-{ TARGET_NR_fgetxattr, "fgetxattr" , NULL, NULL, NULL },
+{ TARGET_NR_fgetxattr, "fgetxattr" , NULL, print_fgetxattr, NULL },
 #endif
 #ifdef TARGET_NR_finit_module
 { TARGET_NR_finit_module, "finit_module" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_flistxattr
-{ TARGET_NR_flistxattr, "flistxattr" , NULL, NULL, NULL },
+{ TARGET_NR_flistxattr, "flistxattr" , NULL, print_flistxattr,
+                        print_syscall_ret_flistxattr},
 #endif
 #ifdef TARGET_NR_flock
 { TARGET_NR_flock, "flock" , NULL, NULL, NULL },
@@ -233,7 +234,7 @@
 { TARGET_NR_fork, "fork" , "%s()", NULL, NULL },
 #endif
 #ifdef TARGET_NR_fremovexattr
-{ TARGET_NR_fremovexattr, "fremovexattr" , NULL, NULL, NULL },
+{ TARGET_NR_fremovexattr, "fremovexattr" , NULL, print_fremovexattr, NULL },
 #endif
 #ifdef TARGET_NR_fsetxattr
 { TARGET_NR_fsetxattr, "fsetxattr" , NULL, NULL, NULL },
@@ -396,7 +397,7 @@
 { TARGET_NR_getuid32, "getuid32" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_getxattr
-{ TARGET_NR_getxattr, "getxattr" , NULL, NULL, NULL },
+{ TARGET_NR_getxattr, "getxattr" , NULL, print_getxattr, NULL },
 #endif
 #ifdef TARGET_NR_getxgid
 { TARGET_NR_getxgid, "getxgid" , NULL, NULL, NULL },
@@ -480,7 +481,7 @@
 { TARGET_NR_lchown32, "lchown32" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_lgetxattr
-{ TARGET_NR_lgetxattr, "lgetxattr" , NULL, NULL, NULL },
+{ TARGET_NR_lgetxattr, "lgetxattr" , NULL, print_lgetxattr, NULL },
 #endif
 #ifdef TARGET_NR_link
 { TARGET_NR_link, "link" , NULL, print_link, NULL },
@@ -495,10 +496,12 @@
 { TARGET_NR_listen, "listen" , "%s(%d,%d)", NULL, NULL },
 #endif
 #ifdef TARGET_NR_listxattr
-{ TARGET_NR_listxattr, "listxattr" , NULL, NULL, NULL },
+{ TARGET_NR_listxattr, "listxattr" , NULL, print_listxattr,
+                       print_syscall_ret_listxattr},
 #endif
 #ifdef TARGET_NR_llistxattr
-{ TARGET_NR_llistxattr, "llistxattr" , NULL, NULL, NULL },
+{ TARGET_NR_llistxattr, "llistxattr" , NULL, print_llistxattr,
+                        print_syscall_ret_llistxattr},
 #endif
 #ifdef TARGET_NR__llseek
 { TARGET_NR__llseek, "_llseek" , NULL, print__llseek, NULL },
@@ -510,7 +513,7 @@
 { TARGET_NR_lookup_dcookie, "lookup_dcookie" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_lremovexattr
-{ TARGET_NR_lremovexattr, "lremovexattr" , NULL, NULL, NULL },
+{ TARGET_NR_lremovexattr, "lremovexattr" , NULL, print_lremovexattr, NULL },
 #endif
 #ifdef TARGET_NR_lseek
 { TARGET_NR_lseek, "lseek" , NULL, NULL, NULL },
@@ -1116,7 +1119,7 @@
 { TARGET_NR_remap_file_pages, "remap_file_pages" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_removexattr
-{ TARGET_NR_removexattr, "removexattr" , NULL, NULL, NULL },
+{ TARGET_NR_removexattr, "removexattr" , NULL, print_removexattr, NULL },
 #endif
 #ifdef TARGET_NR_rename
 { TARGET_NR_rename, "rename" , NULL, print_rename, NULL },
-- 
2.17.1

[PATCH v4 4/6] linux-user: Add strace support for printing arguments of lseek()

[Filip Bozuta]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

This patch implements strace argument printing functionality for syscall:

    *lseek - reposition read/write file offset

         off_t lseek(int fd, off_t offset, int whence)
         man page: https://www.man7.org/linux/man-pages/man2/lseek.2.html

Implementation notes:

    The syscall's third argument "whence" has predefined values:
    "SEEK_SET","SEEK_CUR","SEEK_END","SEEK_DATA","SEEK_HOLE"
    and thus a separate printing function "print_lseek" was stated
    in file "strace.list". This function is defined in "strace.c"
    by using an existing function "print_raw_param()" to print
    the first and second argument and a switch(case) statement
    for the predefined values of the third argument.
    Values "SEEK_DATA" and "SEEK_HOLE" are defined in kernel version 3.1.
    That is the reason why case statements for these values are
    enwrapped in #ifdef directive.

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/strace.c    | 31 +++++++++++++++++++++++++++++++
 linux-user/strace.list |  2 +-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index f76bbbc1ff..db561dc4c9 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -1841,6 +1841,37 @@ print__llseek(const struct syscallname *name,
 }
 #endif
 
+#ifdef TARGET_NR_lseek
+static void
+print_lseek(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);
+    print_raw_param(TARGET_ABI_FMT_ld, arg1, 0);
+    switch (arg2) {
+    case SEEK_SET:
+        qemu_log("SEEK_SET"); break;
+    case SEEK_CUR:
+        qemu_log("SEEK_CUR"); break;
+    case SEEK_END:
+        qemu_log("SEEK_END"); break;
+#ifdef SEEK_DATA
+    case SEEK_DATA:
+        qemu_log("SEEK_DATA"); break;
+#endif
+#ifdef SEEK_HOLE
+    case SEEK_HOLE:
+        qemu_log("SEEK_HOLE"); break;
+#endif
+    default:
+        print_raw_param("%#x", arg2, 1);
+    }
+    print_syscall_epilogue(name);
+}
+#endif
+
 #if defined(TARGET_NR_socket)
 static void
 print_socket(const struct syscallname *name,
diff --git a/linux-user/strace.list b/linux-user/strace.list
index af12b23276..905a9c395c 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -516,7 +516,7 @@
 { TARGET_NR_lremovexattr, "lremovexattr" , NULL, print_lremovexattr, NULL },
 #endif
 #ifdef TARGET_NR_lseek
-{ TARGET_NR_lseek, "lseek" , NULL, NULL, NULL },
+{ TARGET_NR_lseek, "lseek" , NULL, print_lseek, NULL },
 #endif
 #ifdef TARGET_NR_lsetxattr
 { TARGET_NR_lsetxattr, "lsetxattr" , NULL, NULL, NULL },
-- 
2.17.1

[PATCH v4 5/6] linux-user: Add strace support for printing arguments of chown()/lchown()

[Filip Bozuta]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

This patch implements strace argument printing functionality for syscalls:

    *chown, lchown - change ownership of a file

        int chown(const char *pathname, uid_t owner, gid_t group)
        int lchown(const char *pathname, uid_t owner, gid_t group)
        man page: https://www.man7.org/linux/man-pages/man2/lchown.2.html

Implementation notes:

    Both syscalls use strings as arguments and thus a separate
    printing function was stated in "strace.list" for them.
    Both syscalls share the same number and types of arguments
    and thus share a same definition in file "syscall.c".
    This defintion uses existing functions "print_string()" to
    print the string argument and "print_raw_param()" to print
    other two arguments that are of basic types.

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/strace.c    | 15 +++++++++++++++
 linux-user/strace.list |  4 ++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index db561dc4c9..f44ab0ab84 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -1460,6 +1460,21 @@ print_chmod(const struct syscallname *name,
 }
 #endif
 
+#if defined(TARGET_NR_chown) || defined(TARGET_NR_lchown)
+static void
+print_chown(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("%d", arg1, 0);
+    print_raw_param("%d", arg2, 1);
+    print_syscall_epilogue(name);
+}
+#define print_lchown     print_chown
+#endif
+
 #ifdef TARGET_NR_clock_adjtime
 static void
 print_clock_adjtime(const struct syscallname *name,
diff --git a/linux-user/strace.list b/linux-user/strace.list
index 905a9c395c..633f43f490 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -71,7 +71,7 @@
 { TARGET_NR_chmod, "chmod" , NULL, print_chmod, NULL },
 #endif
 #ifdef TARGET_NR_chown
-{ TARGET_NR_chown, "chown" , NULL, NULL, NULL },
+{ TARGET_NR_chown, "chown" , NULL, print_chown, NULL },
 #endif
 #ifdef TARGET_NR_chown32
 { TARGET_NR_chown32, "chown32" , NULL, NULL, NULL },
@@ -475,7 +475,7 @@
 { TARGET_NR_kill, "kill", NULL, print_kill, NULL },
 #endif
 #ifdef TARGET_NR_lchown
-{ TARGET_NR_lchown, "lchown" , NULL, NULL, NULL },
+{ TARGET_NR_lchown, "lchown" , NULL, print_lchown, NULL },
 #endif
 #ifdef TARGET_NR_lchown32
 { TARGET_NR_lchown32, "lchown32" , NULL, NULL, NULL },
-- 
2.17.1

[PATCH v4 6/6] linux-user: Add strace support for printing arguments of fallocate()

[Filip Bozuta]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

This patch implements strace argument printing functionality for following syscall:

    *fallocate - manipulate file space

        int fallocate(int fd, int mode, off_t offset, off_t len)
        man page: https://www.man7.org/linux/man-pages/man2/fallocate.2.html

Implementation notes:

    This syscall's second argument "mode" is composed of predefined values
    which represent flags that determine the type of operation that is
    to be performed on the file space. For that reason, a printing
    function "print_fallocate" was stated in file "strace.list". This printing
    function uses an already existing function "print_flags()" to print flags of
    the "mode" argument. These flags are stated inside an array "falloc_flags"
    that contains values of type "struct flags". These values are instantiated
    using an existing macro "FLAG_GENERIC()". Most of these flags are defined
    after kernel version 3.0 which is why they are enwrapped in an #ifdef
    directive.
    The syscall's third ant fourth argument are of type "off_t" which can
    cause variations between 32/64-bit architectures. To handle this variation,
    function "target_offset64()" was copied from file "strace.c" and used in
    "print_fallocate" to print "off_t" arguments for 32-bit architectures.

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
---
 linux-user/qemu.h      | 16 ++++++++++++++++
 linux-user/strace.c    | 40 ++++++++++++++++++++++++++++++++++++++++
 linux-user/strace.list |  2 +-
 linux-user/syscall.c   | 16 ----------------
 4 files changed, 57 insertions(+), 17 deletions(-)

diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 8f938b8105..be67391ba4 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -670,6 +670,22 @@ static inline int is_error(abi_long ret)
     return (abi_ulong)ret >= (abi_ulong)(-4096);
 }
 
+#if TARGET_ABI_BITS == 32
+static inline uint64_t target_offset64(uint32_t word0, uint32_t word1)
+{
+#ifdef TARGET_WORDS_BIGENDIAN
+    return ((uint64_t)word0 << 32) | word1;
+#else
+    return ((uint64_t)word1 << 32) | word0;
+#endif
+}
+#else /* TARGET_ABI_BITS == 32 */
+static inline uint64_t target_offset64(uint64_t word0, uint64_t word1)
+{
+    return word0;
+}
+#endif /* TARGET_ABI_BITS != 32 */
+
 /**
  * preexit_cleanup: housekeeping before the guest exits
  *
diff --git a/linux-user/strace.c b/linux-user/strace.c
index f44ab0ab84..4dbed81a55 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -1143,6 +1143,26 @@ UNUSED static struct flags statx_mask[] = {
     FLAG_END,
 };
 
+UNUSED static struct flags falloc_flags[] = {
+    FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
+    FLAG_GENERIC(FALLOC_FL_PUNCH_HOLE),
+#ifdef FALLOC_FL_NO_HIDE_STALE
+    FLAG_GENERIC(FALLOC_FL_NO_HIDE_STALE),
+#endif
+#ifdef FALLOC_FL_COLLAPSE_RANGE
+    FLAG_GENERIC(FALLOC_FL_COLLAPSE_RANGE),
+#endif
+#ifdef FALLOC_FL_ZERO_RANGE
+    FLAG_GENERIC(FALLOC_FL_ZERO_RANGE),
+#endif
+#ifdef FALLOC_FL_INSERT_RANGE
+    FLAG_GENERIC(FALLOC_FL_INSERT_RANGE),
+#endif
+#ifdef FALLOC_FL_UNSHARE_RANGE
+    FLAG_GENERIC(FALLOC_FL_UNSHARE_RANGE),
+#endif
+};
+
 /*
  * print_xxx utility functions.  These are used to print syscall
  * parameters in certain format.  All of these have parameter
@@ -1560,6 +1580,26 @@ print_faccessat(const struct syscallname *name,
 }
 #endif
 
+#ifdef TARGET_NR_fallocate
+static void
+print_fallocate(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);
+    print_flags(falloc_flags, arg1, 0);
+#if TARGET_ABI_BITS == 32
+    print_raw_param("%" PRIu64, target_offset64(arg2, arg3), 0);
+    print_raw_param("%" PRIu64, target_offset64(arg4, arg5), 1);
+#else
+    print_raw_param(TARGET_ABI_FMT_ld, arg2, 0);
+    print_raw_param(TARGET_ABI_FMT_ld, arg3, 1);
+#endif
+    print_syscall_epilogue(name);
+}
+#endif
+
 #ifdef TARGET_NR_fchmodat
 static void
 print_fchmodat(const struct syscallname *name,
diff --git a/linux-user/strace.list b/linux-user/strace.list
index 633f43f490..10e3e4a814 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -182,7 +182,7 @@
 { TARGET_NR_fadvise64_64, "fadvise64_64" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_fallocate
-{ TARGET_NR_fallocate, "fallocate" , NULL, NULL, NULL },
+{ TARGET_NR_fallocate, "fallocate" , NULL, print_fallocate, NULL },
 #endif
 #ifdef TARGET_NR_fanotify_init
 { TARGET_NR_fanotify_init, "fanotify_init" , NULL, NULL, NULL },
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 009bb67422..7cc5a65b4f 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -6608,22 +6608,6 @@ void syscall_init(void)
     }
 }
 
-#if TARGET_ABI_BITS == 32
-static inline uint64_t target_offset64(uint32_t word0, uint32_t word1)
-{
-#ifdef TARGET_WORDS_BIGENDIAN
-    return ((uint64_t)word0 << 32) | word1;
-#else
-    return ((uint64_t)word1 << 32) | word0;
-#endif
-}
-#else /* TARGET_ABI_BITS == 32 */
-static inline uint64_t target_offset64(uint64_t word0, uint64_t word1)
-{
-    return word0;
-}
-#endif /* TARGET_ABI_BITS != 32 */
-
 #ifdef TARGET_NR_truncate64
 static inline abi_long target_truncate64(void *cpu_env, const char *arg1,
                                          abi_long arg2,
-- 
2.17.1

Re: [PATCH v4 0/6] Add strace support for printing arguments of selected syscalls

[no-reply]

Patchew URL: https://patchew.org/QEMU/20200616103927.20222-1-filip.bozuta@syrmia.com/



Hi,

This series seems to have some coding style problems. See output below for
more information:

Subject: [PATCH v4 0/6] Add strace support for printing arguments of selected syscalls
Type: series
Message-id: 20200616103927.20222-1-filip.bozuta@syrmia.com

=== TEST SCRIPT BEGIN ===
#!/bin/bash
git rev-parse base > /dev/null || exit 0
git config --local diff.renamelimit 0
git config --local diff.renames True
git config --local diff.algorithm histogram
./scripts/checkpatch.pl --mailback base..
=== TEST SCRIPT END ===

Switched to a new branch 'test'
756604e linux-user: Add strace support for printing arguments of fallocate()
25680d5 linux-user: Add strace support for printing arguments of chown()/lchown()
cadd65d linux-user: Add strace support for printing arguments of lseek()
eb40627 linux-user: Add strace support for printing argument of syscalls used for extended attributes
47226e8 linux-user: Add strace support for a group of syscalls
3e531d0 linux-user: Extend strace support to enable argument printing after syscall execution

=== OUTPUT BEGIN ===
1/6 Checking commit 3e531d0470d2 (linux-user: Extend strace support to enable argument printing after syscall execution)
2/6 Checking commit 47226e8674a7 (linux-user: Add strace support for a group of syscalls)
3/6 Checking commit eb40627b1196 (linux-user: Add strace support for printing argument of syscalls used for extended attributes)
4/6 Checking commit cadd65d9f866 (linux-user: Add strace support for printing arguments of lseek())
5/6 Checking commit 25680d5e1b01 (linux-user: Add strace support for printing arguments of chown()/lchown())
6/6 Checking commit 756604eefe06 (linux-user: Add strace support for printing arguments of fallocate())
ERROR: storage class should be at the beginning of the declaration
#69: FILE: linux-user/strace.c:1146:
+UNUSED static struct flags falloc_flags[] = {

total: 1 errors, 0 warnings, 104 lines checked

Patch 6/6 has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

=== OUTPUT END ===

Test command exited with code: 1


The full log is available at
http://patchew.org/logs/20200616103927.20222-1-filip.bozuta@syrmia.com/testing.checkpatch/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com

Re: [PATCH v4 1/6] linux-user: Extend strace support to enable argument printing after syscall execution

[Laurent Vivier]

Le 16/06/2020 à 12:39, Filip Bozuta a écrit :
> From: Filip Bozuta <Filip.Bozuta@syrmia.com>
> 
>     Structure "struct syscallname" in file "strace.c" is used for "-strace"
>     to print arguments and return values of syscalls. The last field of
>     this structure "result" represents the calling function that prints the
>     return values. This field was extended in this patch so that this function
>     takes all syscalls arguments beside the return value. In this way, it enables
>     "-strace" to print arguments of syscalls that have changed after the syscall
>     execution. This extension will be useful as there are many syscalls that
>     return values inside their arguments (i.e. listxattr() that returns the list
>     of extended attributes inside the "list" argument).
> 
> Implementation notes:
> 
>     Since there are already three existing "print_syscall_ret*" functions inside
>     "strace.c" ("print_syscall_ret_addr()", "print_syscall_ret_adjtimex()",
>     "print_syscall_ret_newselect()"), they were changed to have all syscall arguments
>     beside the return value. This was done so that these functions don't cause build
>     errors (even though syscall arguments are not used in these functions).
>     There is code repetition in these functions for checking the return value
>     and printing the approppriate error message (this code is also located in
>     print_syscall_ret() at the end of "strace.c"). That is the reason why a
>     function "syscall_print_err()" was added for this code and put inside these
>     functions.
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
>  linux-user/qemu.h    |  4 ++-
>  linux-user/strace.c  | 67 ++++++++++++++++++++++++++------------------
>  linux-user/syscall.c |  2 +-
>  3 files changed, 43 insertions(+), 30 deletions(-)
> 
> diff --git a/linux-user/qemu.h b/linux-user/qemu.h
> index ce902f5132..8f938b8105 100644
> --- a/linux-user/qemu.h
> +++ b/linux-user/qemu.h
> @@ -383,7 +383,9 @@ int host_to_target_waitstatus(int status);
>  void print_syscall(int num,
>                     abi_long arg1, abi_long arg2, abi_long arg3,
>                     abi_long arg4, abi_long arg5, abi_long arg6);
> -void print_syscall_ret(int num, abi_long arg1);
> +void print_syscall_ret(int num, abi_long ret,
> +                       abi_long arg1, abi_long arg2, abi_long arg3,
> +                       abi_long arg4, abi_long arg5, abi_long arg6);
>  /**
>   * print_taken_signal:
>   * @target_signum: target signal being taken
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 0d9095c674..805fcb9fd1 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -19,7 +19,9 @@ struct syscallname {
>      void (*call)(const struct syscallname *,
>                   abi_long, abi_long, abi_long,
>                   abi_long, abi_long, abi_long);
> -    void (*result)(const struct syscallname *, abi_long);
> +    void (*result)(const struct syscallname *, abi_long,
> +                   abi_long, abi_long, abi_long,
> +                   abi_long, abi_long, abi_long);
>  };
>  
>  #ifdef __GNUC__
> @@ -736,17 +738,29 @@ print_ipc(const struct syscallname *name,
>   */
>  
>  static void
> -print_syscall_ret_addr(const struct syscallname *name, abi_long ret)
> +print_syscall_err(abi_long ret)
>  {
>      const char *errstr = NULL;
>  
> +    qemu_log(" = ");
>      if (ret < 0) {
> +        qemu_log("-1 errno=%d", errno);
>          errstr = target_strerror(-ret);
> +        if (errstr) {
> +            qemu_log(" (%s)", errstr);
> +        }
>      }
> -    if (errstr) {
> -        qemu_log(" = -1 errno=%d (%s)\n", (int)-ret, errstr);
> -    } else {
> -        qemu_log(" = 0x" TARGET_ABI_FMT_lx "\n", ret);
> +}
> +
> +static void
> +print_syscall_ret_addr(const struct syscallname *name, abi_long ret,
> +                       abi_long arg0, abi_long arg1, abi_long arg2,
> +                       abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_err(ret);
> +
> +    if (ret >= 0) {
> +        qemu_log("0x" TARGET_ABI_FMT_lx "\n", ret);
>      }
>  }
>  
> @@ -760,7 +774,9 @@ print_syscall_ret_raw(struct syscallname *name, abi_long ret)
>  
>  #ifdef TARGET_NR__newselect
>  static void
> -print_syscall_ret_newselect(const struct syscallname *name, abi_long ret)
> +print_syscall_ret_newselect(const struct syscallname *name, abi_long ret,
> +                            abi_long arg0, abi_long arg1, abi_long arg2,
> +                            abi_long arg3, abi_long arg4, abi_long arg5)
>  {
>      qemu_log(" = 0x" TARGET_ABI_FMT_lx " (", ret);
>      print_fdset(newselect_arg1,newselect_arg2);

print_syscall_ret_newselect() was already displaying arg1...arg5 by
storing them before the call in some global variables.
Now, you can remove these global variables and use the value from the
function parameters.

Thanks,
Laurent

Re: [PATCH v4 6/6] linux-user: Add strace support for printing arguments of fallocate()

[Laurent Vivier]

Le 16/06/2020 à 12:39, Filip Bozuta a écrit :
> From: Filip Bozuta <Filip.Bozuta@syrmia.com>
> 
> This patch implements strace argument printing functionality for following syscall:
> 
>     *fallocate - manipulate file space
> 
>         int fallocate(int fd, int mode, off_t offset, off_t len)
>         man page: https://www.man7.org/linux/man-pages/man2/fallocate.2.html
> 
> Implementation notes:
> 
>     This syscall's second argument "mode" is composed of predefined values
>     which represent flags that determine the type of operation that is
>     to be performed on the file space. For that reason, a printing
>     function "print_fallocate" was stated in file "strace.list". This printing
>     function uses an already existing function "print_flags()" to print flags of
>     the "mode" argument. These flags are stated inside an array "falloc_flags"
>     that contains values of type "struct flags". These values are instantiated
>     using an existing macro "FLAG_GENERIC()". Most of these flags are defined
>     after kernel version 3.0 which is why they are enwrapped in an #ifdef
>     directive.
>     The syscall's third ant fourth argument are of type "off_t" which can
>     cause variations between 32/64-bit architectures. To handle this variation,
>     function "target_offset64()" was copied from file "strace.c" and used in
>     "print_fallocate" to print "off_t" arguments for 32-bit architectures.
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
>  linux-user/qemu.h      | 16 ++++++++++++++++
>  linux-user/strace.c    | 40 ++++++++++++++++++++++++++++++++++++++++
>  linux-user/strace.list |  2 +-
>  linux-user/syscall.c   | 16 ----------------
>  4 files changed, 57 insertions(+), 17 deletions(-)
> 

Match v2, so

Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Re: [PATCH v4 3/6] linux-user: Add strace support for printing argument of syscalls used for extended attributes

[Laurent Vivier]

Le 16/06/2020 à 12:39, Filip Bozuta a écrit :
> From: Filip Bozuta <Filip.Bozuta@syrmia.com>
> 
> This patch implements strace argument printing functionality for following syscalls:
> 
>     *getxattr, lgetxattr, fgetxattr - retrieve an extended attribute value
> 
>         ssize_t getxattr(const char *path, const char *name, void *value, size_t size)
>         ssize_t lgetxattr(const char *path, const char *name, void *value, size_t size)
>         ssize_t fgetxattr(int fd, const char *name, void *value, size_t size)
>         man page: https://www.man7.org/linux/man-pages/man2/getxattr.2.html
> 
>     *listxattr, llistxattr, flistxattr - list extended attribute names
> 
>         ssize_t listxattr(const char *path, char *list, size_t size)
>         ssize_t llistxattr(const char *path, char *list, size_t size)
>         ssize_t flistxattr(int fd, char *list, size_t size)
>         man page: https://www.man7.org/linux/man-pages/man2/listxattr.2.html
> 
>     *removexattr, lremovexattr, fremovexattr - remove an extended attribute
> 
>          int removexattr(const char *path, const char *name)
>          int lremovexattr(const char *path, const char *name)
>          int fremovexattr(int fd, const char *name)
>          man page: https://www.man7.org/linux/man-pages/man2/removexattr.2.html
> 
> Implementation notes:
> 
>     All of the syscalls have strings as argument types and thus a separate
>     printing function was stated in file "strace.list" for every one of them.
>     All of these printing functions were defined in "strace.c" using existing
>     printing functions for appropriate argument types:
>        "print_string()" - for (const char*) type
>        "print_pointer()" - for (char*) and (void *) type
>        "print_raw_param()" for (int) and (size_t) type
>     Syscalls "getxattr()" and "lgetxattr()" have the same number and type of
>     arguments and thus their print functions ("print_getxattr", "print_lgetxattr")
>     share a same definition. The same statement applies to syscalls "listxattr()"
>     and "llistxattr()".
>     Function "print_syscall_ret_listxattr()" was added to print the returned list
>     of extended attributes for syscalls "print_listxattr(), print_llistxattr() and
>     print_flistxattr()".
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
>  linux-user/strace.c    | 122 +++++++++++++++++++++++++++++++++++++++++
>  linux-user/strace.list |  21 ++++---
>  2 files changed, 134 insertions(+), 9 deletions(-)
> 
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 6d7accaa4c..f76bbbc1ff 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -833,6 +833,41 @@ print_syscall_ret_adjtimex(const struct syscallname *name, abi_long ret,
>  }
>  #endif
>  
> +#if defined(TARGET_NR_listxattr) || defined(TARGET_NR_llistxattr) \
> + || defined(TARGGET_NR_flistxattr)
> +static void
> +print_syscall_ret_listxattr(const struct syscallname *name, abi_long ret,
> +                            abi_long arg0, abi_long arg1, abi_long arg2,
> +                            abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_err(ret);
> +
> +    if (ret >= 0) {
> +        qemu_log(TARGET_ABI_FMT_ld, ret);
> +        qemu_log(" (list = ");
> +        if (arg1 != 0) {
> +            abi_long bts_printed = 0;
> +            abi_long attr = arg1;
> +            while (bts_printed < ret) {

I don't think you need a new variable, you can do

               while (ret) {

> +                if (attr != arg1) {
> +                    qemu_log(",");
> +                }
> +                print_string(attr, 1);
> +                bts_printed += target_strlen(attr) + 1;

and
                   ret -= target_strlen(attr) + 1;

> +                attr += target_strlen(attr) + 1;
> +            }
> +        } else {
> +            qemu_log("NULL");
> +        }
> +        qemu_log(")");
> +    }
> +
> +    qemu_log("\n");
> +}
> +#define print_syscall_ret_llistxattr     print_syscall_ret_listxattr
> +#define print_syscall_ret_flistxattr     print_syscall_ret_listxattr
> +#endif
> +
>  UNUSED static struct flags access_flags[] = {
>      FLAG_GENERIC(F_OK),
>      FLAG_GENERIC(R_OK),

Thanks,
Laurent