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[v2,09/17] linux-user: fix /proc/self/stat handling

Message ID 20200414200631.12799-10-alex.bennee@linaro.org
State Superseded
Headers show
Series more randome fixes (user, pie, docker and gdbstub) | expand

Commit Message

Alex Bennée April 14, 2020, 8:06 p.m. UTC 
In the original bug report long files names in Guix caused
/proc/self/stat be truncated without the trailing ") " as specified in
proc manpage which says:
    (2) comm  %s
           The  filename of the executable, in parentheses.  This
           is visible whether or not the  executable  is  swapped
           out.

In the kernel this is currently done by do_task_stat calling
proc_task_name() which uses a structure limited by TASK_COMM_LEN (16).

Additionally it should only be reporting the executable name rather
than the full path. Fix both these failings while cleaning up the code
to use GString to build up the reported values. As the whole function
is cleaned up also adjust the white space to the current coding style.

Message-ID: <fb4c55fa-d539-67ee-c6c9-de8fb63c8488@inria.fr>
Reported-by: Brice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

---
 linux-user/syscall.c | 43 +++++++++++++++++++------------------------
 1 file changed, 19 insertions(+), 24 deletions(-)

-- 
2.20.1
diff mbox series

Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 6495ddc4cda..674f70e70a5 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7295,34 +7295,29 @@  static int open_self_stat(void *cpu_env, int fd)
 {
     CPUState *cpu = env_cpu((CPUArchState *)cpu_env);
     TaskState *ts = cpu->opaque;
-    abi_ulong start_stack = ts->info->start_stack;
+    g_autoptr(GString) buf = g_string_new(NULL);
     int i;
 
     for (i = 0; i < 44; i++) {
-      char buf[128];
-      int len;
-      uint64_t val = 0;
-
-      if (i == 0) {
-        /* pid */
-        val = getpid();
-        snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
-      } else if (i == 1) {
-        /* app name */
-        snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
-      } else if (i == 27) {
-        /* stack bottom */
-        val = start_stack;
-        snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
-      } else {
-        /* for the rest, there is MasterCard */
-        snprintf(buf, sizeof(buf), "0%c", i == 43 ? '\n' : ' ');
-      }
+        if (i == 0) {
+            /* pid */
+            g_string_printf(buf, FMT_pid " ", getpid());
+        } else if (i == 1) {
+            /* app name */
+            gchar *bin = g_strrstr(ts->bprm->argv[0], "/");
+            bin = bin ? bin + 1 : ts->bprm->argv[0];
+            g_string_printf(buf, "(%.15s) ", bin);
+        } else if (i == 27) {
+            /* stack bottom */
+            g_string_printf(buf, TARGET_ABI_FMT_ld " ", ts->info->start_stack);
+        } else {
+            /* for the rest, there is MasterCard */
+            g_string_printf(buf, "0%c", i == 43 ? '\n' : ' ');
+        }
 
-      len = strlen(buf);
-      if (write(fd, buf, len) != len) {
-          return -1;
-      }
+        if (write(fd, buf->str, buf->len) != buf->len) {
+            return -1;
+        }
     }
 
     return 0;