[PATCH v1 10/11] linux-user: fix /proc/self/stat handling

[Alex Bennée]

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.

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: <address@hidden>
Reported-by: Brice Goglin <address@hidden>
Cc: Philippe_Mathieu-Daudé <address@hidden>
Signed-off-by: Alex Bennée <address@hidden>
---
 linux-user/syscall.c | 43 +++++++++++++++++++------------------------
 1 file changed, 19 insertions(+), 24 deletions(-)

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;
-- 
2.20.1