MDEV-30815 Printing a stack trace leaks file descriptors.bb-10.5-MDEV-30815

	In situations where mariadbd emits a lot of stack traces it can
        run out of file descriptors. Each time the pipe to the external
        utility addr2line is opened, those file descriptor are never closed.

4 files changed, 58 insertions, 46 deletions

diff --git a/include/my_stacktrace.h b/include/my_stacktrace.h
index 20b86f45232..924f198be3e 100644
--- a/include/my_stacktrace.h
+++ b/include/my_stacktrace.h
@@ -75,7 +75,8 @@ typedef struct {
 
 #ifdef HAVE_MY_ADDR_RESOLVE
 int my_addr_resolve(void *ptr, my_addr_loc *loc);
-const char *my_addr_resolve_init();
+const char *my_addr_resolve_init(void *ptr);
+void my_addr_resolve_close();
 #else
 #define my_addr_resolve_init()  (0)
 #define my_addr_resolve(A,B)    (1)
diff --git a/mysys/my_addr_resolve.c b/mysys/my_addr_resolve.c
index 336e419806d..e4d3fd1fff6 100644
--- a/mysys/my_addr_resolve.c
+++ b/mysys/my_addr_resolve.c
@@ -115,7 +115,7 @@ int my_addr_resolve(void *ptr, my_addr_loc *loc)
   return 1;
 }
 
-const char *my_addr_resolve_init()
+const char *my_addr_resolve_init(void *ptr)
 {
   if (!bfdh)
   {
@@ -145,6 +145,11 @@ const char *my_addr_resolve_init()
 err:
   return bfd_errmsg(bfd_get_error());
 }
+
+
+void my_addr_resolve_close()
+{
+}
 #elif defined(HAVE_LIBELF_H)
 /*
   another possible implementation.
@@ -171,19 +176,11 @@ static char addr2line_binary[1024];
 static char output[1024];
 static struct pollfd poll_fds;
 static void *addr_offset;
+Dl_info info;
+
 
 int start_addr2line_fork(const char *binary_path)
 {
-
-  if (pid > 0)
-  {
-    /* Don't leak FDs */
-    close(in[1]);
-    close(out[0]);
-    /* Don't create zombie processes. */
-    waitpid(pid, NULL, 0);
-  }
-
   if (pipe(in) < 0)
     return 1;
   if (pipe(out) < 0)
@@ -211,6 +208,16 @@ int start_addr2line_fork(const char *binary_path)
   return 0;
 }
 
+
+void my_addr_resolve_close()
+{
+  /* Don't leak FDs */
+  close(in[1]);
+  close(out[0]);
+  /* Don't create zombie processes. */
+  waitpid(pid, NULL, 0);
+}
+
 static int first_error= 0;
 
 static int addr_resolve(void *ptr, my_addr_loc *loc)
@@ -297,48 +304,50 @@ static int addr_resolve(void *ptr, my_addr_loc *loc)
 
 int my_addr_resolve(void *ptr, my_addr_loc *loc)
 {
-  Dl_info info;
+#ifndef __PIE__
+  addr_offset= (void*) info.dli_fbase;
+  if (strcmp(info.dli_fname, my_progname) == 0 &&
+      addr_resolve((void*) my_addr_resolve, loc) == 0 &&
+      strcmp(loc->func, "my_addr_resolve") == 0)
+    addr_offset= 0;
+#endif
 
+  return addr_resolve((void*) (ptr - addr_offset), loc);
+}
+
+
+const char *my_addr_resolve_init(void *ptr)
+{
   if (!dladdr(ptr, &info))
-    return 1;
+    return "dladdr() error";
 
-  if (strcmp(addr2line_binary, info.dli_fname))
-  {
-    /*
-      We use dli_fname in case the path is longer than the length of
-      our static string. We don't want to allocate anything
-      dynamically here as we are in a "crashed" state.
+  /*
+    We use dli_fname in case the path is longer than the length of
+    our static string. We don't want to allocate anything
+    dynamically here as we are in a "crashed" state.
     */
-    if (start_addr2line_fork(info.dli_fname))
+
+  if (start_addr2line_fork(info.dli_fname))
+  {
+    if (!first_error++)
     {
-      if (!first_error++)
-        fputs("Can't start addr2line\n", stderr);
-      addr2line_binary[0] = '\0';
-      return 2;
+      fputs("Can't start addr2line\n", stderr);
+      my_addr_resolve_close();
     }
-    /* Save result for future comparisons. */
-    strnmov(addr2line_binary, info.dli_fname, sizeof(addr2line_binary));
-
-    /*
-      Check if we should use info.dli_fbase as an offset or not
-      for the base program. This is depending on if the compilation is
-      done with PIE or not.
-    */
-    addr_offset= (void*) info.dli_fbase;
-#ifndef __PIE__
-    if (strcmp(info.dli_fname, my_progname) == 0 &&
-        addr_resolve((void*) my_addr_resolve, loc) == 0 &&
-	strcmp(loc->func, "my_addr_resolve") == 0)
-      addr_offset= 0;
-#endif
+    addr2line_binary[0] = '\0';
+    return "fork() error";
   }
 
-  return addr_resolve((void*) (ptr - addr_offset), loc);
-}
+  /* Save result for future comparisons. */
+  strnmov(addr2line_binary, info.dli_fname, sizeof(addr2line_binary));
 
+  /*
+    Check if we should use info.dli_fbase as an offset or not
+    for the base program. This is depending on if the compilation is
+    done with PIE or not.
+  */
+  addr_offset= (void*) info.dli_fbase;
 
-const char *my_addr_resolve_init()
-{
   return 0;
 }
 #endif
diff --git a/mysys/safemalloc.c b/mysys/safemalloc.c
index 8ccc49bbb23..ba22d629dae 100644
--- a/mysys/safemalloc.c
+++ b/mysys/safemalloc.c
@@ -225,7 +225,7 @@ static void print_stack(void **frame)
   const char *err;
   int i;
 
-  if ((err= my_addr_resolve_init()))
+  if ((err= my_addr_resolve_init(frame[0])))
   {
     fprintf(stderr, "(my_addr_resolve failure: %s)\n", err);
     return;
@@ -243,6 +243,7 @@ static void print_stack(void **frame)
       fprintf(stderr, "%s:%u", loc.file, loc.line);
   }
   fprintf(stderr, "\n");
+  my_addr_resolve_close();
 }
 #else
 #define print_stack(X)          fprintf(stderr, "???\n")
diff --git a/mysys/stacktrace.c b/mysys/stacktrace.c
index 5718b2e762d..6a9161460a0 100644
--- a/mysys/stacktrace.c
+++ b/mysys/stacktrace.c
@@ -185,7 +185,7 @@ static int print_with_addr_resolve(void **addrs, int n)
   int i;
   const char *err;
 
-  if ((err= my_addr_resolve_init()))
+  if ((err= my_addr_resolve_init(addrs[0])))
   {
     my_safe_printf_stderr("(my_addr_resolve failure: %s)\n", err);
     return 0;
@@ -200,6 +200,7 @@ static int print_with_addr_resolve(void **addrs, int n)
       my_safe_printf_stderr("%s:%u(%s)[%p]\n",
               loc.file, loc.line, loc.func, addrs[i]);
   }
+  my_addr_resolve_close();
   return 1;
 }
 #endif