[binutils-gdb] gdbserver: move main_lm handling into caller

[binutils-gdb] gdbserver: move main_lm handling into caller

[Markus Metzger]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ad10f44e568806c2399f9405f4588f3e27f7d9ae

commit ad10f44e568806c2399f9405f4588f3e27f7d9ae
Author: Markus Metzger <markus.t.metzger@intel.com>
Date:   Tue Mar 15 17:41:13 2022 +0100

    gdbserver: move main_lm handling into caller
    
    When listing SVR4 shared libraries, special care has to be taken about the
    first library in the default namespace as that refers to the main
    executable.  The load map address of this main executable is provided in
    an attribute of the library-list-svr4 element.
    
    Move that code from where we enumerate libraries inside a single namespace
    to where we generate the rest of the library-list-svr4 element.  This
    allows us to complete the library-list-svr4 element inside one function.
    
    There should be no functional change.

Diff:
---
 gdbserver/linux-low.cc | 96 +++++++++++++++++++++++++-------------------------
 1 file changed, 48 insertions(+), 48 deletions(-)

diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index af3c4b35cd9..e83ccceed83 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -6490,8 +6490,7 @@ static const link_map_offsets lmo_64bit_offsets =
 
 static void
 read_link_map (std::string &document, CORE_ADDR lm_addr, CORE_ADDR lm_prev,
-	       int ptr_size, const link_map_offsets *lmo, bool ignore_first,
-	       int &header_done)
+	       int ptr_size, const link_map_offsets *lmo)
 {
   CORE_ADDR l_name, l_addr, l_ld, l_next, l_prev;
 
@@ -6516,37 +6515,19 @@ read_link_map (std::string &document, CORE_ADDR lm_addr, CORE_ADDR lm_prev,
 	  break;
 	}
 
-      /* Ignore the first entry even if it has valid name as the first entry
-	 corresponds to the main executable.  The first entry should not be
-	 skipped if the dynamic loader was loaded late by a static executable
-	 (see solib-svr4.c parameter ignore_first).  But in such case the main
-	 executable does not have PT_DYNAMIC present and this function already
-	 exited above due to failed get_r_debug.  */
-      if (ignore_first && lm_prev == 0)
-	string_appendf (document, " main-lm=\"0x%s\"", paddress (lm_addr));
-      else
+      /* Not checking for error because reading may stop before we've got
+	 PATH_MAX worth of characters.  */
+      libname[0] = '\0';
+      linux_read_memory (l_name, libname, sizeof (libname) - 1);
+      libname[sizeof (libname) - 1] = '\0';
+      if (libname[0] != '\0')
 	{
-	  /* Not checking for error because reading may stop before
-	     we've got PATH_MAX worth of characters.  */
-	  libname[0] = '\0';
-	  linux_read_memory (l_name, libname, sizeof (libname) - 1);
-	  libname[sizeof (libname) - 1] = '\0';
-	  if (libname[0] != '\0')
-	    {
-	      if (!header_done)
-		{
-		  /* Terminate `<library-list-svr4'.  */
-		  document += '>';
-		  header_done = 1;
-		}
-
-	      string_appendf (document, "<library name=\"");
-	      xml_escape_text_append (&document, (char *) libname);
-	      string_appendf (document, "\" lm=\"0x%s\" l_addr=\"0x%s\" "
-			      "l_ld=\"0x%s\"/>",
-			      paddress (lm_addr), paddress (l_addr),
-			      paddress (l_ld));
-	    }
+	  string_appendf (document, "<library name=\"");
+	  xml_escape_text_append (&document, (char *) libname);
+	  string_appendf (document, "\" lm=\"0x%s\" l_addr=\"0x%s\" "
+			  "l_ld=\"0x%s\"/>",
+			  paddress (lm_addr), paddress (l_addr),
+			  paddress (l_ld));
 	}
 
       lm_prev = lm_addr;
@@ -6567,7 +6548,6 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
   int pid, is_elf64;
   unsigned int machine;
   CORE_ADDR lm_addr = 0, lm_prev = 0;
-  int header_done = 0;
 
   if (writebuf != NULL)
     return -2;
@@ -6624,8 +6604,10 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
 
      Otherwise, start with R_DEBUG and traverse all namespaces we find.  */
   if (lm_addr != 0)
-    read_link_map (document, lm_addr, lm_prev, ptr_size, lmo, false,
-		   header_done);
+    {
+      document += ">";
+      read_link_map (document, lm_addr, lm_prev, ptr_size, lmo);
+    }
   else
     {
       if (lm_prev != 0)
@@ -6641,7 +6623,10 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
       if (r_debug == (CORE_ADDR) -1)
 	return -1;
 
-      bool ignore_first = true;
+      /* Terminate the header if we end up with an empty list.  */
+      if (r_debug == 0)
+	document += ">";
+
       while (r_debug != 0)
 	{
 	  int r_version = 0;
@@ -6668,15 +6653,36 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
 	      break;
 	    }
 
-	  read_link_map (document, lm_addr, 0, ptr_size, lmo,
-			 ignore_first, header_done);
+	  /* We read the entire namespace.  */
+	  lm_prev = 0;
+
+	  /* The first entry corresponds to the main executable unless the
+	     dynamic loader was loaded late by a static executable.  But
+	     in such case the main executable does not have PT_DYNAMIC
+	     present and we would not have gotten here.  */
+	  if (r_debug == priv->r_debug)
+	    {
+	      if (lm_addr != 0)
+		string_appendf (document, " main-lm=\"0x%s\">",
+				paddress (lm_addr));
+	      else
+		document += ">";
+
+	      lm_prev = lm_addr;
+	      if (read_one_ptr (lm_addr + lmo->l_next_offset,
+				&lm_addr, ptr_size) != 0)
+		{
+		  warning ("unable to read l_next from 0x%s",
+			   paddress (lm_addr + lmo->l_next_offset));
+		  break;
+		}
+	    }
+
+	  read_link_map (document, lm_addr, lm_prev, ptr_size, lmo);
 
 	  if (r_version < 2)
 	    break;
 
-	  /* Only applies to the default namespace.  */
-	  ignore_first = false;
-
 	  if (read_one_ptr (r_debug + lmo->r_next_offset, &r_debug,
 			    ptr_size) != 0)
 	    {
@@ -6687,13 +6693,7 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
 	}
     }
 
-  if (!header_done)
-    {
-      /* Empty list; terminate `<library-list-svr4'.  */
-      document += "/>";
-    }
-  else
-    document += "</library-list-svr4>";
+  document += "</library-list-svr4>";
 
   int document_len = document.length ();
   if (offset < document_len)