libdwfl: Ignore debuginfo-path hits that find the main file again.

2 files changed, 31 insertions, 2 deletions

diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 347ebcf4..d9b216d5 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,10 @@
+2010-06-14  Roland McGrath  <roland@redhat.com>
+
+	* find-debuginfo.c (try_open): Take new arg MAIN_STAT.  Compare
+	candidate file to that st_dev/st_ino and pretend it didn't exist
+	if they match.
+	(find_debuginfo_in_path): Update caller, pass main file's info.
+
 2010-05-20  Roland McGrath  <roland@redhat.com>
 
 	* linux-proc-maps.c (find_sysinfo_ehdr): Renamed to ...
diff --git a/libdwfl/find-debuginfo.c b/libdwfl/find-debuginfo.c
index 8fdaeb39..375bbaa8 100644
--- a/libdwfl/find-debuginfo.c
+++ b/libdwfl/find-debuginfo.c
@@ -51,13 +51,15 @@
 #include <stdio.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <sys/stat.h>
 #include "system.h"
 
 
 /* Try to open64 [DIR/][SUBDIR/]DEBUGLINK, return file descriptor or -1.
    On success, *DEBUGINFO_FILE_NAME has the malloc'd name of the open file.  */
 static int
-try_open (const char *dir, const char *subdir, const char *debuglink,
+try_open (const struct stat64 *main_stat,
+	  const char *dir, const char *subdir, const char *debuglink,
 	  char **debuginfo_file_name)
 {
   char *fname;
@@ -72,9 +74,19 @@ try_open (const char *dir, const char *subdir, const char *debuglink,
 	    : asprintf (&fname, "%s/%s/%s", dir, subdir, debuglink)) < 0)
     return -1;
 
+  struct stat64 st;
   int fd = TEMP_FAILURE_RETRY (open64 (fname, O_RDONLY));
   if (fd < 0)
     free (fname);
+  else if (fstat64 (fd, &st) == 0
+	   && st.st_ino == main_stat->st_ino
+	   && st.st_dev == main_stat->st_dev)
+    {
+      /* This is the main file by another name.  Don't look at it again.  */
+      close (fd);
+      errno = ENOENT;
+      fd = -1;
+    }
   else
     *debuginfo_file_name = fname;
 
@@ -162,6 +174,16 @@ find_debuginfo_in_path (Dwfl_Module *mod, const char *file_name,
       ++path;
     }
 
+  /* XXX dev/ino should be cached in struct dwfl_file.  */
+  struct stat64 main_stat;
+  if (unlikely ((mod->main.fd != -1 ? fstat64 (mod->main.fd, &main_stat)
+		 : file_name != NULL ? stat64 (file_name, &main_stat)
+		 : -1) < 0))
+    {
+      main_stat.st_dev = 0;
+      main_stat.st_ino = 0;
+    }
+
   char *file_dirname = (file_basename == file_name ? NULL
 			: strndupa (file_name, file_basename - 1 - file_name));
   char *p;
@@ -199,7 +221,7 @@ find_debuginfo_in_path (Dwfl_Module *mod, const char *file_name,
 	}
 
       char *fname = NULL;
-      int fd = try_open (dir, subdir, debuglink_file, &fname);
+      int fd = try_open (&main_stat, dir, subdir, debuglink_file, &fname);
       if (fd < 0)
 	switch (errno)
 	  {