compiler: Move import of Go export data to gcc side of interface.

	* go-backend.c: #include "simple-object.h" and "intl.h".
	(GO_EXPORT_SEGMENT_NAME): Define if not defined.
	(GO_EXPORT_SECTION_NAME): Likewise.
	(go_write_export_data): Use GO_EXPORT_SECTION_NAME.
	(go_read_export_data): New function.
	* go-c.h (go_read_export_data): Declare.

From-SVN: r182321

1 files changed, 95 insertions, 2 deletions

diff --git a/gcc/go/go-backend.c b/gcc/go/go-backend.c
index 62102a2e..4d1ea82 100644
--- a/gcc/go/go-backend.c
+++ b/gcc/go/go-backend.c
@@ -20,16 +20,31 @@ along with GCC; see the file COPYING3.  If not see
 #include "config.h"
 #include "system.h"
 #include "coretypes.h"
+#include "simple-object.h"
 #include "tm.h"
 #include "rtl.h"
 #include "tree.h"
 #include "tm_p.h"
+#include "intl.h"
 #include "output.h"
 #include "target.h"
 #include "common/common-target.h"
 
 #include "go-c.h"
 
+/* The segment name we pass to simple_object_start_read to find Go
+   export data.  */
+
+#ifndef GO_EXPORT_SEGMENT_NAME
+#define GO_EXPORT_SEGMENT_NAME "__GNU_GO"
+#endif
+
+/* The section name we use when reading and writing export data.  */
+
+#ifndef GO_EXPORT_SECTION_NAME
+#define GO_EXPORT_SECTION_NAME ".go_export"
+#endif
+
 /* This file holds all the cases where the Go frontend needs
    information from gcc's backend.  */
 
@@ -95,7 +110,7 @@ go_imported_unsafe (void)
 }
 
 /* This is called by the Go frontend proper to add data to the
-   .go_export section.  */
+   section containing Go export data.  */
 
 void
 go_write_export_data (const char *bytes, unsigned int size)
@@ -105,9 +120,87 @@ go_write_export_data (const char *bytes, unsigned int size)
   if (sec == NULL)
     {
       gcc_assert (targetm_common.have_named_sections);
-      sec = get_section (".go_export", SECTION_DEBUG, NULL);
+      sec = get_section (GO_EXPORT_SECTION_NAME, SECTION_DEBUG, NULL);
     }
 
   switch_to_section (sec);
   assemble_string (bytes, size);
 }
+
+/* The go_read_export_data function is called by the Go frontend
+   proper to read Go export data from an object file.  FD is a file
+   descriptor open for reading.  OFFSET is the offset within the file
+   where the object file starts; this will be 0 except when reading an
+   archive.  On success this returns NULL and sets *PBUF to a buffer
+   allocated using malloc, of size *PLEN, holding the export data.  If
+   the data is not found, this returns NULL and sets *PBUF to NULL and
+   *PLEN to 0.  If some error occurs, this returns an error message
+   and sets *PERR to an errno value or 0 if there is no relevant
+   errno.  */
+
+const char *
+go_read_export_data (int fd, off_t offset, char **pbuf, size_t *plen,
+		     int *perr)
+{
+  simple_object_read *sobj;
+  const char *errmsg;
+  off_t sec_offset;
+  off_t sec_length;
+  int found;
+  char *buf;
+  ssize_t c;
+
+  *pbuf = NULL;
+  *plen = 0;
+
+  sobj = simple_object_start_read (fd, offset, GO_EXPORT_SEGMENT_NAME,
+				   &errmsg, perr);
+  if (sobj == NULL)
+    {
+      /* If we get an error here, just pretend that we didn't find any
+	 export data.  This is the right thing to do if the error is
+	 that the file was not recognized as an object file.  This
+	 will ignore file I/O errors, but it's not too big a deal
+	 because we will wind up giving some other error later.  */
+      return NULL;
+    }
+
+  found = simple_object_find_section (sobj, GO_EXPORT_SECTION_NAME,
+				      &sec_offset, &sec_length,
+				      &errmsg, perr);
+  simple_object_release_read (sobj);
+  if (!found)
+    return errmsg;
+
+  if (lseek (fd, offset + sec_offset, SEEK_SET) < 0)
+    {
+      *perr = errno;
+      return _("lseek failed while reading export data");
+    }
+
+  buf = XNEWVEC (char, sec_length);
+  if (buf == NULL)
+    {
+      *perr = errno;
+      return _("memory allocation failed while reading export data");
+    }
+
+  c = read (fd, buf, sec_length);
+  if (c < 0)
+    {
+      *perr = errno;
+      free (buf);
+      return _("read failed while reading export data");
+    }
+
+  if (c < sec_length)
+    {
+      free (buf);
+      return _("short read while reading export data");
+    }
+
+  *pbuf = buf;
+  *plen = sec_length;
+
+  return NULL;
+}