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From: Alan Modra <amodra@gmail.com>
Date: Tue, 5 Jun 2018 21:04:00 +0930
Subject: [PATCH] PR23254, ld.bfd mishandles file pointers while scanning
archive
Best practice is to not mix lseek/read with fseek/fread on the same
underlying file descriptor, as not all stdio implementations will cope.
Since the plugin uses lseek/read while bfd uses fseek/fread this patch
reopens the file for exclusive use by the plugin rather than trying to
restore the file descriptor. That allows the plugin to read the file
after plugin_call_claim_file too.
bfd/
PR 23254
* plugin.c (bfd_plugin_open_input): Allow for possibility of
nested archives. Open file again for plugin.
(try_claim): Don't save and restore file position. Close file
if not claimed.
* sysdep.h (O_BINARY): Define.
ld/
PR 23254
* plugin.c (plugin_call_claim_file): Revert 2016-07-19 patch.
(plugin_object_p): Don't dup file descriptor.
---
--- a/bfd/plugin.c
+++ b/bfd/plugin.c
@@ -165,14 +165,22 @@ bfd_plugin_open_input (bfd *ibfd, struct
bfd *iobfd;
iobfd = ibfd;
- if (ibfd->my_archive && !bfd_is_thin_archive (ibfd->my_archive))
- iobfd = ibfd->my_archive;
+ while (iobfd->my_archive
+ && !bfd_is_thin_archive (iobfd->my_archive))
+ iobfd = iobfd->my_archive;
file->name = iobfd->filename;
if (!iobfd->iostream && !bfd_open_file (iobfd))
return 0;
- file->fd = fileno ((FILE *) iobfd->iostream);
+ /* The plugin API expects that the file descriptor won't be closed
+ and reused as done by the bfd file cache. So open it again.
+ dup isn't good enough. plugin IO uses lseek/read while BFD uses
+ fseek/fread. It isn't wise to mix the unistd and stdio calls on
+ the same underlying file descriptor. */
+ file->fd = open (file->name, O_RDONLY | O_BINARY);
+ if (file->fd < 0)
+ return 0;
if (iobfd == ibfd)
{
@@ -196,12 +204,12 @@ try_claim (bfd *abfd)
int claimed = 0;
struct ld_plugin_input_file file;
+ file.handle = abfd;
if (!bfd_plugin_open_input (abfd, &file))
return 0;
- file.handle = abfd;
- off_t cur_offset = lseek (file.fd, 0, SEEK_CUR);
claim_file (&file, &claimed);
- lseek (file.fd, cur_offset, SEEK_SET);
+ if (!claimed)
+ close (file.fd);
return claimed;
}
--- a/bfd/sysdep.h
+++ b/bfd/sysdep.h
@@ -108,6 +108,10 @@ extern char *strrchr ();
#ifndef O_ACCMODE
#define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
#endif
+/* Systems that don't already define this, don't need it. */
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
#ifndef SEEK_SET
#define SEEK_SET 0
--- a/ld/plugin.c
+++ b/ld/plugin.c
@@ -1053,14 +1053,10 @@ plugin_call_claim_file (const struct ld_
{
if (curplug->claim_file_handler)
{
- off_t cur_offset;
enum ld_plugin_status rv;
called_plugin = curplug;
- cur_offset = lseek (file->fd, 0, SEEK_CUR);
rv = (*curplug->claim_file_handler) (file, claimed);
- if (!*claimed)
- lseek (file->fd, cur_offset, SEEK_SET);
called_plugin = NULL;
if (rv != LDPS_OK)
set_plugin_error (curplug->name);
@@ -1126,12 +1122,6 @@ plugin_object_p (bfd *ibfd)
}
file.handle = input;
- /* The plugin API expects that the file descriptor won't be closed
- and reused as done by the bfd file cache. So dup one. */
- file.fd = dup (file.fd);
- if (file.fd < 0)
- return NULL;
-
input->abfd = abfd;
input->view_buffer.addr = NULL;
input->view_buffer.filesize = 0;
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