elf: Implement DT_AUDIT, DT_DEPAUDIT support [BZ #24943]
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Message ID 874l21ctb6.fsf@oldenburg2.str.redhat.com
State New
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  • elf: Implement DT_AUDIT, DT_DEPAUDIT support [BZ #24943]
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Florian Weimer Aug. 28, 2019, 1:29 p.m. UTC
binutils ld has supported --audit, --depaudit for a long time,
only support in glibc has been missing.

2019-08-27  Florian Weimer  <fweimer@redhat.com>

	[BZ #24943]
	elf: Implement DT_AUDIT, DT_DEPAUDIT support.
	* elf/rtld.c (enum audit_iter_list_state): Define.
	(struct audit_list_iter): Add state member.
	(audit_list_iter_init): Initialize state.
	(audit_list_iter_fetch_index): New function.
	(audit_list_iter_fetch_string): Likewise.
	(audit_list_iter_next): Add main_map argument.  Call
	audit_list_iter_fetch_string to fetch more strings.
	(load_audit_modules): Adjust call to audit_list_iter_next.
	(dl_main): Call load_audit_modules in more cases.
	* elf/Makefile (tests): Add tst-audit14, tst-audit15, tst-audit16.
	(modules-names): Add tst-auditlogmod-1, tst-auditlogmod-2,
	tst-auditlogmod-3.
	(LDFLAGS-tst-audit14): Use tst-auditlogmod-1.so as an audit
	module.
	(tst-auditlogmod-1.so): Link with libsupport.
	(tst-audit14.out): Depend on tst-auditlogmod-1.so.
	(LDFLAGS-tst-audit15) Use tst-auditlogmod-1.so,
	tst-auditlogmod-2.so as audit modules.
	(tst-auditlogmod-2.so): Link with libsupport.
	(tst-audit15.out): Depend on tst-auditlogmod-1.so,
	tst-auditlogmod-2.so.
	(LDFLAGS-tst-audit16) Use tst-auditlogmod-1.so,
	tst-auditlogmod-2.so, tst-auditlogmod-3.so as audit modules.
	(tst-auditlogmod-3.so): Link with libsupport.
	(tst-audit16.out): Depend on tst-auditlogmod-1.so,
	tst-auditlogmod-2.so, tst-auditlogmod-3.so.
	* elf/tst-audit14.c: New file.
	* elf/tst-audit15.c: Likewise.
	* elf/tst-audit16.c: Likewise.
	* elf/tst-auditlogmod-1.c: Likewise.
	* elf/tst-auditlogmod-2.c: Likewise.
	* elf/tst-auditlogmod-3.c: Likewise.
	* support/xstdio.h (xgetline): Declare.
	* support/Makefile (libsupport-routines): Add xgetline.
	* support/xgetline.c: New file.

Patch
diff mbox series

diff --git a/NEWS b/NEWS
index a64b89986a..932ac9d9df 100644
--- a/NEWS
+++ b/NEWS
@@ -21,6 +21,9 @@  Major new features:
   18661-1:2014 and TS 18661-3:2015 as amended by the resolution of
   Clarification Request 13 to TS 18661-3.
 
+* The GNU C Library now loads audit modules listed in the DT_AUDIT and
+  DT_DEPAUDIT dynamic section entries of the main executable.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The totalorder and totalordermag functions, and the corresponding
diff --git a/elf/Makefile b/elf/Makefile
index d470e41402..442e898a97 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -192,7 +192,8 @@  tests += restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-latepthread tst-tls-manydynamic tst-nodelete-dlclose \
 	 tst-debug1 tst-main1 tst-absolute-sym tst-absolute-zero tst-big-note \
 	 tst-unwind-ctor tst-unwind-main tst-audit13 \
-	 tst-sonamemove-link tst-sonamemove-dlopen tst-dlopen-aout
+	 tst-sonamemove-link tst-sonamemove-dlopen tst-dlopen-aout \
+	 tst-audit14 tst-audit15 tst-audit16
 #	 reldep9
 tests-internal += loadtest unload unload2 circleload1 \
 	 neededtest neededtest2 neededtest3 neededtest4 \
@@ -279,7 +280,8 @@  modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		tst-main1mod tst-libc_dlvsym-dso tst-absolute-sym-lib \
 		tst-absolute-zero-lib tst-big-note-lib tst-unwind-ctor-lib \
 		tst-audit13mod1 tst-sonamemove-linkmod1 \
-		tst-sonamemove-runmod1 tst-sonamemove-runmod2
+		tst-sonamemove-runmod1 tst-sonamemove-runmod2 \
+		tst-auditlogmod-1 tst-auditlogmod-2 tst-auditlogmod-3
 # Most modules build with _ISOMAC defined, but those filtered out
 # depend on internal headers.
 modules-names-tests = $(filter-out ifuncmod% tst-libc_dlvsym-dso tst-tlsmod%,\
@@ -1410,6 +1412,22 @@  $(objpfx)tst-audit13.out: $(objpfx)tst-audit13mod1.so
 LDFLAGS-tst-audit13mod1.so = -Wl,-z,lazy
 tst-audit13-ENV = LD_AUDIT=$(objpfx)tst-audit13mod1.so
 
+LDFLAGS-tst-audit14 = -Wl,--audit=tst-auditlogmod-1.so
+$(objpfx)tst-auditlogmod-1.so: $(libsupport)
+$(objpfx)tst-audit14.out: $(objpfx)tst-auditlogmod-1.so
+LDFLAGS-tst-audit15 = \
+  -Wl,--audit=tst-auditlogmod-1.so,--depaudit=tst-auditlogmod-2.so
+$(objpfx)tst-auditlogmod-2.so: $(libsupport)
+$(objpfx)tst-audit15.out: \
+  $(objpfx)tst-auditlogmod-1.so $(objpfx)tst-auditlogmod-2.so
+LDFLAGS-tst-audit16 = \
+  -Wl,--audit=tst-auditlogmod-1.so:tst-auditlogmod-2.so \
+  -Wl,--depaudit=tst-auditlogmod-3.so
+$(objpfx)tst-auditlogmod-3.so: $(libsupport)
+$(objpfx)tst-audit16.out: \
+  $(objpfx)tst-auditlogmod-1.so $(objpfx)tst-auditlogmod-2.so \
+  $(objpfx)tst-auditlogmod-3.so
+
 # tst-sonamemove links against an older implementation of the library.
 LDFLAGS-tst-sonamemove-linkmod1.so = \
   -Wl,--version-script=tst-sonamemove-linkmod1.map \
diff --git a/elf/rtld.c b/elf/rtld.c
index c9490ff694..38bc44dc76 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -186,6 +186,15 @@  static struct audit_list
   struct audit_list *next;
 } *audit_list;
 
+/* State flag for hte struct audit_list_iter iterator.  */
+enum audit_iter_list_state
+  {
+    audit_iter_list_in_string,
+    audit_iter_list_in_dt_audit,
+    audit_iter_list_in_dt_depaudit,
+    audit_iter_list_in_list,
+  };
+
 /* Iterator for audit_list_string followed by audit_list.  */
 struct audit_list_iter
 {
@@ -196,6 +205,9 @@  struct audit_list_iter
      the first element.  */
   struct audit_list *previous;
 
+  /* One of the enum audit_iter_list_state values.  */
+  unsigned char state;
+
   /* Scratch buffer for returning a name which is part of
      audit_list_string.  */
   char fname[SECURE_NAME_LIMIT];
@@ -207,14 +219,66 @@  audit_list_iter_init (struct audit_list_iter *iter)
 {
   iter->audit_list_tail = audit_list_string;
   iter->previous = NULL;
+  iter->state = audit_iter_list_in_string;
+}
+
+/* Look up the INDEX of a dynamic tag in MAIN_MAP and store it in
+   ITER->audit_list_tail if it exists.  */
+static void
+audit_list_iter_fetch_index (struct audit_list_iter *iter,
+			     struct link_map *main_map, size_t index)
+{
+  if (main_map->l_info[index] != NULL)
+    iter->audit_list_tail
+      = ((const char *) D_PTR (main_map, l_info[DT_STRTAB])
+	 +  main_map->l_info[index]->d_un.d_val);
+}
+
+/* Advance ITER->state and put the next string into
+   ITER->audit_list_tail.  */
+static void
+audit_list_iter_fetch_string (struct audit_list_iter *iter,
+			      struct link_map *main_map)
+{
+  /* Advance the state.  */
+  ++iter->state;
+  assert (iter->state <= audit_iter_list_in_list);
+
+  /* Default to a missing string.  */
+  iter->audit_list_tail = NULL;
+
+  /* Determine the next string.  */
+  switch ((enum audit_iter_list_state) iter->state)
+    {
+    case audit_iter_list_in_string:
+      /* Not possible because state was advanced.  */
+      __builtin_unreachable ();
+    case audit_iter_list_in_dt_audit:
+      audit_list_iter_fetch_index (iter, main_map, ADDRIDX (DT_AUDIT));
+      break;
+    case audit_iter_list_in_dt_depaudit:
+      audit_list_iter_fetch_index (iter, main_map, ADDRIDX (DT_DEPAUDIT));
+      break;
+    case audit_iter_list_in_list:
+      /* No DT_* tag left to process.  */
+      return;
+    }
 }
 
 /* Iterate through both audit_list_string and audit_list.  */
 static const char *
-audit_list_iter_next (struct audit_list_iter *iter)
+audit_list_iter_next (struct audit_list_iter *iter, struct link_map *main_map)
 {
-  if (iter->audit_list_tail != NULL)
+  while (iter->state != audit_iter_list_in_list)
     {
+      /* If the current string is missing or exhausted, fetch the next
+	 string.  This advances iter->state.  */
+      if (iter->audit_list_tail == NULL || *iter->audit_list_tail == '\0')
+	{
+	  audit_list_iter_fetch_string (iter, main_map);
+	  continue;
+	}
+
       /* First iterate over audit_list_string.  */
       while (*iter->audit_list_tail != '\0')
 	{
@@ -239,7 +303,9 @@  audit_list_iter_next (struct audit_list_iter *iter)
 	    return iter->fname;
 	  /* Otherwise, wrap around and try the next name.  */
 	}
-      /* Fall through to the procesing of audit_list.  */
+
+      /* Fetch the next audit string, or fall through to linked list
+	 processing below.  */
     }
 
   if (iter->previous == NULL)
@@ -1065,7 +1131,7 @@  load_audit_modules (struct link_map *main_map)
 
   while (true)
     {
-      const char *name = audit_list_iter_next (&al_iter);
+      const char *name = audit_list_iter_next (&al_iter, main_map);
       if (name == NULL)
 	break;
       load_audit_module (name, &last_audit);
@@ -1612,7 +1678,9 @@  ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
   /* If we have auditing DSOs to load, do it now.  */
   bool need_security_init = true;
   if (__glibc_unlikely (audit_list != NULL)
-      || __glibc_unlikely (audit_list_string != NULL))
+      || __glibc_unlikely (audit_list_string != NULL)
+      || __glibc_unlikely (main_map->l_info[ADDRIDX (DT_AUDIT)] != NULL)
+      || __glibc_unlikely (main_map->l_info[ADDRIDX (DT_DEPAUDIT)] != NULL))
     {
       /* Since we start using the auditing DSOs right away we need to
 	 initialize the data structures now.  */
diff --git a/elf/tst-audit14.c b/elf/tst-audit14.c
new file mode 100644
index 0000000000..a8a60d46fc
--- /dev/null
+++ b/elf/tst-audit14.c
@@ -0,0 +1,46 @@ 
+/* Main program with DT_AUDIT.  One audit module.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/xstdio.h>
+
+static int
+do_test (void)
+{
+  /* Verify what the audit module has written.  This test assumes that
+     standard output has been redirected to a regular file.  */
+  FILE *fp = xfopen ("/dev/stdout", "r");
+
+  char *buffer = NULL;
+  size_t buffer_length = 0;
+  size_t line_length = xgetline (&buffer, &buffer_length, fp);
+  const char *message = "info: tst-auditlogmod-1.so loaded\n";
+  TEST_COMPARE_BLOB (message, strlen (message), buffer, line_length);
+
+  /* No more audit module output.  */
+  line_length = xgetline (&buffer, &buffer_length, fp);
+  TEST_COMPARE_BLOB ("", 0, buffer, line_length);
+
+  free (buffer);
+  xfclose (fp);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/elf/tst-audit15.c b/elf/tst-audit15.c
new file mode 100644
index 0000000000..4d74c24789
--- /dev/null
+++ b/elf/tst-audit15.c
@@ -0,0 +1,50 @@ 
+/* Main program with DT_AUDIT and DT_DEPAUDIT.  Two audit modules.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/xstdio.h>
+
+static int
+do_test (void)
+{
+  /* Verify what the audit modules have written.  This test assumes
+     that standard output has been redirected to a regular file.  */
+  FILE *fp = xfopen ("/dev/stdout", "r");
+
+  char *buffer = NULL;
+  size_t buffer_length = 0;
+  size_t line_length = xgetline (&buffer, &buffer_length, fp);
+  const char *message = "info: tst-auditlogmod-1.so loaded\n";
+  TEST_COMPARE_BLOB (message, strlen (message), buffer, line_length);
+
+  line_length = xgetline (&buffer, &buffer_length, fp);
+  message = "info: tst-auditlogmod-2.so loaded\n";
+  TEST_COMPARE_BLOB (message, strlen (message), buffer, line_length);
+
+  /* No more audit module output.  */
+  line_length = xgetline (&buffer, &buffer_length, fp);
+  TEST_COMPARE_BLOB ("", 0, buffer, line_length);
+
+  free (buffer);
+  xfclose (fp);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/elf/tst-audit16.c b/elf/tst-audit16.c
new file mode 100644
index 0000000000..2e62a0bf7e
--- /dev/null
+++ b/elf/tst-audit16.c
@@ -0,0 +1,54 @@ 
+/* Main program with DT_AUDIT and DT_DEPAUDIT.  Three audit modules.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/xstdio.h>
+
+static int
+do_test (void)
+{
+  /* Verify what the audit modules have written.  This test assumes
+     that standard output has been redirected to a regular file.  */
+  FILE *fp = xfopen ("/dev/stdout", "r");
+
+  char *buffer = NULL;
+  size_t buffer_length = 0;
+  size_t line_length = xgetline (&buffer, &buffer_length, fp);
+  const char *message = "info: tst-auditlogmod-1.so loaded\n";
+  TEST_COMPARE_BLOB (message, strlen (message), buffer, line_length);
+
+  line_length = xgetline (&buffer, &buffer_length, fp);
+  message = "info: tst-auditlogmod-2.so loaded\n";
+  TEST_COMPARE_BLOB (message, strlen (message), buffer, line_length);
+
+  line_length = xgetline (&buffer, &buffer_length, fp);
+  message = "info: tst-auditlogmod-3.so loaded\n";
+  TEST_COMPARE_BLOB (message, strlen (message), buffer, line_length);
+
+  /* No more audit module output.  */
+  line_length = xgetline (&buffer, &buffer_length, fp);
+  TEST_COMPARE_BLOB ("", 0, buffer, line_length);
+
+  free (buffer);
+  xfclose (fp);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/elf/tst-auditlogmod-1.c b/elf/tst-auditlogmod-1.c
new file mode 100644
index 0000000000..c7ae665f6e
--- /dev/null
+++ b/elf/tst-auditlogmod-1.c
@@ -0,0 +1,27 @@ 
+/* Audit module which logs that it was loaded.  Variant 1.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <link.h>
+#include <support/support.h>
+
+unsigned int
+la_version (unsigned int v)
+{
+  write_message ("info: tst-auditlogmod-1.so loaded\n");
+  return LAV_CURRENT;
+}
diff --git a/elf/tst-auditlogmod-2.c b/elf/tst-auditlogmod-2.c
new file mode 100644
index 0000000000..7e7ea054f9
--- /dev/null
+++ b/elf/tst-auditlogmod-2.c
@@ -0,0 +1,27 @@ 
+/* Audit module which logs that it was loaded.  Variant 2.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <link.h>
+#include <support/support.h>
+
+unsigned int
+la_version (unsigned int v)
+{
+  write_message ("info: tst-auditlogmod-2.so loaded\n");
+  return LAV_CURRENT;
+}
diff --git a/elf/tst-auditlogmod-3.c b/elf/tst-auditlogmod-3.c
new file mode 100644
index 0000000000..bae6c9b717
--- /dev/null
+++ b/elf/tst-auditlogmod-3.c
@@ -0,0 +1,27 @@ 
+/* Audit module which logs that it was loaded.  Variant 3.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <link.h>
+#include <support/support.h>
+
+unsigned int
+la_version (unsigned int v)
+{
+  write_message ("info: tst-auditlogmod-3.so loaded\n");
+  return LAV_CURRENT;
+}
diff --git a/support/Makefile b/support/Makefile
index ab66913a02..cc3dbf259e 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -92,6 +92,7 @@  libsupport-routines = \
   xfopen \
   xfork \
   xftruncate \
+  xgetline \
   xgetsockname \
   xlisten \
   xlseek \
diff --git a/support/xgetline.c b/support/xgetline.c
new file mode 100644
index 0000000000..a535b22a2d
--- /dev/null
+++ b/support/xgetline.c
@@ -0,0 +1,39 @@ 
+/* getline with error checking.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xstdio.h>
+
+size_t
+xgetline (char **buffer, size_t *length,  FILE *fp)
+{
+  TEST_VERIFY (!ferror (fp));
+  ssize_t ret = getline (buffer, length, fp);
+  if (ferror (fp))
+    {
+      TEST_VERIFY (ret < 0);
+      FAIL_EXIT1 ("getline: %m");
+    }
+  if (feof (fp))
+    {
+      TEST_VERIFY (ret <= 0);
+      return 0;
+    }
+  TEST_VERIFY (ret > 0);
+  return ret;
+}
diff --git a/support/xstdio.h b/support/xstdio.h
index 9d4e66dbfd..c7a4a47e67 100644
--- a/support/xstdio.h
+++ b/support/xstdio.h
@@ -19,6 +19,7 @@ 
 #ifndef SUPPORT_XSTDIO_H
 #define SUPPORT_XSTDIO_H
 
+#include <stddef.h>
 #include <stdio.h>
 #include <sys/cdefs.h>
 
@@ -27,6 +28,11 @@  __BEGIN_DECLS
 FILE *xfopen (const char *path, const char *mode);
 void xfclose (FILE *);
 
+/* Read a line from FP, using getline.  *BUFFER must be NULL, or a
+   heap-allocated pointer of *LENGTH bytes.  Return the number of bytes
+   in the line if a line was read, or 0 on EOF.  */
+size_t xgetline (char **buffer, size_t *length,  FILE *fp);
+
 __END_DECLS
 
 #endif /* SUPPORT_XSTDIO_H */