libelf: Tidy up logging and remove dependency on stdio.

libelf now permits callers to specify logging callback functions,
rather than a FILE*.  libelf's non-Xen callers are all libxc users, so
the stdio dependency and the default logging callback function (which
calls vfprintf) is now in libxc.

Xen's use of libxc is unaffected in this patch.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

7 files changed, 61 insertions, 15 deletions

diff --git a/tools/libxc/xc_dom_elfloader.c b/tools/libxc/xc_dom_elfloader.c
index f9bbd85ba3..280f722d30 100644
--- a/tools/libxc/xc_dom_elfloader.c
+++ b/tools/libxc/xc_dom_elfloader.c
@@ -9,6 +9,7 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdarg.h>
 #include <inttypes.h>
 
 #include "xg_private.h"
@@ -18,6 +19,17 @@
 
 /* ------------------------------------------------------------------------ */
 
+static void log_callback(struct elf_binary *elf, void *caller_data,
+                         int iserr, const char *fmt, va_list al) {
+    vfprintf(caller_data,fmt,al);
+}
+
+void xc_elf_set_logfile(struct elf_binary *elf, FILE *f, int verbose) {
+    elf_set_log(elf, log_callback, f, verbose);
+}
+
+/* ------------------------------------------------------------------------ */
+
 static char *xc_dom_guest_type(struct xc_dom_image *dom,
                                struct elf_binary *elf)
 {
@@ -137,8 +149,9 @@ static int xc_dom_load_elf_symtab(struct xc_dom_image *dom,
     }
     if ( elf_init(&syms, hdr + sizeof(int), size - sizeof(int)) )
         return -1;
+
     if ( xc_dom_logfile )
-        elf_set_logfile(&syms, xc_dom_logfile, 1);
+        xc_elf_set_logfile(&syms, xc_dom_logfile, 1);
 
     symtab = dom->bsd_symtab_start + sizeof(int);
     maxaddr = elf_round_up(&syms, symtab + elf_size(&syms, syms.ehdr) +
@@ -231,7 +244,7 @@ static int xc_dom_parse_elf_kernel(struct xc_dom_image *dom)
     dom->private_loader = elf;
     rc = elf_init(elf, dom->kernel_blob, dom->kernel_size);
     if ( xc_dom_logfile )
-        elf_set_logfile(elf, xc_dom_logfile, 1);
+        xc_elf_set_logfile(elf, xc_dom_logfile, 1);
     if ( rc != 0 )
     {
         xc_dom_panic(XC_INVALID_KERNEL, "%s: corrupted ELF image\n",
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 2d01467d82..f63f96deb7 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -19,6 +19,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <xen/xen.h>
 #include <xen/domctl.h>
 #include <xen/physdev.h>
@@ -1474,4 +1475,8 @@ int xc_memshr_debug_gref(int xc_handle,
                          uint32_t domid,
                          grant_ref_t gref);
 
+struct elf_binary;
+void xc_elf_set_logfile(struct elf_binary *elf, FILE *f, int verbose);
+/* Useful for callers who also use libelf. */
+
 #endif /* XENCTRL_H */
diff --git a/tools/xcutils/readnotes.c b/tools/xcutils/readnotes.c
index b770f56fe9..270c48b017 100644
--- a/tools/xcutils/readnotes.c
+++ b/tools/xcutils/readnotes.c
@@ -170,7 +170,7 @@ int main(int argc, char **argv)
 		fprintf(stderr, "File %s is not an ELF image\n", f);
 		return 1;
 	}
-	elf_set_logfile(&elf, stderr, 0);
+	xc_elf_set_logfile(&elf, stderr, 0);
 
 	count = elf_phdr_count(&elf);
 	for ( h=0; h < count; h++)
diff --git a/xen/common/libelf/libelf-loader.c b/xen/common/libelf/libelf-loader.c
index 5e86555817..f50524f690 100644
--- a/xen/common/libelf/libelf-loader.c
+++ b/xen/common/libelf/libelf-loader.c
@@ -2,6 +2,8 @@
  * parse and load elf binaries
  */
 
+#include <stdarg.h>
+
 #include "libelf-private.h"
 
 /* ------------------------------------------------------------------------ */
@@ -72,9 +74,25 @@ int elf_init(struct elf_binary *elf, const char *image, size_t size)
 }
 
 #ifndef __XEN__
-void elf_set_logfile(struct elf_binary *elf, FILE * log, int verbose)
+void elf_call_log_callback(struct elf_binary *elf, int iserr,
+                           const char *fmt,...) {
+    va_list al;
+
+    if (!elf->log_callback)
+        return;
+    if (!(iserr || elf->verbose))
+        return;
+
+    va_start(al,fmt);
+    elf->log_callback(elf, elf->log_caller_data, iserr, fmt, al);
+    va_end(al);
+}
+    
+void elf_set_log(struct elf_binary *elf, elf_log_callback *log_callback,
+                 void *log_caller_data, int verbose)
 {
-    elf->log = log;
+    elf->log_callback = log_callback;
+    elf->log_caller_data = log_caller_data;
     elf->verbose = verbose;
 }
 #else
diff --git a/xen/common/libelf/libelf-private.h b/xen/common/libelf/libelf-private.h
index e207b690c4..fcce9e331a 100644
--- a/xen/common/libelf/libelf-private.h
+++ b/xen/common/libelf/libelf-private.h
@@ -11,6 +11,8 @@
 #include <asm/byteorder.h>
 #include <public/elfnote.h>
 
+/* we would like to use elf->log_callback but we can't because
+ * there is no vprintk in Xen */
 #define elf_msg(elf, fmt, args ... ) \
    if (elf->verbose) printk(fmt, ## args )
 #define elf_err(elf, fmt, args ... ) \
@@ -54,13 +56,12 @@
 #include "xenctrl.h"
 #include "xc_private.h"
 
-#define elf_msg(elf, fmt, args ... ) \
-    if (elf->log && elf->verbose) fprintf(elf->log, fmt , ## args )
-#define elf_err(elf, fmt, args ... ) do {               \
-    if (elf->log)                                       \
-        fprintf(elf->log, fmt , ## args );              \
-    xc_set_error(XC_INVALID_KERNEL, fmt , ## args );    \
-} while (0)
+#define elf_msg(elf, fmt, args ... )                    \
+    elf_call_log_callback(elf, 0, fmt , ## args );
+#define elf_err(elf, fmt, args ... )                    \
+    elf_call_log_callback(elf, 1, fmt , ## args );
+
+void elf_call_log_callback(struct elf_binary*, int iserr, const char *fmt,...);
 
 #define safe_strcpy(d,s)                        \
 do { strncpy((d),(s),sizeof((d))-1);            \
diff --git a/xen/common/libelf/libelf-relocate.c b/xen/common/libelf/libelf-relocate.c
index 89cea4411b..fe9891da70 100644
--- a/xen/common/libelf/libelf-relocate.c
+++ b/xen/common/libelf/libelf-relocate.c
@@ -289,7 +289,7 @@ static int elf_reloc_section(struct elf_binary *elf,
         value = elf_uval(elf, sym, st_value);
         value += r_addend;
 
-        if ( elf->log && (elf->verbose > 1) )
+        if ( elf->log_callback && (elf->verbose > 1) )
         {
             uint64_t st_name = elf_uval(elf, sym, st_name);
             const char *name = st_name ? elf->sym_strtab + st_name : "*NONE*";
diff --git a/xen/include/xen/libelf.h b/xen/include/xen/libelf.h
index 1c92a73f1d..584d8b3b2d 100644
--- a/xen/include/xen/libelf.h
+++ b/xen/include/xen/libelf.h
@@ -37,6 +37,13 @@
 #else
 #include <xen/elfnote.h>
 #include <xen/features.h>
+
+#include <stdarg.h>
+
+struct elf_binary;
+typedef void elf_log_callback(struct elf_binary*, void *caller_data,
+                              int iserr, const char *fmt, va_list al);
+
 #endif
 
 /* ------------------------------------------------------------------------ */
@@ -99,7 +106,8 @@ struct elf_binary {
 
 #ifndef __XEN__
     /* misc */
-    FILE *log;
+    elf_log_callback *log_callback;
+    void *log_caller_data;
 #endif
     int verbose;
 };
@@ -183,7 +191,8 @@ int elf_init(struct elf_binary *elf, const char *image, size_t size);
 #ifdef __XEN__
 void elf_set_verbose(struct elf_binary *elf);
 #else
-void elf_set_logfile(struct elf_binary *elf, FILE * log, int verbose);
+void elf_set_log(struct elf_binary *elf, elf_log_callback*,
+                 void *log_caller_pointer, int verbose);
 #endif
 
 void elf_parse_binary(struct elf_binary *elf);