[Xen-devel] [PATCH v4 2/4] build/printf: fix incorrect format specifiers

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

The following incorrect format specifiers and incorrect number of parameters
passed to printf like functions are reported by clang:

mce.c:601:18: error: data argument not used by format string 
[-Werror,-Wformat-extra-args]
                 smp_processor_id());
                 ^

xenpm.c:102:23: error: data argument not used by format string 
[-Werror,-Wformat-extra-args]
                what, argv[argc > 1]);
                      ^

libxl_internal.c:25:69: error: data argument not used by format string
      [-Werror,-Wformat-extra-args]
    libxl__log(ctx, XTL_CRITICAL, ENOMEM, 0,0, func, INVALID_DOMID, L);
                                                                    ^
libxl_internal.c:24:17: note: expanded from macro 'L'
          func, (unsigned long)nmemb, (unsigned long)size
                ^
libxl_internal.c:26:21: error: data argument not used by format string
      [-Werror,-Wformat-extra-args]
    fprintf(stderr, L);
                    ^
libxl_internal.c:24:17: note: expanded from macro 'L'
          func, (unsigned long)nmemb, (unsigned long)size
                ^

This patch contains the fixes for them and enables -Wformat for clang.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
NB: FWIW, there's a way to disable extra arguments checks
(-Wno-format-extra-args), that would prevent us from having to apply some of
the changes here. However, given that there are not that many occurrences, I
would rather leave the full checks of Wformat enabled.

NB2: this has only been tested with a FreeBSD clang build (3.8.0), and only
against the components that build on FreeBSD (ie: no qemu-trad, and certainly
no blktap).
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Christoph Egger <chegger@xxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changes since v2:
 - Remove the printf related comment near the -Wno-format.

Changes since v1:
 - Change the format string for MCE to avoid duplicating CPU%i.
 - Remove the grant-ref format specifier change, it's already taken care in
   patch #1.
---
 Config.mk                     |  3 +--
 tools/libxl/libxl_internal.c  | 21 ++++++++++++++++-----
 tools/misc/xenpm.c            | 13 ++++++++-----
 xen/arch/x86/cpu/mcheck/mce.c |  5 ++---
 4 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/Config.mk b/Config.mk
index 3a1d960..7d08d16 100644
--- a/Config.mk
+++ b/Config.mk
@@ -213,9 +213,8 @@ CFLAGS += -std=gnu99
 CFLAGS += -Wall -Wstrict-prototypes
 
 # Clang complains about macros that expand to 'if ( ( foo == bar ) ) ...'
-# and is over-zealous with the printf format lint
 # and is a bit too fierce about unused return values
-CFLAGS-$(clang) += -Wno-parentheses -Wno-format -Wno-unused-value
+CFLAGS-$(clang) += -Wno-parentheses -Wno-unused-value
 
 $(call cc-option-add,HOSTCFLAGS,HOSTCC,-Wdeclaration-after-statement)
 $(call cc-option-add,CFLAGS,CC,-Wdeclaration-after-statement)
diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
index d288215..f492dae 100644
--- a/tools/libxl/libxl_internal.c
+++ b/tools/libxl/libxl_internal.c
@@ -20,14 +20,25 @@
 void libxl__alloc_failed(libxl_ctx *ctx, const char *func,
                          size_t nmemb, size_t size) {
 #define M "libxl: FATAL ERROR: memory allocation failure"
-#define L (size ? M " (%s, %lu x %lu)\n" : M " (%s)\n"), \
-          func, (unsigned long)nmemb, (unsigned long)size
-    libxl__log(ctx, XTL_CRITICAL, ENOMEM, 0,0, func, INVALID_DOMID, L);
-    fprintf(stderr, L);
+#define M_SIZE M " (%s, %lu x %lu)\n"
+#define M_NSIZE M " (%s)\n"
+    if (size) {
+       libxl__log(ctx, XTL_CRITICAL, ENOMEM, 0, 0, func, INVALID_DOMID,
+                  M_SIZE, func, (unsigned long)nmemb, (unsigned long)size);
+       fprintf(stderr, M_SIZE, func, (unsigned long)nmemb,
+               (unsigned long)size);
+    } else {
+       libxl__log(ctx, XTL_CRITICAL, ENOMEM, 0, 0, func, INVALID_DOMID,
+                  M_NSIZE, func);
+       fprintf(stderr, M_NSIZE, func);
+
+    }
+
     fflush(stderr);
     _exit(-1);
+#undef M_NSIZE
+#undef M_SIZE
 #undef M
-#undef L
 }
 
 void libxl__ptr_add(libxl__gc *gc, void *ptr)
diff --git a/tools/misc/xenpm.c b/tools/misc/xenpm.c
index a2edee5..ded40b9 100644
--- a/tools/misc/xenpm.c
+++ b/tools/misc/xenpm.c
@@ -93,13 +93,16 @@ static void parse_cpuid(const char *arg, int *cpuid)
 static void parse_cpuid_and_int(int argc, char *argv[],
                                 int *cpuid, int *val, const char *what)
 {
-    if ( argc > 1 )
-        parse_cpuid(argv[0], cpuid);
+    if ( argc == 0 )
+    {
+         fprintf(stderr, "Missing %s\n", what);
+         exit(EINVAL);
+    }
 
-    if ( argc == 0 || sscanf(argv[argc > 1], "%d", val) != 1 )
+    parse_cpuid(argv[0], cpuid);
+    if ( sscanf(argv[1], "%d", val) != 1 )
     {
-        fprintf(stderr, argc ? "Invalid %s '%s'\n" : "Missing %s\n",
-                what, argv[argc > 1]);
+        fprintf(stderr, "Invalid %s '%s'\n", what, argv[1]);
         exit(EINVAL);
     }
 }
diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 2695b0c..6616026 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -595,9 +595,8 @@ int show_mca_info(int inited, struct cpuinfo_x86 *c)
             [mcheck_intel] = "Intel"
         };
 
-        snprintf(prefix, ARRAY_SIZE(prefix),
-                 g_type != mcheck_unset ? XENLOG_WARNING "CPU%i: "
-                 : XENLOG_INFO,
+        snprintf(prefix, ARRAY_SIZE(prefix), "%sCPU%u: ",
+                 g_type != mcheck_unset ? XENLOG_WARNING : XENLOG_INFO,
                  smp_processor_id());
         BUG_ON(inited >= ARRAY_SIZE(type_str));
         switch (inited) {
-- 
2.10.1 (Apple Git-78)


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