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[PATCH v3 1/1] x86, relocs: add printf attribute to die()

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  [PATCH v3 1/1] x86, relocs: add printf attribute to die() Nicolas Iooss <nicolas.iooss_linux@m4x.org> - 2016-12-18 20:50 +0100

#1544194 — [PATCH v3 1/1] x86, relocs: add printf attribute to die()

Adding such an attribute helps to detect errors in the format string at
build time. After doing this, the compiler complains about such issues:

    arch/x86/tools/relocs.c:460:5: error: format specifies type 'int'
    but the argument has type 'Elf64_Xword' (aka 'unsigned long')
    [-Werror,-Wformat]
                                    sec->shdr.sh_size);
                                    ^~~~~~~~~~~~~~~~~
    arch/x86/tools/relocs.c:464:5: error: format specifies type 'int'
    but the argument has type 'Elf64_Off' (aka 'unsigned long')
    [-Werror,-Wformat]
                                    sec->shdr.sh_offset, strerror(errno));
                                    ^~~~~~~~~~~~~~~~~~~

When relocs.c is included by relocs_32.c, sec->shdr.sh_size and
sec->shdr.sh_offset are 32-bit unsigned integers. When the file is
included by relocs_64.c, these expressions are 64-bit unsigned integers.

Introduce a PRIuELF macro to define the right format to use when
printing sh_size and sh_offset values.

While at it, constify the format attribute of die().

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
---
I sent the first versions of this patch in September (cf.
https://patchwork.kernel.org/patch/9312665/) but it has not been
applied.

As commit adee8705d251 ("x86/build: Annotate die() with noreturn to fix
build warning on clang") introduced the noreturn attribute to die(),
this patch now only adds the printf attribute.

 arch/x86/tools/relocs.c        | 14 +++++++-------
 arch/x86/tools/relocs.h        |  3 ++-
 arch/x86/tools/relocs_32.c     |  3 +++
 arch/x86/tools/relocs_64.c     |  3 +++
 arch/x86/tools/relocs_common.c |  2 +-
 5 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 0c2fae8d929d..4cad603b8d58 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -397,7 +397,7 @@ static void read_shdrs(FILE *fp)
 		    ehdr.e_shnum);
 	}
 	if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
-		die("Seek to %d failed: %s\n",
+		die("Seek to %"PRIuELF" failed: %s\n",
 			ehdr.e_shoff, strerror(errno));
 	}
 	for (i = 0; i < ehdr.e_shnum; i++) {
@@ -431,11 +431,11 @@ static void read_strtabs(FILE *fp)
 		}
 		sec->strtab = malloc(sec->shdr.sh_size);
 		if (!sec->strtab) {
-			die("malloc of %d bytes for strtab failed\n",
+			die("malloc of %"PRIuELF" bytes for strtab failed\n",
 				sec->shdr.sh_size);
 		}
 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
-			die("Seek to %d failed: %s\n",
+			die("Seek to %"PRIuELF" failed: %s\n",
 				sec->shdr.sh_offset, strerror(errno));
 		}
 		if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
@@ -456,11 +456,11 @@ static void read_symtabs(FILE *fp)
 		}
 		sec->symtab = malloc(sec->shdr.sh_size);
 		if (!sec->symtab) {
-			die("malloc of %d bytes for symtab failed\n",
+			die("malloc of %"PRIuELF" bytes for symtab failed\n",
 				sec->shdr.sh_size);
 		}
 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
-			die("Seek to %d failed: %s\n",
+			die("Seek to %"PRIuELF" failed: %s\n",
 				sec->shdr.sh_offset, strerror(errno));
 		}
 		if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
@@ -489,11 +489,11 @@ static void read_relocs(FILE *fp)
 		}
 		sec->reltab = malloc(sec->shdr.sh_size);
 		if (!sec->reltab) {
-			die("malloc of %d bytes for relocs failed\n",
+			die("malloc of %"PRIuELF" bytes for relocs failed\n",
 				sec->shdr.sh_size);
 		}
 		if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
-			die("Seek to %d failed: %s\n",
+			die("Seek to %"PRIuELF" failed: %s\n",
 				sec->shdr.sh_offset, strerror(errno));
 		}
 		if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
diff --git a/arch/x86/tools/relocs.h b/arch/x86/tools/relocs.h
index 1d23bf953a4a..f41416c31608 100644
--- a/arch/x86/tools/relocs.h
+++ b/arch/x86/tools/relocs.h
@@ -16,7 +16,8 @@
 #include <regex.h>
 #include <tools/le_byteshift.h>
 
-void die(char *fmt, ...) __attribute__((noreturn));
+void die(const char *fmt, ...) __attribute__((noreturn))
+	__attribute__((format(printf, 1, 2)));
 
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
diff --git a/arch/x86/tools/relocs_32.c b/arch/x86/tools/relocs_32.c
index b2ade2bb4162..8024ec473e6a 100644
--- a/arch/x86/tools/relocs_32.c
+++ b/arch/x86/tools/relocs_32.c
@@ -14,4 +14,7 @@
 #define ELF_ST_BIND(o)		ELF32_ST_BIND(o)
 #define ELF_ST_VISIBILITY(o)	ELF32_ST_VISIBILITY(o)
 
+/* printf format for Elf32_Off */
+#define PRIuELF PRIu32
+
 #include "relocs.c"
diff --git a/arch/x86/tools/relocs_64.c b/arch/x86/tools/relocs_64.c
index 56b61b743c4c..2cf4de5c9d99 100644
--- a/arch/x86/tools/relocs_64.c
+++ b/arch/x86/tools/relocs_64.c
@@ -14,4 +14,7 @@
 #define ELF_ST_BIND(o)          ELF64_ST_BIND(o)
 #define ELF_ST_VISIBILITY(o)    ELF64_ST_VISIBILITY(o)
 
+/* printf format for Elf64_Off */
+#define PRIuELF PRIu64
+
 #include "relocs.c"
diff --git a/arch/x86/tools/relocs_common.c b/arch/x86/tools/relocs_common.c
index acab636bcb34..30adb44eff79 100644
--- a/arch/x86/tools/relocs_common.c
+++ b/arch/x86/tools/relocs_common.c
@@ -1,6 +1,6 @@
 #include "relocs.h"
 
-void die(char *fmt, ...)
+void die(const char *fmt, ...)
 {
 	va_list ap;
 	va_start(ap, fmt);
-- 
2.11.0

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