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fdtdump: Fix signedness comparisons warnings 

With -Wsign-compare, compilers warn about a mismatching signedness in
comparisons in fdtdump.c.

The "len" parameter to valid_header() refers to a memory size, not a
file offset, so the (unsigned) size_t is better fit, and fixes the
warning nicely.

In the main function we compare the difference between two pointers,
which produces a signed ptrdiff_t type. However the while loop above the
comparison makes sure that "p" always points before "endp" (by virtue of
the limit in the memchr() call). This means "endp - p" is never
negative, so we can safely cast this expression to an unsigned type.

This fixes "make fdtdump", when compiled with -Wsign-compare.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Message-Id: <20210611171040.25524-3-andre.przywara@arm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
main
Andre Przywara 2021-06-11 18:10:34 +01:00 committed by David Gibson
parent b6910bec11
commit 24e7f511fd
1 changed files with 3 additions and 3 deletions
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6
fdtdump.c
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@ -18,7 +18,7 @@
#include "util.h" #include "util.h"


#define FDT_MAGIC_SIZE 4 #define FDT_MAGIC_SIZE 4
#define MAX_VERSION 17 #define MAX_VERSION 17U


#define ALIGN(x, a) (((x) + ((a) - 1)) & ~((a) - 1)) #define ALIGN(x, a) (((x) + ((a) - 1)) & ~((a) - 1))
#define PALIGN(p, a) ((void *)(ALIGN((unsigned long)(p), (a)))) #define PALIGN(p, a) ((void *)(ALIGN((unsigned long)(p), (a))))
@ -163,7 +163,7 @@ static const char * const usage_opts_help[] = {
USAGE_COMMON_OPTS_HELP USAGE_COMMON_OPTS_HELP
}; };


static bool valid_header(char *p, off_t len) static bool valid_header(char *p, size_t len)
{ {
if (len < sizeof(struct fdt_header) || if (len < sizeof(struct fdt_header) ||
fdt_magic(p) != FDT_MAGIC || fdt_magic(p) != FDT_MAGIC ||
@ -235,7 +235,7 @@ int main(int argc, char *argv[])
} }
++p; ++p;
} }
if (!p || endp - p < sizeof(struct fdt_header)) if (!p || (size_t)(endp - p) < sizeof(struct fdt_header))
die("%s: could not locate fdt magic\n", file); die("%s: could not locate fdt magic\n", file);
printf("%s: found fdt at offset %#tx\n", file, p - buf); printf("%s: found fdt at offset %#tx\n", file, p - buf);
buf = p; buf = p;