grub_min(a,b) and grub_max(a,b) use a relatively naive implementation
which leads to several problems:
- they evaluate their parameters more than once
- the naive way to address this, to declare temporary variables in a
statement-expression, isn't resilient against nested uses, because
MIN(a,MIN(b,c)) results in the temporary variables being declared in
two nested scopes, which may result in a build warning depending on
your build options.
This patch changes our implementation to use a statement-expression
inside a helper macro, and creates the symbols for the temporary
variables with __COUNTER__ (A GNU C cpp extension) and token pasting to
create uniquely named internal variables.
Signed-off-by: Peter Jones <pjo...@redhat.com>
---
grub-core/fs/reiserfs.c | 28 +++++++++-------------------
grub-core/loader/multiboot_elfxx.c | 4 +---
include/grub/misc.h | 25 +++++++++++++++++++++++--
3 files changed, 33 insertions(+), 24 deletions(-)
diff --git a/grub-core/fs/reiserfs.c b/grub-core/fs/reiserfs.c
index 36b26ac98a0..42818c37622 100644
--- a/grub-core/fs/reiserfs.c
+++ b/grub-core/fs/reiserfs.c
@@ -42,16 +42,6 @@
GRUB_MOD_LICENSE ("GPLv3+");
-#define MIN(a, b) \
- ({ typeof (a) _a = (a); \
- typeof (b) _b = (b); \
- _a < _b ? _a : _b; })
-
-#define MAX(a, b) \
- ({ typeof (a) _a = (a); \
- typeof (b) _b = (b); \
- _a > _b ? _a : _b; })
-
#define REISERFS_SUPER_BLOCK_OFFSET 0x10000
#define REISERFS_MAGIC_LEN 12
#define REISERFS_MAGIC_STRING "ReIsEr"
@@ -1076,7 +1066,7 @@ grub_reiserfs_read_real (struct grub_fshelp_node *node,
grub_reiserfs_set_key_type (&key, GRUB_REISERFS_ANY, 2);
initial_position = off;
current_position = 0;
- final_position = MIN (len + initial_position, node->size);
+ final_position = grub_min (len + initial_position, node->size);
grub_dprintf ("reiserfs",
"Reading from %lld to %lld (%lld instead of requested %ld)\n",
(unsigned long long) initial_position,
@@ -1115,8 +1105,8 @@ grub_reiserfs_read_real (struct grub_fshelp_node *node,
grub_dprintf ("reiserfs_blocktype", "D: %u\n", (unsigned) block);
if (initial_position < current_position + item_size)
{
- offset = MAX ((signed) (initial_position - current_position), 0);
- length = (MIN (item_size, final_position - current_position)
+ offset = grub_max ((signed) (initial_position -
current_position), 0);
+ length = (grub_min (item_size, final_position - current_position)
- offset);
grub_dprintf ("reiserfs",
"Reading direct block %u from %u to %u...\n",
@@ -1161,9 +1151,9 @@ grub_reiserfs_read_real (struct grub_fshelp_node *node,
grub_dprintf ("reiserfs_blocktype", "I: %u\n", (unsigned) block);
if (current_position + block_size >= initial_position)
{
- offset = MAX ((signed) (initial_position - current_position),
- 0);
- length = (MIN (block_size, final_position - current_position)
+ offset = grub_max ((signed) (initial_position -
current_position),
+ 0);
+ length = (grub_min (block_size, final_position -
current_position)
- offset);
grub_dprintf ("reiserfs",
"Reading indirect block %u from %u to %u...\n",
@@ -1205,7 +1195,7 @@ grub_reiserfs_read_real (struct grub_fshelp_node *node,
switch (found.type)
{
case GRUB_REISERFS_DIRECT:
- read_length = MIN (len, item_size - file->offset);
+ read_length = grub_min (len, item_size - file->offset);
grub_disk_read (found.data->disk,
(found.block_number * block_size) /
GRUB_DISK_SECTOR_SIZE,
grub_le_to_cpu16 (found.header.item_location) +
file->offset,
@@ -1224,12 +1214,12 @@ grub_reiserfs_read_real (struct grub_fshelp_node *node,
item_size, (char *) indirect_block_ptr);
if (grub_errno)
goto fail;
- len = MIN (len, file->size - file->offset);
+ len = grub_min (len, file->size - file->offset);
for (indirect_block = file->offset / block_size;
indirect_block < indirect_block_count && read_length < len;
indirect_block++)
{
- read = MIN (block_size, len - read_length);
+ read = grub_min (block_size, len - read_length);
grub_disk_read (found.data->disk,
(grub_le_to_cpu32
(indirect_block_ptr[indirect_block]) * block_size) / GRUB_DISK_SECTOR_SIZE,
file->offset % block_size, read,
diff --git a/grub-core/loader/multiboot_elfxx.c
b/grub-core/loader/multiboot_elfxx.c
index 6801f0ddf2b..8744be14a46 100644
--- a/grub-core/loader/multiboot_elfxx.c
+++ b/grub-core/loader/multiboot_elfxx.c
@@ -35,9 +35,7 @@
#endif
#include <grub/i386/relocator.h>
-
-#define CONCAT(a,b) CONCAT_(a, b)
-#define CONCAT_(a,b) a ## b
+#include <grub/misc.h>
#pragma GCC diagnostic ignored "-Wcast-align"
diff --git a/include/grub/misc.h b/include/grub/misc.h
index 7d2b5519690..83b31799722 100644
--- a/include/grub/misc.h
+++ b/include/grub/misc.h
@@ -35,6 +35,14 @@
#define ARRAY_SIZE(array) (sizeof (array) / sizeof (array[0]))
#define COMPILE_TIME_ASSERT(cond) switch (0) { case 1: case !(cond): ; }
+#ifndef CONCAT_
+#define CONCAT_(a, b) a ## b
+#endif
+
+#ifndef CONCAT
+#define CONCAT(a, b) CONCAT_(a, b)
+#endif
+
#define grub_dprintf(condition, ...) grub_real_dprintf(GRUB_FILE, __LINE__,
condition, __VA_ARGS__)
void *EXPORT_FUNC(grub_memmove) (void *dest, const void *src, grub_size_t n);
@@ -495,8 +503,21 @@ void EXPORT_FUNC(grub_real_boot_time) (const char *file,
#define grub_boot_time(...)
#endif
-#define grub_max(a, b) (((a) > (b)) ? (a) : (b))
-#define grub_min(a, b) (((a) < (b)) ? (a) : (b))
+#define _grub_min(a, b, _a, _b)
\
+ ({ typeof (a) _a = (a); \
+ typeof (b) _b = (b); \
+ _a < _b ? _a : _b; })
+#define grub_min(a, b) _grub_min(a, b, \
+ CONCAT(_a_,__COUNTER__), \
+ CONCAT(_b_,__COUNTER__))
+
+#define _grub_max(a, b, _a, _b)
\
+ ({ typeof (a) _a = (a); \
+ typeof (b) _b = (b); \
+ _a > _b ? _a : _b; })
+#define grub_max(a, b) _grub_max(a, b, \
+ CONCAT(_a_,__COUNTER__), \
+ CONCAT(_b_,__COUNTER__))
#define grub_log2ull(n) (GRUB_TYPE_BITS (grub_uint64_t) - __builtin_clzll (n)
- 1)
--
2.34.1
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