Commit 8e6c2fec authored by Rusty Russell's avatar Rusty Russell

structeq: fix case where we mark padding as unknown.

And change semantics: a negative number means "up to this much padding".
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent d98e77e5
...@@ -9,14 +9,15 @@ ...@@ -9,14 +9,15 @@
/** /**
* STRUCTEQ_DEF - define an ..._eq function to compare two structures. * STRUCTEQ_DEF - define an ..._eq function to compare two structures.
* @sname: name of the structure, and function (<sname>_eq) to define. * @sname: name of the structure, and function (<sname>_eq) to define.
* @padbytes: number of bytes of expected padding, or -1 if unknown. * @padbytes: number of bytes of expected padding, or negative "max".
* @...: name of every member of the structure. * @...: name of every member of the structure.
* *
* This generates a single memcmp() call in the common case where the * This generates a single memcmp() call in the common case where the
* structure contains no padding. Since it can't tell the difference between * structure contains no padding. Since it can't tell the difference between
* padding and a missing member, @padbytes can be used to assert that * padding and a missing member, @padbytes can be used to assert that
* there isn't any, or how many we expect. -1 means "expect some", since * there isn't any, or how many we expect. A negative number means
* it can be platform dependent. * "up to or equal to that amount of padding", as padding can be
* platform dependent.
*/ */
#define STRUCTEQ_DEF(sname, padbytes, ...) \ #define STRUCTEQ_DEF(sname, padbytes, ...) \
static inline bool CPPMAGIC_GLUE2(sname, _eq)(const struct sname *_a, \ static inline bool CPPMAGIC_GLUE2(sname, _eq)(const struct sname *_a, \
...@@ -25,7 +26,7 @@ static inline bool CPPMAGIC_GLUE2(sname, _eq)(const struct sname *_a, \ ...@@ -25,7 +26,7 @@ static inline bool CPPMAGIC_GLUE2(sname, _eq)(const struct sname *_a, \
BUILD_ASSERT(((padbytes) < 0 && \ BUILD_ASSERT(((padbytes) < 0 && \
CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, \ CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, \
__VA_ARGS__)) \ __VA_ARGS__)) \
> sizeof(*_a)) \ - (padbytes) >= sizeof(*_a)) \
|| CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, \ || CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, \
__VA_ARGS__)) \ __VA_ARGS__)) \
+ (padbytes) == sizeof(*_a)); \ + (padbytes) == sizeof(*_a)); \
......
...@@ -2,11 +2,12 @@ ...@@ -2,11 +2,12 @@
struct mydata { struct mydata {
int start, end; int start, end;
int pad;
}; };
#ifdef FAIL #ifdef FAIL
#define PADDING -1 #define PADDING -1 /* We have more than 1 byte padding */
#else #else
#define PADDING 0 #define PADDING sizeof(int)
#endif #endif
STRUCTEQ_DEF(mydata, PADDING, start, end); STRUCTEQ_DEF(mydata, PADDING, start, end);
......
#include <ccan/structeq/structeq.h>
struct mydata {
int start, end;
int pad;
};
#ifdef FAIL
#define PADDING -1
#else
#define PADDING -(int)sizeof(int)
#endif
STRUCTEQ_DEF(mydata, PADDING, start, end);
int main(void)
{
struct mydata a = { 0, 100 };
return mydata_eq(&a, &a);
}
#include <ccan/structeq/structeq.h>
#include <ccan/tap/tap.h>
/* In theory, this could be generated without padding, if alignof(int) were 0,
* and test would fail. Call me when that happens. */
struct mydata {
char start;
int end;
};
STRUCTEQ_DEF(mydata, -3, start, end);
struct mydata2 {
char start;
int end;
};
STRUCTEQ_DEF(mydata2, -4, start, end);
int main(void)
{
struct mydata a, b;
/* This is how many tests you plan to run */
plan_tests(3);
a.start = 0;
a.end = 100;
ok1(mydata_eq(&a, &a));
b = a;
ok1(mydata_eq(&a, &b));
b.end++;
ok1(!mydata_eq(&a, &b));
/* This exits depending on whether all tests passed */
return exit_status();
}
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