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mirror of https://git.tartarus.org/simon/putty.git synced 2025-01-08 08:58:00 +00:00
putty-source/sshcr.h
Simon Tatham 76430f8237 Assorted benign warning fixes.
These were just too footling for even me to bother splitting up into
multiple commits:

 - a couple of int -> size_t changes left out of the big-bang commit
   0cda34c6f

 - a few 'const' added to pointer-type casts that are only going to be
   read from (leaving out the const provokes a warning if the pointer
   was const _before_ the cast)

 - a couple of 'return' statements trying to pass the void return of
   one function through to another.

 - another missing (void) in a declaration in putty.h (but this one
   didn't cause any knock-on confusion).

 - a few tweaks to macros, to arrange that they eat a semicolon after
   the macro call (extra do ... while (0) wrappers, mostly, and one
   case where I had to do it another way because the macro included a
   variable declaration intended to remain in scope)

 - reworked key_type_to_str to stop putting an unreachable 'break'
   statement after every 'return'

 - removed yet another type-check of a function loaded from a Windows
   system DLL

 - and finally, a totally spurious semicolon right after an open brace
   in mainchan.c.
2020-01-29 06:44:18 +00:00

88 lines
3.3 KiB
C

/*
* Coroutine mechanics used in PuTTY's SSH code.
*/
#ifndef PUTTY_SSHCR_H
#define PUTTY_SSHCR_H
/*
* If these macros look impenetrable to you, you might find it helpful
* to read
*
* https://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
*
* which explains the theory behind these macros.
*
* In particular, if you are getting `case expression not constant'
* errors when building with MS Visual Studio, this is because MS's
* Edit and Continue debugging feature causes their compiler to
* violate ANSI C. To disable Edit and Continue debugging:
*
* - right-click ssh.c in the FileView
* - click Settings
* - select the C/C++ tab and the General category
* - under `Debug info:', select anything _other_ than `Program
* Database for Edit and Continue'.
*/
#define crBegin(v) do { int *crLine = &v; switch(v) { case 0:
#define crBeginState crBegin(s->crLine)
#define crStateP(t, v) \
struct t *s; \
if (!(v)) { s = (v) = snew(struct t); s->crLine = 0; } \
s = (v);
#define crState(t) crStateP(t, ssh->t)
#define crFinish(z) } *crLine = 0; return (z); } while (0)
#define crFinishV } *crLine = 0; return; } while (0)
#define crFinishFreed(z) } return (z); } while (0)
#define crFinishFreedV } return; } while (0)
#define crFinishFree(z) } sfree(s); return (z); } while (0)
#define crFinishFreeV } sfree(s); return; } while (0)
#define crReturn(z) \
do {\
*crLine =__LINE__; return (z); case __LINE__:;\
} while (0)
#define crReturnV \
do {\
*crLine=__LINE__; return; case __LINE__:;\
} while (0)
#define crStop(z) do{ *crLine = 0; return (z); }while(0)
#define crStopV do{ *crLine = 0; return; }while(0)
/*
* The crMaybeWaitUntil macros could have been more easily written in
* terms of the simple crReturn above, by writing things like
*
* while (!condition) { crReturn(whatever); }
*
* (or do-while in the case of crWaitUntil). But it's better to do it
* directly by writing _once_ to crLine before first testing the
* condition, because this way it's robust against the condition check
* potentially freeing the entire coroutine state structure as a side
* effect (as long as it also evaluates false if it does that),
* because we don't write into crLine between the condition evaluating
* to false and the 'return' statement.
*/
#define crMaybeWaitUntil(c) \
do { \
*crLine =__LINE__; \
case __LINE__: if (!(c)) return 0; \
} while (0)
#define crMaybeWaitUntilV(c) \
do { \
*crLine =__LINE__; \
case __LINE__: if (!(c)) return; \
} while (0)
#define crWaitUntil(c) \
do { \
*crLine =__LINE__; return; \
case __LINE__: if (!(c)) return 0; \
} while (0)
#define crWaitUntilV(c) \
do { \
*crLine =__LINE__; return; \
case __LINE__: if (!(c)) return; \
} while (0)
#endif /* PUTTY_SSHCR_H */