Re: [PATCH setxkbmap; 2nd try] Consistent handling of memory allocation errors.

2011-02-25 Thread Alan Coopersmith 
On 02/25/11 11:43 AM, Van de Bugger wrote:
 Macro `OOM' (Out of memory) introduced for checking and reporting
 memory allocation errors. The same macro is used in all the cases.
 
 One check was missed in original source; fixed.
 
 Signed-off-by: Van de Bugger van.de.bug...@gmail.com
 ---
  setxkbmap.c |   27 +--
  1 files changed, 9 insertions(+), 18 deletions(-)
 
 diff --git a/setxkbmap.c b/setxkbmap.c
 index f7dbade..7aa56f7 100644
 --- a/setxkbmap.c
 +++ b/setxkbmap.c
 @@ -170,6 +170,8 @@ static int deviceSpec = XkbUseCoreKbd;
  #define ERR2(s,a,b) fprintf(stderr,s,a,b)
  #define ERR3(s,a,b,c)   fprintf(stderr,s,a,b,c)
  
 +#define OOM(ptr){ if ((ptr) == NULL) { ERR(Out of memory.\n); 
 abort(); }; }

There's an extra ; between the last two }'s there.   Also, you probably want to
stick with the original exit(-1), not force a core dump with abort();

The idiom normally used in the X code (and much C code in fact) for a
compound statement in a macro like this you want to make look like a
function call is:

#define OOM(ptr) \
do { if ((ptr) == NULL) { ERR(Out of memory.\n); abort(); } } while (0)

The do { ... } while(0) allows OOM(); to end with a ; without any compiler
warnings about empty statements or without causing any issues in breaking
other blocks, like if/else pairs, that you may wind up adjacent to.

For more complete explanations, see:
http://kernelnewbies.org/FAQ/DoWhile0
http://www.rtems.com/ml/rtems-users/2001/august/msg00086.html

http://stackoverflow.com/questions/923822/whats-the-use-of-do-while0-when-we-define-a-macro

-- 
-Alan Coopersmith-alan.coopersm...@oracle.com
 Oracle Solaris Platform Engineering: X Window System

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Re: [PATCH setxkbmap; 2nd try] Consistent handling of memory allocation errors.

2011-02-25 Thread Van de Bugger 
Got it. See the next version.

On Fri, 2011-02-25 at 14:50 -0800, Alan Coopersmith wrote:
 On 02/25/11 11:43 AM, Van de Bugger wrote:
  Macro `OOM' (Out of memory) introduced for checking and reporting
  memory allocation errors. The same macro is used in all the cases.
  
  One check was missed in original source; fixed.
  
  Signed-off-by: Van de Bugger van.de.bug...@gmail.com
  ---
   setxkbmap.c |   27 +--
   1 files changed, 9 insertions(+), 18 deletions(-)
  
  diff --git a/setxkbmap.c b/setxkbmap.c
  index f7dbade..7aa56f7 100644
  --- a/setxkbmap.c
  +++ b/setxkbmap.c
  @@ -170,6 +170,8 @@ static int deviceSpec = XkbUseCoreKbd;
   #define ERR2(s,a,b) fprintf(stderr,s,a,b)
   #define ERR3(s,a,b,c)   fprintf(stderr,s,a,b,c)
   
  +#define OOM(ptr){ if ((ptr) == NULL) { ERR(Out of memory.\n); 
  abort(); }; }
 
 There's an extra ; between the last two }'s there.   Also, you probably want 
 to
 stick with the original exit(-1), not force a core dump with abort();
 
 The idiom normally used in the X code (and much C code in fact) for a
 compound statement in a macro like this you want to make look like a
 function call is:
 
 #define OOM(ptr) \
 do { if ((ptr) == NULL) { ERR(Out of memory.\n); abort(); } } while (0)
 
 The do { ... } while(0) allows OOM(); to end with a ; without any compiler
 warnings about empty statements or without causing any issues in breaking
 other blocks, like if/else pairs, that you may wind up adjacent to.
 
 For more complete explanations, see:
   http://kernelnewbies.org/FAQ/DoWhile0
   http://www.rtems.com/ml/rtems-users/2001/august/msg00086.html
   
 http://stackoverflow.com/questions/923822/whats-the-use-of-do-while0-when-we-define-a-macro
 


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