[PATCH] Improve portability

[Dan Fandrich]

On Sun, Sep 06, 2009 at 02:23:58AM +0200, Denys Vlasenko wrote:
> Applied part of the patch (see attached). If you want
> the rest to be applied, please explain why each kind
> of change is necessary or useful.

The remaining patches fall mostly into these four categories:

1) Empty struct initializers, e.g.

 static const struct suffix_mult sfx[] = {
    { "s", 1 },
    { }	 		// <= should be { "", 0 }
 };

I'm unable to determine if this is actually allowed by ANSI C or not, but
at least two compilers I've tried don't handle it.

2) Automatic variables used as initializers, e.g.

 char delim = 1;
 const char delimiter[2] = { delim, 0 };

C90 requires automatic struct variables to have initializers containing
only constant expressions.

3) #include files added to satisfy dependencies required by system include
files that are not self-contained, which happens in some non-glibc systems.
Requiring <sys/socket.h> before <netinet/in.h> seems to be a relatively 
common one on pre-SuS systems.

4) Conditional operator missing the second expression, e.g.

  getlogin() ? : getpwuid(cur_uid))

Most of these were taken up from the first patch, but the ones that weren't
seem to be the ones that required a function call be called again in the
second expression. In those cases, I added a temporary variable to hold the
result of the function to avoid a duplicate expensive function call and/or
potential race condition. For readability, I changed some of these to use
the MAX() macro instead.


The remaining two patches are these:

diff --git a/editors/awk.c b/editors/awk.c
index cef7334..4c2837a 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -114,7 +114,7 @@ typedef struct nvblock_s {
 	var *pos;
 	struct nvblock_s *prev;
 	struct nvblock_s *next;
-	var nv[0];
+	var nv[];
 } nvblock;
 
 typedef struct tsplitter_s {

Explicitly zero-length arrays seems to be allowed in C++ but not C, which
uses an empty array size instead.

diff --git a/libbb/login.c b/libbb/login.c
index ba9f4d2..3e6f7c4 100644
--- a/libbb/login.c
+++ b/libbb/login.c
@@ -9,7 +9,7 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include <sys/param.h>  /* MAXHOSTNAMELEN */
+#include <sys/types.h>
 #include <sys/utsname.h>
 #include "libbb.h"
 
MAXHOSTNAMELEN isn't referenced in this file, so I removed that include line.
The sys/types.h file was included because sys/utsname.h isn't self-contained
on Watcom C (I don't know how common this is compared to the netinet/in.h
case).

>>> Dan
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