[PATCH 0/10] fix error return code

[Julia Lawall]

These patches fix cases where the return code appears to be unintentially
nonnegative.

The complete semantic match that finds the problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@ok exists@
identifier f,ret,i;
expression e;
constant c;
@@

f(...) {
<+...
(
return -c@i;
|
ret = -c@i;
... when != ret = e
return ret;
|
if (ret < 0) { ... return ret; }
)
...+> }

@r exists@
identifier ret,l,ok.f;
expression e1,e2,e3;
statement S;
position p1,p2,p3;
@@

f(...) {
... when any
(
if@p1 (\(ret < 0\|ret != 0\))
 { ... return ret; }
|
ret@p1 = 0
)
... when != ret = e1
    when != &ret
(
 if (<+... ret = e3 ...+>) S
|
 if (<+... &ret ...+>) S
|
if@p2(...)
 {
  ... when != ret = e2
      when forall
 return@p3 ret;
}
)
... when any
}

@bad exists@
position r.p1,r.p2;
statement S1,S2;
identifier r.ret;
expression e1;
@@

(
if@p1 (\(ret < 0\|ret != 0\)) S1
|
ret@p1 = 0
)
... when any
ret = e1
... when any
if@p2(...) S2

@bad2@
position r.p1,r.p2;
identifier r.ret;
expression e1;
statement S2;
@@

ret@p1 = 0
... when != if (...) { ... ret = e1 ... return ret; }
    when any
if@p2(...) S2


@script:python depends on !bad && !bad2@
p1 << r.p1;
p2 << r.p2;
p3 << r.p3;
@@

cocci.print_main("",p1)
cocci.print_secs("",p2)
cocci.print_secs("",p3)
// </smpl>

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