[sanitizer_common] Rewrite more Posix tests to use asserts

[mgorny]

Summary

Rewrite the tests for Posix functions that silently 'return 1'
or 'exit(1)' on error, to instead verbosely report the error using
assert. This is based on requests made in review of D56136.

[mgorny]

Updated to cover functions which used exit(1) too.

[krytarowski]

test/sanitizer_common/TestCases/Posix/devname_r.cc

21 ↗

(On Diff #179693)

While there.. devname_r has a broken interceptor for !NetBSD. Wrong return type.

test/sanitizer_common/TestCases/Posix/fgets.cc

 // RUN: %clangxx -g %s -o %t && %run %t
 
+#include <assert.h>
 #include <stdio.h>
 
 int main(int argc, char **argv) {
-  FILE *fp;
-  char buf[2];
-  char *s;
-
-  fp = fopen(argv[0], "r");
-  if (!fp)
-    return 1;
+  FILE *fp = fopen(argv[0], "r");
+  assert(fp);
 
-  s = fgets(buf, sizeof(buf), fp);
-  if (!s)
-    return 2;
+  char buf[2];
+  char *s = fgets(buf, sizeof(buf), fp);
+  assert(s);
 
-  fclose(fp);
+  assert(!fclose(fp));
   return 0;
 }

test/sanitizer_common/TestCases/Posix/fputs_puts.cc

 // RUN: %clangxx -g %s -o %t && %run %t | FileCheck %s
 // CHECK: {{^foobar$}}
 
+#include <assert.h>
 #include <stdio.h>
 
 int main(void) {
-  int r;
-
-  r = fputs("foo", stdout);
-  if (r < 0)
-    return 1;
-
-  r = puts("bar");
-  if (r < 0)
-    return 1;
+  assert(fputs("foo", stdout) >= 0);
+  assert(puts("bar") >= 0);
 
   return 0;
 }