[clang] [clang][analyzer] Support 'tello' and 'fseeko' in the StreamChecker (PR #77580)

[Balázs Kéri via cfe-commits]

================
@@ -324,6 +355,57 @@ void error_fseek_0(void) {
   fclose(F);
 }
 
+void error_fseeko_0(void) {
+  FILE *F = fopen("file", "r");
+  if (!F)
+    return;
+  int rc = fseeko(F, 0, SEEK_SET);
+  if (rc) {
+    int IsFEof = feof(F), IsFError = ferror(F);
+    // Get ferror or no error, but not feof.
+    clang_analyzer_eval(IsFError);
+    // expected-warning at -1 {{FALSE}}
+    // expected-warning at -2 {{TRUE}}
+    clang_analyzer_eval(IsFEof);
+    // expected-warning at -1 {{FALSE}}
+    // Error flags should not change.
+    clang_analyzer_eval(feof(F)); // expected-warning {{FALSE}}
+    if (IsFError)
+      clang_analyzer_eval(ferror(F)); // expected-warning {{TRUE}}
+    else
+      clang_analyzer_eval(ferror(F)); // expected-warning {{FALSE}}
+  } else {
+    clang_analyzer_eval(feof(F));   // expected-warning {{FALSE}}
+    clang_analyzer_eval(ferror(F)); // expected-warning {{FALSE}}
+    // Error flags should not change.
+    clang_analyzer_eval(feof(F));   // expected-warning {{FALSE}}
+    clang_analyzer_eval(ferror(F)); // expected-warning {{FALSE}}
+  }
+  fclose(F);
+}
+
+void error_ftell(void) {
+  FILE *F = fopen("file", "r");
+  if (!F)
+    return;
+  long Ret = ftell(F);
+  if (!(Ret >= 0)) {
+    clang_analyzer_eval(Ret == -1L); // expected-warning {{TRUE}}
+  }
+  fclose(F);
+}
+
+void error_ftello(void) {
+  FILE *F = fopen("file", "r");
+  if (!F)
+    return;
+  off_t Ret = ftello(F);
+  if (!(Ret == -1)) {
+    clang_analyzer_eval(Ret >= 0);   // expected-warning {{TRUE}}
+  }
+  fclose(F);
+}
+
----------------
balazske wrote:

This test should be better:
```
void error_ftell(void) {
  FILE *F = fopen("file", "r");
  if (!F)
    return;
  long rc = ftell(F);
  if (rc >= 0)
    clang_analyzer_warnIfReached(); // expected-warning {{REACHABLE}}
  else
    clang_analyzer_eval(rc == -1); // expected-warning {{TRUE}}  
  clang_analyzer_eval(feof(F) && ferror(F)); // expected-warning {{FALSE}}
  StreamTesterChecker_make_feof_stream(F);
  rc = ftell(F);
  clang_analyzer_eval(feof(F)); // expected-warning {{TRUE}}
  clang_analyzer_eval(ferror(F)); // expected-warning {{FALSE}}
  StreamTesterChecker_make_ferror_stream(F);
  rc = ftell(F);
  clang_analyzer_eval(feof(F)); // expected-warning {{FALSE}}
  clang_analyzer_eval(ferror(F)); // expected-warning {{TRUE}}
  fclose(F);
}
```

https://github.com/llvm/llvm-project/pull/77580