[compiler-rt] [sanitizer_common] Add tests for more stdio.h functions

[mgorny]

Summary

Add two new test cases that test the following stdio.h functions:

• clearerr()
• feof()
• ferror()
• fileno()
• fgetc()
• getc()
• ungetc()

[krytarowski]

test/sanitizer_common/TestCases/Posix/feof_fileno_ferror.cc

8

Please move local variable declaration to the first line used (whenever possible)

test/sanitizer_common/TestCases/Posix/fgetc_ungetc_getc.cc

7

FILE *fp = fp = fopen(argv[0], "r");

[vitalybuka]

test/sanitizer_common/TestCases/Posix/feof_fileno_ferror.cc

50

why does this close file only on success?
I assume normal test behavior is return 0;
So please replace all return N with asserts so when it fail we will have verbose output
e.g

assert(close(fd) != -1);
....
assert(ferror(fp));

[mgorny]

test/sanitizer_common/TestCases/Posix/feof_fileno_ferror.cc

50

Will do. I've copied this from fgets.cc, fputs_puts.cc tests, and wrongly presumed it's expected coding style.

[mgorny]

Moved variable definitions, and added asserts.

[krytarowski]

test/sanitizer_common/TestCases/Posix/feof_fileno_ferror.cc

39

assert(!fclose(fp));

test/sanitizer_common/TestCases/Posix/fgetc_ungetc_getc.cc

18

assert(!fclose(fp));

[krytarowski]

test/sanitizer_common/TestCases/Posix/feof_fileno_ferror.cc

39

alternatively != EOF

[mgorny]

test/sanitizer_common/TestCases/Posix/feof_fileno_ferror.cc

39

It will fail most likely, due to us closing the fd before. However, I'm not sure if we want to strictly rely on this error condition.

[mgorny]

(Do you have another idea how to reliably trigger ferror?)

[krytarowski]

test/sanitizer_common/TestCases/Posix/feof_fileno_ferror.cc

39

Ah, OK. Please just add a comment that this call might fail.

[mgorny]

Added asserts for fclose().

test/sanitizer_common/TestCases/Posix/feof_fileno_ferror.cc

+// RUN: %clangxx -g %s -o %t && %run %t
+
+#include <assert.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int main(int argc, char **argv) {
+  FILE *fp = fopen(argv[0], "r");
+  assert(fp);
+
+  // file should be good upon opening
+  assert(!feof(fp) && !ferror(fp));
+
+  // read until EOF
+  char buf[BUFSIZ];
+  while (fread(buf, 1, sizeof buf, fp) != 0) {}
+  assert(feof(fp));
+
+  // clear EOF
+  clearerr(fp);
+  assert(!feof(fp) && !ferror(fp));
+
+  // get file descriptor
+  int fd = fileno(fp);
+  assert(fd != -1);
+
+  // break the file by closing underlying descriptor
+  assert(close(fd) != -1);
+
+  // verify that an error is signalled
+  assert(fread(buf, 1, sizeof buf, fp) == 0);
+  assert(ferror(fp));
+
+  // clear error
+  clearerr(fp);
+  assert(!feof(fp) && !ferror(fp));
+
+  // fclose() will return EBADF because of closed fd
+  assert(fclose(fp) == -1);
+  return 0;
+}

test/sanitizer_common/TestCases/Posix/fgetc_ungetc_getc.cc

+// RUN: %clangxx -g %s -o %t && %run %t
+
+#include <assert.h>
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  FILE *fp = fopen(argv[0], "r");
+  assert(fp);
+
+  // the file should be at least one character long, always
+  assert(fgetc(fp) != EOF);
+  // POSIX guarantees being able to ungetc() at least one character
+  assert(ungetc('X', fp) != EOF);
+  // check whether ungetc() worked
+  assert(getc(fp) == 'X');
+
+  assert(!fclose(fp));
+  return 0;
+}