Added c_compare_file function plus a test function.

Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/std/c_file.c

@@ -28,6 +28,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <string.h>
 
 #include "c_file.h"
 #include "c_string.h"
@@ -195,3 +196,84 @@ int c_rename( const char *src, const char *dst ) {
 
     return rc;
 }
+
+int c_compare_file( const char *f1, const char *f2 ) {
+  mbchar_t *wf1, *wf2;
+  int fd1 = -1, fd2 = -1;
+  size_t size1, size2;
+  char buffer1[BUFFER_SIZE];
+  char buffer2[BUFFER_SIZE];
+  csync_stat_t stat1;
+  csync_stat_t stat2;
+
+  int rc = -1;
+
+  if(f1 == NULL || f2 == NULL) return -1;
+
+  wf1 = c_utf8_to_locale(f1);
+  if(wf1 == NULL) {
+    return -1;
+  }
+
+  wf2 = c_utf8_to_locale(f2);
+  if(wf2 == NULL) {
+    return -1;
+  }
+
+  /* compare size first. */
+  rc = _tstat(wf1, &stat1);
+  if(rc< 0) {
+    goto out;
+  }
+  rc = _tstat(wf2, &stat2);
+  if(rc < 0) {
+    goto out;
+  }
+
+  /* if sizes are different, the files can not be equal. */
+  if( stat1.st_size != stat2.st_size ) {
+    rc = 0;
+    goto out;
+  }
+
+#ifdef _WIN32
+  _fmode = _O_BINARY;
+#endif
+
+  fd1 = _topen(wf1, O_RDONLY);
+  if(fd1 < 0) {
+    rc = -1;
+    goto out;
+  }
+  fd2 = _topen(wf2, O_RDONLY);
+  if(fd2 < 0) {
+    rc = -1;
+    goto out;
+  }
+
+  while( (size1 = read(fd1, buffer1, BUFFER_SIZE)) > 0 ) {
+    size2 = read( fd2, buffer2, BUFFER_SIZE );
+
+    if( size1 != size2 ) {
+      rc = 0;
+      goto out;
+    }
+    if(memcmp(buffer1, buffer2, size1) != 0) {
+      /* buffers are different */
+      rc = 0;
+      goto out;
+    }
+  }
+
+  rc = 1;
+
+out:
+
+  if(fd1 > -1) close(fd1);
+  if(fd2 > -1) close(fd2);
+
+  c_free_locale_string( wf1 );
+  c_free_locale_string( wf2 );
+  return rc;
+
+}

src/std/c_file.h

@@ -64,6 +64,16 @@ int c_isfile(const char *path);
  */
 int c_copy(const char *src, const char *dst, mode_t mode);
 
+/**
+ * @brief Compare the content of two files byte by byte.
+ * @param f1     Path of file 1
+ * @param f2     Path of file 2
+ *
+ * @return       0 if the files differ, 1 if the files are equal or -1 on
+ *               error with errno set.
+ */
+int c_compare_file( const char *f1, const char *f2 );
+
 /**
  * @brief move a file from source to destination.
  *

tests/std_tests/check_std_c_file.c

@@ -86,12 +86,68 @@ static void check_c_copy_isdir(void **state)
     assert_int_equal(errno, EISDIR);
 }
 
+static void check_c_compare_file(void **state)
+{
+  int rc;
+  (void) state;
+
+  rc = c_copy(check_src_file, check_dst_file, 0644);
+  assert_int_equal(rc, 0);
+
+  rc = c_compare_file( check_src_file, check_dst_file );
+  assert_int_equal(rc, 1);
+
+  /* Check error conditions */
+  rc = c_compare_file( NULL, check_dst_file );
+  assert_int_equal(rc, -1);
+  rc = c_compare_file( check_dst_file, NULL );
+  assert_int_equal(rc, -1);
+  rc = c_compare_file( NULL, NULL );
+  assert_int_equal(rc, -1);
+
+  rc = c_compare_file( check_src_file, "/I_do_not_exist_in_the_filesystem.dummy");
+  assert_int_equal(rc, -1);
+  rc = c_compare_file( "/I_do_not_exist_in_the_filesystem.dummy", check_dst_file);
+  assert_int_equal(rc, -1);
+
+  rc = system("echo \"hallo42\" > /tmp/check/foo.txt");
+  assert_int_equal(rc, 0);
+  rc = system("echo \"hallo52\" > /tmp/check/bar.txt");
+  assert_int_equal(rc, 0);
+  rc = c_compare_file( check_src_file, check_dst_file );
+  assert_int_equal(rc, 0);
+
+  /* Create two 1MB random files */
+  rc = system("dd if=/dev/urandom of=/tmp/check/foo.txt bs=1024 count=1024");
+  assert_int_equal(rc, 0);
+  rc = system("dd if=/dev/urandom of=/tmp/check/bar.txt bs=1024 count=1024");
+  assert_int_equal(rc, 0);
+  rc = c_compare_file( check_src_file, check_dst_file );
+  assert_int_equal(rc, 0);
+
+  /* Create two 1MB random files with different size */
+  rc = system("dd if=/dev/urandom of=/tmp/check/foo.txt bs=1024 count=1024");
+  assert_int_equal(rc, 0);
+  rc = system("dd if=/dev/urandom of=/tmp/check/bar.txt bs=1024 count=1020");
+  assert_int_equal(rc, 0);
+  rc = c_compare_file( check_src_file, check_dst_file );
+  assert_int_equal(rc, 0);
+
+  /* compare two big files which are equal */
+  rc = c_copy(check_src_file, check_dst_file, 0644);
+  assert_int_equal(rc, 0);
+
+  rc = c_compare_file( check_src_file, check_dst_file );
+  assert_int_equal(rc, 1);
+}
+
 int torture_run_tests(void)
 {
   const UnitTest tests[] = {
       unit_test_setup_teardown(check_c_copy, setup, teardown),
       unit_test(check_c_copy_same_file),
       unit_test_setup_teardown(check_c_copy_isdir, setup, teardown),
+      unit_test_setup_teardown(check_c_compare_file, setup, teardown),
   };
 
   return run_tests(tests);