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-rw-r--r--lib/mlibc/tests/ansi/ungetc.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/lib/mlibc/tests/ansi/ungetc.c b/lib/mlibc/tests/ansi/ungetc.c
new file mode 100644
index 0000000..8773c6d
--- /dev/null
+++ b/lib/mlibc/tests/ansi/ungetc.c
@@ -0,0 +1,74 @@
+#include <stdio.h>
+#include <assert.h>
+
+#ifdef USE_HOST_LIBC
+#define TEST_FILE "ungetc-host-libc.tmp"
+#else
+#define TEST_FILE "ungetc.tmp"
+#endif
+
+void test(int buffering) {
+ FILE *f = fopen(TEST_FILE, "w");
+ for(int c = '0'; c <= '9'; c++) {
+ fputc(c, f);
+ }
+ fclose(f);
+
+ f = fopen(TEST_FILE, "r");
+ if (!buffering) {
+ setbuf(f, NULL);
+ }
+
+ assert(ungetc('x', f) == 'x');
+ assert(fgetc(f) == 'x');
+
+ // Test pushing back the same character
+ for (int c = '0'; c <= '9'; c++) {
+ assert(fgetc(f) == c);
+ assert(ungetc(c, f) == c);
+ assert(fgetc(f) == c);
+ }
+ assert(fgetc(f) == EOF);
+ assert(ungetc(EOF, f) == EOF);
+
+ // Even though the spec does not guarantee it, we should be able to
+ // ungetc more than one character.
+ assert(ungetc('x', f) == 'x');
+ assert(ungetc('y', f) == 'y');
+ assert(fgetc(f) == 'y');
+ assert(fgetc(f) == 'x');
+
+ // Seeking should discard the effects of ungetc.
+ assert(ungetc('x', f) == 'x');
+ rewind(f);
+
+ // Test pushing back a different character
+ for (int c = '0'; c <= '9'; c++) {
+ assert(fgetc(f) == c);
+ assert(ungetc(c - '0' + 'a', f) == c - '0' + 'a');
+ assert(fgetc(f) == c - '0' + 'a');
+ }
+
+#ifndef USE_HOST_LIBC
+ // Too many ungetcs should fail.
+ int eof = 0;
+ for (int i = 0; i < 100; i++) {
+ if (ungetc('x', f) == EOF) {
+ eof = 1;
+ break;
+ }
+ }
+ assert(eof);
+#endif
+
+ fclose(f);
+
+ // TODO: Test with other operations, like fread.
+}
+
+int main() {
+ fprintf(stderr, "with buffering...\n");
+ test(1);
+ fprintf(stderr, "without buffering...\n");
+ test(0);
+}