first cut of tracking previous return values with ftell()/fseek() as POC

5 files changed, 47 insertions, 6 deletions

diff --git a/src/_safety.h b/src/_safety.h
index 37b66915..85637013 100644
--- a/src/_safety.h
+++ b/src/_safety.h
@@ -4,6 +4,7 @@
 _Noreturn void __undefined(const char *, ...);
 
 #include <errno.h>
+#include <stdlib.h>
 #include <stdio.h>
 /*
 #include "stdlib/_stdlib.h"
@@ -28,6 +29,30 @@ extern struct __checked_call {
 #ifndef NDEBUG
 #define UNDEFINED(...) __undefined(__VA_ARGS__)
 
+#define ADD_PREV(__val, __arr, __count) do { \
+	void *tmp = realloc((__arr), ((__count) + 1) * sizeof((__arr)[0])); \
+	if (tmp == NULL) { \
+		fprintf(stderr, "Out of memory tracking values\n"); \
+		abort(); \
+	} \
+	(__arr) = tmp; \
+	(__arr)[__count] = __val; \
+	(__count)++; \
+} while (0)
+
+#define ASSERT_PREV(__val, __arr, __count, __prev) do { \
+	int __found = 0; \
+	for (size_t __i = 0; __i < (__count); __i++) { \
+		if ((__arr)[__i] == (__val)) { \
+			__found = 1; \
+			break; \
+		} \
+	} \
+	if (!__found) { \
+		UNDEFINED("In call to %s(): %s was not returned by a previous call to %s", __func__, #__val, __prev); \
+	} \
+} while (0)
+
 #define ASSERT_NONNULL(__ptr) do { \
 	if (!__ptr) { \
 		UNDEFINED("In call to %s(), parameter %s cannot be NULL", __func__, #__ptr); \
diff --git a/src/stdio/_stdio.h b/src/stdio/_stdio.h
index d47ac5dd..c69b3787 100644
--- a/src/stdio/_stdio.h
+++ b/src/stdio/_stdio.h
@@ -59,7 +59,7 @@ struct __FILE {
 	int thread;		/* the owning thread if locked */
 
 	int orientation:2;	/* 0 = undetermind, < 0 = byte, > 0 = wide */
-	int operation;		/* TODO: previous operation, NONE, INPUT, OUTPUT (are there others?) */
+	int operation:2;	/* TODO: previous operation, NONE, INPUT, OUTPUT (are there others?) */
 	int eof:1;		/* eof indicator */
 	int err:1;		/* error indicator */
 	int text:1;		/* is this a text file? */
@@ -67,6 +67,11 @@ struct __FILE {
 	#ifdef _POSIX_C_SOURCE
 	pid_t pipe_pid;		/* if stream is a pipe, the child pid */
 	#endif
+
+	fpos_t *valid_fpos;
+	size_t nvalid_fpos;
+	long int *valid_ftell;
+	size_t nvalid_ftell;
 };
 
 struct io_options {
diff --git a/src/stdio/freopen.c b/src/stdio/freopen.c
index 3a1ef656..d431b0e3 100644
--- a/src/stdio/freopen.c
+++ b/src/stdio/freopen.c
@@ -96,6 +96,12 @@ FILE * freopen(const char * restrict filename, const char * restrict mode, FILE
 		stream->buf = stream->ibuf;
 	}
 
+	free(stream->valid_fpos);
+	stream->nvalid_fpos = 0;
+
+	free(stream->valid_ftell);
+	stream->nvalid_ftell = 0;
+
 	stream->text = !(strchr(mode, 'b'));
 
 	/*
diff --git a/src/stdio/fseek.c b/src/stdio/fseek.c
index 47388c9a..9f4bd733 100644
--- a/src/stdio/fseek.c
+++ b/src/stdio/fseek.c
@@ -12,8 +12,7 @@ int fseek(FILE *stream, long int offset, int whence)
 		if (whence != SEEK_SET) {
 			UNDEFINED("In call to fseek(): Only SEEK_SET is supported for text files");
 		}
-		/* if offset is not previous */
-		/* UNDEFINED("fseek() on text files requires an offset previously returned by ftell()"); */
+		ASSERT_PREV(offset, stream->valid_ftell, stream->nvalid_ftell, "ftell");
 	}
 
 	if (whence == SEEK_CUR) {
diff --git a/src/stdio/ftell.c b/src/stdio/ftell.c
index f68c18b2..ad23bf31 100644
--- a/src/stdio/ftell.c
+++ b/src/stdio/ftell.c
@@ -5,15 +5,21 @@
 
 long int ftell(FILE *stream)
 {
+	long int ret = -1L;
+
 	SIGNAL_SAFE(0);
+	ASSERT_STREAM(stream, 0, 0);
 
-	(void)stream;
-	/* TODO */
 	/*
 	RETURN_SUCCESS(the current file position);
 	RETURN_FAILURE(LITERAL(-1L));
 	*/
-	return -1L;
+	
+	if (stream->text) {
+		ADD_PREV(ret, stream->valid_ftell, stream->nvalid_ftell);
+	}
+
+	return ret;
 }
 
 /***