From ac8df6d29d109f8f1ea2b22cf1402a4a37059fee Mon Sep 17 00:00:00 2001
From: Intel A80486DX2-66 <larry.holst@disroot.org>
Date: Tue, 9 Jul 2024 14:53:20 +0300
Subject: [PATCH] support non-POSIX functions `fseek` and `ftell`

---
 include/common.h          | 12 ++++++++++++
 include/file_boundaries.h |  2 +-
 src/corrupter.c           | 17 +++++++++--------
 src/file_boundaries.c     |  8 ++++----
 4 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/include/common.h b/include/common.h
index 11e8f4e..a5a0fde 100644
--- a/include/common.h
+++ b/include/common.h
@@ -89,6 +89,18 @@ enum configurations {
 #define STR_YN_YES "yes"
 #define STR_YN_NO "no"
 
+#ifdef HAVE_NO_FSEEKO_FTELLO
+# define FSEEK_MACRO fseek
+# define FTELL_MACRO ftell
+typedef long file_offset_t;
+# define FILE_OFFSET_C(x) ((x)##L)
+#else
+# define FSEEK_MACRO fseeko
+# define FTELL_MACRO ftello
+typedef off_t file_offset_t;
+# define FILE_OFFSET_C(x) ((off_t) x)
+#endif
+
 /* macros: lambdas */
 #define STRINGIZE(x) #x
 #define INT2STR(x) STRINGIZE(x)
diff --git a/include/file_boundaries.h b/include/file_boundaries.h
index 31072ff..bba61dc 100644
--- a/include/file_boundaries.h
+++ b/include/file_boundaries.h
@@ -13,7 +13,7 @@
 /* structures */
 struct _file_boundaries {
 	bool invalid_file;
-	off_t start, end;
+	file_offset_t start, end;
 };
 
 /* typedefs */
diff --git a/src/corrupter.c b/src/corrupter.c
index 305e08b..2d16445 100644
--- a/src/corrupter.c
+++ b/src/corrupter.c
@@ -54,20 +54,21 @@ Corrupter_Result* corrupt_file(Corrupter_Param* param) {
 	// copy and cast parameters
 	FILE* file = param->file;
 	uint8_t probability = param->probability;
-	off_t threshold = (off_t) param->threshold;
+	file_offset_t threshold = (file_offset_t) param->threshold;
 	uint8_t config = param->config;
 
 	// refuse to operate on non-seekable streams
-	if (fseeko(file, 0L, SEEK_SET) != 0 || ftello(file) != 0) {
+	if (FSEEK_MACRO(file, FILE_OFFSET_C(0), SEEK_SET) != 0 ||
+	    FTELL_MACRO(file) != 0) {
 		errno = ESPIPE;
 		result->error = true;
 		return result;
 	}
 
 	// determine file size
-	off_t start = 0, end;
-	fseeko(file, 0L, SEEK_END);
-	end = ftello(file);
+	file_offset_t start = 0, end;
+	FSEEK_MACRO(file, FILE_OFFSET_C(0), SEEK_END);
+	end = FTELL_MACRO(file);
 
 	// determine file boundaries
 	const char* failed_function = NULL;
@@ -107,8 +108,8 @@ Corrupter_Result* corrupt_file(Corrupter_Param* param) {
 		rewind(file);
 
 		// iterate over the file contents
-		for (off_t i = start; i < end; i++) {
-			fseeko(file, i, SEEK_SET);
+		for (file_offset_t i = start; i < end; i++) {
+			FSEEK_MACRO(file, i, SEEK_SET);
 			byte byte_value;
 			if (fread(&byte_value, sizeof(byte), 1, file) != 1) {
 				result->error = true;
@@ -144,7 +145,7 @@ Corrupter_Result* corrupt_file(Corrupter_Param* param) {
 				damaged_byte = true;
 
 				// write the modified byte back to the file
-				fseeko(file, i, SEEK_SET);
+				FSEEK_MACRO(file, i, SEEK_SET);
 				if (fwrite(&byte_value, sizeof(byte), 1, file) == 1)
 					continue;
 
diff --git a/src/file_boundaries.c b/src/file_boundaries.c
index 4b8b806..542a493 100644
--- a/src/file_boundaries.c
+++ b/src/file_boundaries.c
@@ -59,7 +59,7 @@ file_boundaries_t* determine_boundaries_WAV(FILE* file) {
 		DETERMINE_BOUNDARIES_FREAD_ERROR_HANDLING;
 	}
 
-	fseeko(file, (off_t) chunk_size - 4, SEEK_CUR);
+	FSEEK_MACRO(file, (file_offset_t) chunk_size - FILE_OFFSET_C(4), SEEK_CUR);
 
 	while (true) {
 		if (fread(chunk_id, 1, 4, file) != 4 ||
@@ -71,12 +71,12 @@ file_boundaries_t* determine_boundaries_WAV(FILE* file) {
 			reorder_b32(&chunk_size);
 
 		if (!strncmp(chunk_id, WAV_SUBCHUNK_DATA_ID, 4)) {
-			boundaries->start = ftello(file);
-			boundaries->end = ftello(file) + (off_t) chunk_size;
+			boundaries->start = FTELL_MACRO(file);
+			boundaries->end = FTELL_MACRO(file) + (file_offset_t) chunk_size;
 			break;
 		}
 
-		fseeko(file, chunk_size, SEEK_CUR);
+		FSEEK_MACRO(file, chunk_size, SEEK_CUR);
 	}
 
 	boundaries->invalid_file = false;