Add os_usleep with bounded sleep loop returning on signal interruption and use it in bandwidth limiter

cmdline/bw.c

@@ -42,7 +42,7 @@ void bw_limit(struct snapraid_bw* bw, uint64_t bytes)
 	bw->total += bytes;
 	done = bw->total;
 
-	eta = done * 1000 / bw->limit;
+	eta = (done / bw->limit) * 1000 + (done % bw->limit) * 1000 / bw->limit;
 
 	/*
 	 * To prevent accumulating unlimited credit during long pauses
@@ -61,10 +61,7 @@ void bw_limit(struct snapraid_bw* bw, uint64_t bytes)
 #endif
 
 	if (eta > elapsed) {
-		eta -= elapsed;
-		if (eta > 1000)
-			eta = 1000;
-		usleep((unsigned)eta * 1000);
+		os_usleep((eta - elapsed) * 1000);
 	}
 }
 

os/mingw.c

@@ -469,10 +469,10 @@ static int windows_info2stat(const BY_HANDLE_FILE_INFORMATION* info, const FILE_
 	 * the nFileIndexHigh and nFileIndexLow members. This API is an extended version
 	 * that includes 128-bit file identifiers.  If GetFileInformationByHandle returns
 	 * FILE_INVALID_FILE_ID, the identifier may only be described in 128 bit form.
-	 * 
+	 *
 	 * From Microsoft "[MS-FSCC]: File System Control Codes - 11/21/2025 v60.0 - 6 Appendix B: Product Behavior"
 	 * https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/d4bc551b-7aaf-4b4f-ba0e-3a75e7c528f0
-	 * 
+	 *
 	 * 64bitFileID Generate Stable Unique
 	 * FAT           Yes      No     No
 	 * EXFAT         Yes      No     No
@@ -492,7 +492,7 @@ static int windows_info2stat(const BY_HANDLE_FILE_INFORMATION* info, const FILE_
 	 *
 	 * From Microsoft "[MS-FSCC]: File System Control Codes - 11/21/2025 v60.0 - 2.1.9 64-bit file ID"
 	 * https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/2d3333fe-fc98-4a6f-98a2-4bb805aff407?utm_source=chatgpt.com
-	 * 
+	 *
 	 * A 64-bit file ID value uniquely identifies a file within a given volume. This
 	 * identifier is generated and stored by the file system. The identifier SHOULD
 	 * be unique to the volume and stable until the file is deleted.
@@ -1600,11 +1600,6 @@ unsigned windows_sleep(unsigned seconds)
 	return seconds;
 }
 
-void windows_usleep(uint64_t useconds)
-{
-	Sleep(useconds / 1000);
-}
-
 int windows_link(const char* existing, const char* file)
 {
 	wchar_t conv_buf_file[CONV_MAX];
@@ -3458,6 +3453,27 @@ uint64_t os_tick_ms(void)
 	return GetTickCount64();
 }
 
+int os_usleep(uint64_t usec)
+{
+	while (usec > 0) {
+		unsigned chunk = 1000000;
+		if (usec < chunk)
+			chunk = (unsigned)usec;
+
+		if (os_signal_interrupt()) {
+			errno = EINTR;
+			return -1;
+		}
+
+		Sleep(chunk / 1000);
+
+		usec -= chunk;
+	}
+
+	return 0;
+}
+
+
 void os_privileges_acquire(void)
 {
 }

os/mingw.h

@@ -156,8 +156,6 @@ wchar_t* u8tou16_mayfail(wchar_t* conv_buf, size_t number_of_wchar, const char*
 #define stat_desc windows_stat_desc
 #undef sleep
 #define sleep windows_sleep
-#undef usleep
-#define usleep windows_usleep
 /* 4==DIR, 5,6,7=free, 8==REG */
 #define S_IFLNK 0x5000 /* Symbolic link to file */
 #define S_ISLNK(m) (((m) & _S_IFMT) == S_IFLNK)
@@ -434,16 +432,12 @@ const char* windows_stat_desc(struct stat* st);
  */
 unsigned windows_sleep(unsigned seconds);
 
-/**
- * Like usleep().
- */
-void windows_usleep(uint64_t useconds);
-
 /**
  * Like readlink().
  */
 int windows_readlink(const char* file, char* buffer, size_t size);
 
+
 /**
  * Like symlink().
  * Return ENOSYS if symlinks are not supported.

os/os.h

@@ -307,6 +307,16 @@ uint64_t os_tick_ms(void);
  */
 uint64_t os_tick_sec(void);
 
+/**
+ * Sleep for the specified number of microseconds.
+ *
+ * Loops in bounded intervals and returns on the first error or signal interruption.
+ * \param usec Number of microseconds to sleep.
+ * \return 0 on success, -1 on error.
+ */
+int os_usleep(uint64_t usec);
+
+
 /**
  * Abort the process with a stacktrace.
  */
@@ -343,3 +353,4 @@ int os_randomize(void* ptr, size_t size);
 int os_get_optimal_cpu(void);
 
 #endif
+

os/unix.c

@@ -1694,6 +1694,34 @@ uint64_t os_tick_sec(void)
 	return ts.tv_sec;
 }
 
+int os_usleep(uint64_t usec)
+{
+	while (usec > 0) {
+		unsigned chunk = 999999;
+		if (usec < chunk)
+			chunk = (unsigned)usec;
+
+		if (os_signal_interrupt()) {
+			errno = EINTR;
+			return -1;
+		}
+
+		/*
+		 * Sleep in intervals of at most 999999 microseconds because POSIX usleep()
+		 * only accepts values less than 1,000,000 microseconds (< 1 second)
+		 * and may fail with EINVAL for larger values.
+		 */
+		if (usleep(chunk) != 0)
+			return -1;
+
+		usec -= chunk;
+	}
+
+	return 0;
+}
+
+
+
 int os_randomize(void* ptr, size_t size)
 {
 	int f;