DataFlash: enable minimal file mode

This adds a "minimal" dataflash mode with a board specific macro. The
QURT port uses this to avoid problematic system calls that are buggy
in the QURT RTOS

With some pending updates to QURT we may be able to remove some (or
all) of this

libraries/DataFlash/DataFlash_File.cpp

@@ -17,6 +17,7 @@
 #if HAL_OS_POSIX_IO
 #include "DataFlash_File.h"
 
+#include <AP_Common/AP_Common.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -34,7 +35,7 @@
 #ifdef __APPLE__
 #include <sys/param.h>
 #include <sys/mount.h>
-#else
+#elif !DATAFLASH_FILE_MINIMAL
 #include <sys/statfs.h>
 #endif
 
@@ -98,7 +99,7 @@ void DataFlash_File::Init()
 
     semaphore = hal.util->new_semaphore();
     if (semaphore == nullptr) {
-        hal.console->printf("Failed to create DataFlash_File semaphore\n");
+        AP_HAL::panic("Failed to create DataFlash_File semaphore");
         return;
     }
     
@@ -122,6 +123,7 @@ void DataFlash_File::Init()
         _log_directory = custom_dir;
     }
 
+#if !DATAFLASH_FILE_MINIMAL
     ret = stat(_log_directory, &st);
     if (ret == -1) {
         ret = mkdir(_log_directory, 0777);
@@ -130,6 +132,8 @@ void DataFlash_File::Init()
         hal.console->printf("Failed to create log directory %s\n", _log_directory);
         return;
     }
+#endif
+    
     if (_writebuf != NULL) {
         free(_writebuf);
         _writebuf = NULL;
@@ -166,12 +170,20 @@ void DataFlash_File::Init()
 
 bool DataFlash_File::file_exists(const char *filename) const
 {
+#if DATAFLASH_FILE_MINIMAL
+    int fd = open(filename, O_RDONLY);
+    if (fd == -1) {
+        return false;
+    }
+    close(fd);
+#else
     struct stat st;
     if (stat(filename, &st) == -1) {
         // hopefully errno==ENOENT.  If some error occurs it is
         // probably better to assume this file exists.
         return false;
     }
+#endif
     return true;
 }
 
@@ -208,11 +220,16 @@ bool DataFlash_File::CardInserted(void)
 // returns -1 on error
 int64_t DataFlash_File::disk_space_avail()
 {
+#if !DATAFLASH_FILE_MINIMAL
     struct statfs stats;
     if (statfs(_log_directory, &stats) < 0) {
         return -1;
     }
     return (((int64_t)stats.f_bavail) * stats.f_bsize);
+#else
+    // return a fake disk space size
+    return 100*1000*1000UL;
+#endif
 }
 
 // returns the total amount of disk space (in use + available) in
@@ -220,11 +237,16 @@ int64_t DataFlash_File::disk_space_avail()
 // returns -1 on error
 int64_t DataFlash_File::disk_space()
 {
+#if !DATAFLASH_FILE_MINIMAL
     struct statfs stats;
     if (statfs(_log_directory, &stats) < 0) {
         return -1;
     }
     return (((int64_t)stats.f_blocks) * stats.f_bsize);
+#else
+    // return fake disk space size
+    return 200*1000*1000UL;
+#endif
 }
 
 // returns the available space in _log_directory as a percentage
@@ -247,6 +269,9 @@ float DataFlash_File::avail_space_percent()
 // returns 0 if no log was found
 uint16_t DataFlash_File::find_oldest_log()
 {
+#if DATAFLASH_FILE_MINIMAL
+    return 0;
+#else
     if (_cached_oldest_log != 0) {
         return _cached_oldest_log;
     }
@@ -306,8 +331,10 @@ uint16_t DataFlash_File::find_oldest_log()
     _cached_oldest_log = current_oldest_log;
 
     return current_oldest_log;
+#endif
 }
 
+#if !DATAFLASH_FILE_MINIMAL
 void DataFlash_File::Prep_MinSpace()
 {
     const uint16_t first_log_to_remove = find_oldest_log();
@@ -364,13 +391,16 @@ void DataFlash_File::Prep_MinSpace()
         }
     } while (log_to_remove != first_log_to_remove);
 }
+#endif
 
 void DataFlash_File::Prep() {
     if (hal.util->get_soft_armed()) {
         // do not want to do any filesystem operations while we are e.g. flying
         return;
     }
+#if !DATAFLASH_FILE_MINIMAL
     Prep_MinSpace();
+#endif
 }
 
 bool DataFlash_File::NeedPrep()
@@ -419,6 +449,7 @@ void DataFlash_File::EraseAll()
 {
     uint16_t log_num;
     stop_logging();
+#if !DATAFLASH_FILE_MINIMAL
     for (log_num=1; log_num<=MAX_LOG_FILES; log_num++) {
         char *fname = _log_file_name(log_num);
         if (fname == NULL) {
@@ -432,7 +463,7 @@ void DataFlash_File::EraseAll()
         unlink(fname);
         free(fname);
     }
-
+#endif
     _cached_oldest_log = 0;
 }
 
@@ -536,22 +567,24 @@ uint16_t DataFlash_File::find_last_log()
     if (fname == NULL) {
         return ret;
     }
-    FILE *f = ::fopen(fname, "r");
+    int fd = open(fname, O_RDONLY);
     free(fname);
-    if (f != NULL) {
+    if (fd != -1) {
         char buf[10];
         memset(buf, 0, sizeof(buf));
-        // PX4 doesn't have fscanf()
+        if (read(fd, buf, sizeof(buf)-1) > 0) {
-        if (fread(buf, 1, sizeof(buf)-1, f) > 0) {
             sscanf(buf, "%u", &ret);            
         }
-        fclose(f);    
+        close(fd);    
     }
     return ret;
 }
 
 uint32_t DataFlash_File::_get_log_size(const uint16_t log_num) const
 {
+#if DATAFLASH_FILE_MINIMAL
+    return 1;
+#else
     char *fname = _log_file_name(log_num);
     if (fname == NULL) {
         return 0;
@@ -563,10 +596,14 @@ uint32_t DataFlash_File::_get_log_size(const uint16_t log_num) const
     }
     free(fname);
     return st.st_size;
+#endif
 }
 
 uint32_t DataFlash_File::_get_log_time(const uint16_t log_num) const
 {
+#if DATAFLASH_FILE_MINIMAL
+    return 0;
+#else
     char *fname = _log_file_name(log_num);
     if (fname == NULL) {
         return 0;
@@ -578,6 +615,7 @@ uint32_t DataFlash_File::_get_log_time(const uint16_t log_num) const
     }
     free(fname);
     return st.st_mtime;
+#endif
 }
 
 /*
@@ -813,14 +851,19 @@ uint16_t DataFlash_File::start_new_log(void)
 
     // now update lastlog.txt with the new log number
     fname = _lastlog_file_name();
-    FILE *f = ::fopen(fname, "w");
+
-    if (f == NULL) {
+    // we avoid fopen()/fprintf() here as it is not available on as many
+    // systems as open/write (specifically the QURT RTOS)
+    int fd = open(fname, O_WRONLY|O_CREAT, 0644);
     free(fname);
+    if (fd == -1) {
         return 0xFFFF;
     }
-    fprintf(f, "%u\r\n", (unsigned)log_num);
+
-    fclose(f);    
+    char buf[30];
-    free(fname);
+    snprintf(buf, sizeof(buf), "%u\r\n", (unsigned)log_num);
+    write(fd, buf, strlen(buf));
+    close(fd);
 
     return log_num;
 }
@@ -948,6 +991,7 @@ void DataFlash_File::ListAvailableLogs(AP_HAL::BetterStream *port)
     }
     port->printf("\n%u logs\n", (unsigned)num_logs);
 
+#if !DATAFLASH_FILE_MINIMAL
     for (uint16_t i=1; i<=num_logs; i++) {
         uint16_t log_num = _log_num_from_list_entry(i);
         char *filename = _log_file_name(log_num);
@@ -968,6 +1012,7 @@ void DataFlash_File::ListAvailableLogs(AP_HAL::BetterStream *port)
             free(filename);
         }
     }
+#endif
     port->println();    
 }
 
@@ -1047,7 +1092,7 @@ void DataFlash_File::_io_timer(void)
           write.
          */
         BUF_ADVANCEHEAD(_writebuf, nwritten);
-#if CONFIG_HAL_BOARD != HAL_BOARD_SITL && CONFIG_HAL_BOARD_SUBTYPE != HAL_BOARD_SUBTYPE_LINUX_NONE
+#if CONFIG_HAL_BOARD != HAL_BOARD_SITL && CONFIG_HAL_BOARD_SUBTYPE != HAL_BOARD_SUBTYPE_LINUX_NONE && CONFIG_HAL_BOARD != HAL_BOARD_QURT
         ::fsync(_write_fd);
 #endif
     }

libraries/DataFlash/DataFlash_File.h

@@ -14,6 +14,18 @@
 
 #include "DataFlash_Backend.h"
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_QURT
+/*
+  the QURT port has a limited range of system calls available. It
+  cannot provide all the facilities that DataFlash_File wants. It can
+  provide enough to be useful though, which is what
+  DATAFLASH_FILE_MINIMAL is for
+ */
+#define DATAFLASH_FILE_MINIMAL 1
+#else
+#define DATAFLASH_FILE_MINIMAL 0
+#endif
+
 class DataFlash_File : public DataFlash_Backend
 {
 public:

libraries/DataFlash/LogFile.cpp

@@ -36,9 +36,11 @@ void DataFlash_Class::Init(const struct LogStructure *structures, uint8_t num_ty
         DFMessageWriter_DFLogStart *message_writer =
             new DFMessageWriter_DFLogStart(_firmware_string);
         if (message_writer != NULL)  {
+#if HAL_OS_POSIX_IO
             backends[_next_backend] = new DataFlash_File(*this,
                                                          message_writer,
                                                          HAL_BOARD_LOG_DIRECTORY);
+#endif
         }
         if (backends[_next_backend] == NULL) {
             hal.console->printf("Unable to open DataFlash_File");