SLS: add support to request slides dir re-read

A re-read of the slides dir can now be requested by storing a file named
`REQUEST_SLIDES_DIR_REREAD` into the slides dir. When the next slide is
going to be encoded and this file is present, the slides dir is re-read
and this file is deleted.

3 files changed, 30 insertions, 5 deletions

diff --git a/src/odr-padenc.cpp b/src/odr-padenc.cpp
index 94f3d68..461502e 100644
--- a/src/odr-padenc.cpp
+++ b/src/odr-padenc.cpp
@@ -350,8 +350,26 @@ int PadEncoder::EncodeSlide(bool skip_if_already_queued) {
         return 0;
     }
 
+    // check for slides dir re-read request
+    std::string request_reread_path = std::string(options.sls_dir) + "/" + SLSEncoder::REQUEST_REREAD_FILENAME;
+    struct stat request_reread_stat;
+    if (stat(request_reread_path.c_str(), &request_reread_stat)) {
+        // ignore missing request file
+        if (errno != ENOENT) {
+            perror("ODR-PadEnc Error: could not retrieve slides dir re-read request file stat");
+            return 1;
+        }
+    } else {
+        // handle request
+        fprintf(stderr, "ODR-PadEnc received slides dir re-read request!\n");
+        if (unlink(request_reread_path.c_str()))
+            perror(("ODR-PadEnc Error: erasing file '" + request_reread_path +"' failed").c_str());
+
+        slides.Clear();
+    }
+
     // usually invoked once
-    for(;;) {
+    for (;;) {
         // try to read slides dir (if present)
         if (slides.Empty()) {
             if (!slides.InitFromDir(options.sls_dir))
@@ -366,7 +384,7 @@ int PadEncoder::EncodeSlide(bool skip_if_already_queued) {
             if (sls_encoder.encodeSlide(slide.filepath, slide.fidx, options.raw_slides)) {
                 slides_success = true;
                 if (options.erase_after_tx) {
-                    if (unlink(slide.filepath.c_str()) == -1)
+                    if (unlink(slide.filepath.c_str()))
                         perror(("ODR-PadEnc Error: erasing file '" + slide.filepath +"' failed").c_str());
                 }
             } else {
diff --git a/src/sls.cpp b/src/sls.cpp
index 4d24358..8963b65 100644
--- a/src/sls.cpp
+++ b/src/sls.cpp
@@ -3,7 +3,7 @@
 
     Copyright (C) 2014, 2015 Matthias P. Braendli (http://opendigitalradio.org)
 
-    Copyright (C) 2015, 2016, 2017 Stefan Pöschel (http://opendigitalradio.org)
+    Copyright (C) 2015, 2016, 2017, 2018 Stefan Pöschel (http://opendigitalradio.org)
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -111,12 +111,16 @@ int SlideStore::FilterSlides(const struct dirent* file) {
     if(SLSEncoder::isSlideParamFileFilename(name))
         return 0;
 
+    // skip re-read request file
+    if(name == SLSEncoder::REQUEST_REREAD_FILENAME.c_str())
+        return 0;
+
     return 1;
 }
 
 bool SlideStore::InitFromDir(const std::string& dir) {
     // start with empty list
-    slides.clear();
+    Clear();
 
     struct dirent** dir_entries;
     int dir_count = scandir(dir.c_str(), &dir_entries, FilterSlides, alphasort);
@@ -257,6 +261,7 @@ const int    SLSEncoder::MINQUALITY      =    40; // Do not allow the image comp
 const std::string SLSEncoder::SLS_PARAMS_SUFFIX = ".sls_params";
 const int SLSEncoder::APPTYPE_MOT_START = 12;
 const int SLSEncoder::APPTYPE_MOT_CONT = 13;
+const std::string SLSEncoder::REQUEST_REREAD_FILENAME = "REQUEST_SLIDES_DIR_REREAD";
 
 
 void SLSEncoder::warnOnSmallerImage(size_t height, size_t width, const std::string& fname) {
diff --git a/src/sls.h b/src/sls.h
index 9695544..3d6a407 100644
--- a/src/sls.h
+++ b/src/sls.h
@@ -3,7 +3,7 @@
 
     Copyright (C) 2014, 2015 Matthias P. Braendli (http://opendigitalradio.org)
 
-    Copyright (C) 2015, 2016, 2017 Stefan Pöschel (http://opendigitalradio.org)
+    Copyright (C) 2015, 2016, 2017, 2018 Stefan Pöschel (http://opendigitalradio.org)
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -196,6 +196,7 @@ public:
     bool InitFromDir(const std::string& dir);
 
     bool Empty() {return slides.empty();}
+    void Clear() {slides.clear();}
     slide_metadata_t GetSlide();
 };
 
@@ -247,6 +248,7 @@ private:
 public:
     static const int APPTYPE_MOT_START;
     static const int APPTYPE_MOT_CONT;
+    static const std::string REQUEST_REREAD_FILENAME;
 
     SLSEncoder(PADPacketizer* pad_packetizer) : pad_packetizer(pad_packetizer), cindex_header(0), cindex_body(0) {}