readh5: new --quiet flag, catch overflow

Very large datasets may not fit in the default read buffer, so we must
check if the write pointer has crossed the boundary of that buffer (in
which case it's flushed and the write pointer set back to its start).

examples/readh5.cpp

@@ -21,13 +21,14 @@ int main(int argc, char **argv)
 {
     if (argc < 3)
     {
-        fprintf(stdout, "Syntax: %s <file.h5> <dataset> [palette dataset]\n", argv[0]);
+        fprintf(stdout, "Syntax: %s <file.h5> <dataset> [palette dataset] [--quiet]\n", argv[0]);
         return 1;
     }
 
     std::string hdf5_file = argv[1];
     std::string hdf5_dataset = argv[2];
-    std::string hdf5_palette = argc > 3 ? argv[3] : "";
+    std::string hdf5_palette = argc <= 3 || strcmp(argv[3], "--quiet") == 0 ? "" : argv[3];
+    bool quiet = strcmp(argv[argc-1], "--quiet") == 0;
 
     // Enable printing UTF-8 characters
     setlocale(LC_ALL, "en_US.UTF-8");
@@ -102,51 +103,61 @@ int main(int argc, char **argv)
     }
     H5Fclose(file_id);
 
-    // Image-based datasets needs to be stretched a little bit so they look prettier on
-    // the console. They also look better when rendered as special characters instead
-    // of a collection of 0s and 1s.
-    bool is_tux = hdf5_dataset.compare("Tux") == 0;
-
-    char line[8192];
-    char *cur = line, *end = line + sizeof(line);
-    memset(line, 0, sizeof(line));
-    for (size_t i=0; i<dims[0]*dims[1]; ++i)
+    if (! quiet)
     {
-        if (i && i%dims[0] == 0)
-        {
-            printf("%s\n", line);
-            memset(line, 0, sizeof(line));
-            cur = line;
-        }
+        // Image-based datasets needs to be stretched a little bit so they look prettier on
+        // the console. They also look better when rendered as special characters instead
+        // of a collection of 0s and 1s.
+        bool is_tux = hdf5_dataset.compare("Tux") == 0;
 
-        if (is_tux)
-        {
-            wchar_t shade = 0x2592;
-            int *rdata_int = (int *) rdata;
-            cur += snprintf(cur, end-cur, "%lc%lc", rdata_int[i] == 1 ? ' ' : shade, rdata_int[i] == 1 ? ' ' : shade);
-        }
-        else if (hdf5_palette.size())
+        char line[8192];
+        char *cur = line, *end = line + sizeof(line);
+        memset(line, 0, sizeof(line));
+        for (size_t i=0; i<dims[0]*dims[1]; ++i)
         {
-            pal_t *pal_ptr = (pal_t *) pal;
-            uint8_t data = rdata[i];
-            if (pal_ptr)
+            if (i && i%dims[0] == 0)
             {
-                // Render this pixel using Truecolor ANSI escape codes
-                pal_t *color = &pal_ptr[data];
-                cur += snprintf(cur, end-cur, "\033[48;2;%d;%d;%dm**\033[0m", color->r, color->g, color->b);
+                printf("%s\n", line);
+                memset(line, 0, sizeof(line));
+                cur = line;
+            }
+            else if (cur > end)
+            {
+                printf("%s", line);
+                memset(line, 0, sizeof(line));
+                cur = line;
+            }
+
+            if (is_tux)
+            {
+                wchar_t shade = 0x2592;
+                int *rdata_int = (int *) rdata;
+                cur += snprintf(cur, end-cur, "%lc%lc", rdata_int[i] == 1 ? ' ' : shade, rdata_int[i] == 1 ? ' ' : shade);
+            }
+            else if (hdf5_palette.size())
+            {
+                pal_t *pal_ptr = (pal_t *) pal;
+                uint8_t data = rdata[i];
+                if (pal_ptr)
+                {
+                    // Render this pixel using Truecolor ANSI escape codes
+                    pal_t *color = &pal_ptr[data];
+                    cur += snprintf(cur, end-cur, "\033[48;2;%d;%d;%dm**\033[0m", color->r, color->g, color->b);
+                }
+                else
+                    cur += snprintf(cur, end-cur, "%c%c", data, data);
             }
             else
-                cur += snprintf(cur, end-cur, "%c%c", data, data);
-        }
-        else
-        {
-            if (is_float)
-                cur += snprintf(cur, end-cur, "%.1f ", (float) rdata[i]);
-            else
-                cur += snprintf(cur, end-cur, "%d", (int) rdata[i]);
+            {
+                if (is_float)
+                    cur += snprintf(cur, end-cur, "%.1f ", (float) rdata[i]);
+                else
+                    cur += snprintf(cur, end-cur, "%d", (int) rdata[i]);
+            }
         }
+        printf("%s\n", line);
     }
-    printf("%s\n", line);
 
+    delete[] rdata;
     return 0;
 }