feat: add back-end

back-end/cfg.txt

@@ -0,0 +1,12 @@
+api =
+{
+port = 65535;
+};
+pq =
+{
+db = "database";
+host = "localhost";
+port = 5432;
+secret = "secret";
+user = "user";
+}

back-end/main.c

@@ -0,0 +1,52 @@
+#include <stdio.h>
+//for use of exit()
+#include <stdlib.h>
+//for use of libconfig
+#include <libconfig.h>
+
+int main(int argc, char *argv[]) {
+  fprintf(stdout,"main() Started...\n");
+
+  /*read command line*/
+  if (argc > 1){
+    printf("main() argv[1]: %s\n", argv[1]);
+  }else{
+    fprintf(stderr, "Usage: %s <path to config file>\n", argv[0]);
+    exit(1);
+  }
+
+  config_t cfg;
+  const char *str;
+  int port;
+
+  /*initialise new and EMPTY config*/
+  config_init(&cfg);
+
+  /* Read the file. If there is an error, report it and exit. */
+  if(! config_read_file(&cfg, argv[1]))
+  {
+    fprintf(stderr, "%s:%d - %s\n", config_error_file(&cfg),
+            config_error_line(&cfg), config_error_text(&cfg));
+    /*destroy config, BUT NOT the structure*/
+    config_destroy(&cfg);
+    return(EXIT_FAILURE);
+  }
+
+  /*lookup db string*/
+  if(config_lookup_string(&cfg, "pq.db", &str)){
+    printf("db: %s\n", str);
+  }else{
+    fprintf(stderr, "No 'db' setting in configuration file.\n");
+  }
+
+  /*lookup port int*/
+  if(config_lookup_int(&cfg, "pq.port", &port)){
+    printf("port: %d\n", port);
+  }else{
+    fprintf(stderr, "No 'port' setting in configuration file.\n");
+  }
+
+  config_destroy(&cfg);
+  fprintf(stdout,"main() Done.\n");
+  return(EXIT_SUCCESS);
+}

back-end/makefile

@@ -0,0 +1,24 @@
+# Docu
+#
+#$@ is the name of the file to be made
+#$? is the names of the changed dependents
+#$< the name of the related file that caused the action
+#$* the prefix shared by target and dependent files
+#
+# Others
+RM      = /bin/rm -f
+#
+# Source, Executable, Includes, Library Defines
+EXE    = main
+#
+# Compiler, Linker Defines
+CC      = /usr/bin/gcc
+#
+all: main.o
+	$(CC) main.c -L/usr/lib/x86_64-linux-gnu -lconfig -Wall -o $(EXE)
+#
+main.o:
+	$(CC) -c main.c
+# Clean Up Objects, Exectuables, Dumps out of source directory
+clean:
+	$(RM) *.o $(EXE) *~

back-end/readme.md

@@ -0,0 +1,23 @@
+* install dependencies on Debian Bullseye
+
+```
+sudo apt install libconfig-dev --no-install-recommends
+```
+
+* build
+
+```
+make clean all
+```
+
+* cleanup
+
+```
+make clean
+```
+
+* run
+
+```
+./main
+```